/* ===========================================================
   David Su — Academic site
   Modern editorial style
   =========================================================== */

:root {
  --color-bg: #f9fafb;
  --color-bg-alt: #eef2f6;
  --color-ink: #14202c;
  --color-ink-soft: #48586a;
  --color-accent: #003262;      /* UC Berkeley blue */
  --color-accent-soft: #3b7ea1; /* Founders Rock blue */
  --color-gold: #fdb515;        /* California gold */
  --color-gold-deep: #b8860b;
  --color-line: #dbe2ea;
  --max-width: 900px;
  --font-serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-sans);
  color: var(--color-ink);
  background: var(--color-bg);
  line-height: 1.65;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--color-accent);
  text-decoration: none;
}
a:hover { text-decoration: underline; }

.wrap {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- Header / Nav ---------- */

header.site-header {
  border-bottom: 1px solid var(--color-line);
  background: var(--color-bg);
  position: sticky;
  top: 0;
  z-index: 10;
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 18px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.nav-name {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 1.05rem;
  color: var(--color-ink);
  letter-spacing: 0.01em;
}

.nav-name span {
  color: var(--color-accent);
}

header.site-header {
  border-bottom: 3px solid var(--color-gold);
}

nav.nav-links {
  display: flex;
  gap: 22px;
  flex-wrap: wrap;
}

nav.nav-links a {
  color: var(--color-ink-soft);
  font-size: 0.92rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

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

/* ---------- Hero ---------- */

.hero {
  padding: 64px 0 48px;
  border-bottom: 1px solid var(--color-line);
}

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

.avatar {
  width: 240px;
  height: 240px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-accent), var(--color-gold));
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-serif);
  font-size: 4rem;
  font-weight: 600;
  flex-shrink: 0;
  overflow: hidden;
  padding: 5px;
}

.avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 50%;
  border: 3px solid var(--color-bg);
}

@media (max-width: 620px) {
  .avatar { width: 180px; height: 180px; font-size: 3rem; }
}

.hero-text h1 {
  font-family: var(--font-serif);
  font-size: 2.4rem;
  font-weight: 600;
  margin: 0 0 6px;
  line-height: 1.15;
}

.hero-title {
  font-size: 1.05rem;
  color: var(--color-ink-soft);
  margin: 0 0 4px;
}

.hero-affil {
  font-size: 0.98rem;
  color: var(--color-ink-soft);
  margin: 0 0 16px;
}

.hero-links {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  font-size: 0.92rem;
}

.hero-links a {
  border: 1px solid var(--color-line);
  padding: 6px 14px;
  border-radius: 999px;
  color: var(--color-ink);
  font-weight: 500;
}

.hero-links a:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  text-decoration: none;
}

/* ---------- Main sections ---------- */

main {
  padding: 48px 0 80px;
}

section.block {
  margin-bottom: 52px;
}

section.block h2 {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 600;
  margin: 0 0 20px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--color-accent);
  display: inline-block;
}

.lede {
  font-size: 1.12rem;
  color: var(--color-ink-soft);
  max-width: 66ch;
}

.interest-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 8px;
}

.interest-tags span {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-line);
  color: var(--color-ink-soft);
  padding: 6px 14px;
  border-radius: 999px;
  font-size: 0.88rem;
}

/* Entry list pattern used across Education / Publications / Awards / etc. */

.entry {
  display: grid;
  grid-template-columns: 130px 1fr;
  gap: 18px;
  padding: 18px 0;
  border-bottom: 1px solid var(--color-line);
}

.entry:last-child { border-bottom: none; }

.entry .when {
  font-size: 0.86rem;
  color: var(--color-ink-soft);
  font-weight: 600;
  letter-spacing: 0.02em;
  padding-top: 2px;
}

.entry .what h3 {
  font-family: var(--font-serif);
  font-size: 1.08rem;
  font-weight: 600;
  margin: 0 0 4px;
}

.entry .what p {
  margin: 0 0 4px;
  color: var(--color-ink-soft);
  font-size: 0.96rem;
}

.entry .what .meta {
  font-size: 0.86rem;
  color: var(--color-accent);
  font-weight: 500;
}

.award-badge {
  display: inline-block;
  background: var(--color-gold);
  color: #1c1408;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  padding: 2px 9px;
  border-radius: 4px;
  margin-right: 6px;
  margin-bottom: 4px;
  text-transform: uppercase;
}

@media (max-width: 620px) {
  .entry { grid-template-columns: 1fr; gap: 4px; }
  .hero-grid { flex-direction: column; align-items: flex-start; text-align: left; }
  .hero h1 { font-size: 1.9rem; }
}

/* ---------- Research statement / projects ---------- */

.project {
  margin-bottom: 34px;
  padding-bottom: 34px;
  border-bottom: 1px solid var(--color-line);
}
.project:last-child { border-bottom: none; margin-bottom: 0; padding-bottom: 0; }

.project h3 {
  font-family: var(--font-serif);
  font-size: 1.18rem;
  font-weight: 600;
  margin: 0 0 10px;
}

.project p {
  color: var(--color-ink-soft);
  margin: 0 0 12px;
  font-size: 0.98rem;
}

.project .paper {
  margin: 14px 0 10px;
  padding-left: 16px;
  border-left: 2px solid var(--color-line);
}

.project .paper p {
  margin: 0 0 6px;
  color: var(--color-ink);
  font-size: 0.95rem;
}

.project .paper .award-badge {
  margin-top: 4px;
}

/* ---------- Footer ---------- */

footer {
  border-top: 1px solid var(--color-line);
  padding: 32px 0;
  color: var(--color-ink-soft);
  font-size: 0.86rem;
}

footer a { color: var(--color-ink-soft); text-decoration: underline; }

/* ---------- Utility ---------- */

.cta-btn {
  display: inline-block;
  background: var(--color-accent);
  color: #fff !important;
  padding: 10px 20px;
  border-radius: 6px;
  font-weight: 600;
  font-size: 0.92rem;
}
.cta-btn:hover { background: #001f3f; text-decoration: none; }

/* ---------- Key-work highlight (homepage) ---------- */

.key-work {
  background: var(--color-bg-alt);
  border-left: 5px solid var(--color-gold);
  border-radius: 6px;
  padding: 28px 32px;
  margin: 28px 0 0;
}

.key-work .kicker {
  display: block;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: 10px;
}

.key-work p {
  font-size: 1.22rem;
  line-height: 1.6;
  color: var(--color-ink);
  margin: 0 0 14px;
}

.key-work p:last-child { margin-bottom: 0; }

.key-work .paper-title {
  font-family: var(--font-serif);
  font-style: italic;
  font-weight: 600;
}