/* ===== CSS Variables ===== */
:root {
    --color-bg: #F3F3F3;
    --color-white: #FFFFFF;
    --color-text: #3B3B3B;
    --color-text-secondary: #616161;
    --color-accent: #005FB8;
    --color-accent-hover: #0258A8;
    --color-border: #E5E5E5;
    --color-shadow: rgba(0, 0, 0, 0.06);
    --font-stack: 'Helvetica Neue', Helvetica, Arial, sans-serif;
    --max-width: 1100px;
    --radius: 8px;
}

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

body {
    font-family: var(--font-stack);
    font-weight: 300;
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

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

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

img {
    max-width: 100%;
}

/* ===== Container ===== */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
    width: 100%;
}

/* ===== Navigation ===== */
.navbar {
    background: var(--color-white);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.navbar .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.navbar-brand {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-text);
    letter-spacing: -0.02em;
}

.navbar-brand:hover {
    color: var(--color-accent);
}

.navbar-links {
    display: flex;
    gap: 32px;
    list-style: none;
}

.navbar-links a {
    color: var(--color-text-secondary);
    font-size: 0.95rem;
    font-weight: 400;
    padding: 4px 0;
    border-bottom: 2px solid transparent;
    transition: color 0.2s, border-color 0.2s;
}

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

.navbar-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.navbar-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--color-text);
    margin: 5px 0;
    transition: 0.3s;
}

/* ===== Hero ===== */
.hero {
    background: var(--color-white);
    border-bottom: 1px solid var(--color-border);
    padding: 64px 0;
}

.hero .container {
    display: flex;
    align-items: center;
    gap: 40px;
}

.hero-photo {
    width: 240px;
    height: 240px;
    border-radius: 50%;
    object-fit: cover;
    flex-shrink: 0;
    border: 3px solid var(--color-border);
}

.hero-text h1 {
    font-size: 2.5rem;
    font-weight: 600;
    letter-spacing: -0.02em;
    margin-bottom: 8px;
}

.hero .tagline {
    font-size: 1.7rem;
    color: var(--color-text-secondary);
    margin-bottom: 4px;
}

.hero .affiliation {
    font-size: 1rem;
    color: var(--color-accent);
    font-weight: 500;
}

/* ===== Main Content ===== */
main {
    flex: 1;
    padding: 48px 0;
}

/* ===== Section Headings ===== */
.section-title {
    font-size: 1.5rem;
    font-weight: 500;
    margin-bottom: 24px;
    letter-spacing: -0.01em;
}

.section-subtitle {
    font-size: 1rem;
    color: var(--color-text-secondary);
    margin-bottom: 32px;
    max-width: 640px;
}

/* ===== Cards ===== */
.card {
    background: var(--color-white);
    border-radius: var(--radius);
    box-shadow: 0 1px 3px var(--color-shadow);
    padding: 24px;
    transition: box-shadow 0.2s;
}

.card:hover {
    box-shadow: 0 4px 12px var(--color-shadow);
}

/* Highlight cards on homepage */
.highlight-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
    margin-top: 32px;
}

.highlight-card {
    text-align: center;
    padding: 32px 24px;
}

.highlight-card h3 {
    font-size: 1.1rem;
    font-weight: 500;
    margin-bottom: 8px;
}

.highlight-card p {
    color: var(--color-text-secondary);
    font-size: 0.9rem;
    margin-bottom: 16px;
}

.highlight-card .card-link {
    font-weight: 500;
    font-size: 0.9rem;
}

/* ===== About Section ===== */
.about {
    margin-bottom: 48px;
}

.about p {
    font-size: 1.05rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
}

/* ===== Year Dividers (Publications) ===== */
.year-group {
    margin-bottom: 40px;
}

.year-label {
    font-size: 1.25rem;
    font-weight: 500;
    color: var(--color-accent);
    margin-bottom: 16px;
    padding-bottom: 8px;
    border-bottom: 1px solid var(--color-accent);
    display: inline-block;
}

/* Publication cards */
.pub-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.pub-card {
    padding: 20px 24px;
}

.pub-card .pub-title {
    font-size: 1rem;
    font-weight: 500;
    margin-bottom: 6px;
}

.pub-card .pub-authors {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    margin-bottom: 10px;
    line-height: 1.5;
}

.pub-card .pub-links {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

.pub-card .pub-links a {
    font-size: 0.85rem;
    font-weight: 500;
}

/* ===== Software Grid ===== */
.software-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 24px;
}

.software-card h3 {
    font-size: 1.05rem;
    font-weight: 500;
    margin-bottom: 8px;
}

.software-card p {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    margin-bottom: 12px;
    line-height: 1.5;
}

.software-card .meta {
    display: flex;
    align-items: center;
    gap: 12px;
}

.badge {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 500;
    padding: 3px 10px;
    border-radius: 12px;
    text-transform: uppercase;
    letter-spacing: 0.03em;
}

.badge-julia {
    background: #9558B2;
    color: white;
}

.badge-python {
    background: #3776AB;
    color: white;
}

.badge-matlab {
    background: #e16737;
    color: white;
}

.badge-octave {
    background: #0790C0;
    color: white;
}

/* ===== Teaching ===== */
.course-list {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.course-card h3 {
    font-size: 1.05rem;
    font-weight: 500;
    margin-bottom: 4px;
}

.course-card .semester {
    font-size: 0.85rem;
    color: var(--color-accent);
    font-weight: 500;
    margin-bottom: 8px;
}

.course-card p {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    line-height: 1.5;
}

/* ===== Page Header ===== */
.page-header {
    background: var(--color-white);
    border-bottom: 1px solid var(--color-border);
    padding: 40px 0;
}

.page-header h1 {
    font-size: 2rem;
    font-weight: 600;
    letter-spacing: -0.02em;
}

.page-header p {
    color: var(--color-text-secondary);
    margin-top: 8px;
}

/* ===== Footer ===== */
footer {
    background: var(--color-white);
    border-top: 1px solid var(--color-border);
    padding: 32px 0;
    margin-top: auto;
}

footer .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
}

footer .footer-info {
    font-size: 0.85rem;
    color: var(--color-text-secondary);
}

footer .footer-links {
    display: flex;
    gap: 20px;
    list-style: none;
}

footer .footer-links a {
    font-size: 0.85rem;
    color: var(--color-text-secondary);
}

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

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .hero .container {
        flex-direction: column;
        text-align: center;
    }

    .hero-photo {
        width: 110px;
        height: 110px;
    }

    .hero-text h1 {
        font-size: 1.6rem;
    }

    .hero {
        padding: 40px 0;
    }

    main {
        padding: 32px 0;
    }

    .navbar-links {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: var(--color-white);
        border-bottom: 1px solid var(--color-border);
        padding: 16px 24px;
        gap: 16px;
    }

    .navbar-links.open {
        display: flex;
    }

    .navbar-toggle {
        display: block;
    }

    .navbar .container {
        position: relative;
    }

    .highlight-grid {
        grid-template-columns: 1fr;
    }

    .software-grid {
        grid-template-columns: 1fr;
    }

    footer .container {
        flex-direction: column;
        text-align: center;
    }
}