/* ==========================================================
   Ying Shi — Academic Website
   Clean & minimal: generous white space, restrained color
   ========================================================== */

:root {
  --ink: #1c1e21;          /* near-black body text */
  --ink-soft: #55595f;     /* secondary text */
  --accent: #1e407c;       /* Penn State Beaver Blue */
  --accent-dark: #001e44;  /* Penn State Nittany Navy */
  --accent-soft: #e9eff8;  /* pale blue wash */
  --rule: #d9e2ef;         /* hairline dividers, blue-tinted */
  --bg: #ffffff;
  --serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

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

/* ---------- layout ---------- */

.container {
  max-width: 760px;
  margin: 0 auto;
  padding: 0 24px;
}

main.container { padding-top: 48px; padding-bottom: 80px; }

/* ---------- header / nav ---------- */

header {
  background: var(--accent-dark);
}

.nav {
  max-width: 760px;
  margin: 0 auto;
  padding: 20px 24px;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px 24px;
}

.nav .brand {
  font-family: var(--serif);
  font-size: 1.25rem;
  font-weight: 600;
  color: #ffffff;
  text-decoration: none;
  letter-spacing: 0.01em;
}

.nav ul {
  list-style: none;
  display: flex;
  gap: 26px;
  margin: 0;
  padding: 0;
}

.nav a.navlink {
  text-decoration: none;
  color: rgba(255, 255, 255, 0.82);
  font-size: 0.95rem;
  padding-bottom: 3px;
}

.nav a.navlink:hover { color: #ffffff; }

.nav a.navlink.active {
  color: #ffffff;
  font-weight: 600;
  border-bottom: 2px solid rgba(255, 255, 255, 0.9);
}

/* ---------- typography ---------- */

h1, h2, h3 {
  font-family: var(--serif);
  font-weight: 600;
  line-height: 1.25;
  color: var(--ink);
}

h1 { font-size: 2.1rem; margin: 0 0 6px; }

h2 {
  font-size: 1.35rem;
  margin: 56px 0 18px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--rule);
  color: var(--accent);
}

h2:first-child { margin-top: 0; }

h3 { font-size: 1.08rem; margin: 28px 0 8px; }

p { margin: 0 0 16px; }

a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--accent-dark); }

.muted { color: var(--ink-soft); }
.small { font-size: 0.92rem; }

/* ---------- home hero ---------- */

.hero {
  display: flex;
  gap: 44px;
  align-items: flex-start;
  margin-bottom: 8px;
}

.hero-text { flex: 1; }

.hero .subtitle {
  font-size: 1.05rem;
  color: var(--ink-soft);
  margin: 0 0 20px;
}

.portrait {
  width: 200px;
  height: 260px;
  object-fit: cover;
  object-position: top;
  border-radius: 6px;
  border: 4px solid var(--accent-soft);
  flex-shrink: 0;
}

/* ---------- interest tags ---------- */

.tags { display: flex; flex-wrap: wrap; gap: 8px; margin: 18px 0 0; padding: 0; list-style: none; }

.tags li {
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.85rem;
  padding: 4px 12px;
  border-radius: 999px;
}

/* ---------- news list ---------- */

.news { list-style: none; margin: 0; padding: 0; }

.news li {
  display: flex;
  gap: 20px;
  padding: 12px 0;
  border-bottom: 1px solid var(--rule);
}

.news li:last-child { border-bottom: none; }

.news .date {
  flex: 0 0 90px;
  color: var(--ink-soft);
  font-size: 0.88rem;
  padding-top: 2px;
  white-space: nowrap;
}

/* ---------- papers ---------- */

.paper {
  margin: 0 0 30px;
  padding-left: 18px;
  border-left: 3px solid var(--accent-soft);
}

.paper .title {
  font-family: var(--serif);
  font-size: 1.06rem;
  font-weight: 600;
  margin: 0 0 4px;
}

.paper .byline { color: var(--ink-soft); font-size: 0.92rem; margin: 0 0 4px; }

.paper .status {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 2px 10px;
  border-radius: 999px;
  margin: 4px 0 8px;
}

.paper details { margin-top: 6px; }

.paper summary {
  cursor: pointer;
  color: var(--accent);
  font-size: 0.92rem;
  user-select: none;
}

.paper details p { margin-top: 10px; font-size: 0.95rem; color: var(--ink); }

/* ---------- teaching ---------- */

table.evals {
  border-collapse: collapse;
  width: 100%;
  margin: 18px 0 28px;
  font-size: 0.95rem;
}

table.evals th, table.evals td {
  text-align: left;
  padding: 10px 14px;
  border-bottom: 1px solid var(--rule);
}

table.evals th {
  font-weight: 600;
  color: var(--ink-soft);
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

blockquote.student {
  margin: 0 0 18px;
  padding: 14px 20px;
  background: var(--accent-soft);
  border-radius: 6px;
  font-size: 0.96rem;
  font-style: italic;
  color: var(--ink);
}

blockquote.student p { margin: 0; }

/* ---------- buttons ---------- */

.btn {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 600;
  padding: 10px 22px;
  border-radius: 6px;
  margin: 6px 0;
}

.btn:hover { background: var(--accent-dark); color: #fff; }

.btn.ghost {
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--accent);
}

/* ---------- footer ---------- */

footer {
  background: var(--accent-dark);
  padding: 26px 0 34px;
  color: rgba(255, 255, 255, 0.88);
  font-size: 0.88rem;
}

footer a { color: #ffffff; }
footer a:hover { color: #ffffff; opacity: 0.85; }
footer .flinks { margin-top: 6px; }

/* ---------- contact links ---------- */

.contact-links { display: flex; flex-wrap: wrap; gap: 10px; margin: 14px 0 0; padding: 0; list-style: none; }

.contact-links a {
  display: inline-block;
  border: 1px solid var(--accent);
  color: var(--accent);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 600;
  padding: 7px 16px;
  border-radius: 999px;
}

.contact-links a:hover { background: var(--accent-soft); }

/* ---------- mobile ---------- */

@media (max-width: 640px) {
  body { font-size: 16px; }
  .hero { flex-direction: column-reverse; gap: 28px; }
  .portrait { width: 150px; height: 182px; }
  .news li { flex-direction: column; gap: 2px; }
  .news .date { flex: none; }
  h1 { font-size: 1.7rem; }
}