/* Google Fonts Import */
@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+TC:wght@300;400;500;700&family=Noto+Serif+TC:wght@400;600;700&display=swap');

/* CSS Reset & Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Light Theme (Default) */
    --bg-primary: #ffffff;
    --bg-secondary: #f5f5f7;
    --text-primary: #1d1d1f;
    --text-secondary: #515154;
    --accent-color: #0066cc;
    --border-color: #d2d2d7;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --scrollbar-thumb: #c1c1c1;
    --scrollbar-track: #f1f1f1;
    
    /* Font Variables */
    --base-font-size: 18px;
    --line-height: 1.8;
    --font-family: 'Noto Sans TC', sans-serif;
    --content-width: 80%;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    
    /* Animation */
    --transition-speed: 0.3s;
}

/* Dark Mode Theme */
body.dark-mode {
    --bg-primary: #121212;
    --bg-secondary: #1e1e1e;
    --text-primary: #e0e0e0;
    --text-secondary: #a0a0a0;
    --accent-color: #79b8ff;
    --border-color: #333333;
    --shadow-color: rgba(0, 0, 0, 0.4);
    --scrollbar-thumb: #555555;
    --scrollbar-track: #2c2c2c;
}

/* Sepia Theme */
body.sepia-mode {
    --bg-primary: #f8f1e3;
    --bg-secondary: #f1e7d5;
    --text-primary: #5f4b32;
    --text-secondary: #7a6b55;
    --accent-color: #9e7e57;
    --border-color: #d3c7b1;
    --shadow-color: rgba(95, 75, 50, 0.1);
    --scrollbar-thumb: #c2b59b;
    --scrollbar-track: #f1e7d5;
}

body {
    font-family: var(--font-family);
    font-size: var(--base-font-size);
    line-height: var(--line-height);
    color: var(--text-primary);
    background-color: var(--bg-primary);
    transition: background-color var(--transition-speed), color var(--transition-speed);
}

/* Scrollbar Styling */
::-webkit-scrollbar {
    width: 10px;
}

::-webkit-scrollbar-track {
    background: var(--scrollbar-track);
}

::-webkit-scrollbar-thumb {
    background: var(--scrollbar-thumb);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-secondary);
}

/* App Container */
.app-container {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* Header Styles */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-lg);
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 10;
}

.header-title {
    display: flex;
    align-items: center;
}

.header-title h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.header-controls {
    display: flex;
    gap: var(--spacing-md);
}

header button {
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.2rem;
    cursor: pointer;
    padding: var(--spacing-sm);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color var(--transition-speed);
}

header button:hover {
    background-color: var(--border-color);
}

.mobile-menu-button {
    display: none;
    margin-right: var(--spacing-md);
}

/* Main Container */
.main-container {
    display: flex;
    flex: 1;
    position: relative;
}

/* Sidebar Styles */
#sidebar {
    width: 280px;
    background-color: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    overflow-y: auto;
    height: calc(100vh - 60px);
    position: sticky;
    top: 60px;
    transition: transform var(--transition-speed);
}

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

.sidebar-header h2 {
    font-size: 1.2rem;
    font-weight: 500;
}

.sidebar-close-button {
    display: none;
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.2rem;
    cursor: pointer;
}

/* Volumes Container */
.volumes-container {
    display: flex;
    overflow-x: auto;
    border-bottom: 1px solid var(--border-color);
    padding: var(--spacing-sm) 0;
}

.volume-tab {
    padding: var(--spacing-sm) var(--spacing-md);
    white-space: nowrap;
    cursor: pointer;
    color: var(--text-secondary);
    transition: color var(--transition-speed);
}

.volume-tab.active {
    color: var(--accent-color);
    font-weight: 500;
    border-bottom: 2px solid var(--accent-color);
}

/* Chapters Container */
.chapters-container {
    padding: var(--spacing-sm) 0;
}

.chapter-link {
    display: block;
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--text-primary);
    text-decoration: none;
    transition: background-color var(--transition-speed);
    cursor: pointer;
}

.chapter-link.active {
    background-color: rgba(var(--accent-color-rgb), 0.1);
    color: var(--accent-color);
    font-weight: 500;
}

.chapter-link:hover {
    background-color: var(--border-color);
}

/* Main Content */
main {
    flex: 1;
    padding: var(--spacing-lg);
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.chapter-container {
    width: var(--content-width);
    max-width: 1200px;
}

.chapter-header {
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

.chapter-header h2 {
    font-size: 1.8rem;
    font-weight: 700;
}

.chapter-content {
    font-size: var(--base-font-size);
    line-height: var(--line-height);
}

.chapter-content h1, 
.chapter-content h2, 
.chapter-content h3 {
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
}

.chapter-content p {
    margin-bottom: var(--spacing-md);
    text-align: justify;
}

.chapter-content hr {
    margin: var(--spacing-xl) 0;
    border: none;
    border-top: 1px solid var(--border-color);
}

/* Chapter Navigation */
.chapter-navigation {
    display: flex;
    justify-content: space-between;
    width: var(--content-width);
    max-width: 1200px;
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-lg);
}

.nav-button {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: 4px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    transition: background-color var(--transition-speed);
}

.nav-button:hover:not(:disabled) {
    background-color: var(--border-color);
}

.nav-button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* Loading State */
.loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 30vh;
    color: var(--text-secondary);
}

.loading i {
    font-size: 2rem;
    margin-bottom: var(--spacing-md);
}

/* Settings Panel */
.settings-panel {
    position: fixed;
    top: 60px;
    right: 0;
    width: 320px;
    height: calc(100vh - 60px);
    background-color: var(--bg-primary);
    border-left: 1px solid var(--border-color);
    transform: translateX(100%);
    transition: transform var(--transition-speed);
    z-index: 100;
    overflow-y: auto;
    box-shadow: -5px 0 15px var(--shadow-color);
}

.settings-panel.visible {
    transform: translateX(0);
}

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

.settings-header h3 {
    font-size: 1.2rem;
    font-weight: 500;
}

.settings-header button {
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.2rem;
    cursor: pointer;
}

.settings-content {
    padding: var(--spacing-md);
}

.setting-group {
    margin-bottom: var(--spacing-lg);
}

.setting-group label {
    display: block;
    margin-bottom: var(--spacing-sm);
    color: var(--text-secondary);
    font-weight: 500;
}

.setting-group select {
    width: 100%;
    padding: var(--spacing-sm);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-family: var(--font-family);
    font-size: 0.9rem;
}

.range-container {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.range-container input[type="range"] {
    width: 80%;
}

.range-container span {
    width: 20%;
    text-align: right;
    font-size: 0.9rem;
}

.theme-options {
    display: flex;
    gap: var(--spacing-md);
}

.theme-button {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
    background: none;
    border: none;
    cursor: pointer;
    color: var(--text-secondary);
}

.theme-button.active {
    color: var(--accent-color);
}

.theme-preview {
    width: 60px;
    height: 40px;
    border-radius: 4px;
    border: 1px solid var(--border-color);
}

.light-preview {
    background-color: #ffffff;
    border: 1px solid #d2d2d7;
}

.sepia-preview {
    background-color: #f8f1e3;
    border: 1px solid #d3c7b1;
}

.dark-preview {
    background-color: #121212;
    border: 1px solid #333333;
}

/* Hidden Class */
.hidden {
    display: none;
}

/* Overlay for Mobile */
.overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 5;
}

/* Responsive Design */
@media (max-width: 1024px) {
    :root {
        --content-width: 90%;
    }
    
    #sidebar {
        width: 240px;
    }
}

@media (max-width: 768px) {
    .mobile-menu-button {
        display: block;
    }
    
    .sidebar-close-button {
        display: block;
    }
    
    #sidebar {
        position: fixed;
        left: 0;
        top: 0;
        height: 100vh;
        width: 280px;
        transform: translateX(-100%);
        z-index: 20;
        box-shadow: 5px 0 15px var(--shadow-color);
    }
    
    #sidebar.visible {
        transform: translateX(0);
    }
    
    .overlay.visible {
        display: block;
    }
    
    .settings-panel {
        width: 100%;
    }
    
    .chapter-navigation {
        width: 100%;
    }
}

@media (max-width: 480px) {
    :root {
        --spacing-md: 0.75rem;
        --spacing-lg: 1rem;
        --base-font-size: 16px;
    }
    
    header {
        padding: var(--spacing-sm) var(--spacing-md);
    }
    
    .header-title h1 {
        font-size: 1.2rem;
    }
    
    main {
        padding: var(--spacing-md);
    }
    
    .chapter-header h2 {
        font-size: 1.5rem;
    }
    
    .chapter-content {
        font-size: var(--base-font-size);
    }
}