/* 1. FONTS & GLOBAL VARIABLES */
@import url('https://fonts.googleapis.com/css2?family=Libre+Baskerville:ital@1&family=Inter:wght@400;500;600;700;800&display=swap');

:root {
    --text-main: #1a1a1a;
    --text-muted: #666666;
    --purdue-gold: #CEB888;
    --border-light: #f0f0f0;
    --bg-white: #ffffff;
}

/* 2. RESET & BASE STYLES */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* Keep the entire course site white, including the html background */
html,
body {
    min-height: 100%;
    background: #ffffff !important;
}

html {
    background-color: #ffffff !important;
}

body {
    font-family: 'Inter', -apple-system, sans-serif;
    color: var(--text-main);
    line-height: 1.6;
    background: #ffffff !important;
    -webkit-font-smoothing: antialiased;
    font-size: 16px;

    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* Undo the new main-site global main padding */
body > .container main {
    padding: 0;
}

/* 3. LAYOUT CONTAINERS */
.container {
    width: 100%;
    max-width: 850px;
    margin: 0 auto;
    padding: 60px 40px;
    flex: 1;
}

/* 4. NAVIGATION */
.top-nav {
    border-bottom: 1px solid var(--border-light);
    padding: 24px 0;
    position: sticky;
    top: 0;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(5px);
    z-index: 100;
}

.nav-container {
    max-width: 850px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 40px;
}

.nav-logo {
    font-weight: 700;
    text-decoration: none;
    color: #000;
    font-size: 1.3rem;
    letter-spacing: -0.5px;
    transition: 0.2s ease;
}

.nav-logo:hover {
    color: var(--purdue-gold);
}

.nav-links a {
    text-decoration: none;
    color: var(--text-muted);
    margin-left: 25px;
    font-size: 1rem;
    font-weight: 600;
    transition: 0.2s ease;
}

.nav-links a.active {
    color: #000;
    border-bottom: 2px solid var(--purdue-gold);
    padding-bottom: 4px;
}

.nav-links a:hover {
    color: var(--purdue-gold);
}

/* 5. HEADERS & TITLES */
header {
    margin-bottom: 40px;
}

h1 {
    font-size: 3rem;
    font-weight: 800;
    letter-spacing: -1.5px;
    margin-bottom: 8px;
    line-height: 1.1;
}

.section-title {
    font-size: 0.75rem;
    font-weight: 800;
    letter-spacing: 1.2px;
    text-transform: uppercase;
    border-bottom: 2px solid var(--purdue-gold);
    display: inline-block;
    padding-bottom: 3px;
    margin-bottom: 10px;
    margin-top: 45px;
    color: #000;
}

/* 6. LECTURE NOTES: CHAPTER TITLES */
.sub-section-label {
    display: block;
    margin-top: 10px;
    margin-bottom: 10px;
    font-family: 'Libre Baskerville', serif;
    font-style: italic;
    font-size: 1rem;
    color: #010f1d;
    font-weight: 500;
    text-transform: none;
    letter-spacing: 0;
}

/* 7. LIST & TABLE STYLES */
.section-list {
    list-style: none;
}

.section-item {
    padding: 12px 0;
    border-bottom: 1px solid var(--border-light);
}

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

.section-link {
    font-weight: 500;
    text-decoration: none;
    color: #000;
    font-size: 1.05rem;
    transition: color 0.2s;
}

.section-link:hover {
    color: var(--purdue-gold);
}

.item-desc {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-top: 2px;
}

.table-wrap {
    margin-top: 25px;
    border: 1px solid var(--border-light);
    border-radius: 8px;
    overflow-x: auto;
    max-height: 500px;
    overflow-y: auto;
}

table.data-table th {
    position: sticky;
    top: 0;
    background: var(--bg-white);
    z-index: 10;
}

/* 8. TALKS & SEMINARS */
.talks-list p {
    margin-bottom: 8px;
    font-size: 0.9rem;
    line-height: 1.5;
    color: var(--text-main);
}

/* 9. FOOTER */
.footer-signature {
    width: 100%;
    flex-shrink: 0;
    padding: 30px 0;
    border-top: 1px solid var(--border-light);
    background: #ffffff;
}

.footer-signature p {
    max-width: 850px;
    margin: 0 auto;
    padding: 0 30px;
    font-size: 0.75rem;
    color: var(--text-muted);
    letter-spacing: 1px;
}

/* 10. MOBILE RESPONSIVENESS */
@media (max-width: 600px) {
    h1 {
        font-size: 2.2rem;
    }

    .container {
        padding: 40px 20px;
    }

    .nav-container {
        padding: 0 20px;
    }

    .footer-signature p {
        padding: 0 20px;
    }

    .nav-links {
        display: flex;
        gap: 10px;
    }

    .nav-links a {
        margin-left: 0;
        font-size: 0.8rem;
    }
}

/* 11. PROFILE LAYOUT */
.profile-flex {
    display: flex;
    gap: 50px;
    align-items: flex-start;
    margin-top: 40px;
}

.profile-text {
    flex: 2;
}

.profile-text .section-title {
    margin-top: 0 !important;
}

.profile-image-container {
    flex: 1;
    display: flex;
    justify-content: flex-end;
    padding-top: 5px;
}

.profile-photo {
    width: 100%;
    max-width: 260px;
    height: auto;
    border-radius: 12px;
    border: 3px solid var(--purdue-gold);
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
}

.accessibility-report {
    margin-top: 30px;
    margin-bottom: -10px;
    font-size: 0.75rem;
    color: #555;
    font-family: "Libre Baskerville", serif;
}

.source-note {
    font-size: 0.75rem;
    color: #666;
    margin-left: 4px;
}

.source-note a {
    color: #4a6fa5;
    text-decoration: none;
    border-bottom: 1px solid transparent;
    transition: border-color 0.2s ease, color 0.2s ease;
}

.source-note a:hover {
    color: #2f4f7f;
    border-bottom: 1px solid #2f4f7f;
}