/* CSS VARIABLES - THEME DEFINITIONS */
:root {
    /* Default Sepia Theme Values */
    --bg-color: #f5efeb;
    --text-color: #2d221e;
    --card-bg: #eae1db;
    --accent-color: #b36d59;
    --border-color: #d5c7bf;
    
    /* Layout Constants */
    --max-reading-width: 720px;
    --font-ui: 'Outfit', 'Kanit', sans-serif;
    --font-reading: 'Noto Serif Thai', 'Sarabun', serif;
    
    /* Animation Constants */
    --transition-speed: 0.3s;
}

/* BASE STYLES & RESET */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: var(--font-ui);
    transition: background-color var(--transition-speed) ease, color var(--transition-speed) ease;
    line-height: 1.6;
    overflow-x: hidden;
}

body.reader-mode-active {
    font-family: var(--font-reading);
}

a {
    color: var(--accent-color);
    text-decoration: none;
    transition: opacity var(--transition-speed);
}

a:hover {
    opacity: 0.8;
    text-decoration: underline;
}

.hidden {
    display: none !important;
}

/* TOP READING PROGRESS BAR */
#reading-progress {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background-color: transparent;
    z-index: 1000;
    display: none;
}

#progress-bar {
    width: 0%;
    height: 100%;
    background-color: var(--accent-color);
    transition: width 0.1s ease;
}

/* LAYOUT CONTAINER */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ==========================================================================
   LANDING VIEW STYLE (Modern Minimalist Landing Page)
   ========================================================================== */
#landing-view {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 60px 20px;
    animation: fadeIn 0.6s ease-out;
}

.landing-card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    padding: 40px;
    width: 100%;
    max-width: 800px;
    display: flex;
    flex-direction: row;
    gap: 40px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
    transition: background-color var(--transition-speed), border-color var(--transition-speed);
}

.cover-wrapper {
    flex: 0 0 260px;
    width: 260px;
    aspect-ratio: 3 / 4;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.15);
    border: 1px solid var(--border-color);
}

.cover-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center top;
    display: block;
}

.book-info {
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.book-title {
    font-size: 2.8rem;
    font-weight: 600;
    letter-spacing: -1px;
    margin-bottom: 5px;
    color: var(--text-color);
}

.book-subtitle {
    font-size: 1.1rem;
    color: var(--accent-color);
    margin-bottom: 25px;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.book-meta {
    font-size: 0.95rem;
    opacity: 0.8;
    margin-bottom: 20px;
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 10px;
}

.book-description {
    font-size: 1rem;
    line-height: 1.7;
    opacity: 0.9;
    margin-bottom: 30px;
}

.book-description p {
    margin-bottom: 14px;
}

.book-description p:last-child {
    margin-bottom: 0;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background-color: var(--accent-color);
    color: #ffffff;
    border: none;
    padding: 14px 28px;
    font-size: 1rem;
    font-weight: 500;
    border-radius: 10px;
    cursor: pointer;
    transition: transform 0.2s, opacity 0.2s, background-color 0.2s;
    font-family: var(--font-ui);
}

.btn:hover {
    opacity: 0.9;
    transform: translateY(-2px);
}

.btn:active {
    transform: translateY(0);
}

/* ==========================================================================
   READER VIEW STYLE (Designed for long reading sessions)
   ========================================================================== */
#reader-view {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* STICKY HEADER CONTROLS */
.reader-header {
    position: sticky;
    top: 0;
    background-color: var(--bg-color);
    border-bottom: 1px solid var(--border-color);
    padding: 15px 0;
    z-index: 100;
    transition: background-color var(--transition-speed), border-color var(--transition-speed);
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.left-controls, .right-controls {
    display: flex;
    align-items: center;
    gap: 15px;
}

.header-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-color);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 1.1rem;
    transition: background-color var(--transition-speed), border-color var(--transition-speed), transform 0.1s;
}

.header-btn:hover {
    background-color: var(--card-bg);
}

.header-btn:active {
    transform: scale(0.95);
}

/* THEME CONTROLS */
.theme-selector {
    display: flex;
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    padding: 3px;
}

.theme-btn {
    background: transparent;
    border: none;
    color: var(--text-color);
    padding: 6px 14px;
    font-size: 0.85rem;
    font-weight: 500;
    border-radius: 17px;
    cursor: pointer;
    transition: background-color 0.2s, color 0.2s;
    font-family: var(--font-ui);
}

.theme-btn.active {
    background-color: var(--accent-color);
    color: #ffffff;
}

/* FONT CONTROLS */
.font-controls {
    display: flex;
    align-items: center;
    gap: 8px;
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    padding: 3px;
}

.font-btn {
    background: transparent;
    border: none;
    color: var(--text-color);
    width: 30px;
    height: 30px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1rem;
    font-weight: bold;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color 0.2s;
}

.font-btn:hover {
    background-color: var(--border-color);
}

.font-size-val {
    font-size: 0.85rem;
    font-weight: 500;
    min-width: 20px;
    text-align: center;
}

/* READING CONTENT AREA */
.reader-body {
    flex: 1;
    padding: 60px 0 100px 0;
}

.reading-container {
    max-width: var(--max-reading-width);
    margin: 0 auto;
    padding: 0 20px;
}

#chapter-title {
    font-size: 1.8rem;
    font-weight: 600;
    margin-bottom: 40px;
    text-align: center;
    color: var(--text-color);
}

#content-area {
    font-family: var(--font-reading);
    line-height: 1.8;
    color: var(--text-color);
    transition: font-size 0.2s;
    overflow-wrap: break-word;
    word-break: break-word;
}

/* Content typography */
#content-area p {
    margin-bottom: 24px;
    text-indent: 2em; /* Indent paragraphs for a novel-like experience */
    text-align: justify;
}

#content-area h1 {
    font-size: 1.8rem;
    margin: 40px 0 20px 0;
    text-align: center;
}

#content-area h2 {
    font-size: 1.4rem;
    margin: 30px 0 15px 0;
    text-align: center;
}

#content-area h3 {
    font-size: 1.2rem;
    margin: 25px 0 10px 0;
}

#content-area blockquote {
    border-left: 4px solid var(--accent-color);
    padding-left: 20px;
    margin: 30px 0;
    font-style: italic;
    opacity: 0.9;
}

#content-area hr {
    border: none;
    border-top: 1px dashed var(--border-color);
    margin: 40px auto;
    width: 50%;
}

#content-area strong {
    font-weight: 600;
}

/* ALERT BLOCKS (from markdown notes) */
.alert {
    padding: 20px;
    margin: 30px 0;
    border-radius: 12px;
    border-left: 5px solid var(--accent-color);
    background-color: var(--card-bg);
    transition: background-color var(--transition-speed);
}

.alert p {
    text-indent: 0 !important;
    margin-bottom: 0 !important;
}

.alert strong {
    display: block;
    margin-bottom: 8px;
    text-transform: uppercase;
    font-size: 0.85rem;
    letter-spacing: 1px;
}

/* PAGINATION FOOTER */
.reader-footer {
    border-top: 1px solid var(--border-color);
    padding: 40px 0 60px 0;
    background-color: var(--bg-color);
    transition: background-color var(--transition-speed), border-color var(--transition-speed);
}

.footer-container {
    max-width: var(--max-reading-width);
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    padding: 0 20px;
}

.footer-btn {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    color: var(--text-color);
    padding: 10px 20px;
    font-size: 0.9rem;
    font-weight: 500;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color var(--transition-speed), border-color var(--transition-speed), transform 0.1s;
    font-family: var(--font-ui);
}

.footer-btn:hover:not(:disabled) {
    background-color: var(--border-color);
}

.footer-btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

.footer-btn:active:not(:disabled) {
    transform: scale(0.98);
}

/* ==========================================================================
   SIDEBAR DRAWER MENU STYLES
   ========================================================================== */
#sidebar {
    position: fixed;
    top: 0;
    left: -320px;
    width: 320px;
    height: 100vh;
    background-color: var(--card-bg);
    border-right: 1px solid var(--border-color);
    z-index: 1000;
    box-shadow: 10px 0 30px rgba(0,0,0,0.05);
    transition: left var(--transition-speed) cubic-bezier(0.2, 0.8, 0.2, 1);
    display: flex;
    flex-direction: column;
}

#sidebar.open {
    left: 0;
}

.sidebar-header {
    padding: 25px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.sidebar-title {
    font-size: 1.2rem;
    font-weight: 600;
}

.sidebar-body {
    flex: 1;
    overflow-y: auto;
    padding: 20px 0;
}

#sidebar-menu {
    list-style: none;
}

.sidebar-item {
    padding: 15px 25px;
    display: flex;
    align-items: center;
    gap: 15px;
    cursor: pointer;
    transition: background-color 0.2s;
    border-left: 4px solid transparent;
}

.sidebar-item:hover {
    background-color: var(--bg-color);
}

.sidebar-item.active {
    border-left-color: var(--accent-color);
    background-color: var(--bg-color);
}

.sidebar-item .num {
    font-size: 0.85rem;
    font-weight: bold;
    color: var(--accent-color);
    opacity: 0.8;
}

.sidebar-item .name {
    font-size: 0.95rem;
    font-weight: 500;
}

/* ==========================================================================
   UTILITY & DYNAMIC COMPONENTS (Loader, Error, Animations)
   ========================================================================== */
.loader-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 100px 0;
    gap: 20px;
}

.loader {
    width: 48px;
    height: 48px;
    border: 3px solid var(--border-color);
    border-radius: 50%;
    display: inline-block;
    position: relative;
    box-sizing: border-box;
    animation: rotation 1s linear infinite;
}

.loader::after {
    content: '';  
    box-sizing: border-box;
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 3px solid transparent;
    border-bottom-color: var(--accent-color);
}

.error-container {
    text-align: center;
    padding: 80px 20px;
    border: 1px dashed var(--border-color);
    border-radius: 12px;
    background-color: var(--card-bg);
}

.error-container h3 {
    margin-bottom: 12px;
}

.error-container p {
    margin-bottom: 24px;
    opacity: 0.8;
}

@keyframes rotation {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(15px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ==========================================================================
   RESPONSIVE DESIGN SYSTEM (MOBILE-FIRST)
   ========================================================================== */
@media (max-width: 768px) {
    .landing-card {
        flex-direction: column;
        padding: 30px 20px;
        gap: 25px;
    }
    
    .cover-wrapper {
        flex: 0 0 auto;
        width: 75%;
        max-width: 260px;
        aspect-ratio: 3 / 4;
        margin: 0 auto;
    }
    
    .book-title {
        font-size: 2.2rem;
        text-align: center;
    }
    
    .book-subtitle {
        text-align: center;
        margin-bottom: 20px;
    }
    
    .book-meta {
        grid-template-columns: 1fr;
        gap: 8px;
        font-size: 0.9rem;
    }
    
    .book-description {
        text-align: left;
        font-size: 0.95rem;
    }
    
    .btn {
        width: 100%;
    }
    
    .reader-header {
        padding: 10px 0;
    }
    
    .header-btn {
        width: 36px;
        height: 36px;
        font-size: 1rem;
    }
    
    .theme-btn {
        padding: 5px 10px;
        font-size: 0.8rem;
    }
    
    .font-btn {
        width: 26px;
        height: 26px;
        font-size: 0.85rem;
    }
    
    .reader-body {
        padding: 30px 0 60px 0;
    }
    
    #chapter-title {
        font-size: 1.5rem;
        margin-bottom: 25px;
    }
    
    #content-area p {
        margin-bottom: 20px;
    }
    
    .footer-container {
        padding: 0 15px;
    }
}

/* ==========================================================================
   GLOSSARY HOVER TOOLTIPS
   ========================================================================== */
.glossary-term {
    border-bottom: 1.5px dashed var(--accent-color);
    cursor: help;
    position: relative;
    color: var(--accent-color);
    font-weight: 500;
}

/* Tooltip container styling */
.glossary-term::after {
    content: attr(data-definition);
    position: absolute;
    bottom: 130%;
    left: 50%;
    transform: translateX(-50%) translateY(10px);
    background-color: var(--card-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 10px 14px;
    font-size: 0.85rem;
    font-weight: 400;
    width: 260px;
    max-width: 80vw;
    box-shadow: 0 4px 15px var(--shadow-color);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s ease, transform 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    z-index: 200;
    line-height: 1.5;
    text-align: left;
    white-space: normal;
    font-family: var(--font-ui);
}

/* Tooltip pointer triangle */
.glossary-term::before {
    content: '';
    position: absolute;
    bottom: 118%;
    left: 50%;
    transform: translateX(-50%) translateY(10px);
    border-width: 6px;
    border-style: solid;
    border-color: var(--border-color) transparent transparent transparent;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s ease, transform 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    z-index: 201;
}

.glossary-term:hover::after,
.glossary-term:hover::before {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
    pointer-events: auto;
}

/* ==========================================================================
   MOBILE BOTTOM SHEET FOR GLOSSARY
   ========================================================================== */
.bottom-sheet {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 1000;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    pointer-events: auto;
    transition: visibility 0.3s ease;
}

.bottom-sheet.hidden {
    visibility: hidden;
    pointer-events: none;
}

.bottom-sheet-backdrop {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.4);
    backdrop-filter: blur(4px);
    opacity: 0;
    transition: opacity 0.3s ease;
}

.bottom-sheet.open .bottom-sheet-backdrop {
    opacity: 1;
}

.bottom-sheet-content {
    position: relative;
    background-color: var(--card-bg);
    border-top: 1px solid var(--border-color);
    border-radius: 20px 20px 0 0;
    padding: 24px 24px 40px 24px;
    box-shadow: 0 -8px 24px rgba(0, 0, 0, 0.15);
    transform: translateY(100%);
    transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    z-index: 1;
    color: var(--text-color);
}

.bottom-sheet.open .bottom-sheet-content {
    transform: translateY(0);
}

.bottom-sheet-drag-handle {
    width: 40px;
    height: 4px;
    background-color: var(--border-color);
    border-radius: 2px;
    margin: 0 auto 16px auto;
}

.bottom-sheet-close {
    position: absolute;
    top: 16px;
    right: 16px;
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--text-color);
    opacity: 0.6;
    cursor: pointer;
    padding: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    line-height: 1;
    transition: opacity 0.2s ease;
}

.bottom-sheet-close:hover {
    opacity: 1;
}

#bottom-sheet-term {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--accent-color);
    margin: 0 0 12px 0;
    font-family: var(--font-ui);
}

#bottom-sheet-definition {
    font-size: 0.95rem;
    line-height: 1.6;
    margin: 0;
    font-family: var(--font-reading);
}

/* On screens larger than 768px, disable the bottom sheet logic (just in case) */
@media (min-width: 769px) {
    .bottom-sheet {
        display: none !important;
    }
}

/* Disable desktop hover tooltip when on mobile/touch screens to avoid duplicate UI */
@media (max-width: 768px) {
    .glossary-term::after,
    .glossary-term::before {
        display: none !important;
    }
    .glossary-term {
        border-bottom-style: solid; /* Make it look like a tappable link */
        -webkit-tap-highlight-color: rgba(var(--accent-color-rgb), 0.1);
    }
}

/* Optimize very small screen viewports (width < 480px) to prevent layout break */
@media (max-width: 480px) {
    .left-controls, .right-controls {
        gap: 6px;
    }
    
    .theme-btn {
        padding: 4px 6px;
        font-size: 0.75rem;
    }
    
    .font-btn {
        width: 24px;
        height: 24px;
        font-size: 0.8rem;
    }
    
    .font-size-val {
        font-size: 0.8rem;
        min-width: 14px;
    }
    
    .header-btn {
        width: 32px;
        height: 32px;
        font-size: 0.9rem;
    }

    .container {
        padding: 0 16px;
    }

    .bottom-sheet-content {
        padding: 20px 20px 32px 20px;
    }
}

/* ==========================================================================
   COPYRIGHT NOTICES
   ========================================================================== */
.landing-footer {
    margin-top: 30px;
    font-size: 0.85rem;
    color: var(--text-color);
    opacity: 0.6;
    text-align: center;
    font-family: var(--font-ui);
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
    padding: 0 20px;
}

.chapter-copyright {
    margin-top: 60px;
    text-align: center;
    opacity: 0.6;
    font-size: 0.85rem;
}

.chapter-copyright hr {
    margin-bottom: 25px !important;
    border: none;
    border-top: 1px dashed var(--border-color);
    width: 60%;
    margin-left: auto;
    margin-right: auto;
}

.chapter-copyright p {
    text-indent: 0 !important;
    text-align: center !important;
    line-height: 1.6;
}