/* MyNextLesson - Enterprise Educational Synthesis Platform */
/* Consolidated styles with performance optimizations and accessibility compliance */

:root {
    /* Color System */
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --primary-light: #3b82f6;
    --secondary-color: #7c3aed;
    --secondary-dark: #6d28d9;
    --accent-color: #f59e0b;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
    
    /* Text Colors */
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-muted: #9ca3af;
    --text-inverse: #ffffff;
    
    /* Background Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --bg-overlay: rgba(0, 0, 0, 0.5);
    --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    
    /* Border System */
    --border-color: #e5e7eb;
    --border-radius: 12px;
    --border-radius-lg: 16px;
    --border-radius-sm: 6px;
    
    /* Shadow System */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    
    /* Spacing */
    --spacing-1: 0.25rem;
    --spacing-2: 0.5rem;
    --spacing-3: 0.75rem;
    --spacing-4: 1rem;
    --spacing-5: 1.25rem;
    --spacing-6: 1.5rem;
    --spacing-8: 2rem;
    --spacing-10: 2.5rem;
    --spacing-12: 3rem;
    
    /* Transitions */
    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-fast: all 0.1s ease;
    --transition-slow: all 0.3s ease;
    
    /* Performance Budgets */
    --synthesis-time: 200ms;
    --initial-load: 3000ms;
    --cache-hit: 10ms;
    --parameter-change: 50ms;
}

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

*::before,
*::after {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-family);
    color: var(--text-primary);
    background: var(--bg-gradient);
    min-height: 100vh;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    text-rendering: optimizeLegibility;
}

/* Accessibility */
.skip-link {
    position: absolute;
    top: -40px;
    left: 6px;
    background: var(--primary-color);
    color: var(--text-inverse);
    padding: 8px;
    text-decoration: none;
    border-radius: var(--border-radius-sm);
    z-index: 10000;
    transition: var(--transition);
}

.skip-link:focus {
    top: 6px;
}

.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;
}

/* Focus Management */
*:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

*:focus:not(:focus-visible) {
    outline: none;
}

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

/* Header */
.header {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    padding: var(--spacing-4) var(--spacing-8);
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
}

.logo h1 {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: var(--spacing-1);
}

.tagline {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    font-weight: 500;
}

.live-indicator {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    background: var(--success-color);
    color: var(--text-inverse);
    padding: var(--spacing-2) var(--spacing-4);
    border-radius: var(--border-radius);
    font-size: var(--font-size-sm);
    font-weight: 600;
}

.pulse {
    width: 8px;
    height: 8px;
    background: var(--text-inverse);
    border-radius: 50%;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0% { opacity: 1; }
    50% { opacity: 0.5; }
    100% { opacity: 1; }
}

/* Main Content */
.main-content {
    flex: 1;
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: var(--spacing-8);
    padding: var(--spacing-8);
    max-width: 1400px;
    margin: 0 auto;
    width: 100%;
}

/* Controls Panel */
.controls-panel {
    background: var(--bg-primary);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-8);
    box-shadow: var(--shadow-lg);
    height: fit-content;
    position: sticky;
    top: 100px;
}

.controls-panel h2 {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-2);
}

.description {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-6);
    font-size: var(--font-size-sm);
}

.control-group {
    margin-bottom: var(--spacing-6);
}

.control-group label {
    display: block;
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-3);
}

/* Age Control */
.age-control {
    display: flex;
    align-items: center;
    gap: var(--spacing-4);
    margin-bottom: var(--spacing-3);
}

.slider {
    flex: 1;
    height: 6px;
    border-radius: 3px;
    background: var(--bg-tertiary);
    outline: none;
    cursor: pointer;
    appearance: none;
    -webkit-appearance: none;
    transition: var(--transition);
}

.slider::-webkit-slider-thumb {
    appearance: none;
    -webkit-appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.slider::-webkit-slider-thumb:hover {
    background: var(--primary-dark);
    transform: scale(1.1);
    box-shadow: var(--shadow-md);
}

.slider::-moz-range-thumb {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    border: none;
    box-shadow: var(--shadow-sm);
}

.age-display {
    display: flex;
    flex-direction: column;
    align-items: center;
    min-width: 60px;
}

#age-value {
    font-size: var(--font-size-lg);
    font-weight: 700;
    color: var(--primary-color);
}

.age-markers {
    display: flex;
    justify-content: space-between;
    font-size: var(--font-size-xs);
    color: var(--text-muted);
    margin-top: var(--spacing-2);
}

/* Tone Control */
.tone-buttons {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-3);
}

.tone-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-3);
    padding: var(--spacing-4);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    background: var(--bg-primary);
    cursor: pointer;
    transition: var(--transition);
    text-align: left;
    font-family: inherit;
}

.tone-btn:hover {
    border-color: var(--primary-color);
    background: var(--bg-secondary);
}

.tone-btn.active {
    border-color: var(--primary-color);
    background: var(--primary-color);
    color: var(--text-inverse);
}

.tone-emoji {
    font-size: var(--font-size-xl);
}

.tone-name {
    font-weight: 600;
    font-size: var(--font-size-sm);
}

.tone-desc {
    font-size: var(--font-size-xs);
    opacity: 0.8;
}

/* Language Control */
.language-select {
    width: 100%;
    padding: var(--spacing-3);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    background: var(--bg-primary);
    font-family: inherit;
    font-size: var(--font-size-sm);
    cursor: pointer;
    transition: var(--transition);
}

.language-select:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* Synthesis Stats */
.synthesis-stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-4);
    margin-top: var(--spacing-6);
    padding-top: var(--spacing-6);
    border-top: 1px solid var(--border-color);
}

.stat {
    text-align: center;
}

.stat-value {
    display: block;
    font-size: var(--font-size-lg);
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: var(--spacing-1);
}

.stat-label {
    font-size: var(--font-size-xs);
    color: var(--text-muted);
}

/* Lesson Panel */
.lesson-panel {
    background: var(--bg-primary);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-8);
    box-shadow: var(--shadow-lg);
    display: flex;
    flex-direction: column;
}

.lesson-header {
    margin-bottom: var(--spacing-6);
}

.lesson-header h2 {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-4);
    line-height: 1.3;
}

.lesson-meta {
    display: flex;
    gap: var(--spacing-4);
    align-items: center;
}

.lesson-meta span {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    padding: var(--spacing-1) var(--spacing-3);
    background: var(--bg-secondary);
    border-radius: var(--border-radius-sm);
}

#lesson-complexity {
    color: var(--accent-color);
    font-weight: 600;
}

#lesson-duration {
    color: var(--success-color);
    font-weight: 600;
}

.synthesis-indicator {
    color: var(--primary-color);
    font-weight: 600;
}

.synthesis-indicator.synthesizing {
    color: var(--warning-color);
    animation: pulse 1s infinite;
}

/* Avatar */
.avatar-container {
    display: flex;
    align-items: center;
    gap: var(--spacing-4);
    margin-bottom: var(--spacing-6);
    padding: var(--spacing-4);
    background: var(--bg-secondary);
    border-radius: var(--border-radius);
}

.avatar {
    width: 60px;
    height: 60px;
    background: var(--primary-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.avatar:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-md);
}

.avatar-face {
    width: 40px;
    height: 40px;
    position: relative;
}

.avatar-eyes {
    position: absolute;
    top: 10px;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--text-inverse);
    border-radius: 2px;
}

.avatar-mouth {
    position: absolute;
    bottom: 8px;
    left: 50%;
    transform: translateX(-50%);
    width: 20px;
    height: 8px;
    border: 2px solid var(--text-inverse);
    border-top: none;
    border-radius: 0 0 20px 20px;
}

.avatar-name {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--text-primary);
}

/* Lesson Content */
.lesson-content {
    flex: 1;
    margin-bottom: var(--spacing-6);
}

.lesson-section {
    margin-bottom: var(--spacing-6);
    padding: var(--spacing-4);
    background: var(--bg-secondary);
    border-radius: var(--border-radius);
    border-left: 4px solid var(--primary-color);
    transition: var(--transition);
}

.lesson-section h3 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-3);
}

.lesson-section p {
    color: var(--text-secondary);
    line-height: 1.7;
}

.lesson-section.updating {
    background: var(--bg-tertiary);
    animation: shimmer 1.5s infinite;
}

@keyframes shimmer {
    0% { opacity: 1; }
    50% { opacity: 0.7; }
    100% { opacity: 1; }
}

/* Lesson Controls */
.lesson-controls {
    display: flex;
    gap: var(--spacing-4);
    margin-top: auto;
}

.btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    padding: var(--spacing-3) var(--spacing-6);
    border: none;
    border-radius: var(--border-radius);
    font-family: inherit;
    font-size: var(--font-size-sm);
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    justify-content: center;
    min-height: 44px;
}

.btn-primary {
    background: var(--primary-color);
    color: var(--text-inverse);
    flex: 1;
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 2px solid var(--border-color);
}

.btn-secondary:hover {
    background: var(--bg-tertiary);
    border-color: var(--text-secondary);
}

/* Footer */
.footer {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-top: 1px solid var(--border-color);
    padding: var(--spacing-6) var(--spacing-8);
    text-align: center;
}

.footer-content p {
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    margin-bottom: var(--spacing-2);
}

.footer-content p:first-child {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-3);
}

/* Loading Overlay */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--bg-overlay);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
}

.loading-overlay.active {
    opacity: 1;
    visibility: visible;
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--bg-primary);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: var(--spacing-4);
}

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

.loading-overlay p {
    color: var(--text-inverse);
    font-size: var(--font-size-lg);
    font-weight: 500;
}

/* Error Boundary */
.error-boundary {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--bg-overlay);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1001;
}

.error-content {
    background: var(--bg-primary);
    padding: var(--spacing-8);
    border-radius: var(--border-radius-lg);
    text-align: center;
    max-width: 400px;
    box-shadow: var(--shadow-xl);
}

.error-content h3 {
    color: var(--danger-color);
    margin-bottom: var(--spacing-4);
}

.error-content p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-6);
}

/* Responsive Design */
@media (max-width: 1024px) {
    .main-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-6);
        padding: var(--spacing-6);
    }
    
    .controls-panel {
        position: static;
        order: 2;
    }
    
    .lesson-panel {
        order: 1;
    }
}

@media (max-width: 768px) {
    .header {
        padding: var(--spacing-3) var(--spacing-4);
        flex-direction: column;
        gap: var(--spacing-3);
    }
    
    .main-content {
        padding: var(--spacing-4);
    }
    
    .controls-panel,
    .lesson-panel {
        padding: var(--spacing-6);
    }
    
    .lesson-controls {
        flex-direction: column;
    }
    
    .synthesis-stats {
        grid-template-columns: 1fr;
    }
    
    .lesson-meta {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-2);
    }
}

@media (max-width: 480px) {
    .controls-panel,
    .lesson-panel {
        padding: var(--spacing-4);
    }
    
    .lesson-header h2 {
        font-size: var(--font-size-xl);
    }
    
    .tone-buttons {
        gap: var(--spacing-2);
    }
    
    .tone-btn {
        padding: var(--spacing-3);
    }
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
    :root {
        --border-color: #000000;
        --text-secondary: #000000;
        --bg-secondary: #ffffff;
        --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
        --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
        --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.3);
    }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    .pulse {
        animation: none;
    }
    
    .loading-spinner {
        animation: none;
    }
}

/* Print Styles */
@media print {
    .header,
    .controls-panel,
    .lesson-controls,
    .footer {
        display: none;
    }
    
    .main-content {
        grid-template-columns: 1fr;
        padding: 0;
    }
    
    .lesson-panel {
        box-shadow: none;
        border: 1px solid var(--border-color);
    }
}