/* --- Base Variables & Reset --- */
:root {
    --primary-color: #1a2a3a;
    --secondary-color: #3498db;
    --accent-color: #e67e22;
    --text-main: #333333;
    --text-light: #666666;
    --bg-main: #ffffff;
    --bg-light: #f8f9fa;
    --transition-speed: 0.3s;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Open Sans', sans-serif;
    color: var(--text-main);
    line-height: 1.7;
    background-color: var(--bg-main);
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6, .logo {
    font-family: 'Playfair Display', serif;
    color: var(--primary-color);
}

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

a:hover {
    color: var(--accent-color);
}

.text-center { text-align: center; }
.mb-2 { margin-bottom: 2rem; }

/* --- Navigation --- */
#navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(5px);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    z-index: 1000;
    transition: padding var(--transition-speed) ease;
}

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

.nav-container .logo {
    font-size: 1.5rem;
    font-weight: 700;
}

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

.nav-links li a {
    color: var(--text-main);
    font-weight: 600;
    font-size: 0.95rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

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

/* --- Header / Hero Section --- */
#hero {
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    background: linear-gradient(135deg, #1a2a3a 0%, #2c3e50 100%);
    color: #ffffff;
    padding: 0 2rem;
}

#hero h2 {
    color: #ffffff;
    font-size: 4rem;
    margin-bottom: 1rem;
    letter-spacing: 2px;
}

#hero p {
    font-size: 1.2rem;
    font-weight: 300;
    margin-bottom: 0.5rem;
    color: #d1d8e0;
}

#hero .location {
    font-style: italic;
    margin-bottom: 2rem;
    color: #a4b0be;
}

/* --- Layout & Containers --- */
.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 5rem 2rem;
}

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

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background-color: var(--secondary-color);
    margin: 1rem auto 0;
}

.bg-light {
    background-color: var(--bg-light);
}

/* --- Buttons --- */
.btn {
    display: inline-block;
    padding: 12px 28px;
    background-color: var(--secondary-color);
    color: #fff;
    border-radius: 4px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    transition: background-color var(--transition-speed) ease, transform 0.2s ease;
}

.btn:hover {
    background-color: var(--primary-color);
    color: #fff;
    transform: translateY(-2px);
}

.btn-outline {
    background-color: transparent;
    border: 2px solid var(--secondary-color);
    color: var(--secondary-color);
}

.btn-outline:hover {
    background-color: var(--secondary-color);
    color: #fff;
}

/* --- About Section & Images --- */
.about-grid {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 3rem;
    align-items: start;
}

.profile-img {
    width: 100%;
    border-radius: 8px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.15);
}

.about-text p {
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
    color: var(--text-light);
}

.teaching-gallery {
    display: flex;
    gap: 1rem;
    margin-top: 2rem;
}

.gallery-img {
    width: 48%;
    height: auto;
    border-radius: 4px;
    filter: grayscale(20%);
    transition: filter 0.3s ease;
}

.gallery-img:hover {
    filter: grayscale(0%);
}

/* --- Skills Section --- */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.skill-card {
    background: #fff;
    padding: 2.5rem;
    border-radius: 8px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    border-top: 4px solid var(--secondary-color);
    transition: transform var(--transition-speed) ease;
}

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

.skill-card h3 {
    margin-bottom: 1rem;
    font-size: 1.25rem;
}

/* --- Portfolio Grid --- */
.portfolio-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.portfolio-card {
    background: var(--bg-light);
    padding: 2rem;
    border-radius: 8px;
    text-align: center;
    border: 1px solid #eee;
    transition: transform 0.3s ease, border-color 0.3s ease;
}

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

.portfolio-card h3 {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
}

.portfolio-card p {
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
    color: var(--text-light);
}

/* --- Research List --- */
.research-list {
    list-style: none;
    max-width: 900px;
    margin: 0 auto;
}

.research-list li {
    margin-bottom: 1.5rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid #eaeaea;
}

.research-list li:last-child {
    border-bottom: none;
}

.research-list a {
    color: var(--primary-color);
    font-size: 1.1rem;
    display: block;
}

/* --- Contact Section --- */
.contact-links {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 1.5rem;
    margin-top: 2rem;
}

.contact-item {
    padding: 15px 30px;
    background: var(--bg-light);
    border-radius: 50px;
    font-weight: 600;
    color: var(--primary-color);
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
    transition: all var(--transition-speed) ease;
}

.contact-item:hover {
    background: var(--primary-color);
    color: #fff;
    transform: translateY(-3px);
}

/* --- Footer --- */
footer {
    background: var(--primary-color);
    color: #fff;
    text-align: center;
    padding: 2rem;
    font-size: 0.9rem;
}

/* --- Animations --- */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s ease-out, transform 0.8s ease-out;
}

.fade-in.appear {
    opacity: 1;
    transform: translateY(0);
}

/* --- Responsive Design --- */
@media (max-width: 900px) {
    .about-grid {
        grid-template-columns: 1fr;
    }
    .profile-img {
        max-width: 400px;
        margin: 0 auto;
        display: block;
    }
    #hero h2 {
        font-size: 2.5rem;
    }
}