:root {
    --primary-color: #00f2fe;
    --secondary-color: #4facfe;
    --bg-color: #0f172a;
    --text-color: #f1f5f9;
    --text-muted: #94a3b8;
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.1);
    --glass-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Outfit', sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    overflow-x: hidden;
    background-image:
        radial-gradient(at 0% 0%, hsla(253, 16%, 7%, 1) 0, transparent 50%),
        radial-gradient(at 50% 0%, hsla(225, 39%, 30%, 1) 0, transparent 50%),
        radial-gradient(at 100% 0%, hsla(339, 49%, 30%, 1) 0, transparent 50%);
    min-height: 100vh;
}

/* Glassmorphism Utilities */
.glass-nav {
    background: rgba(15, 23, 42, 0.7);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--glass-border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.glass-card {
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: var(--glass-shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.glass-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    border-color: rgba(255, 255, 255, 0.2);
}

/* Navbar */
.navbar {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-weight: 700;
    font-size: 1.5rem;
    color: var(--primary-color);
    text-decoration: none;
    letter-spacing: -0.025em;
}

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

.nav-links a {
    color: var(--text-muted);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

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

/* Hero Section */
.hero {
    max-width: 800px;
    margin: 6rem auto 4rem;
    text-align: center;
    padding: 0 2rem;
}

.hero h1 {
    font-size: 4rem;
    line-height: 1.1;
    margin-bottom: 1.5rem;
    background: linear-gradient(to right, #fff, #94a3b8);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero p {
    font-size: 1.25rem;
    color: var(--text-muted);
    margin-bottom: 2.5rem;
}

.cta-buttons {
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.btn-primary {
    background: linear-gradient(135deg, var(--secondary-color), var(--primary-color));
    color: #000;
    padding: 0.75rem 2rem;
    border-radius: 2rem;
    text-decoration: none;
    font-weight: 600;
    transition: transform 0.2s, opacity 0.2s;
    border: none;
    cursor: pointer;
}

.btn-secondary {
    background: var(--glass-bg);
    color: var(--text-color);
    padding: 0.75rem 2rem;
    border-radius: 2rem;
    text-decoration: none;
    font-weight: 600;
    border: 1px solid var(--glass-border);
    transition: background 0.2s;
    display: flex;
    align-items: center;
}

.btn-primary:hover {
    opacity: 0.9;
    transform: scale(1.05);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.1);
}

/* Features */
.features {
    max-width: 1200px;
    margin: 4rem auto;
    padding: 0 2rem;
}

.features h2,
.topics h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
}

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

.feature-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

/* Topics */
.topics {
    max-width: 1200px;
    margin: 4rem auto;
    padding: 0 2rem;
}

.topic-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
}

.topic-card {
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.topic-info h3 {
    margin-bottom: 0.25rem;
}

/* Quiz UI */
.quiz-container {
    max-width: 800px;
    margin: 4rem auto;
    padding: 0 1rem;
}

.question-text {
    font-size: 1.5rem;
    font-weight: 600;
    margin: 2rem 0;
}

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

.option-btn {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--glass-border);
    padding: 1rem;
    border-radius: 0.75rem;
    color: var(--text-color);
    text-align: left;
    font-size: 1.1rem;
    cursor: pointer;
    transition: all 0.2s;
}

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

.option-btn:disabled {
    cursor: default;
    opacity: 0.7;
}

.option-btn.correct {
    background: rgba(34, 197, 94, 0.2);
    border-color: #22c55e;
    color: #4ade80;
}

.option-btn.wrong {
    background: rgba(239, 68, 68, 0.2);
    border-color: #ef4444;
    color: #f87171;
}

.quiz-header {
    border-bottom: 1px solid var(--glass-border);
    padding-bottom: 1rem;
    margin-bottom: 1rem;
}

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

.progress {
    height: 100%;
    background: var(--primary-color);
    width: 0%;
    transition: width 0.3s ease;
}

.score-circle {
    width: 150px;
    height: 150px;
    border-radius: 50%;
    border: 4px solid var(--primary-color);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 2.5rem;
    font-weight: bold;
    margin: 2rem auto;
    background: var(--glass-bg);
}

.score-display {
    text-align: center;
}

/* Footer */
footer {
    border-top: 1px solid var(--glass-border);
    margin-top: 4rem;
    padding: 3rem 2rem;
    text-align: center;
    background: rgba(15, 23, 42, 0.5);
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 1.5rem;
}

.footer-links a {
    color: var(--text-muted);
    text-decoration: none;
}

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

/* Responsive */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2.5rem;
    }

    .navbar {
        flex-direction: column;
        gap: 1rem;
    }

    .nav-links {
        gap: 1rem;
        font-size: 0.9rem;
    }
}