/* ===== Theme Variables ===== */
:root {
    --bg: #FFFFFF;
    --bg-alt: #F7F5F2;
    --bg-card: #FFFFFF;
    --text: #1A1A1A;
    --text-secondary: #4A4A4A;
    --crimson: #A51C30;
    --crimson-dark: #7A1520;
    --crimson-light: rgba(165,28,48,0.07);
    --border: #DDD;
    --shadow: 0 2px 8px rgba(0,0,0,0.06);
    --hero-bg: #FAF9F7;
    --abstract-bg: #F7F5F2;
}
@media (prefers-color-scheme: dark) {
    :root {
        --bg: #0D1117;
        --bg-alt: #161B22;
        --bg-card: #1C2128;
        --text: #E6EDF3;
        --text-secondary: #8B949E;
        --crimson: #DC3545;
        --crimson-dark: #F06070;
        --crimson-light: rgba(220,53,69,0.1);
        --border: #30363D;
        --shadow: 0 2px 8px rgba(0,0,0,0.3);
        --hero-bg: #161B22;
        --abstract-bg: #161B22;
    }
}

/* ===== Reset & Base ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; scroll-padding-top: 140px; }
body {
    font-family: 'EB Garamond', Garamond, 'Times New Roman', serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    font-size: 17px;
}
a { color: var(--crimson); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--crimson-dark); }

/* ===== Sticky Header ===== */
.site-header {
    position: sticky; top: 0; z-index: 100;
    background: var(--hero-bg);
    border-bottom: 3px solid var(--crimson);
    box-shadow: 0 2px 12px rgba(0,0,0,0.08);
}
@media (prefers-color-scheme: dark) {
    .site-header { box-shadow: 0 2px 12px rgba(0,0,0,0.4); }
}
.header-inner {
    max-width: 960px; margin: 0 auto; padding: 12px 24px;
    display: flex; align-items: center; gap: 20px;
}
.header-photo {
    height: 196px; width: auto;
    border-radius: 6px;
    object-fit: cover;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    flex-shrink: 0;
}
.header-info {
    flex: 1; min-width: 0;
    display: flex; flex-direction: column; justify-content: space-between;
}
.header-name-line {
    font-family: 'EB Garamond', Garamond, serif;
    font-size: 34px; font-weight: 700;
    letter-spacing: 0.02em; line-height: 1.2;
}
.header-name-line .dot {
    display: inline-block;
    margin: 0 0.35em;
    font-weight: 400;
    vertical-align: 0.05em;
    font-size: 1.2em;
}
.header-title {
    font-size: 17px; color: var(--text-secondary);
    line-height: 1.4; margin-top: 2px;
}
.header-nav {
    display: flex; gap: 4px; flex-wrap: wrap; align-items: center;
    margin-top: 8px;
}
.header-nav a {
    font-family: 'EB Garamond', Garamond, serif;
    padding: 5px 12px; border-radius: 5px;
    font-size: 17px; font-weight: 600;
    color: var(--text-secondary);
    transition: all 0.2s;
}
.header-nav a:hover, .header-nav a.active {
    background: var(--crimson-light); color: var(--crimson);
}
.header-nav a.cv-btn {
    background: var(--crimson); color: #FFF; border-radius: 5px;
}
.header-nav a.cv-btn:hover { background: var(--crimson-dark); color: #FFF; }
.header-nav a.hours-btn {
    border: 1px solid var(--border); border-radius: 5px;
}
.header-nav a.hours-btn:hover {
    border-color: var(--crimson); color: var(--crimson); background: var(--crimson-light);
}

/* Hamburger (mobile) */
.hamburger {
    display: none; background: none; border: none;
    color: var(--text); font-size: 24px; cursor: pointer; padding: 4px;
    align-self: center;
}

/* ===== Main Content ===== */
.main { max-width: 960px; margin: 0 auto; padding: 0 24px 60px; }

/* Section */
.section { padding-top: 32px; }
.section-header {
    display: flex; align-items: baseline; gap: 16px; flex-wrap: wrap;
    padding-bottom: 10px; margin-bottom: 28px;
}
.section-title {
    font-family: 'EB Garamond', Garamond, serif;
    font-size: 28px; font-weight: 700;
    letter-spacing: 0.02em;
    margin: 0;
}
.section-title-only {
    font-family: 'EB Garamond', Garamond, serif;
    font-size: 28px; font-weight: 700;
    padding-bottom: 10px; margin-bottom: 28px;
    border-bottom: 3px solid var(--crimson);
    letter-spacing: 0.02em;
}
.section-header .statement-link {
    font-size: 15px; font-weight: 600;
    color: var(--crimson);
    margin-bottom: 0;
    padding: 4px 14px;
    border-radius: 5px;
    background: var(--crimson-light);
    border: 1px solid transparent;
    transition: all 0.2s;
}
.section-header .statement-link:hover {
    background: var(--crimson); color: #FFF;
}
.subsection-title {
    font-size: 18px; font-weight: 700;
    color: var(--crimson);
    text-transform: uppercase;
    letter-spacing: 0.08em;
    margin: 32px 0 16px;
}
.subsection-title:first-of-type { margin-top: 0; }

/* ===== Paper Cards ===== */
.paper {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 20px 24px;
    margin-bottom: 14px;
    transition: border-color 0.2s, box-shadow 0.2s;
}
.paper:hover {
    border-color: var(--crimson);
    box-shadow: var(--shadow);
}
.paper-header {
    display: flex; justify-content: space-between; align-items: flex-start; gap: 12px;
}
.paper-title-area { flex: 1; }
.paper-title {
    font-family: 'EB Garamond', Garamond, serif;
    font-size: 18px; font-weight: 600;
    line-height: 1.4; margin-bottom: 4px;
}
.paper-title a { color: var(--text); }
.paper-title a:hover { color: var(--crimson); }
.paper-tag {
    display: inline-block;
    background: var(--crimson);
    color: #FFF;
    font-family: 'EB Garamond', Garamond, serif;
    font-size: 12px; font-weight: 700;
    padding: 2px 8px; border-radius: 4px;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    margin-right: 6px;
    vertical-align: middle;
}
.paper-meta {
    font-size: 15px; color: var(--text-secondary);
    line-height: 1.5; margin-top: 2px;
}
.paper-links {
    margin-top: 8px;
    display: flex; flex-wrap: wrap; gap: 8px;
}
.paper-links a {
    display: inline-flex; align-items: center; gap: 4px;
    font-size: 14px; font-weight: 500;
    padding: 4px 10px; border-radius: 4px;
    border: 1px solid var(--border);
    color: var(--text-secondary);
    transition: all 0.2s;
}
.paper-links a:hover {
    border-color: var(--crimson); color: var(--crimson);
    background: var(--crimson-light);
}
.abstract-toggle {
    background: none; border: 1px solid var(--border);
    color: var(--text-secondary);
    width: 30px; height: 30px; border-radius: 50%;
    font-size: 18px; line-height: 1;
    cursor: pointer; flex-shrink: 0;
    display: flex; align-items: center; justify-content: center;
    transition: all 0.2s;
    font-family: 'EB Garamond', Garamond, serif;
}
.abstract-toggle:hover {
    border-color: var(--crimson); color: var(--crimson);
    background: var(--crimson-light);
}
.abstract-toggle.open { transform: rotate(45deg); }
.abstract {
    display: none;
    margin-top: 14px; padding: 14px 16px;
    border-top: 1px solid var(--border);
    font-size: 15px; line-height: 1.7;
    color: var(--text-secondary);
    background: var(--abstract-bg);
    border-radius: 6px;
}
.abstract.show { display: block; }

/* ===== Teaching ===== */
.course {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 18px 24px;
    margin-bottom: 12px;
}
.course-name {
    font-family: 'EB Garamond', Garamond, serif;
    font-size: 18px; font-weight: 600;
    margin-bottom: 4px;
}
.course-detail {
    font-size: 15px; color: var(--text-secondary);
    margin-top: 2px;
}
.course-links { margin-top: 6px; }
.course-links a {
    font-size: 14px; font-weight: 500;
    margin-right: 12px;
}

/* ===== Public Goods ===== */
.goods-list { display: flex; flex-direction: column; gap: 10px; }
.goods-item {
    display: flex; align-items: center; gap: 12px;
    padding: 14px 20px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 8px;
    font-weight: 500; font-size: 17px;
    color: var(--text);
    transition: all 0.2s;
}
.goods-item:hover {
    border-color: var(--crimson); color: var(--crimson);
    box-shadow: var(--shadow);
}
.goods-note {
    font-size: 16px; color: var(--text-secondary);
    margin-bottom: 16px;
}

/* ===== Contact ===== */
.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}
.contact-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 24px;
}
.contact-card h3 {
    font-family: 'EB Garamond', Garamond, serif;
    font-size: 17px; font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--crimson);
    margin-bottom: 12px;
}
.contact-card p {
    font-size: 16px; color: var(--text-secondary);
    line-height: 1.7;
}
.contact-card a { font-weight: 500; }
.office-hours-btn {
    display: inline-flex; align-items: center; gap: 8px;
    margin-top: 12px; padding: 10px 20px;
    background: var(--crimson); color: #FFF;
    border-radius: 6px; font-weight: 600;
    font-size: 15px; transition: background 0.2s;
}
.office-hours-btn:hover { background: var(--crimson-dark); color: #FFF; }
.office-hours-note {
    font-size: 14px; color: var(--text-secondary);
    margin-top: 10px; line-height: 1.6;
    font-style: italic;
}
.bu-logo {
    display: block;
    margin-top: 16px;
    max-width: 120px;
    opacity: 0.8;
}

/* ===== Footer ===== */
.footer {
    border-top: 1px solid var(--border);
    padding: 24px;
    text-align: center;
    font-size: 14px;
    color: var(--text-secondary);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    html { scroll-padding-top: 200px; }
    .header-inner { flex-direction: column; text-align: center; gap: 12px; padding: 12px 16px; }
    .header-photo { height: 80px; width: auto; align-self: center; }
    .header-name-line { font-size: 24px; }
    .header-nav { justify-content: center; }
    .header-nav-desktop { display: none; }
    .header-nav-desktop.open { display: flex; flex-direction: column; gap: 2px; }
    .hamburger { display: block; }
    .contact-grid { grid-template-columns: 1fr; }
    .paper { padding: 16px; }
    .paper-header { flex-direction: column; gap: 8px; }
    .abstract-toggle { align-self: flex-start; }
    .section-header { flex-direction: column; gap: 8px; }
}