/* Personal site — clean academic style, inspired by frowang's visual tone */

:root {
  --text: #1a1a1a;
  --text-secondary: #555;
  --text-muted: #888;
  --link: #2b5ce6;
  --link-hover: #1a3fa0;
  --border: #e5e5e5;
  --bg: #fff;
  --bg-subtle: #fafafa;
  --max-width: 680px;
  --font-body: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    "Helvetica Neue", Arial, "PingFang SC", "Hiragino Sans GB",
    "Microsoft YaHei", sans-serif;
  --font-serif: Georgia, "Times New Roman", serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { font-size: 16px; }

body {
  font-family: var(--font-body);
  color: var(--text);
  background: var(--bg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

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

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

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

nav {
  border-bottom: 1px solid var(--border);
  padding: 20px 0;
}

nav .container {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
}

nav .site-name {
  font-weight: 600;
  font-size: 1.05rem;
  color: var(--text);
  text-decoration: none;
}

nav ul {
  list-style: none;
  display: flex;
  gap: 28px;
}

nav ul a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.92rem;
}

nav ul a:hover, nav ul a.active {
  color: var(--link);
}

/* ---------- language switcher ---------- */

nav ul a.lang-switch {
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 1px 8px;
  font-size: 0.82rem;
  color: var(--text-muted);
}

nav ul a.lang-switch:hover {
  color: var(--link);
  border-color: var(--link);
}

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

.hero {
  padding: 64px 0 48px;
}

.hero h1 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 6px;
}

.hero .role {
  font-size: 1.05rem;
  color: var(--text-secondary);
  margin-bottom: 4px;
}

.hero .email {
  font-size: 0.92rem;
  color: var(--text-muted);
  margin-bottom: 20px;
}

.hero .tagline {
  font-size: 1.05rem;
  color: var(--text);
  max-width: 560px;
  margin-bottom: 28px;
}

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

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

.hero .links a:hover { text-decoration: underline; }

.hero .links .sep { color: var(--border); }

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

section {
  padding: 36px 0;
}

section + section { border-top: 1px solid var(--border); }

section h2 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 20px;
  letter-spacing: -0.01em;
}

/* ---------- entries (papers / projects) ---------- */

.entry {
  margin-bottom: 24px;
}

.entry:last-child { margin-bottom: 0; }

.entry-title {
  font-weight: 600;
  font-size: 1.02rem;
  line-height: 1.4;
}

.entry-meta {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin: 3px 0 6px;
}

.entry-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.entry-desc a { color: var(--link); text-decoration: none; }
.entry-desc a:hover { text-decoration: underline; }

.status-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 1px 7px;
  margin-left: 8px;
  vertical-align: 2px;
}

/* ---------- see-all link ---------- */

.see-all {
  margin-top: 16px;
  font-size: 0.92rem;
}

.see-all a {
  color: var(--link);
  text-decoration: none;
}

.see-all a:hover { text-decoration: underline; }

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

footer {
  border-top: 1px solid var(--border);
  padding: 32px 0;
  margin-top: 48px;
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* ---------- page content (research / projects / about) ---------- */

.page-header {
  padding: 48px 0 32px;
}

.page-header h1 {
  font-size: 1.6rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.page-header .subtitle {
  color: var(--text-secondary);
  margin-top: 4px;
}

/* ---------- responsive ---------- */

@media (max-width: 600px) {
  .hero { padding: 40px 0 32px; }
  .hero h1 { font-size: 1.6rem; }
  nav ul { gap: 18px; }
}