/* =====================================================
   Intelligent Software Systems Lab — site stylesheet
   Palette: warm paper ground / KNU burgundy accent
   ===================================================== */

:root {
  --paper: #FAF9F7;
  --paper-2: #F1EEE9;
  --ink: #201C1B;
  --ink-2: #5C5652;
  --accent: #8E2431;
  --accent-ink: #FFFFFF;
  --slate: #44546A;
  --line: #E6E1DB;
  --card: #FFFFFF;
  --wave: #8E2431;
  --shadow: 0 1px 2px rgba(32,28,27,.05), 0 8px 24px rgba(32,28,27,.06);
}
@media (prefers-color-scheme: dark) {
  :root {
    --paper: #1A1817;
    --paper-2: #211E1D;
    --ink: #EDE8E3;
    --ink-2: #A39C96;
    --accent: #D06A75;
    --accent-ink: #1A1817;
    --slate: #9DB0C8;
    --line: #35302D;
    --card: #242120;
    --wave: #D06A75;
    --shadow: 0 1px 2px rgba(0,0,0,.3), 0 8px 24px rgba(0,0,0,.25);
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: "Apple SD Gothic Neo", "Pretendard", "Noto Sans KR", "Malgun Gothic", -apple-system, "Segoe UI", sans-serif;
  line-height: 1.65;
  font-size: 16px;
}
.serif {
  font-family: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, "Noto Serif KR", serif;
}
a { color: inherit; }
a:focus-visible, button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 2px;
}
img { max-width: 100%; }
.wrap { max-width: 1080px; margin: 0 auto; padding: 0 24px; }

/* ---------- header ---------- */
header.site {
  position: sticky; top: 0; z-index: 20;
  background: color-mix(in srgb, var(--paper) 88%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
@supports not (background: color-mix(in srgb, red 50%, blue)) {
  header.site { background: var(--paper); }
}
.site-inner {
  display: flex; align-items: center; justify-content: space-between;
  gap: 24px; padding: 14px 24px; max-width: 1080px; margin: 0 auto;
  flex-wrap: wrap;
}
.brand { display: flex; align-items: baseline; gap: 10px; text-decoration: none; }
.brand .mark { font-weight: 800; font-size: 18px; letter-spacing: -.01em; }
.brand .mark em { font-style: normal; color: var(--accent); }
.brand .univ { font-size: 12px; color: var(--ink-2); letter-spacing: .06em; }
nav.main { display: flex; gap: 4px; flex-wrap: wrap; align-items: center; }
nav.main a {
  text-decoration: none; font-size: 14.5px; font-weight: 600;
  padding: 7px 12px; border-radius: 6px; color: var(--ink-2);
}
nav.main a:hover { color: var(--ink); background: var(--paper-2); }
nav.main a.on { color: var(--accent); }
nav.main a.join { color: var(--accent-ink); background: var(--accent); margin-left: 6px; }
nav.main a.join:hover { filter: brightness(1.08); color: var(--accent-ink); }
.menu-btn {
  display: none; background: none; border: 1px solid var(--line); border-radius: 8px;
  padding: 7px 12px; font-size: 15px; color: var(--ink); cursor: pointer;
}

/* ---------- hero (home) ---------- */
.hero { position: relative; border-bottom: 1px solid var(--line); overflow: hidden; }
.hero-grid {
  display: grid; grid-template-columns: 1.15fr .85fr; gap: 48px;
  padding: 72px 0 64px; align-items: center;
}
.eyebrow {
  font-size: 12px; font-weight: 700; letter-spacing: .18em;
  text-transform: uppercase; color: var(--accent); margin: 0 0 18px;
}
h1.hero-title {
  font-size: clamp(34px, 4.6vw, 52px);
  line-height: 1.22; letter-spacing: -.015em;
  margin: 0 0 22px; font-weight: 700; text-wrap: balance;
  word-break: keep-all;
}
h1, h2, h3, .lede, .hero-lede, .card p, .area p { word-break: keep-all; }
h1.hero-title .kw { color: var(--accent); }
.hero-lede { font-size: 17px; color: var(--ink-2); max-width: 34em; margin: 0 0 30px; }
.hero-cta { display: flex; gap: 12px; flex-wrap: wrap; }
.btn {
  display: inline-block; text-decoration: none; font-weight: 700; font-size: 15px;
  padding: 12px 22px; border-radius: 8px; border: 1.5px solid transparent;
}
.btn-primary { background: var(--accent); color: var(--accent-ink); }
.btn-primary:hover { filter: brightness(1.08); }
.btn-ghost { border-color: var(--line); color: var(--ink); }
.btn-ghost:hover { border-color: var(--ink-2); }
.seis-box { position: relative; }
.seis-box canvas { width: 100%; height: 280px; display: block; }
.seis-caption {
  font-size: 12px; color: var(--ink-2); letter-spacing: .08em;
  text-transform: uppercase; margin-top: 10px; display: flex; justify-content: space-between;
  border-top: 1px solid var(--line); padding-top: 8px;
}

/* ---------- page head (subpages) ---------- */
.page-head { border-bottom: 1px solid var(--line); padding: 52px 0 40px; }
.page-head h1 {
  font-size: clamp(30px, 4vw, 40px); margin: 0 0 12px;
  letter-spacing: -.015em; font-weight: 700; text-wrap: balance;
}
.page-head .lede { font-size: 16.5px; color: var(--ink-2); max-width: 44em; margin: 0; }
.page-head .lede a { color: var(--accent); }

/* ---------- stats strip ---------- */
.stats { border-bottom: 1px solid var(--line); background: var(--paper-2); }
.stats-inner {
  display: grid; grid-template-columns: repeat(4, 1fr);
  max-width: 1080px; margin: 0 auto; padding: 0 24px;
}
.stat { padding: 26px 20px; border-left: 1px solid var(--line); }
.stat:first-child { border-left: none; padding-left: 0; }
.stat b {
  display: block; font-size: 30px; font-weight: 800; letter-spacing: -.02em;
  font-variant-numeric: tabular-nums;
}
.stat span { font-size: 13.5px; color: var(--ink-2); }

/* ---------- sections ---------- */
section { padding: 64px 0; }
.sec-head {
  display: flex; align-items: baseline; justify-content: space-between;
  gap: 16px; margin-bottom: 32px;
}
h2.sec-title { font-size: 27px; letter-spacing: -.01em; margin: 0; font-weight: 700; }
.sec-more { font-size: 14px; font-weight: 600; color: var(--accent); text-decoration: none; white-space: nowrap; }
.sec-more:hover { text-decoration: underline; }
.alt { background: var(--paper-2); border-block: 1px solid var(--line); }

/* ---------- research cards ---------- */
.cards { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }
.card {
  background: var(--card); border: 1px solid var(--line); border-radius: 10px;
  padding: 26px 26px 24px; box-shadow: var(--shadow);
  text-decoration: none; display: block; color: inherit;
}
a.card:hover { border-color: var(--accent); }
.card h3 { margin: 0 0 10px; font-size: 18.5px; letter-spacing: -.01em; }
.card p { margin: 0 0 14px; font-size: 15px; color: var(--ink-2); }
.tags { display: flex; flex-wrap: wrap; gap: 6px; }
.tag {
  font-size: 12px; font-weight: 600; color: var(--slate);
  border: 1px solid var(--line); border-radius: 99px; padding: 3px 10px;
}
.venue {
  font-size: 12.5px; color: var(--accent); font-weight: 700;
  letter-spacing: .05em; margin-bottom: 8px; display: block;
}

/* ---------- research page ---------- */
.area { padding: 44px 0; border-bottom: 1px solid var(--line); }
.area:last-of-type { border-bottom: none; }
.area h3 { font-size: 21px; margin: 0 0 6px; letter-spacing: -.01em; }
.area .venue { margin-bottom: 12px; }
.area p { color: var(--ink-2); max-width: 46em; margin: 0 0 16px; }
.area ul.rep { margin: 0; padding-left: 20px; font-size: 14.5px; color: var(--ink-2); }
.area ul.rep li { margin: 6px 0; }
.area ul.rep b { color: var(--ink); font-weight: 600; }
.sponsors {
  display: flex; flex-wrap: wrap; gap: 28px; align-items: center;
  padding: 20px 0 4px;
}
.sponsors img { height: 44px; width: auto; }
@media (prefers-color-scheme: dark) {
  .sponsors img { background: #FFFFFF; padding: 6px 10px; border-radius: 8px; }
}
.videos { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.videos .lead-video { grid-column: 1 / -1; }
.video-frame { position: relative; width: 100%; aspect-ratio: 16 / 9; }
.video-frame iframe {
  position: absolute; inset: 0; width: 100%; height: 100%;
  border: 0; border-radius: 10px; box-shadow: var(--shadow);
}

/* ---------- people ---------- */
.people-group { padding: 44px 0; border-bottom: 1px solid var(--line); }
.people-group:last-of-type { border-bottom: none; }
.people-group > h2 {
  font-size: 22px; margin: 0 0 26px; letter-spacing: -.01em;
}
.prof-card {
  display: grid; grid-template-columns: 240px 1fr; gap: 32px;
  background: var(--card); border: 1px solid var(--line); border-radius: 12px;
  padding: 32px; box-shadow: var(--shadow); align-items: start;
}
.prof-card img { width: 100%; border-radius: 10px; display: block; }
.prof-card h3 { margin: 0 0 4px; font-size: 22px; }
.prof-card .role { color: var(--accent); font-weight: 700; font-size: 13.5px; letter-spacing: .04em; margin: 0 0 14px; }
.prof-card p { margin: 0 0 12px; font-size: 15px; color: var(--ink-2); }
.prof-card .contact { font-size: 14px; color: var(--ink); }
.prof-card .contact a { color: var(--accent); text-decoration: none; }
.prof-card .contact a:hover { text-decoration: underline; }
.people-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.person {
  background: var(--card); border: 1px solid var(--line); border-radius: 10px;
  overflow: hidden; box-shadow: var(--shadow);
}
.person img { width: 100%; aspect-ratio: 6 / 7; object-fit: cover; display: block; }
.person .ph {
  width: 100%; aspect-ratio: 6 / 7; display: flex; align-items: center; justify-content: center;
  background: var(--paper-2); color: var(--ink-2); font-size: 44px; font-weight: 800;
  letter-spacing: .04em;
}
.person .p-body { padding: 16px 18px 18px; }
.person h3 { margin: 0 0 2px; font-size: 16.5px; }
.person .p-role { font-size: 12.5px; color: var(--accent); font-weight: 700; margin: 0 0 8px; }
.person p { margin: 0; font-size: 13.5px; color: var(--ink-2); line-height: 1.6; }
.alumni-cols { display: grid; grid-template-columns: 1fr 1fr; gap: 8px 40px; }
ul.plain { list-style: none; margin: 0; padding: 0; }
ul.plain li {
  padding: 9px 2px; border-bottom: 1px dashed var(--line); font-size: 14.5px;
}
ul.plain li b { font-weight: 600; }
ul.plain li .dest { color: var(--ink-2); font-size: 13.5px; }

/* ---------- news ---------- */
ul.news { list-style: none; margin: 0; padding: 0; }
ul.news li {
  display: grid; grid-template-columns: 110px 1fr; gap: 20px;
  padding: 15px 4px; border-bottom: 1px solid var(--line); font-size: 15.5px;
}
ul.news li:last-child { border-bottom: none; }
ul.news time {
  font-weight: 700; color: var(--accent); font-size: 13.5px;
  letter-spacing: .04em; padding-top: 2px; font-variant-numeric: tabular-nums;
}
.year-block { padding: 34px 0 8px; }
.year-block h2 {
  font-size: 20px; margin: 0 0 8px; color: var(--ink);
  letter-spacing: .02em;
}

/* ---------- publications ---------- */
.pub-links { display: flex; gap: 10px; margin-top: 18px; flex-wrap: wrap; }
.pub-links a {
  font-size: 13.5px; font-weight: 600; text-decoration: none;
  border: 1px solid var(--line); border-radius: 99px; padding: 6px 14px; color: var(--ink);
}
.pub-links a:hover { border-color: var(--accent); color: var(--accent); }
.pub-year { padding: 30px 0 6px; }
.pub-year h2 {
  font-size: 21px; margin: 0 0 4px; color: var(--accent); letter-spacing: .01em;
  font-variant-numeric: tabular-nums;
}
ul.pub-list { list-style: none; margin: 0; padding: 0; }
ul.pub-list li {
  padding: 13px 2px; border-bottom: 1px solid var(--line);
  font-size: 15px; line-height: 1.6;
}
ul.pub-list li:last-child { border-bottom: none; }
ul.pub-list .t { font-weight: 600; }
ul.pub-list .v { color: var(--ink-2); }
ul.pub-list .v b { color: var(--ink); }
ul.pub-list a { color: var(--accent); }
.badge {
  display: inline-block; font-size: 11.5px; font-weight: 700;
  color: var(--accent); border: 1px solid currentColor; border-radius: 4px;
  padding: 0 6px; margin-left: 6px; vertical-align: 1px; white-space: nowrap;
}
.badge.gold { color: #8A6D1D; }
@media (prefers-color-scheme: dark) { .badge.gold { color: #D4B457; } }

/* ---------- gallery ---------- */
.album { padding: 34px 0; border-bottom: 1px solid var(--line); }
.album:last-of-type { border-bottom: none; }
.album .a-head { display: flex; align-items: baseline; gap: 14px; margin-bottom: 16px; flex-wrap: wrap; }
.album h2 { font-size: 19px; margin: 0; letter-spacing: -.01em; }
.album time { font-size: 13.5px; color: var(--accent); font-weight: 700; font-variant-numeric: tabular-nums; }
.album-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
.album-grid a { display: block; border-radius: 8px; overflow: hidden; background: var(--paper-2); }
.album-grid img {
  width: 100%; aspect-ratio: 4 / 3; object-fit: cover; display: block;
  transition: transform .25s ease;
}
.album-grid a:hover img { transform: scale(1.03); }

/* ---------- join band ---------- */
.join-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 40px;
  background: var(--card); border: 1px solid var(--line); border-radius: 12px;
  padding: 44px; box-shadow: var(--shadow);
}
.join-grid h2 { margin: 0 0 14px; font-size: 25px; }
.join-grid p { margin: 0 0 20px; color: var(--ink-2); font-size: 15.5px; }
.join-list { list-style: none; padding: 0; margin: 0 0 4px; }
.join-list li {
  padding: 12px 0 12px 26px; border-bottom: 1px dashed var(--line);
  font-size: 15px; position: relative;
}
.join-list li::before {
  content: ""; position: absolute; left: 4px; top: 1.35em;
  width: 8px; height: 8px; border-radius: 50%; background: var(--accent);
}
.join-list li:last-child { border-bottom: none; }

/* ---------- footer ---------- */
footer.site {
  border-top: 1px solid var(--line); padding: 36px 0 48px;
  font-size: 13.5px; color: var(--ink-2);
}
.foot-inner { display: flex; justify-content: space-between; gap: 24px; flex-wrap: wrap; }
footer.site a { color: var(--accent); text-decoration: none; }
footer.site a:hover { text-decoration: underline; }

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  .people-grid { grid-template-columns: repeat(2, 1fr); }
  .album-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 860px) {
  .hero-grid { grid-template-columns: 1fr; gap: 36px; padding: 48px 0; }
  .stats-inner { grid-template-columns: repeat(2, 1fr); }
  .stat:nth-child(odd) { border-left: none; padding-left: 0; }
  .stat { padding: 18px 16px; }
  .cards { grid-template-columns: 1fr; }
  .videos { grid-template-columns: 1fr; }
  .join-grid { grid-template-columns: 1fr; padding: 30px; }
  .prof-card { grid-template-columns: 1fr; }
  .prof-card img { max-width: 260px; }
  .alumni-cols { grid-template-columns: 1fr; }
  .menu-btn { display: block; }
  nav.main {
    display: none; width: 100%; flex-direction: column; align-items: stretch;
    padding-bottom: 10px;
  }
  nav.main.open { display: flex; }
  nav.main a { padding: 11px 12px; }
  ul.news li { grid-template-columns: 1fr; gap: 2px; }
}
@media (max-width: 560px) {
  .people-grid { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .album-grid img { transition: none; }
}