/* ===== CSS Variables & Design Tokens ===== */
:root {
    /* Primary Colors */
    --primary-hue: 250;
    --primary-50: hsl(var(--primary-hue), 100%, 97%);
    --primary-100: hsl(var(--primary-hue), 100%, 94%);
    --primary-200: hsl(var(--primary-hue), 100%, 86%);
    --primary-300: hsl(var(--primary-hue), 100%, 76%);
    --primary-400: hsl(var(--primary-hue), 100%, 66%);
    --primary-500: hsl(var(--primary-hue), 100%, 60%);
    --primary-600: hsl(var(--primary-hue), 100%, 50%);
    --primary-700: hsl(var(--primary-hue), 100%, 42%);
    
    /* Accent Colors */
    --accent-green: hsl(152, 76%, 50%);
    --accent-green-light: hsl(152, 76%, 95%);
    --accent-red: hsl(0, 84%, 60%);
    --accent-red-light: hsl(0, 84%, 95%);
    --accent-yellow: hsl(45, 100%, 51%);
    --accent-orange: hsl(25, 100%, 55%);
    
    /* Neutral Colors */
    --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;
    
    /* Background */
    --bg-gradient-start: #0f0c29;
    --bg-gradient-mid: #302b63;
    --bg-gradient-end: #24243e;
    
    /* Glass Effect */
    --glass-bg: rgba(255, 255, 255, 0.1);
    --glass-border: rgba(255, 255, 255, 0.2);
    --glass-shadow: rgba(0, 0, 0, 0.3);
    
    /* Typography */
    --font-family: 'Outfit', -apple-system, BlinkMacSystemFont, sans-serif;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.5rem;
    --radius-md: 1rem;
    --radius-lg: 1.5rem;
    --radius-xl: 2rem;
    --radius-full: 9999px;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
    --transition-slow: 500ms ease;
}

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

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

body {
    font-family: var(--font-family);
    background: linear-gradient(135deg, var(--bg-gradient-start), var(--bg-gradient-mid), var(--bg-gradient-end));
    min-height: 100vh;
    color: white;
    line-height: 1.6;
    overflow-x: hidden;
}

/* ===== App Container ===== */
.app-container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-lg);
    position: relative;
}

/* ===== Background Decorations ===== */
.bg-decoration {
    position: fixed;
    border-radius: 50%;
    filter: blur(100px);
    opacity: 0.5;
    pointer-events: none;
    z-index: 0;
}

.bg-decoration-1 {
    width: 600px;
    height: 600px;
    background: var(--primary-500);
    top: -200px;
    right: -200px;
    animation: float 20s ease-in-out infinite;
}

.bg-decoration-2 {
    width: 400px;
    height: 400px;
    background: var(--accent-green);
    bottom: -100px;
    left: -100px;
    animation: float 25s ease-in-out infinite reverse;
}

.bg-decoration-3 {
    width: 300px;
    height: 300px;
    background: var(--accent-orange);
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    animation: pulse 15s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0); }
    25% { transform: translate(-30px, 30px); }
    50% { transform: translate(20px, -20px); }
    75% { transform: translate(-20px, -30px); }
}

@keyframes pulse {
    0%, 100% { opacity: 0.3; transform: translate(-50%, -50%) scale(1); }
    50% { opacity: 0.5; transform: translate(-50%, -50%) scale(1.2); }
}

/* ===== Screen Transitions ===== */
.screen {
    display: none;
    width: 100%;
    max-width: 600px;
    animation: fadeIn 0.5s ease;
    position: relative;
    z-index: 1;
}

.screen.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ===== Glass Card ===== */
.glass-card {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-2xl);
    box-shadow: 0 25px 50px -12px var(--glass-shadow);
}

/* ===== Start Screen ===== */
.start-card {
    text-align: center;
}

.logo-container {
    margin-bottom: var(--spacing-lg);
}

.logo-icon {
    font-size: 4rem;
    animation: bounce 2s ease-in-out infinite;
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

.logo-text {
    font-size: 2.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, #fff, var(--primary-200));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-top: var(--spacing-sm);
}

.subtitle {
    color: var(--gray-300);
    font-size: 1.1rem;
    margin-bottom: var(--spacing-xl);
}

/* ===== Category Selector ===== */
.category-selector {
    margin-bottom: var(--spacing-xl);
}

.category-selector h3 {
    font-size: 1rem;
    font-weight: 500;
    color: var(--gray-300);
    margin-bottom: var(--spacing-md);
}

.category-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-md);
}

.category-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-lg);
    background: rgba(255, 255, 255, 0.05);
    border: 2px solid transparent;
    border-radius: var(--radius-lg);
    color: var(--gray-300);
    cursor: pointer;
    transition: all var(--transition-normal);
}

.category-btn:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: translateY(-2px);
}

.category-btn.active {
    border-color: var(--primary-400);
    background: rgba(99, 102, 241, 0.2);
    color: white;
}

.category-icon {
    font-size: 2rem;
}

.category-name {
    font-size: 0.9rem;
    font-weight: 500;
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    border: none;
    border-radius: var(--radius-full);
    font-family: var(--font-family);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-500), var(--primary-600));
    color: white;
    box-shadow: 0 10px 30px -5px rgba(99, 102, 241, 0.5);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 15px 40px -5px rgba(99, 102, 241, 0.6);
}

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

.btn-secondary {
    background: rgba(255, 255, 255, 0.1);
    color: white;
    border: 1px solid var(--glass-border);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.2);
}

.btn-large {
    padding: var(--spacing-lg) var(--spacing-2xl);
    font-size: 1.1rem;
}

/* ===== Quiz Screen ===== */
.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
    gap: var(--spacing-lg);
}

.progress-container {
    flex: 1;
}

.progress-info {
    display: flex;
    justify-content: space-between;
    margin-bottom: var(--spacing-sm);
    font-size: 0.9rem;
    color: var(--gray-300);
}

.timer {
    color: var(--accent-yellow);
    font-weight: 600;
}

.timer.warning {
    color: var(--accent-red);
    animation: pulse-text 0.5s ease-in-out infinite;
}

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

.progress-bar {
    height: 8px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-400), var(--accent-green));
    border-radius: var(--radius-full);
    transition: width var(--transition-normal);
}

.score-display {
    display: flex;
    flex-direction: column;
    align-items: center;
    background: rgba(255, 255, 255, 0.1);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
}

.score-label {
    font-size: 0.75rem;
    color: var(--gray-400);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.score-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-yellow);
}

/* ===== Question Card ===== */
.question-card {
    margin-bottom: var(--spacing-lg);
}

.question-category {
    margin-bottom: var(--spacing-lg);
}

.category-badge {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-md);
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-full);
    font-size: 0.85rem;
    color: var(--gray-300);
}

.question-text {
    font-size: 1.4rem;
    font-weight: 600;
    line-height: 1.5;
    margin-bottom: var(--spacing-xl);
    color: white;
}

/* ===== Options ===== */
.options-container {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.option-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
    background: rgba(255, 255, 255, 0.05);
    border: 2px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-lg);
    color: white;
    font-family: var(--font-family);
    font-size: 1rem;
    text-align: left;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.option-btn:hover:not(:disabled) {
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--primary-400);
    transform: translateX(5px);
}

.option-btn:disabled {
    cursor: not-allowed;
}

.option-btn.correct {
    background: var(--accent-green-light);
    border-color: var(--accent-green);
    color: var(--gray-800);
}

.option-btn.wrong {
    background: var(--accent-red-light);
    border-color: var(--accent-red);
    color: var(--gray-800);
}

.option-label {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-sm);
    font-weight: 600;
    flex-shrink: 0;
}

.option-btn.correct .option-label,
.option-btn.wrong .option-label {
    background: rgba(0, 0, 0, 0.1);
}

.option-text {
    flex: 1;
}

/* ===== Feedback ===== */
.feedback-container {
    margin-top: var(--spacing-xl);
    padding: var(--spacing-lg);
    background: rgba(0, 0, 0, 0.2);
    border-radius: var(--radius-lg);
    animation: slideIn 0.3s ease;
}

.feedback-container.hidden {
    display: none;
}

@keyframes slideIn {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}

.feedback-message {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

.feedback-message.correct {
    color: var(--accent-green);
}

.feedback-message.wrong {
    color: var(--accent-red);
}

.explanation {
    color: var(--gray-300);
    font-size: 0.95rem;
    line-height: 1.6;
}

/* ===== Next Button ===== */
.btn-next {
    width: 100%;
    padding: var(--spacing-lg);
}

.btn-next.hidden {
    display: none;
}

/* ===== Result Screen ===== */
.result-card {
    text-align: center;
}

.result-icon {
    font-size: 5rem;
    margin-bottom: var(--spacing-md);
    animation: celebrate 0.6s ease;
}

@keyframes celebrate {
    0% { transform: scale(0); }
    50% { transform: scale(1.2); }
    100% { transform: scale(1); }
}

.result-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
}

.result-message {
    color: var(--gray-300);
    margin-bottom: var(--spacing-xl);
}

/* ===== Score Circle ===== */
.score-circle-container {
    display: flex;
    justify-content: center;
    margin-bottom: var(--spacing-xl);
}

.score-circle {
    position: relative;
    width: 180px;
    height: 180px;
}

.score-ring {
    width: 100%;
    height: 100%;
    transform: rotate(-90deg);
}

.score-ring-bg {
    fill: none;
    stroke: rgba(255, 255, 255, 0.1);
    stroke-width: 8;
}

.score-ring-progress {
    fill: none;
    stroke: url(#scoreGradient);
    stroke-width: 8;
    stroke-linecap: round;
    stroke-dasharray: 339.292;
    stroke-dashoffset: 339.292;
    transition: stroke-dashoffset 1.5s ease-out;
}

.score-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
}

.final-score {
    display: block;
    font-size: 3rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--accent-yellow), var(--accent-orange));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.score-max {
    font-size: 1rem;
    color: var(--gray-400);
}

/* ===== Stats Grid ===== */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-md);
    background: rgba(255, 255, 255, 0.05);
    border-radius: var(--radius-md);
}

.stat-icon {
    font-size: 1.5rem;
}

.stat-value {
    font-size: 1.5rem;
    font-weight: 700;
}

.stat-label {
    font-size: 0.8rem;
    color: var(--gray-400);
}

/* ===== Result Actions ===== */
.result-actions {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
}

.result-actions .btn {
    flex: 1;
    max-width: 200px;
}

/* ===== Responsive Design ===== */
@media (max-width: 640px) {
    .app-container {
        padding: var(--spacing-md);
    }
    
    .glass-card {
        padding: var(--spacing-lg);
    }
    
    .logo-text {
        font-size: 2rem;
    }
    
    .question-text {
        font-size: 1.2rem;
    }
    
    .category-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-sm);
    }
    
    .category-btn {
        padding: var(--spacing-md);
    }
    
    .category-icon {
        font-size: 1.5rem;
    }
    
    .quiz-header {
        flex-direction: column;
        align-items: stretch;
    }
    
    .score-display {
        flex-direction: row;
        justify-content: center;
        gap: var(--spacing-sm);
    }
    
    .stats-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: var(--spacing-sm);
    }
    
    .result-actions {
        flex-direction: column;
    }
    
    .result-actions .btn {
        max-width: 100%;
    }
}

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

/* ===== Gradient Definitions for SVG ===== */
.score-ring-progress {
    stroke: var(--accent-green);
}