/*
 * Jan van Roestel - Personal Website
 * Dark theme with blue accents
 */

/* ===== CSS Variables ===== */
:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f5f7fa;
    --bg-card: #ffffff;
    --text-primary: #4a5568;
    --text-secondary: #718096;
    --text-heading: #1a202c;
    --accent: #3182ce;
    --accent-hover: #2c5282;
    --border-color: #e2e8f0;
    --nav-bg: rgba(255, 255, 255, 0.95);
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --max-width: 1200px;
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    --font-mono: 'SF Mono', 'Fira Code', Consolas, monospace;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    font-size: 16px;
    line-height: 1.7;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    min-height: 100vh;
}

/* ===== Typography ===== */
h1, h2, h3, h4, h5, h6 {
    color: var(--text-heading);
    font-weight: 600;
    line-height: 1.3;
    margin-bottom: 1rem;
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.1rem; }

p {
    margin-bottom: 1rem;
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: color 0.2s ease;
}

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

ul, ol {
    margin-left: 1.5rem;
    margin-bottom: 1rem;
}

li {
    margin-bottom: 0.5rem;
}

strong, b {
    color: var(--text-heading);
}

/* ===== Navigation ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: var(--nav-bg);
    backdrop-filter: blur(10px);
    z-index: 1000;
    border-bottom: 1px solid var(--border-color);
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.nav-logo {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-heading);
    text-decoration: none;
}

.nav-logo:hover {
    color: var(--accent);
    text-decoration: none;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
    margin: 0;
}

.nav-menu li {
    margin: 0;
}

.nav-menu a {
    color: var(--text-primary);
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent);
    transition: width 0.3s ease;
}

.nav-menu a:hover::after,
.nav-menu a.active::after {
    width: 100%;
}

.nav-menu a:hover {
    color: var(--accent);
    text-decoration: none;
}

/* Mobile menu toggle */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.nav-toggle span {
    display: block;
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    margin: 5px 0;
    transition: 0.3s;
}

/* ===== Main Content ===== */
main {
    padding-top: 70px;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 2rem;
}

section {
    padding: 4rem 0;
}

.section-title {
    margin-bottom: 2rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--accent);
    display: inline-block;
}

/* ===== Hero Section ===== */
.hero {
    min-height: calc(100vh - 70px);
    display: flex;
    align-items: center;
    padding: 4rem 0;
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 4rem;
    align-items: center;
}

.hero-text h1 {
    font-size: 3rem;
    margin-bottom: 0.5rem;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--accent);
    margin-bottom: 1rem;
}

.hero-institution {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.hero-interests {
    margin-bottom: 1.5rem;
}

.hero-links {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.hero-image {
    width: 300px;
    height: 300px;
    border-radius: 50%;
    object-fit: cover;
    border: 4px solid var(--accent);
    box-shadow: var(--shadow);
}

/* ===== Buttons ===== */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 5px;
    font-weight: 500;
    text-decoration: none;
    transition: all 0.3s ease;
}

.btn-primary {
    background: var(--accent);
    color: #ffffff;
}

.btn-primary:hover {
    background: var(--accent-hover);
    color: #ffffff;
    text-decoration: none;
}

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

.btn-outline:hover {
    background: var(--accent);
    color: #ffffff;
    text-decoration: none;
}

/* ===== About Section ===== */
.about-section {
    background: var(--bg-secondary);
}

.about-content {
    max-width: 800px;
}

/* ===== News Section ===== */
.news-section {
    background: var(--bg-primary);
}

.news-list {
    list-style: none;
    margin: 0;
}

.news-item {
    display: grid;
    grid-template-columns: 120px 1fr;
    gap: 1.5rem;
    padding: 1.5rem 0;
    border-bottom: 1px solid var(--border-color);
}

.news-item:last-child {
    border-bottom: none;
}

.news-date {
    color: var(--accent);
    font-weight: 500;
    font-size: 0.9rem;
}

.news-content h4 {
    margin-bottom: 0.5rem;
}

.news-content p {
    color: var(--text-secondary);
    margin: 0;
}

/* ===== Research Cards ===== */
.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
}

.research-card {
    background: var(--bg-secondary);
    border-radius: 10px;
    overflow: hidden;
    border: 1px solid var(--border-color);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.research-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow);
}

.research-card img {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.research-card-content {
    padding: 1.5rem;
}

.research-card h3 {
    margin-bottom: 1rem;
}

.research-card p {
    color: var(--text-secondary);
}

/* ===== Research Detail Section ===== */
.research-topic {
    padding: 3rem 0;
    border-bottom: 1px solid var(--border-color);
}

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

.research-topic-header {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 2rem;
    align-items: start;
}

.research-topic img {
    width: 100%;
    border-radius: 10px;
}

/* ===== Talks List ===== */
.talks-list {
    list-style: none;
    margin: 0;
}

.talk-item {
    display: grid;
    grid-template-columns: 150px 1fr auto;
    gap: 1.5rem;
    padding: 1.5rem 0;
    border-bottom: 1px solid var(--border-color);
    align-items: center;
}

.talk-item:last-child {
    border-bottom: none;
}

.talk-date {
    color: var(--accent);
    font-weight: 500;
}

.talk-title {
    font-weight: 500;
}

.talk-venue {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.talk-links a {
    margin-left: 1rem;
}

/* ===== Education/Experience Cards ===== */
.education-item {
    margin-bottom: 2rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
}

.education-item:last-child {
    border-bottom: none;
}

.education-item h4 {
    color: var(--accent);
    margin-bottom: 0.5rem;
}

/* ===== Contact Page ===== */
.contact-info {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
}

.contact-item {
    margin-bottom: 1.5rem;
}

.contact-item h4 {
    color: var(--accent);
    margin-bottom: 0.5rem;
}

.social-links {
    display: flex;
    gap: 1.5rem;
    margin-top: 2rem;
}

.social-links a {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: var(--bg-secondary);
    border: 2px solid var(--border-color);
    color: var(--text-primary);
    font-size: 1.5rem;
    transition: all 0.3s ease;
}

.social-links a:hover {
    background: var(--accent);
    border-color: var(--accent);
    color: #ffffff;
}

/* ===== Footer ===== */
footer {
    background: var(--bg-secondary);
    padding: 2rem 0;
    text-align: center;
    border-top: 1px solid var(--border-color);
}

footer p {
    color: var(--text-secondary);
    margin: 0;
}

/* ===== Page Header ===== */
.page-header {
    background: var(--bg-secondary);
    padding: 6rem 0 3rem;
    margin-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
}

.page-header h1 {
    margin-bottom: 0.5rem;
}

.page-header p {
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin: 0;
}

/* ===== CV Page ===== */
.cv-download {
    background: var(--bg-secondary);
    padding: 3rem;
    border-radius: 10px;
    text-align: center;
    margin-bottom: 3rem;
}

.cv-download h2 {
    margin-bottom: 1rem;
}

.cv-download p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

/* ===== Responsive Design ===== */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 70px;
        left: 0;
        right: 0;
        background: var(--nav-bg);
        flex-direction: column;
        padding: 1rem 2rem;
        gap: 0;
        border-bottom: 1px solid var(--border-color);
    }

    .nav-menu.active {
        display: flex;
    }

    .nav-menu li {
        padding: 0.75rem 0;
        border-bottom: 1px solid var(--border-color);
    }

    .nav-menu li:last-child {
        border-bottom: none;
    }

    .nav-toggle {
        display: block;
    }

    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-image {
        width: 200px;
        height: 200px;
        margin: 0 auto;
        order: -1;
    }

    .hero-text h1 {
        font-size: 2rem;
    }

    .hero-links {
        justify-content: center;
    }

    .news-item {
        grid-template-columns: 1fr;
        gap: 0.5rem;
    }

    .talk-item {
        grid-template-columns: 1fr;
        gap: 0.5rem;
    }

    .talk-links {
        margin-top: 0.5rem;
    }

    .talk-links a {
        margin-left: 0;
        margin-right: 1rem;
    }

    .contact-info {
        grid-template-columns: 1fr;
    }

    .research-topic-header {
        grid-template-columns: 1fr;
    }

    h1 { font-size: 2rem; }
    h2 { font-size: 1.5rem; }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }

    section {
        padding: 2rem 0;
    }

    .hero {
        padding: 2rem 0;
    }
}