:root {
    color-scheme: light;
    --color-text: #1a1a1a;
    --color-text-light: #5a5a5a;
    --color-bg: #ffffff;
    --color-link: #0066cc;
    --color-link-hover: #004499;
    --color-border: #e5e5e5;
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2.5rem;
    --spacing-xl: 3rem;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.65;
    color: var(--color-text);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

main {
    max-width: 720px;
    margin: 0 auto;
    padding: var(--spacing-lg) var(--spacing-md) var(--spacing-xl);
}

header {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-lg);
    border-bottom: 1px solid var(--color-border);
}

.portrait {
    width: 160px;
    height: 160px;
    overflow: hidden;
    border-radius: 50%;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.portrait:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 32px rgba(0, 0, 0, 0.15);
}

.portrait img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: left bottom;
    transform-origin: left bottom;
    transform: scale(1.155);
}

h1 {
    font-size: clamp(1.75rem, 5vw, 2.25rem);
    margin: 0;
    font-weight: 700;
    letter-spacing: -0.02em;
}

h2 {
    font-size: clamp(1.25rem, 4vw, 1.5rem);
    margin: var(--spacing-xl) 0 var(--spacing-sm);
    font-weight: 600;
    letter-spacing: -0.01em;
    color: var(--color-text);
}

h3 {
    font-size: 1.15rem;
    margin: var(--spacing-lg) 0 var(--spacing-sm);
    font-weight: 600;
    color: var(--color-text);
}

h4 {
    font-size: 0.95rem;
    margin: var(--spacing-md) 0 var(--spacing-xs);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-text-light);
}

p {
    margin: 0 0 var(--spacing-sm);
    max-width: 65ch;
}

header p {
    color: var(--color-text-light);
    margin: 0.25rem 0;
}

ul {
    padding-left: var(--spacing-md);
    margin: 0 0 var(--spacing-md);
    list-style: none;
}

ul li {
    margin-bottom: var(--spacing-xs);
    position: relative;
    padding-left: var(--spacing-md);
}

ul li::before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--color-text-light);
    font-weight: normal;
}

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

a:hover,
a:focus {
    color: var(--color-link-hover);
    text-decoration: underline;
}

a:focus {
    outline: 2px solid var(--color-link);
    outline-offset: 2px;
    border-radius: 2px;
}

.links {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
    justify-content: center;
}

.links a {
    padding: 0.25rem 0.5rem;
}

section {
    margin-bottom: var(--spacing-lg);
}

footer {
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--color-border);
    font-size: 0.875rem;
    color: var(--color-text-light);
    text-align: center;
}

.semester-section {
    margin-left: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.semester-section p {
    margin-bottom: var(--spacing-xs);
    color: var(--color-text);
}

@media (min-width: 640px) {
    main {
        padding: var(--spacing-xl) var(--spacing-lg);
    }
}

/* --- Added Navigation Styles --- */
.main-nav {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    justify-content: center;
    margin-top: var(--spacing-md);
}

.main-nav a {
    padding: 0.5rem 1rem;
    background-color: #f5f5f5;
    border: 1px solid var(--color-border);
    border-radius: 4px;
    font-weight: 500;
    color: var(--color-text);
    transition: all 0.2s ease;
}

.main-nav a:hover,
.main-nav a:focus {
    background-color: var(--color-link);
    color: #ffffff;
    text-decoration: none;
    border-color: var(--color-link);
}

.back-nav {
    margin-bottom: var(--spacing-md);
}

.back-nav a {
    font-weight: 600;
    display: inline-flex;
    align-items: center;
}