/* ------------------------------------------------------------
   molinqin.com — minimal academic single-page stylesheet
   Theme follows the viewer's OS/browser preference automatically.
   ------------------------------------------------------------ */

:root {
  color-scheme: light dark;

  --bg:        #ffffff;
  --bg-elev:   #f6f6f4;
  --fg:        #1c1c1c;
  --fg-muted:  #5f6366;
  --link:      #1f4e8c;
  --link-hover:#0b2f5e;
  --rule:      #e2e2df;
  --nav-bg:    rgba(255, 255, 255, 0.88);

  --serif: "Charter", "Source Serif Pro", "Iowan Old Style", "Palatino Linotype", "Book Antiqua", Georgia, "Times New Roman", serif;
  --sans:  -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;

  --max-w: 46rem;
  --nav-h: 3.25rem;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg:        #131416;
    --bg-elev:   #1b1d20;
    --fg:        #e6e6e3;
    --fg-muted:  #a2a5a9;
    --link:      #8fb4e8;
    --link-hover:#b9d1f3;
    --rule:      #2c2f33;
    --nav-bg:    rgba(19, 20, 22, 0.88);
  }
}

/* ---------- base ---------- */
*, *::before, *::after { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--serif);
  font-size: 1.0625rem;
  line-height: 1.6;
}

a {
  color: var(--link);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color .15s ease, border-color .15s ease;
}
a:hover, a:focus-visible {
  color: var(--link-hover);
  border-bottom-color: currentColor;
}
a:focus-visible { outline: 2px solid var(--link); outline-offset: 2px; }

h1, h2, h3, h4 {
  font-family: var(--serif);
  font-weight: 600;
  line-height: 1.25;
  margin: 0;
}

h1 { font-size: 2rem; letter-spacing: -0.01em; }
h2 {
  font-size: 1.5rem;
  margin: 3rem 0 1.25rem;
  padding-bottom: .4rem;
  border-bottom: 1px solid var(--rule);
}
h3 {
  font-size: 1.125rem;
  margin: 1.75rem 0 .75rem;
}
h4 { font-size: 1.0625rem; }

p { margin: 0 0 .9rem; }
.muted { color: var(--fg-muted); }

ul.plain {
  list-style: none;
  margin: 0;
  padding: 0;
}
ul.plain li { margin-bottom: .6rem; }

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--bg);
  padding: .5rem 1rem;
}
.skip-link:focus { left: 0; z-index: 100; }

/* ---------- navigation ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: var(--nav-bg);
  backdrop-filter: saturate(180%) blur(10px);
  -webkit-backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--rule);
}

.nav {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 1.25rem;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-family: var(--sans);
  font-size: .95rem;
}

.nav-brand {
  font-family: var(--serif);
  font-weight: 600;
  font-size: 1.05rem;
  color: var(--fg);
}
.nav-brand:hover { color: var(--fg); border-bottom-color: transparent; }

.nav-links {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 1.4rem;
}
.nav-links a {
  color: var(--fg-muted);
  padding: .35rem 0;
}
.nav-links a:hover, .nav-links a:focus-visible {
  color: var(--fg);
  border-bottom-color: var(--fg);
}

/* ---------- layout ---------- */
.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 2.5rem 1.25rem 3rem;
}

section { scroll-margin-top: calc(var(--nav-h) + 1rem); }

/* ---------- intro ---------- */
.intro {
  display: flex;
  gap: 2rem;
  align-items: flex-start;
  margin-bottom: 1.75rem;
}

.portrait {
  flex: 0 0 auto;
  width: 180px;
  height: auto;
  border-radius: 6px;
  object-fit: cover;
}

.intro-text h1 .cjk {
  font-weight: 400;
  color: var(--fg-muted);
  font-size: .8em;
  margin-left: .35rem;
}

.tagline {
  margin: .5rem 0 1rem;
  color: var(--fg-muted);
}

.contact {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: .25rem 1.25rem;
  font-family: var(--sans);
  font-size: .95rem;
}

.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  margin-top: .5rem;
}
.two-col h3 { margin-top: 1.25rem; }
.edu-degree { font-weight: 600; }

/* ---------- papers ---------- */
.paper {
  padding: 1rem 0 1.1rem;
  border-bottom: 1px solid var(--rule);
}
.paper:last-child { border-bottom: none; }

.paper-title { margin-bottom: .25rem; }
.paper-authors, .paper-venue, .paper-links {
  margin: 0 0 .2rem;
}
.paper-authors { color: var(--fg-muted); }
.paper-links {
  font-family: var(--sans);
  font-size: .92rem;
  margin-top: .35rem;
}
.paper-links a + a::before,
.paper-links a + span::before {
  content: "·";
  color: var(--fg-muted);
  margin: 0 .5rem;
}

.abstract {
  margin-top: .6rem;
  font-size: .97rem;
}
.abstract summary {
  cursor: pointer;
  font-family: var(--sans);
  font-size: .9rem;
  color: var(--fg-muted);
  user-select: none;
  list-style: none;
  display: inline-flex;
  align-items: center;
  gap: .35rem;
}
.abstract summary::-webkit-details-marker { display: none; }
.abstract summary::before {
  content: "";
  display: inline-block;
  width: .45em;
  height: .45em;
  border-right: 1.5px solid currentColor;
  border-bottom: 1.5px solid currentColor;
  transform: rotate(-45deg);
  transition: transform .15s ease;
  margin-bottom: .1em;
}
.abstract[open] summary::before { transform: rotate(45deg); }
.abstract summary:hover { color: var(--fg); }
.abstract p {
  margin: .6rem 0 0;
  padding: .85rem 1rem;
  background: var(--bg-elev);
  border-left: 3px solid var(--rule);
  border-radius: 0 4px 4px 0;
  text-align: justify;
  hyphens: auto;
}

.course { font-weight: 600; }

/* ---------- footer ---------- */
.site-footer {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 1.5rem 1.25rem 2.5rem;
  border-top: 1px solid var(--rule);
  font-family: var(--sans);
  font-size: .85rem;
  color: var(--fg-muted);
}
.site-footer p { margin: 0 0 .3rem; }

/* ---------- responsive ---------- */
@media (max-width: 640px) {
  body { font-size: 1rem; }
  h1 { font-size: 1.65rem; }
  .nav { padding: 0 1rem; }
  .nav-links { gap: 1rem; }
  .container { padding: 1.75rem 1rem 2.5rem; }
  .intro { flex-direction: column; gap: 1.25rem; }
  .portrait { width: 140px; }
  .two-col { grid-template-columns: 1fr; gap: .5rem; }
  .abstract p { text-align: left; hyphens: none; }
}

@media (max-width: 400px) {
  .nav-brand { display: none; }
  .nav-links { width: 100%; justify-content: space-between; }
}

@media print {
  .site-header { position: static; }
  .abstract { break-inside: avoid; }
  .abstract[open] p { background: none; }
}