:root {
    --bg-color: #0f172a;
    --text-color: #e2e8f0;
    --accent-color: #38bdf8;
    --secondary-bg: #1e293b;
    --card-bg: #334155;
    --font-main: 'Inter', sans-serif;
    --transition-speed: 0.3s;
}

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

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

/* Navigation */
nav {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: rgba(15, 23, 42, 0.9);
    backdrop-filter: blur(10px);
    z-index: 1000;
    padding: 1rem 2rem;
    display: flex;
    justify-content: flex-start;
    gap: 3rem;
    align-items: center;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-color);
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
}

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

.nav-links a:hover,
.nav-links a.active {
    color: var(--accent-color);
}

.menu-toggle {
    display: none;
    cursor: pointer;
    font-size: 1.5rem;
}

/* Hero Section */
.hero {
    height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 0 2rem;
    background: radial-gradient(circle at center, #1e293b 0%, #0f172a 70%);
}

.profile-img {
    width: 150px;
    height: 150px;
    border-radius: 50%;
    object-fit: cover;
    border: 4px solid var(--accent-color);
    margin-bottom: 1.5rem;
    box-shadow: 0 0 20px rgba(56, 189, 248, 0.3);
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
    background: linear-gradient(to right, #fff, #94a3b8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero p {
    font-size: 1.2rem;
    max-width: 600px;
    color: #94a3b8;
    margin-bottom: 2rem;
}

.cta-button {
    padding: 0.8rem 2rem;
    background-color: var(--accent-color);
    color: #0f172a;
    text-decoration: none;
    border-radius: 50px;
    font-weight: 600;
    transition: transform var(--transition-speed), box-shadow var(--transition-speed);
}

.cta-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(56, 189, 248, 0.4);
}

/* Sections */
section {
    padding: 5rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

section h2 {
    font-size: 2.5rem;
    margin-bottom: 3rem;
    text-align: center;
    position: relative;
}

section h2::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background-color: var(--accent-color);
    margin: 1rem auto 0;
    border-radius: 2px;
}

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

.card {
    background-color: var(--secondary-bg);
    padding: 2rem;
    border-radius: 12px;
    transition: transform var(--transition-speed);
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.card:hover {
    transform: translateY(-5px);
    border-color: var(--accent-color);
}

.card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--accent-color);
}

.card p {
    color: #cbd5e1;
    margin-bottom: 1rem;
}

.card-tags {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-top: 1rem;
}

.tag {
    background-color: rgba(56, 189, 248, 0.1);
    color: var(--accent-color);
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.85rem;
}

/* Teaching Section */
.teaching-item {
    background-color: var(--secondary-bg);
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-left: 4px solid var(--accent-color);
}

.teaching-info h3 {
    font-size: 1.2rem;
    margin-bottom: 0.25rem;
}

.teaching-year {
    font-weight: 600;
    color: #94a3b8;
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem;
    background-color: var(--secondary-bg);
    color: #94a3b8;
    margin-top: 4rem;
}

/* Responsive */
@media (max-width: 768px) {
    .menu-toggle {
        display: block;
    }

    nav {
        justify-content: space-between;
    }

    .nav-links {
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background-color: var(--secondary-bg);
        flex-direction: column;
        padding: 2rem;
        gap: 1.5rem;
        text-align: center;
        transform: translateY(-150%);
        transition: transform var(--transition-speed);
    }

    .nav-links.active {
        transform: translateY(0);
        box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
    }

    .hero h1 {
        font-size: 2.5rem;
    }
}