/* ── Variables ─────────────────────────────────────────── */
:root {
  --bg:        #0d1117;
  --surface:   #161b22;
  --border:    #30363d;
  --text:      #e6edf3;
  --muted:     #8b949e;
  --accent:    #58a6ff;
  --accent-dim:#1f6feb33;
  --radius:    8px;
  --max-w:     800px;
}

/* ── Reset ─────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Inter', system-ui, sans-serif;
  font-size: 1rem;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

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

/* ── Layout ────────────────────────────────────────────── */
.container { max-width: var(--max-w); margin: 0 auto; padding: 0 1.5rem; }

section { padding: 3.5rem 0; border-bottom: 1px solid var(--border); }
section:last-of-type { border-bottom: none; }

h2 {
  font-size: 1.1rem; font-weight: 600; text-transform: uppercase;
  letter-spacing: 0.1em; color: var(--muted); margin-bottom: 1.5rem;
}

/* ── Header ────────────────────────────────────────────── */
#header { padding: 4rem 0 3rem; border-bottom: 1px solid var(--border); }
#header h1 { font-size: 2rem; font-weight: 700; letter-spacing: -0.02em; margin-bottom: 1rem; }

.nav-links { display: flex; flex-wrap: wrap; gap: 0.5rem 1.25rem; list-style: none; }
.nav-links a { font-size: 0.9rem; color: var(--muted); display: flex; align-items: center; gap: 0.35rem; transition: color 0.15s; }
.nav-links a:hover { color: var(--accent); text-decoration: none; }

/* ── About ─────────────────────────────────────────────── */
#about p { color: var(--text); margin-bottom: 1.5rem; max-width: 680px; }

.chips { display: flex; flex-wrap: wrap; gap: 0.5rem; }
.chip {
  background: var(--accent-dim); color: var(--accent); border: 1px solid #1f6feb;
  border-radius: 999px; padding: 0.2rem 0.75rem; font-size: 0.8rem; font-weight: 500; white-space: nowrap;
}

/* ── Project cards ─────────────────────────────────────── */
.cards { display: grid; gap: 1rem; }
.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1.4rem 1.6rem;
  transition: border-color 0.15s, box-shadow 0.15s;
}
.card:hover { border-color: var(--accent); box-shadow: 0 0 0 1px var(--accent); }

.card-header {
  display: flex; align-items: baseline; justify-content: space-between;
  flex-wrap: wrap; gap: 0.5rem; margin-bottom: 0.5rem;
}
.card h3 { font-size: 1rem; font-weight: 600; color: var(--accent); }
.card-link {
  font-size: 0.8rem; color: var(--muted); border: 1px solid var(--border);
  border-radius: 4px; padding: 0.15rem 0.6rem;
  transition: border-color 0.15s, color 0.15s; white-space: nowrap;
}
.card-link:hover { border-color: var(--accent); color: var(--accent); text-decoration: none; }
.card p { font-size: 0.9rem; color: var(--muted); margin-bottom: 0.9rem; }

.tag-list { display: flex; flex-wrap: wrap; gap: 0.4rem; }
.tag { background: transparent; color: var(--muted); border: 1px solid var(--border); border-radius: 4px; padding: 0.1rem 0.5rem; font-size: 0.75rem; }

/* ── Papers ────────────────────────────────────────────── */
#papers ul { list-style: none; display: flex; flex-direction: column; gap: 1.1rem; }
#papers li { padding-left: 1.1rem; position: relative; font-size: 0.92rem; }
#papers li::before { content: '–'; position: absolute; left: 0; color: var(--muted); }
.paper-year { color: var(--muted); font-size: 0.8rem; margin-right: 0.4rem; }
.paper-title { color: var(--text); }
.paper-venue { color: var(--muted); font-style: italic; font-size: 0.85rem; }
.paper-link { font-size: 0.8rem; margin-left: 0.4rem; }

/* ── Footer ────────────────────────────────────────────── */
footer { padding: 2rem 0; text-align: center; font-size: 0.82rem; color: var(--muted); }
footer a { color: var(--muted); }
footer a:hover { color: var(--accent); }
footer span { margin: 0 0.5rem; }

/* ── Responsive ────────────────────────────────────────── */
@media (max-width: 600px) {
  #header h1 { font-size: 1.5rem; }
  section { padding: 2.5rem 0; }
  .card-header { flex-direction: column; align-items: flex-start; }
}