/* file: /assets/css/style.css (VERSION 2.0 - FULL) */

/* ==========================================================================
   1. THEME & VARIABLES
   ========================================================================== */
:root {
    /*
     * Colour palette for the default (light) theme. These colours are chosen
     * to provide a calm, professional appearance suitable for long reading
     * sessions. Shades of blue and warm tan are used for primary and accent
     * colours respectively. Backgrounds are slightly off‑white to reduce eye
     * strain and text colours provide sufficient contrast.
     */
    --color-primary: #3b5b7e;      /* Main colour for titles, buttons, links */
    --color-primary-dark: #2e4a64; /* Hover state for buttons */
    --color-accent: #d8a36e;       /* Accent for highlights, borders */
    --color-bg: #f5f7fa;           /* Main background (very light grey) */
    --color-bg-secondary: #eceff4; /* Secondary backgrounds (cards, toolbars) */
    --color-surface: #ffffff;      /* Surfaces for cards, containers */
    --color-text: #333333;         /* Main text colour (dark grey) */
    --color-text-muted: #666666;   /* Secondary text (muted) */
    --color-border: #d4d9e2;       /* Border colour (light grey) */
    --color-error: #d9534f;        /* Error messages */

    /*
     * Font families. We define separate variables for sans, serif and mono
     * families to enable quick switching at runtime via JavaScript. Default
     * reader fonts are sans‑serif for body and serif for headings.
     */
    --font-sans: 'Be Vietnam Pro', 'Noto Sans', sans-serif;
    --font-serif: 'Noto Serif', serif;
    --font-mono: 'Courier Prime', monospace;
    --font-heading: var(--font-serif);
    --font-body: var(--font-sans);

    --container-width: 1100px;
    --border-radius: 8px;
}

/* Dark Mode Theme (Ví dụ) */
body.dark-mode {
    /* Colour palette for dark mode. Deep blues and muted teals provide
       a comfortable contrast without being harsh on the eyes. */
    --color-primary: #669bbc;
    --color-accent: #e6af5c;
    --color-bg: #1f2937;
    --color-bg-secondary: #273143;
    --color-surface: #2f3a53;
    --color-text: #e5e5e5;
    --color-text-muted: #b0b0b0;
    --color-border: #3c4a63;
    --color-primary-dark: #517ca3;
}

/* Sepia theme variables. Sepia tones reduce contrast and emulate the look of
   aged paper for a softer reading experience. */
body.sepia-mode {
    --color-primary: #795548;
    --color-accent: #d8b384;
    --color-bg: #f5ecd8;
    --color-bg-secondary: #ede3c7;
    --color-surface: #fdf6e3;
    --color-text: #4e342e;
    --color-text-muted: #7b5e57;
    --color-border: #e1d1b5;
    --color-primary-dark: #5e3f33;
}

/* ==========================================================================
   2. GLOBAL STYLES & RESETS
   ========================================================================== */
/* Import fonts for improved Vietnamese support. We include Be Vietnam Pro for sans-serif,
   Noto Serif for serif combinations and Courier Prime for monospace reading. */
@import url('https://fonts.googleapis.com/css2?family=Be+Vietnam+Pro:wght@400;500;700&family=Noto+Sans:wght@400;700&family=Noto+Serif:wght@400;700&family=Courier+Prime:wght@400;700&display=swap');

* { box-sizing: border-box; }
body {
    font-family: var(--font-body);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    margin: 0;
}
.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 20px;
}

/* ==========================================================================
   3. AUTH & LIBRARY PAGE STYLES
   ========================================================================== */
/* ... CSS cho trang login & library như cũ ... */
.book-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 30px;
    /* Ensure child elements stretch uniformly and do not overlap. */
    align-items: stretch;
}
.book-card {
    background-color: var(--color-surface);
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
    transition: transform 0.2s ease-in-out;
    text-decoration: none;
    color: var(--color-text);
    display: flex;
    flex-direction: column;
    margin-bottom: 20px; /* Add spacing below cards to prevent sticking together */
}
.book-card:hover { transform: translateY(-5px); }
.book-card__cover img { width: 100%; height: 350px; object-fit: cover; }
.book-card__info { padding: 15px; flex-grow: 1; }
.book-card__title { font-family: var(--font-heading); font-size: 1.1em; margin: 0 0 5px 0; }
.book-card__author { font-size: 0.9em; color: var(--color-text-muted); }
.book-card__status { padding: 5px 15px; background-color: var(--color-bg); text-align: center; font-weight: 500; }
.book-card__status--free { color: var(--color-primary); }
.book-card__status--paid { color: var(--color-text-muted); }
.book-card__status--owned { background-color: var(--color-primary); color: white; }

/* Quick action buttons overlay on book cards */
.book-card {
    position: relative;
}
.book-card__actions {
    position: absolute;
    top: 10px;
    right: 10px;
    display: flex;
    gap: 8px;
    opacity: 0;
    transition: opacity 0.2s ease;
    /* Raise z-index so overlay stays above book cover */
    z-index: 3;
    pointer-events: none; /* allow underlying clicks when hidden */
}
.book-card:hover .book-card__actions {
    opacity: 1;
    pointer-events: auto; /* enable buttons when visible */
}
.book-card__actions .action-btn {
    background: rgba(255, 255, 255, 0.8);
    border: none;
    border-radius: 50%;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    transition: background-color 0.2s ease;
}
.book-card__actions .action-btn:hover {
    background: rgba(255,255,255,1);
}
.book-card__actions .action-btn i {
    color: var(--color-primary);
    font-size: 0.85em;
}

/* Drag-and-drop handle and row styles for chapters reorder */
.drag-cell {
    width: 42px;
    text-align: center;
}
.drag-handle {
    cursor: grab;
    user-select: none;
    padding: 4px 6px;
    display: inline-block;
}
tr.dragging {
    opacity: 0.6;
}
.drag-placeholder {
    outline: 2px dashed var(--color-border);
    background: rgba(255, 255, 255, 0.04);
}

/* Move up/down buttons cell for chapters reorder */
.move-cell {
    width: 60px;
    text-align: center;
}

/* Frontend toast notifications */
.notice-container {
    position: fixed;
    bottom: 20px;
    right: 20px;
    z-index: 11000;
    display: flex;
    flex-direction: column;
    gap: 10px;
}
.notice {
    padding: 10px 15px;
    border-radius: 6px;
    color: #fff;
    box-shadow: 0 2px 6px rgba(0,0,0,0.2);
    font-size: 0.9em;
    animation: fadeInOut 3.5s forwards;
}
.notice-info { background-color: #5a98de; }
.notice-success { background-color: #28a745; }
.notice-error { background-color: #dc3545; }
.notice-warning { background-color: #ffc107; color: #333; }

@keyframes fadeInOut {
    0% { opacity: 0; transform: translateY(20px); }
    10% { opacity: 1; transform: translateY(0); }
    90% { opacity: 1; }
    100% { opacity: 0; transform: translateY(-20px); }
}

/* Inline quick actions under book title */
.book-card__actions-inline {
    display: flex;
    gap: 8px;
    margin-top: 10px;
    flex-wrap: wrap;
}
/* Quick action buttons inside card. Use accent colours and pill shape for
   improved visibility. White text ensures legibility on coloured backgrounds. */
.book-card__actions-inline .action-btn {
    background-color: var(--color-accent);
    border: none;
    border-radius: 20px;
    padding: 6px 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    font-size: 0.85em;
    color: #fff;
    transition: background-color 0.25s ease;
}
.book-card__actions-inline .action-btn i {
    margin-right: 4px;
    color: #fff;
}
.book-card__actions-inline .action-btn:hover {
    background-color: var(--color-primary);
}

/* Admin notice modal styling */
.admin-notice {
    position: fixed;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0,0,0,0.35);
    z-index: 10000;
}
.admin-notice__panel {
    background: var(--color-surface, #fff);
    border: 1px solid var(--color-border, #ccc);
    border-radius: 12px;
    padding: 16px 18px;
    min-width: 280px;
    max-width: 480px;
    display: flex;
    gap: 12px;
    align-items: flex-start;
    box-shadow: 0 2px 8px rgba(0,0,0,0.2);
}
.admin-notice__icon {
    font-size: 22px;
    line-height: 1;
}
.admin-notice__content h4 {
    margin-top: 0;
    margin-bottom: 6px;
}

/* Details modal styles */
#details-modal .modal-content {
    max-width: 480px;
    padding: 20px;
    background-color: var(--color-surface);
    border-radius: var(--border-radius);
    box-shadow: 0 2px 10px rgba(0,0,0,0.15);
}
.book-details-header {
    display: flex;
    gap: 15px;
    margin-bottom: 15px;
}
.book-details-header .details-cover {
    width: 100px;
    height: 140px;
    object-fit: cover;
    border-radius: var(--border-radius);
    box-shadow: 0 2px 6px rgba(0,0,0,0.1);
}
.details-author {
    color: var(--color-text-muted);
    margin: 0 0 5px 0;
    font-size: 0.9em;
}
.details-price {
    font-weight: bold;
    color: var(--color-primary);
    margin: 0;
}
.book-details-body p {
    margin: 10px 0;
    line-height: 1.5;
}
#details-modal .modal-actions {
    margin-top: 20px;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

/* ==================== Custom Additions for Version 3.6 ==================== */

/* Quick filter chips */
#quick-filter-container {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin: 15px 0;
}
.filter-chip {
    background-color: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: 16px;
    padding: 6px 12px;
    font-size: 0.9em;
    cursor: pointer;
    color: var(--color-text);
    transition: background-color 0.2s ease, color 0.2s ease;
    user-select: none;
}
.filter-chip.active,
.filter-chip:hover {
    background-color: var(--color-primary);
    color: #fff;
    border-color: var(--color-primary);
}

/* Continue Reading section */
.continue-reading-section {
    padding: 40px 0;
    background-color: var(--color-bg);
}
.continue-reading-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 20px;
}
.continue-card {
    display: flex;
    flex-direction: column;
    text-decoration: none;
    color: var(--color-text);
    background-color: var(--color-surface);
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    transition: transform 0.2s ease;
}
.continue-card:hover {
    transform: translateY(-4px);
}
.continue-card__cover img {
    width: 100%;
    height: 160px;
    object-fit: cover;
}
.continue-card__info {
    padding: 10px;
}
.continue-card__info h4 {
    margin: 0;
    font-size: 1em;
    font-family: var(--font-heading);
}
.continue-card__info p {
    margin: 4px 0 0;
    font-size: 0.85em;
    color: var(--color-text-muted);
}

/* Book card progress bar */
.book-card__progress {
    margin-top: 8px;
}

/* Spacing adjustments for search and filter controls on the library page */
.filter-controls .row {
    row-gap: 10px;
}
.filter-controls input[type="text"] {
    margin-bottom: 0;
}
.book-card__progress .progress-bar {
    height: 4px;
    border-radius: 2px;
    background-color: var(--color-primary);
}
.book-card__progress span {
    display: block;
    font-size: 0.75em;
    color: var(--color-text-muted);
    margin-top: 2px;
}

/* Search bar within filter-controls on library page */
.filter-controls input[type="text"] {
    width: 100%;
    padding: 8px 12px;
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    background-color: var(--color-surface);
    color: var(--color-text);
    font-size: 0.95em;
}

/* ==========================================================================
   4.a. DARK MODE TOGGLE
   ========================================================================== */
/* Style for the dark mode toggle button in the header */
.dark-mode-toggle {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.2em;
    color: var(--color-text-muted);
    margin-left: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 5px;
    border-radius: 50%;
    transition: background-color 0.2s ease, color 0.2s ease;
}
.dark-mode-toggle:hover {
    background-color: var(--color-bg-secondary);
    color: var(--color-primary);
}

/* Make sure the icon scales appropriately */
.dark-mode-toggle i {
    pointer-events: none;
}

/* ==========================================================================
   4. READER PAGE LAYOUT & TOC
   ========================================================================== */
.reader-layout {
    display: grid;
    /* Provide a third column for notes. The default width of the notes column is 0. */
    grid-template-columns: 300px 1fr 0;
    height: 100vh;
    overflow: hidden;
}

/* When notes panel is open, allocate space for it */
body.notes-open .reader-layout {
    grid-template-columns: 300px 1fr 300px;
}
.reader-sidebar { background-color: var(--color-surface); border-right: 1px solid var(--color-border); display: flex; flex-direction: column; height: 100vh; }

/* Notes sidebar inherits most styles from reader-sidebar but uses border-left */
/* Notes sidebar is hidden by default on desktop and becomes visible when body has .notes-open */
#reader-notes-sidebar {
    border-right: none;
    border-left: 1px solid var(--color-border);
    display: none;
}

body.notes-open #reader-notes-sidebar {
    display: flex;
}

/* Additional styling for notes panel */
.notes-header {
    padding: 20px;
    border-bottom: 1px solid var(--color-border);
    display: flex;
    align-items: center;
    justify-content: space-between;
}
.notes-header h3 {
    margin: 0;
    font-size: 1.1em;
}
.close-notes {
    background: none;
    border: none;
    color: var(--color-text-muted);
    font-size: 1.2em;
    cursor: pointer;
}
.notes-content {
    padding: 15px;
    overflow-y: auto;
    flex-grow: 1;
    font-size: 0.9em;
    color: var(--color-text);
}

.sidebar-header { padding: 20px; border-bottom: 1px solid var(--color-border); }
.back-to-library { display: inline-block; margin-bottom: 15px; color: var(--color-text-muted); text-decoration: none; }
.sidebar-header h3 { margin: 0; font-size: 1.2em; }
.sidebar-header .dark-mode-toggle {
    margin-left: auto;
}
.sidebar-content { overflow-y: auto; flex-grow: 1; padding: 10px 0; }
.reader-main { overflow-y: auto; height: 100vh; }
.chapter-container { max-width: 720px; margin: 60px auto; padding: 0; }
.chapter-body p { line-height: 1.7; font-size: 1.05em; }

/* ==========================================================================
   5.a. CHAPTER TOOLBAR (Search & Font Size Controls)
   ========================================================================== */
.chapter-toolbar {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 15px;
    background-color: var(--color-bg-secondary);
    border-bottom: 1px solid var(--color-border);
    padding: 10px 20px;
    position: sticky;
    top: 0;
    z-index: 998;
}

/* Style for the font combo selector on the chapter toolbar */
.chapter-toolbar select.font-combo-select {
    background-color: var(--color-surface);
    color: var(--color-text);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: 6px 18px 6px 8px;
    font-size: 0.9em;
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='10' viewBox='0 0 20 20'%3E%3Cpolygon points='0,0 20,0 10,10' fill='%23666666'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 6px center;
}

.chapter-toolbar select.font-combo-select:hover {
    background-color: var(--color-bg);
}
.chapter-toolbar .chapter-search {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-grow: 1;
}
.chapter-toolbar .chapter-search input {
    flex-grow: 1;
    padding: 6px 10px;
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    background-color: var(--color-surface);
    color: var(--color-text);
    font-size: 0.95em;
}
.chapter-toolbar .chapter-search button {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: 6px 8px;
    cursor: pointer;
    color: var(--color-text);
    font-size: 0.9em;
    transition: background-color 0.2s ease;
}
.chapter-toolbar .chapter-search button:hover {
    background-color: var(--color-bg);
}
.chapter-toolbar .search-result-count {
    font-size: 0.85em;
    color: var(--color-text-muted);
    min-width: 40px;
}
.chapter-toolbar .font-size-controls {
    display: flex;
    align-items: center;
    gap: 5px;
}
.chapter-toolbar .font-size-controls button {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: 6px 10px;
    cursor: pointer;
    font-size: 0.95em;
    transition: background-color 0.2s ease;
}
.chapter-toolbar .font-size-controls button:hover {
    background-color: var(--color-bg);
}

/*
 * The chapter toolbar now also displays book and chapter titles and groups
 * the reader controls (font size buttons and dark mode toggle) on the right.
 */
.chapter-toolbar .chapter-info {
    flex: 1;
    min-width: 0; /* allow ellipsis on long titles */
    display: flex;
    flex-direction: column;
    gap: 2px;
}
.chapter-toolbar .chapter-info .book-title {
    font-weight: 600;
    font-size: 1.1em;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}
.chapter-toolbar .chapter-info .chapter-title {
    font-size: 0.95em;
    color: var(--color-text-muted);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}
.chapter-toolbar .reader-controls {
    display: flex;
    align-items: center;
    gap: 8px;
}
.chapter-toolbar .reader-controls button {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: 6px 10px;
    cursor: pointer;
    font-size: 0.95em;
    transition: background-color 0.2s ease;
}
.chapter-toolbar .reader-controls button:hover {
    background-color: var(--color-bg);
}
.chapter-toolbar .reader-controls .dark-mode-toggle {
    font-size: 1.2em;
    padding: 6px;
}

/* Jump to top button appears in the bottom right corner of the reader page */
#jump-to-top {
    position: fixed;
    right: 30px;
    bottom: 30px;
    width: 45px;
    height: 45px;
    display: none;
    border-radius: 50%;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    background-color: var(--color-primary);
    color: #fff;
    z-index: 997;
}
#jump-to-top.show {
    display: flex;
}

/* Highlighted search results */
mark.search-highlight {
    background-color: #fff3a3;
    color: inherit;
    padding: 0;
}
mark.search-highlight.active-highlight {
    background-color: #ffdd57;
    border-bottom: 2px solid var(--color-primary);
}

/* TOC Styles */
.toc-phase-group { border-bottom: 1px solid var(--color-border); }
.toc-phase-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
    cursor: pointer;
    transition: background-color 0.2s;
}
.toc-phase-header:hover { background-color: var(--color-bg-secondary); }
.toc-phase-title { margin: 0; font-size: 0.9em; font-weight: 700; text-transform: uppercase; color: var(--color-text-muted); }
.toc-phase-toggle { transition: transform 0.3s ease; }
.toc-phase-group.open .toc-phase-toggle { transform: rotate(90deg); }
.toc-chapter-list { 
    list-style: none; padding: 0; margin: 0;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease-in-out;
}
.toc-phase-group.open .toc-chapter-list {
    max-height: 6000px; /* Một giá trị đủ lớn */
}
.toc-chapter-item a { display: flex; align-items: center; gap: 10px; padding: 12px 20px; text-decoration: none; color: var(--color-text); border-left: 4px solid transparent; }
.toc-chapter-item a:hover { background-color: var(--color-bg-secondary); }
.toc-chapter-item.active a { background-color: #eaf3e2; border-left-color: var(--color-primary); font-weight: 700; }
.toc-chapter-item .chapter-icon { font-size: 1.1em; width: 20px; text-align: center; color: var(--color-text-muted); }
.toc-chapter-item.active .chapter-icon { color: var(--color-primary); }

/* ==========================================================================
   5. READER PAGE CONTENT STYLES
   ========================================================================== */

/* Header chương */
.chapter-header { text-align: center; margin-bottom: 50px; }
.chapter-cover-image { width: 100%; max-height: 350px; object-fit: cover; border-radius: var(--border-radius); margin-bottom: 20px; }
.chapter-title { font-size: 1.8em; margin: 0 0 10px 0; color: var(--color-primary-dark); font-family: var(--font-heading); }
.chapter-meta { color: var(--color-text-muted); }

/* --- Phân cấp Block --- */
/* Giải quyết vấn đề \n */
.paragraph-content, .toolkit-definition, .role-body, .instruction, .step-list li {
    white-space: pre-wrap;
}
/* Cấp 1: Nội dung chính */
.main-content-block { border: none; background: none; padding: 0; margin: 0; }
.main-content-block > .block-title { display: none; } /* Ẩn tiêu đề "Nội dung chính" */
.main-content-block h2.subheading { font-family: var(--font-heading); font-size: 2em; margin: 2.5em 0 1em 0; padding-bottom: 10px; border-bottom: 2px solid var(--color-border); color: var(--color-text); }
.main-content-block > div {
    margin: 2.5em 0; /* Khoảng cách đồng đều giữa các block */
}
.main-content-block > div > h4 { /* Tiêu đề con của các block */
    font-family: var(--font-heading);
    font-size: 1.2em;
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 1em;
    color: var(--color-text);
}
.quote-block { border-left: 4px solid var(--color-accent); padding-left: 20px; margin: 2em 0; font-style: italic; color: var(--color-text-muted); }
.quote-block .author { display: block; text-align: right; font-weight: bold; font-style: normal; margin-top: 10px; }
.analogy-block { margin: 2em 0; }
.analogy-block h4 { font-family: var(--font-heading); }
.analogy-block dt { font-weight: 700; margin-top: 1em; }
.analogy-block dd { margin-left: 0; padding-left: 20px; border-left: 2px solid var(--color-border); }

/* Cấp 2: Block Chú giải (Nền nhạt, không viền đậm) */
.content-block.annotation-block { padding: 25px; margin: 30px 0; border-radius: var(--border-radius); background-color: var(--color-bg-secondary); border: 1px solid var(--color-border); }
.objectives-block ul, .summary-block .takeaways-list { list-style: none; padding-left: 0; }
.objectives-block li, .summary-block .takeaways-list li { /*display: flex;*/ align-items: flex-start; gap: 10px; margin-bottom: 12px; }
.objectives-block i, .summary-block .takeaways-list i { color: var(--color-primary); margin-top: 5px; }
/* Marketer's Toolkit (Thiết kế lại) */
.marketers-toolkit-block .toolkit-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 15px;
}
.marketers-toolkit-block .toolkit-card {
    padding: 20px;
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    background-color: var(--color-surface);
}
.marketers-toolkit-block .toolkit-term {
    font-weight: 700;
    margin: 0 0 8px 0;
    font-family: var(--font-heading);
}
.marketers-toolkit-block .toolkit-definition {
    margin: 0;
    font-size: 0.95em;
    color: var(--color-text-muted);
}
.insight-text { font-family: var(--font-heading); font-style: italic; font-size: 1.1em; text-align: center; }
/* Question List */
.question-list-block ul {
    list-style: none;
    padding-left: 0;
}
.question-list-block li {
    background: var(--color-bg-secondary);
    padding: 15px;
    border-radius: var(--border-radius);
    border-left: 3px solid var(--color-accent);
    margin-bottom: 10px;
}

/* Role Description */
.role-description-block .role-card {
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    overflow: hidden;
    margin-bottom: 15px;
}
.role-description-block .role-header {
    background-color: var(--color-bg-secondary);
    padding: 10px 15px;
    font-family: var(--font-heading);
}
.role-description-block .role-body {
    padding: 15px;
}

/* Table */
.table-container {
    overflow-x: auto; /* Cho phép cuộn ngang trên mobile */
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
}
.table-container table {
    width: 100%;
    border-collapse: collapse;
}
.table-container th, .table-container td {
    padding: 12px 15px;
    text-align: left;
    border-bottom: 1px solid var(--color-border);
}
.table-container th {
    background-color: var(--color-bg-secondary);
    font-weight: 600;
}
.table-container tbody tr:last-child td {
    border-bottom: none;
}
.table-container tbody tr:hover {
    background-color: #fcfcfc;
}

/* Checklist */
.checklist-block ul {
    list-style: none;
    padding: 0;
}
.checklist-block li {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.05em;
    padding: 8px 0;
}
.checklist-block li i {
    color: var(--color-primary);
}

/* Step-by-Step */
.step-by-step-block .step-list {
    list-style: none;
    padding-left: 0;
    counter-reset: step-counter;
}
.step-by-step-block .step-list li {
    display: flex;
    align-items: flex-start;
    gap: 15px;
    margin-bottom: 15px;
    position: relative;
    padding-left: 45px;
}
.step-by-step-block .step-list li::before {
    counter-increment: step-counter;
    content: counter(step-counter);
    position: absolute;
    left: 0;
    top: 0;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    background-color: var(--color-primary);
    color: white;
    font-weight: bold;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* Code Block */
/* Bạn cần thêm thư viện highlight.js để phần này đẹp */
/* Ví dụ: <link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/11.7.0/styles/default.min.css"> */
/* Và <script src="//cdnjs.cloudflare.com/ajax/libs/highlight.js/11.7.0/highlight.min.js"></script> */
.code-block-container {
    border-radius: var(--border-radius);
    border: 0px solid var(--color-border);
    overflow: hidden;
    background-color: #efefef;
    /*color: #e5e5e5;*/
    font-family: monospace;
}

.code-block-header {
    background-color: #444;
    color: #eee;
    padding: 8px 15px;
    font-family: monospace;
    text-transform: uppercase;
}
.code-block-container pre { margin: 0; }
.code-block-container pre code { padding: 20px !important; color: #e5e5e5;}

/* Formula Block */
/* Bạn cần thêm thư viện MathJax hoặc KaTeX để render công thức */
.formula-block {
    text-align: center;
    padding: 20px;
    background: var(--color-bg-secondary);
    border-radius: var(--border-radius);
    font-size: 1.2em;
}
.formula-name {
    font-style: italic;
    color: var(--color-text-muted);
    margin-bottom: 10px;
}

/* Cấp 3: Block Hành động & Cảnh báo (Nền màu + Viền đậm) */
.content-block.action-alert-block, .alert-block { padding: 25px; margin: 30px 0; border-radius: var(--border-radius); border-left-width: 5px; border-left-style: solid; border-top: 1px; border-right: 1px; border-bottom: 1px; }
.mythbuster-block { background-color: #fff5f5; border-color: #e53e3e; }
.exercise-block { background-color: #f0fff4; border-color: #38a169; }
.alert-block-info { background-color: #ebf8ff; border-color: #3182ce; }
.alert-block-warning { background-color: #fff3cd; border-color: #ffeeba; }

/* Block Teaser mới */
.teaser-block {
    padding: 25px 30px; /* Padding nhỏ hơn */
    margin: 50px 0 30px 0;
    border-radius: var(--border-radius);
    background-color: transparent; /* Nền trong suốt */
    border-top: 2px solid var(--color-border); /* Chỉ có một đường kẻ ngang phía trên */
    border-bottom: 2px solid var(--color-border); /* Và một đường kẻ ngang phía dưới */
    border-left: none; /* Bỏ viền trái */
    border-right: none;
    /*text-align: center;*/ /* Căn giữa */
}

.teaser-block p {
    font-style: italic; /* In nghiêng để tạo sự khác biệt */
    font-size: 1.1em; /* Cỡ chữ to hơn một chút */
    color: var(--color-text-muted); /* Màu chữ mờ hơn */
    line-height: 1.7;
    margin: 0; /* Bỏ margin mặc định của thẻ p */
}

/* Block chung */
.block-title { display: flex; align-items: center; gap: 12px; font-family: var(--font-heading); margin-top: 0; }
.block-title i { color: var(--color-primary); }

/* --- Navigation, Error, Loader & Responsive --- */
.chapter-navigation { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin-top: 50px; border-top: 1px solid var(--color-border); padding-top: 30px; }
.nav-button { display: flex; align-items: center; gap: 15px; padding: 15px 20px; border-radius: var(--border-radius); background-color: var(--color-bg-secondary); text-decoration: none; color: var(--color-text); transition: background-color 0.2s; }
.nav-button:hover { background-color: #eaf3e2; color: var(--color-primary-dark); }
.nav-button.next { justify-content: flex-end; text-align: right; }
.nav-button .nav-label { font-weight: 500; }
.nav-button i { font-size: 1.5em; color: var(--color-primary); }
.error-container { padding: 30px; background-color: #fff5f5; border: 1px solid #fc8181; border-radius: var(--border-radius); text-align: center; margin: 40px; }
.error-container h3 { color: #c53030; margin-top: 0; }
.error-details { background-color: #fed7d7; padding: 10px; border-radius: 4px; font-family: monospace; text-align: left; white-space: pre-wrap; word-break: break-all; font-size: 0.9em; color: #742a2a; }
.loader-container { padding: 50px; text-align: center; font-size: 1.2em; color: var(--color-text-muted); }
#reading-progress-bar { position: fixed; top: 0; left: 0; height: 4px; background-color: var(--color-primary); width: 0; z-index: 1001; transition: width 0.1s linear; }

.mobile-header {
    display: none; /* Mặc định ẩn trên desktop */
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 50px;
    background-color: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    z-index: 999;
    align-items: center;
    justify-content: space-between;
    padding: 0 10px;
}
.mobile-header-button {
    background: none;
    border: none;
    font-size: 1.2em;
    padding: 10px;
    cursor: pointer;
    color: var(--color-text-muted);
}
.mobile-header-title {
    font-weight: 500;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}
#toc-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
    z-index: 999;
}

/* Styles cho Modal */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.6);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}
.modal-content {
    background-color: var(--color-surface);
    padding: 30px;
    border-radius: var(--border-radius);
    max-width: 600px;
    width: 90%;
    text-align: center;
    position: relative;
}
.modal-close {
    position: absolute;
    top: 10px;
    right: 15px;
    background: none;
    border: none;
    font-size: 1.5em;
    cursor: pointer;
    color: var(--color-text-muted);
}
.modal-actions {
    margin-top: 20px;
    display: flex;
    gap: 15px;
    justify-content: center;
}
.button, a.button {
    display: inline-block;
    padding: 10px 20px;
    background-color: var(--color-primary);
    color: white;
    border: none;
    border-radius: 5px;
    text-decoration: none;
    font-weight: 500;
    cursor: pointer;
}
a.button-secondary {
    background-color: var(--color-bg-secondary);
    color: var(--color-text);
    border: 1px solid var(--color-border);
}

/* ==========================================================================
   X. AUTHENTICATION PAGES (login.html, register.html)
   ========================================================================== */
.auth-page {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    background-color: var(--color-bg);
}

.auth-container {
    background-color: var(--color-surface);
    padding: 40px;
    border-radius: var(--border-radius);
    box-shadow: 0 10px 30px rgba(0,0,0,0.07);
    width: 100%;
    max-width: 420px;
    text-align: center;
}
.auth-logo {
    display: inline-block;
    margin-bottom: 20px;
    font-size: 1.5em;
    font-weight: 700;
    text-decoration: none;
    color: var(--color-primary);
}
.auth-container h2 {
    font-family: var(--font-heading);
    margin: 0 0 10px 0;
}
.auth-subtitle {
    margin: 0 0 30px 0;
    color: var(--color-text-muted);
}
.form-group {
    text-align: left;
    margin-bottom: 20px;
}
.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
}
.form-group input {
    width: 100%;
    padding: 12px 15px;
    border: 1px solid var(--color-border);
    border-radius: 5px;
    font-size: 1em;
    font-family: var(--font-body);
}
.form-group input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(85, 107, 47, 0.1);
}
.auth-message {
    min-height: 20px;
    margin-bottom: 15px;
    font-weight: 500;
}
.auth-message.error { color: var(--color-error); }
.auth-message.success { color: #2f855a; }
.auth-button {
    width: 100%;
    padding: 15px;
    font-size: 1.1em;
    margin-bottom: 20px;
}
.auth-switch {
    border-top: 1px solid var(--color-border);
    padding-top: 20px;
    color: var(--color-text-muted);
}
.auth-switch a {
    color: var(--color-primary);
    font-weight: 500;
    text-decoration: none;
}
.auth-switch a:hover {
    text-decoration: underline;
}


/* ==========================================================================
   Y. SITE HEADER (index.html)
   ========================================================================== */
.site-header {
    background-color: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
}
.site-header.sticky {
    position: sticky;
    top: 0;
    z-index: 998;
}
.header-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}
.logo {
    font-size: 1.4em;
    font-weight: 700;
    text-decoration: none;
    color: var(--color-primary-dark);
}
.main-nav {
    display: flex;
    gap: 30px;
}
.main-nav a {
    text-decoration: none;
    color: var(--color-text-muted);
    font-weight: 500;
    transition: color 0.2s;
}
.main-nav a:hover {
    color: var(--color-primary);
}
.header-actions {
    display: flex;
    align-items: center;
    gap: 20px;
}
.search-bar {
    position: relative;
}
.search-bar input {
    padding: 8px 15px 8px 35px;
    border: 1px solid var(--color-border);
    border-radius: 20px;
    width: 200px;
    transition: width 0.3s;
}
.search-bar input:focus {
    width: 250px;
    outline: none;
    border-color: var(--color-primary);
}
.search-bar i {
    position: absolute;
    left: 15px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--color-text-muted);
}
#user-info-container {
    display: flex;
    align-items: center;
    gap: 10px;
}
.user-email {
    font-weight: 500;
}
.mobile-menu-toggle {
    display: none; /* Ẩn trên desktop */
    background: none;
    border: none;
    font-size: 1.5em;
    cursor: pointer;
}
.mobile-nav-menu {
    position: fixed;
    top: 0;
    left: -320px; /* Ẩn ngoài màn hình */
    width: 300px;
    height: 100vh;
    background-color: var(--color-surface);
    box-shadow: 5px 0 15px rgba(0,0,0,0.2);
    z-index: 1000;
    transition: left 0.3s ease-in-out;
    display: flex;
    flex-direction: column;
    padding: 20px;
}
body.mobile-nav-open .mobile-nav-menu {
    left: 0; /* Hiện menu */
}
.close-mobile-nav {
    background: none;
    border: none;
    font-size: 2em;
    position: absolute;
    top: 10px;
    right: 10px;
    cursor: pointer;
    color: var(--color-text-muted);
}

.mobile-main-nav a, .mobile-auth-actions a, .mobile-auth-actions button {
    display: block;
    padding: 12px 0;
    text-decoration: none;
    color: var(--color-text);
    font-weight: 500;
    border-bottom: 1px solid var(--color-border);
}

.mobile-main-nav a:last-child, .mobile-auth-actions button:last-child {
    border-bottom: none;
}
.mobile-auth-actions {
    margin-top: 20px;
    padding-top: 20px;
    border-top: 1px solid var(--color-border);
}
.mobile-auth-actions .button {
    width: 100%;
    margin-bottom: 10px;
}

.mobile-nav-overlay {
    display: none; /* Mặc định ẩn */
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
    z-index: 999;
}

body.mobile-nav-open .mobile-nav-overlay {
    display: block; /* Hiện overlay khi menu mở */
}


@media (max-width: 900px) {
    /* Hide the desktop navigation on smaller screens */
    .main-nav { display: none; }
    /* Hide header action items (login, user email and dark mode) on mobile. They are now provided inside the mobile menu. */
    .header-actions { display: none; }
    .mobile-menu-toggle { display: block; }
}

/*
 * Mobile controls that live inside the slide‑out navigation. This includes
 * the dark mode toggle now that header actions are hidden on small screens.
 */
.mobile-controls {
    margin-top: 20px;
    padding-top: 20px;
    border-top: 1px solid var(--color-border);
    display: flex;
    justify-content: flex-start;
    align-items: center;
}
.mobile-controls .dark-mode-toggle {
    background: none;
    border: none;
    font-size: 1.3em;
    cursor: pointer;
    color: var(--color-text);
}


/* ==========================================================================
   Z. HERO SECTION & MODAL STYLES (index.html)
   ========================================================================== */
.hero-section {
    padding: 40px 0;
    text-align: center;
    background-color: #eaf3e2; /* Màu nền nhẹ nhàng */
}
.hero-section h1 {
    font-size: 3em;
    font-family: var(--font-heading);
    color: var(--color-primary-dark);
}
.hero-section p {
    font-size: 1.2em;
    max-width: 600px;
    margin: 20px auto 30px auto;
    color: var(--color-text-muted);
}
.button.button-hero {
    padding: 15px 30px;
    font-size: 1.1em;
}

/* Thêm max-width lớn hơn cho modal bảng giá */
#pricing-modal .modal-content {
    max-width: 800px;
}

/* --- Pricing Grid Styles --- */
.pricing-grid {
    display: grid;
    /* Tự động tạo các cột có chiều rộng tối thiểu 250px. 
       Nếu đủ không gian, các cột sẽ tự động dãn ra bằng nhau. */
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px; /* Khoảng cách giữa các cột */
    margin-top: 20px;
    text-align: left;
}

.pricing-card {
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: 25px;
    display: flex;
    flex-direction: column;
    transition: transform 0.2s, box-shadow 0.2s;
}

.pricing-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.08);
}

/* Style cho gói nổi bật (Featured) */
.pricing-card.featured {
    border-width: 2px;
    border-color: var(--color-primary);
    position: relative;
    overflow: hidden;
}

/* Thêm một dải băng "Phổ biến" */
.pricing-card.featured::before {
    content: "Phổ biến";
    position: absolute;
    top: 15px;
    right: -30px;
    background-color: var(--color-primary);
    color: white;
    padding: 5px 30px;
    font-size: 0.8em;
    font-weight: bold;
    transform: rotate(45deg);
    text-align: center;
}

.pricing-card h4 {
    font-family: var(--font-heading);
    margin-top: 0;
    font-size: 1.3em;
    color: var(--color-primary-dark);
}

.pricing-card .price {
    font-size: 2em;
    font-weight: 700;
    margin: 0 0 10px 0;
}

.pricing-card p {
    color: var(--color-text-muted);
    flex-grow: 1; /* Đẩy nút bấm xuống dưới cùng */
}

.pricing-card ul {
    list-style: none;
    padding: 0;
    margin: 20px 0;
}

.pricing-card ul li {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    margin-bottom: 10px;
}

.pricing-card ul li::before {
    content: "\f00c"; /* Font Awesome check icon */
    font-family: "Font Awesome 6 Free";
    font-weight: 900;
    color: var(--color-primary);
    margin-top: 4px;
}

.pricing-card .button {
    width: 100%;
    text-align: center;
    padding: 12px;
}

/* Styles cho Modal Mua sách */
.purchase-modal-header {
    display: flex;
    align-items: flex-start;
    gap: 20px;
    margin-bottom: 20px;
    text-align: left;
}
.purchase-modal-cover {
    width: 80px;
    height: auto;
    border-radius: 4px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}
.purchase-modal-header h3 {
    margin: 0 0 5px 0;
}
.purchase-modal-price {
    font-size: 1.4em;
    font-weight: bold;
    color: var(--color-primary);
    margin: 0;
}
.purchase-instructions {
    text-align: left;
    background-color: var(--color-bg-secondary);
    padding: 15px;
    border-radius: var(--border-radius);
    margin: 20px 0;
}
.purchase-instructions h4 {
    margin-top: 0;
}
.bank-info {
    line-height: 1.8;
    margin: 10px 0;
}
.bank-info code {
    background-color: #e9ecef;
    padding: 2px 6px;
    border-radius: 4px;
    font-family: monospace;
}
.confirmation-note {
    font-size: 0.9em;
    font-style: italic;
    color: var(--color-text-muted);
}

/* Quiz Block */
.quiz-block {
    background-color: #ebf8ff; /* Nền xanh nhạt */
    border-color: #3182ce; /* Viền xanh */
}
.quiz-description {
    font-style: italic;
    color: var(--color-text-muted);
    margin-bottom: 25px;
}
.quiz-question-card {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: 20px;
    margin-bottom: 20px;
}
.quiz-question-card .question-text {
    font-size: 1.1em;
    margin-bottom: 15px;
}
.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 10px;
}
.quiz-option {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 15px;
    border: 1px solid var(--color-border);
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.2s, border-color 0.2s;
}
.quiz-option:hover {
    background-color: var(--color-bg-secondary);
}
.quiz-option input[type="radio"] {
    accent-color: var(--color-primary); /* Màu radio button */
}

/* Feedback sau khi trả lời */
.quiz-feedback {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-top: 15px;
    padding: 10px 15px;
    border-radius: 5px;
}
.quiz-feedback.correct {
    background-color: #f0fff4;
    color: #2f855a;
    border: 1px solid #38a169;
}
.quiz-feedback.incorrect {
    background-color: #fff5f5;
    color: #c53030;
    border: 1px solid #e53e3e;
}
.quiz-feedback .feedback-icon {
    font-size: 1.2em;
}
.quiz-feedback.correct .feedback-icon::before { content: "\f058"; /* check-circle */ font-family: "Font Awesome 6 Free"; font-weight: 900; }
.quiz-feedback.incorrect .feedback-icon::before { content: "\f057"; /* times-circle */ font-family: "Font Awesome 6 Free"; font-weight: 900; }
.quiz-feedback .explanation-text {
    margin-top: 10px;
    font-style: italic;
    color: var(--color-text-muted);
    font-size: 0.95em;
    padding-left: 30px; /* Thụt vào để phân biệt */
    border-left: 2px solid var(--color-border);
}

.quiz-submit-btn {
    margin-top: 20px;
    width: 100%;
}
.quiz-result {
    text-align: center;
    margin-top: 30px;
    padding: 30px;
    background-color: var(--color-bg-secondary);
    border-radius: var(--border-radius);
    font-size: 1.2em;
    font-weight: 600;
}
.quiz-result h3 {
    font-family: var(--font-heading);
    color: var(--color-primary-dark);
    margin-bottom: 15px;
}
.quiz-result-actions {
    display: flex;
    flex-wrap: wrap; /* Cho phép xuống dòng trên mobile */
    justify-content: center;
    gap: 15px;
    margin-top: 25px;
}
.quiz-result-actions .button {
    flex-grow: 1;
    min-width: 150px;
}
.quiz-result-actions .quiz-review-btn {
    background-color: var(--color-primary);
    color: white;
}
.quiz-result-actions .quiz-retake-btn,
.quiz-result-actions .quiz-continue-reading-btn {
    background-color: var(--color-surface);
    color: var(--color-text);
    border: 1px solid var(--color-border);
}
.quiz-result-actions .quiz-retake-btn:hover,
.quiz-result-actions .quiz-continue-reading-btn:hover {
    background-color: var(--color-bg-secondary);
}
/* Review Mode specific styles */
.quiz-block.review-mode .quiz-question-card {
    margin-bottom: 30px; /* Thêm khoảng cách giữa các câu khi review */
}
.quiz-block.review-mode .quiz-submit-btn {
    display: none; /* Ẩn nút khi đang review */
}
/* Container cho nút làm lại bài trong review mode */
.quiz-review-actions {
    text-align: center;
    margin-top: 30px;
}
.quiz-review-actions .button {
    min-width: 200px; /* Đảm bảo nút đủ rộng */
}
/* Quiz Option selected */
.quiz-option.selected-option {
    background-color: var(--color-bg-secondary); /* Nền nhạt hơn khi được chọn */
    border-color: var(--color-primary); /* Viền màu chính */
}
/* Thêm cho nút "Nộp bài" cuối cùng */
.quiz-submit-btn {
    font-size: 1.1em;
    font-weight: 600;
}
/* Review Mode Highlights */
.quiz-question-card .quiz-options label.correct-option-highlight {
    background-color: #d4edda; /* Xanh lá nhạt */
    border-color: #28a745; /* Xanh lá đậm */
}
.quiz-question-card .quiz-options label.incorrect-option-highlight {
    background-color: #f8d7da; /* Đỏ nhạt */
    border-color: #dc3545; /* Đỏ đậm */
}

/* Review Mode styles */
.quiz-question-card.answered .quiz-options label {
    cursor: default; /* Không cho click khi đã trả lời */
}
.quiz-question-card.answered input[type="radio"] {
    cursor: default;
}

/* Mobile Responsive for Reader */
@media (max-width: 900px) {
    /* Collapse sidebars on mobile: show only main content */
    .reader-layout { grid-template-columns: 1fr; }
    .reader-main { padding-top: 50px; } /* Tạo không gian cho header mobile */
    /* Both sidebars become offcanvas panels */
    #reader-toc-sidebar,
    #reader-notes-sidebar {
        position: fixed;
        top: 0;
        width: 280px;
        height: 100vh;
        z-index: 1000;
        box-shadow: 5px 0 15px rgba(0,0,0,0.1);
        transition: transform 0.3s ease-in-out;
        background-color: var(--color-surface);
        overflow-y: auto;
    }
    /* Place TOC to the left */
    #reader-toc-sidebar {
        left: 0;
        transform: translateX(-100%);
        border-right: 1px solid var(--color-border);
    }
    /* Place notes panel to the right */
    #reader-notes-sidebar {
        right: 0;
        transform: translateX(100%);
        border-left: 1px solid var(--color-border);
    }
    /* When body.toc-open: show toc */
    body.toc-open #reader-toc-sidebar {
        transform: translateX(0);
    }
    /* When body.notes-open: show notes */
    body.notes-open #reader-notes-sidebar {
        transform: translateX(0);
    }
    /* Display overlay when any sidebar is open */
    body.toc-open #toc-overlay,
    body.notes-open #toc-overlay {
        display: block;
    }
    .mobile-header { display: flex; }
    .chapter-container { margin: 20px auto; padding: 20px; }
}

body.dark-mode .mythbuster-block { background-color: #35263a; border-color: #e874e7; }
body.dark-mode .exercise-block { background-color: #223d2d; border-color: #61e38e; }
body.dark-mode .alert-block-info { background-color: #233040; border-color: #5db4e6; }
body.dark-mode .alert-block-warning { background-color: #4a3c16; border-color: #ffe17c; color: #fbe39c; }
body.dark-mode .quiz-block { background-color: #1c3442; border-color: #5db4e6; }
body.dark-mode .quiz-feedback.correct { background-color: #1f3828; color: #95f3a5; border-color: #61e38e; }
body.dark-mode .quiz-feedback.incorrect { background-color: #402728; color: #ffaaaa; border-color: #e87474; }
body.dark-mode .toc-chapter-item.active a { background-color: #22304a; border-left-color: var(--color-primary); color: #fff; }
body.dark-mode .toc-chapter-item.active .chapter-icon { color: var(--color-primary); }
body.dark-mode .chapter-toolbar .reader-controls button { color: var(--color-primary); }
body.dark-mode .code-block-container { background-color: #364252;  }

/* ==== SEPIA MODE: BLOCKS, ALERTS, QUIZ, TOC ACTIVE ==== */
body.sepia-mode .mythbuster-block {
    background-color: #f9efea;   /* Vàng nhạt, ngà */
    border-color: #b98b5a;       /* Nâu cam nhạt */
}
body.sepia-mode .exercise-block {
    background-color: #f3efe6;   /* Be, vàng nhạt */
    border-color: #b3a471;       /* Vàng sậm nhẹ */
}
body.sepia-mode .alert-block-info {
    background-color: #f5f1e8;   /* Kem nhạt */
    border-color: #a8956d;       /* Nâu sáng */
    color: #695539;
}
body.sepia-mode .alert-block-warning {
    background-color: #faedd3;   /* Vàng nhạt */
    border-color: #e4c575;       /* Vàng đậm */
    color: #8b7118;
}
body.sepia-mode .content-block.action-alert-block,
body.sepia-mode .alert-block {
    background-color: #f6efe2;   /* Kem ngà */
    border-color: #b98b5a;
    color: #674c23;
}
body.sepia-mode .quiz-block {
    background-color: #f5f1e8;
    border-color: #b98b5a;
}
body.sepia-mode .quiz-feedback.correct {
    background-color: #f4f8ed;
    color: #5a6a41;
    border-color: #b3a471;
}
body.sepia-mode .quiz-feedback.incorrect {
    background-color: #f9e7e6;
    color: #a34d32;
    border-color: #ce7b6b;
}
/* TOC active in sepia mode */
body.sepia-mode .toc-chapter-item.active a {
    background-color: #f3e5be; /* vàng kem nổi bật dịu */
    border-left-color: var(--color-primary);
    color: #6b4e1a;
}
body.sepia-mode .toc-chapter-item.active .chapter-icon {
    color: var(--color-primary);
}

/* Notification bell styling */
/* Notification bell styling (desktop header) */
.notification-bell {
    position: relative;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    color: var(--color-primary);
    margin-right: 0.5rem;
    cursor: pointer;
    transition: color 0.2s ease;
}
.notification-bell:hover {
    color: var(--color-primary-dark);
}
.notification-bell i {
    pointer-events: none;
}
.notification-bell .notif-badge {
    position: absolute;
    top: -4px;
    right: -6px;
    background-color: var(--color-error);
    color: #fff;
    border-radius: 50%;
    padding: 2px 5px;
    font-size: 0.6rem;
    line-height: 1;
}

/* Badges for user entitlements in admin */
.entitlement-badge {
    display: inline-block;
    border-radius: 4px;
    padding: 2px 6px;
    margin: 0 2px 2px 0;
    font-size: 0.75rem;
    color: #fff;
    white-space: nowrap;
}
.entitlement-badge.book-badge {
    background-color: var(--color-primary);
}
.entitlement-badge.package-badge {
    background-color: var(--color-accent);
}

/* Remove cross inside entitlement badge */
.entitlement-badge .remove-ent {
    display: inline-block;
    margin-left: 4px;
    font-weight: bold;
    cursor: pointer;
    color: inherit;
}
.entitlement-badge .remove-ent:hover {
    opacity: 0.8;
}