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

:root {
    /* Color Palette */
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #818cf8;
    --secondary: #f59e0b;
    --secondary-dark: #d97706;
    
    --success: #10b981;
    --warning: #f59e0b;
    --error: #ef4444;
    --info: #3b82f6;
    
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    
    --white: #ffffff;
    --black: #000000;
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-hero: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #d946ef 100%);
    --gradient-card: linear-gradient(145deg, #ffffff 0%, #f8fafc 100%);
    
    /* Typography */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
    --font-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, 'Courier New', monospace;
    
    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 2.5rem;
    --space-3xl: 3rem;
    --space-4xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
    --shadow-2xl: 0 25px 50px -12px rgb(0 0 0 / 0.25);
    
    /* Transitions */
    --transition-fast: 0.15s ease-out;
    --transition-normal: 0.3s ease-out;
    --transition-slow: 0.5s ease-out;
}

/* Dark Mode Variables */
[data-theme="dark"] {
    --gray-50: #1f2937;
    --gray-100: #374151;
    --gray-200: #4b5563;
    --gray-300: #6b7280;
    --gray-400: #9ca3af;
    --gray-500: #d1d5db;
    --gray-600: #e5e7eb;
    --gray-700: #f3f4f6;
    --gray-800: #f9fafb;
    --gray-900: #ffffff;
    
    --white: #111827;
    --gradient-card: linear-gradient(145deg, #1f2937 0%, #374151 100%);
}

/* Base Styles */
html {
    height: 100%;
    scroll-behavior: smooth;
}

body {
    height: 100vh;
    font-family: var(--font-primary);
    background: var(--gradient-hero);
    color: var(--gray-700);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

/* App Container */
#app {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    position: relative;
}

/* Background Pattern */
.bg-pattern {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0.03;
    background-image: 
        radial-gradient(circle at 25% 25%, white 2px, transparent 2px),
        radial-gradient(circle at 75% 75%, white 2px, transparent 2px);
    background-size: 60px 60px;
    pointer-events: none;
    z-index: 0;
}

/* Loading Screen */
.loading-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    backdrop-filter: blur(8px);
}

.loading-content {
    text-align: center;
    color: white;
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-top: 3px solid white;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto var(--space-lg);
}

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

/* Header */
.header {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    box-shadow: var(--shadow-sm);
    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
    position: relative;
    z-index: 100;
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--space-md) var(--space-xl);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-lg);
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.logo-icon {
    font-size: 1.5rem;
    animation: bounce 2s infinite;
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% { transform: translateY(0); }
    40% { transform: translateY(-3px); }
    60% { transform: translateY(-2px); }
}

.logo h1 {
    font-size: 1.4rem;
    font-weight: 700;
    background: var(--gradient-hero);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.beta-tag {
    background: var(--secondary);
    color: white;
    font-size: 0.65rem;
    font-weight: 600;
    padding: 2px var(--space-xs);
    border-radius: var(--radius-sm);
    text-transform: uppercase;
    letter-spacing: 0.025em;
}

.header-controls {
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

/* File Upload */
.file-upload-wrapper {
    position: relative;
}

.file-upload-wrapper input[type="file"] {
    position: absolute;
    opacity: 0;
    width: 1px;
    height: 1px;
    overflow: hidden;
}

.file-upload-btn {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
    padding: var(--space-sm) var(--space-md);
    background: var(--gray-100);
    border: 1px dashed var(--gray-300);
    border-radius: var(--radius-md);
    color: var(--gray-600);
    font-weight: 500;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.file-upload-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
    background: rgba(99, 102, 241, 0.05);
}

.upload-icon {
    font-size: 1.2em;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--space-xs);
    padding: var(--space-sm) var(--space-lg);
    font-weight: 600;
    border-radius: var(--radius-md);
    border: none;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all var(--transition-normal);
    text-decoration: none;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s;
}

.btn:hover::before {
    left: 100%;
}

.btn-primary {
    background: var(--gradient-hero);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

.btn-icon {
    font-size: 1.1em;
}

/* Main Content */
.main-content {
    flex: 1;
    position: relative;
    z-index: 10;
}

/* Welcome Screen */
.welcome-screen {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: calc(100vh - 140px);
    padding: var(--space-xl) var(--space-xl);
}

.welcome-content {
    text-align: center;
    max-width: 800px;
}

.welcome-hero {
    margin-bottom: var(--space-2xl);
}

.hero-icon {
    font-size: 3rem;
    margin-bottom: var(--space-lg);
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

.welcome-hero h2 {
    font-size: 2rem;
    font-weight: 700;
    color: white;
    margin-bottom: var(--space-md);
    text-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

.welcome-hero p {
    font-size: 1.1rem;
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: var(--space-lg);
}

/* Features Grid */
.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-md);
    margin-top: var(--space-xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.feature-card {
    background: var(--gradient-card);
    padding: var(--space-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
    border: 1px solid rgba(255, 255, 255, 0.3);
    backdrop-filter: blur(10px);
    text-align: center;
}

.feature-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    font-size: 1.8rem;
    margin-bottom: var(--space-sm);
    display: block;
}

.feature-card h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--gray-800);
    margin-bottom: var(--space-xs);
}

.feature-card p {
    color: var(--gray-600);
    font-size: 0.85rem;
    line-height: 1.4;
}

/* Presentation Area */
.presentation-area {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--space-4xl) var(--space-xl);
    display: flex;
    flex-direction: column;
    min-height: calc(100vh - 200px);
}

.slide-container {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--space-lg);
}

.content-display {
    width: 100%;
    max-width: 900px;
    min-height: 500px;
    background: var(--gradient-card);
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-2xl);
    border: 1px solid rgba(255, 255, 255, 0.3);
    backdrop-filter: blur(20px);
    padding: var(--space-4xl);
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.content-display::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.5), transparent);
}

.slide-placeholder {
    color: var(--gray-400);
    text-align: center;
}

.placeholder-icon {
    font-size: 3rem;
    margin-bottom: var(--space-lg);
    opacity: 0.5;
}

/* Current Line Styles */
.current-line {
    animation: slideIn 0.6s ease-out;
    width: 100%;
    max-width: 100%;
    word-wrap: break-word;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.current-line h1 {
    font-size: clamp(2rem, 5vw, 4rem);
    font-weight: 700;
    color: var(--gray-800);
    margin: 0;
    line-height: 1.2;
    background: var(--gradient-hero);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.current-line h2 {
    font-size: clamp(1.75rem, 4vw, 3rem);
    font-weight: 600;
    color: var(--gray-700);
    margin: 0;
    line-height: 1.3;
}

.current-line h3 {
    font-size: clamp(1.5rem, 3vw, 2.5rem);
    font-weight: 600;
    color: var(--gray-600);
    margin: 0;
    line-height: 1.3;
}

.current-line h4 {
    font-size: clamp(1.25rem, 2.5vw, 2rem);
    font-weight: 500;
    color: var(--gray-600);
    margin: 0;
}

.current-line p {
    font-size: clamp(1.125rem, 2vw, 1.5rem);
    color: var(--gray-700);
    margin: 0;
    max-width: 90%;
    margin: 0 auto;
    line-height: 1.6;
}

.current-line li {
    font-size: clamp(1rem, 1.8vw, 1.3rem);
    color: var(--gray-700);
    margin: var(--space-md) 0;
    list-style: none;
    position: relative;
    padding-left: var(--space-xl);
}

.current-line li::before {
    content: "▶";
    color: var(--primary);
    font-weight: bold;
    position: absolute;
    left: 0;
}

.current-line blockquote {
    font-size: clamp(1rem, 1.8vw, 1.3rem);
    font-style: italic;
    color: var(--gray-600);
    background: rgba(99, 102, 241, 0.1);
    border-left: 4px solid var(--primary);
    padding: var(--space-xl);
    border-radius: var(--radius-lg);
    margin: 0;
    position: relative;
}

.current-line blockquote::before {
    content: '"';
    font-size: 4rem;
    color: var(--primary);
    position: absolute;
    top: -10px;
    left: 10px;
    opacity: 0.3;
}

.current-line code {
    background: var(--gray-100);
    color: var(--primary-dark);
    padding: var(--space-sm) var(--space-md);
    border-radius: var(--radius-sm);
    font-family: var(--font-mono);
    font-size: 0.9em;
    font-weight: 500;
}

.current-line pre {
    background: var(--gray-800);
    color: var(--gray-100);
    padding: var(--space-xl);
    border-radius: var(--radius-lg);
    margin: 0;
    text-align: left;
    max-width: 90%;
    margin: 0 auto;
    font-family: var(--font-mono);
    font-size: 0.9rem;
    overflow-x: auto;
    box-shadow: var(--shadow-lg);
}

/* Navigation */
.navigation {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-lg);
    padding: var(--space-md) var(--space-lg);
    background: rgba(255, 255, 255, 0.9);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-sm);
    border: 1px solid rgba(255, 255, 255, 0.3);
    backdrop-filter: blur(10px);
    margin-top: var(--space-lg);
}

.nav-btn {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
    padding: var(--space-sm) var(--space-md);
    background: transparent;
    color: var(--gray-600);
    border: 1px solid var(--gray-300);
    border-radius: var(--radius-md);
    font-weight: 500;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition-fast);
    min-width: auto;
}

.nav-btn:hover:not(:disabled) {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.nav-btn:active:not(:disabled) {
    transform: translateY(0);
}

.nav-btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
    transform: none;
    color: var(--gray-400);
    border-color: var(--gray-200);
}

.nav-icon {
    font-size: 1.1rem;
    font-weight: bold;
}

.nav-text {
    font-size: 0.85rem;
}

/* Progress Section */
.progress-section {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    min-width: 160px;
}

.progress-bar {
    flex: 1;
    height: 4px;
    background: var(--gray-200);
    border-radius: var(--radius-sm);
    overflow: hidden;
    position: relative;
}

.progress-fill {
    height: 100%;
    background: var(--gradient-hero);
    border-radius: var(--radius-md);
    transition: width var(--transition-normal);
    position: relative;
}

.progress-fill::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    animation: shimmer 2s infinite;
}

@keyframes shimmer {
    0% { transform: translateX(-100%); }
    100% { transform: translateX(100%); }
}

.progress-text {
    font-weight: 500;
    color: var(--gray-600);
    font-size: 0.8rem;
    white-space: nowrap;
}

/* Control Panel */
.control-panel {
    position: fixed;
    top: 50%;
    right: var(--space-xl);
    transform: translateY(-50%);
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
    z-index: 50;
}

.control-btn {
    width: 48px;
    height: 48px;
    background: var(--gradient-card);
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-md);
    backdrop-filter: blur(10px);
}

.control-btn:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-lg);
}

.control-icon {
    font-size: 1.2rem;
}

/* Footer */
.footer {
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(20px);
    border-top: 1px solid rgba(255, 255, 255, 0.2);
    margin-top: auto;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--space-xl);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-xl);
}

.shortcuts h4 {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--gray-700);
    margin-bottom: var(--space-sm);
}

.shortcut-list {
    display: flex;
    gap: var(--space-lg);
    flex-wrap: wrap;
}

.shortcut {
    font-size: 0.85rem;
    color: var(--gray-600);
}

kbd {
    background: var(--gray-200);
    color: var(--gray-700);
    padding: var(--space-xs) var(--space-sm);
    border-radius: var(--radius-sm);
    font-family: var(--font-mono);
    font-size: 0.8em;
    font-weight: 600;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--gray-300);
}

.footer-info {
    color: var(--gray-500);
    font-size: 0.9rem;
}

/* Utility Classes */
.hidden {
    display: none !important;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Responsive Design */
@media (max-width: 900px) and (min-width: 769px) {
    .features-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: var(--space-sm);
        max-width: 500px;
    }
    
    .feature-card {
        padding: var(--space-md);
    }
    
    .feature-card h3 {
        font-size: 0.95rem;
    }
    
    .feature-card p {
        font-size: 0.8rem;
    }
}

@media (max-width: 768px) {
    .header-content {
        padding: var(--space-sm) var(--space-lg);
        flex-direction: column;
        gap: var(--space-md);
    }
    
    .header-controls {
        width: 100%;
        justify-content: center;
    }
    
    .welcome-hero h2 {
        font-size: 1.6rem;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
        gap: var(--space-sm);
        margin-top: var(--space-lg);
        max-width: 300px;
    }
    
    .presentation-area {
        padding: var(--space-xl) var(--space-lg);
    }
    
    .content-display {
        padding: var(--space-xl);
        min-height: 400px;
    }
    
    .navigation {
        flex-direction: row;
        gap: var(--space-sm);
        padding: var(--space-sm) var(--space-md);
    }
    
    .nav-btn {
        flex: 1;
        justify-content: center;
        padding: var(--space-sm);
    }
    
    .progress-section {
        min-width: 120px;
    }
    
    .control-panel {
        position: static;
        transform: none;
        flex-direction: row;
        justify-content: center;
        margin-top: var(--space-xl);
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
        gap: var(--space-lg);
    }
    
    .shortcut-list {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .logo h1 {
        font-size: 1.5rem;
    }
    
    .welcome-hero h2 {
        font-size: 1.75rem;
    }
    
    .feature-card {
        padding: var(--space-xl);
    }
    
    .content-display {
        padding: var(--space-lg);
    }
    
    .shortcut-list {
        flex-direction: column;
        align-items: center;
    }
}

/* Print Styles */
@media print {
    .header,
    .navigation,
    .control-panel,
    .footer {
        display: none;
    }
    
    .content-display {
        box-shadow: none;
        border: 1px solid #ccc;
    }
}