:root {
    --primary-color: #00f2fe;
    --secondary-color: #4facfe;
    --accent-color: #ff007f;
    --background-dark: #0f172a;
    --background-card: rgba(30, 41, 59, 0.7);
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --glass-border: rgba(255, 255, 255, 0.1);
    --font-main: 'Outfit', sans-serif;
    --transition-speed: 0.3s;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: var(--font-main);
    background-color: var(--background-dark);
    color: var(--text-main);
    line-height: 1.6;
    overflow-x: hidden;
}

/* Glassmorphism Utilities */
.glass-card {
    background: var(--background-card);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.1);
}

.glass-nav {
    background: rgba(15, 23, 42, 0.8);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--glass-border);
    position: sticky;
    top: 0;
    z-index: 1000;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-main);
}

h1 {
    font-size: 3rem;
    line-height: 1.2;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text; /* Standard property for compatibility */
}

h2 {
    font-size: 2rem;
    text-align: center;
    margin-bottom: 2rem;
}

p {
    color: var(--text-muted);
    margin-bottom: 1.5rem;
}

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

/* Navigation */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 5%;
    max-width: 1400px;
    margin: 0 auto;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-links a:hover {
    color: var(--primary-color);
}

/* Hero Section */
.hero {
    padding: 8rem 5% 4rem;
    text-align: center;
    max-width: 1200px;
    margin: 0 auto;
    position: relative;
}

.hero p {
    font-size: 1.25rem;
    max-width: 800px;
    margin: 0 auto 3rem;
}

.cta-buttons {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    flex-wrap: wrap;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: #000;
    padding: 1rem 2rem;
    border-radius: 50px;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: transform var(--transition-speed);
    border: none;
    cursor: pointer;
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 20px rgba(79, 172, 254, 0.3);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-main);
    padding: 1rem 2rem;
    border-radius: 50px;
    font-weight: 600;
    border: 1px solid var(--glass-border);
    transition: background var(--transition-speed);
}

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

/* Features Grid */
.features {
    padding: 4rem 5%;
    max-width: 1400px;
    margin: 0 auto;
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.feature-card {
    padding: 2rem;
    text-align: center;
    transition: transform var(--transition-speed);
}

.feature-card:hover {
    transform: translateY(-5px);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    display: block;
}

/* Topics Section */
.topics {
    padding: 4rem 5%;
    max-width: 1400px;
    margin: 0 auto;
}

.topic-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
}

.topic-card {
    padding: 1.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    cursor: pointer;
    transition: all var(--transition-speed);
}

.topic-card:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: translateX(5px);
    border-color: var(--primary-color);
}

.topic-icon {
    font-size: 2rem;
    background: rgba(255, 255, 255, 0.05);
    padding: 0.5rem;
    border-radius: 12px;
}

/* Quiz Interface */
.quiz-container {
    padding: 6rem 5% 4rem;
    max-width: 800px;
    margin: 0 auto;
    min-height: 80vh;
}

.quiz-header {
    margin-bottom: 2rem;
}

.progress-bar {
    height: 6px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 3px;
    margin-top: 1rem;
    overflow: hidden;
}

.progress {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    width: 0%;
    transition: width 0.3s ease;
}

.question-card {
    padding: 2rem;
    margin-bottom: 2rem;
}

.question-text {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 2rem;
}

.options-grid {
    display: grid;
    gap: 1rem;
}

.option-btn {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--glass-border);
    padding: 1rem;
    border-radius: 12px;
    text-align: left;
    color: var(--text-main);
    cursor: pointer;
    transition: all 0.2s;
    font-size: 1rem;
}

.option-btn:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--primary-color);
}

.option-btn.correct {
    background: rgba(34, 197, 94, 0.2);
    border-color: #22c55e;
}

.option-btn.wrong {
    background: rgba(239, 68, 68, 0.2);
    border-color: #ef4444;
}

.score-display {
    text-align: center;
    padding: 3rem;
}

.score-circle {
    width: 150px;
    height: 150px;
    border-radius: 50%;
    border: 4px solid var(--primary-color);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    font-weight: 700;
    margin: 0 auto 2rem;
    background: rgba(0, 242, 254, 0.1);
}

/* Footer */
footer {
    padding: 3rem 5%;
    text-align: center;
    border-top: 1px solid var(--glass-border);
    margin-top: 4rem;
}

.footer-links {
    margin-bottom: 1.5rem;
}

.footer-links a {
    margin: 0 1rem;
    color: var(--text-muted);
}

.footer-links a:hover {
    color: var(--primary-color);
}

/* Mobile Responsive */
@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }
    
    .hero {
        padding-top: 6rem;
    }

    .navbar {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav-links {
        gap: 1rem;
        font-size: 0.9rem;
    }
}