/* ===================================================================
   Aerospace Robotics Lab — Georgia Tech
   Visual identity: clean black & white (light, monochrome)
   Static site — single shared stylesheet, no build step.
   =================================================================== */

:root {
  --paper:      #ffffff;
  --paper-2:    #f7f7f8;
  --paper-3:    #f0f0f2;
  --hairline:   #e4e4e7;
  --hairline-2: #d2d2d7;

  --ink:        #2a2a30;   /* soft charcoal, headings/accent */
  --ink-2:      #3a3a42;
  --accent:      #2a2a30;
  --accent-dark: #3a3a42;
  --accent-tint: #f0f0f2;
  --gold:        #2a2a30;

  --text:       #3f3f47;
  --text-dim:   #62626b;
  --text-faint: #9094a0;

  --max: 1140px;
  --radius: 16px;
  --mono: "SF Mono", "JetBrains Mono", "Fira Code", ui-monospace, Menlo, Consolas, monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --shadow: 0 1px 2px rgba(17,17,20,.04), 0 10px 30px rgba(17,17,20,.06);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--sans);
  color: var(--text);
  background-color: var(--paper);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; transition: opacity .15s ease; }
a:hover { opacity: .65; }
img { max-width: 100%; display: block; }

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

.label {
  font-family: var(--mono);
  font-size: 12px; letter-spacing: 3px; text-transform: uppercase;
  color: var(--accent); font-weight: 600;
}
.label::before { content: "// "; color: var(--accent); opacity: .5; }

/* ---------------- Header / Nav ---------------- */
.site-header {
  position: sticky; top: 0; z-index: 60;
  background: rgba(255,255,255,.82);
  backdrop-filter: saturate(160%) blur(12px);
  border-bottom: 1px solid var(--hairline);
}
.nav { display: flex; align-items: center; justify-content: space-between; height: 72px; }
.brand { display: flex; align-items: center; gap: 13px; }
.brand .mark {
  position: relative; width: 42px; height: 42px; border-radius: 50%;
  display: grid; place-items: center; flex: 0 0 auto;
  background: var(--ink); border: 1px solid var(--ink);
}
.brand .mark svg { display: block; }
.brand .mark::before {
  content: ""; position: absolute; inset: -5px; border-radius: 50%;
  border: 1px solid var(--hairline-2);
  border-right-color: transparent; border-bottom-color: transparent;
  transform: rotate(35deg);
}
.brand .mark::after {
  content: ""; position: absolute; width: 5px; height: 5px; border-radius: 50%;
  background: var(--ink); top: -2px; right: 6px; border: 1px solid var(--paper);
}
.brand .mark b { font-family: var(--mono); font-size: 13px; color: #fff; font-weight: 700; letter-spacing: .5px; }
.brand .txt b { font-size: 16.5px; color: var(--text); letter-spacing: -.2px; display: block; }
.brand .txt span { display: block; font-size: 11px; color: var(--text-faint); font-family: var(--mono); letter-spacing: 1.5px; text-transform: uppercase; }
.nav-links { display: flex; gap: 2px; align-items: center; }
.nav-links a {
  padding: 9px 13px; border-radius: 9px; font-weight: 600; font-size: 14.5px; color: var(--text-dim);
}
.nav-links a:hover { color: var(--text); background: var(--paper-2); opacity: 1; }
.nav-links a.active { color: var(--accent); }
.nav-toggle { display: none; background: none; border: 0; font-size: 24px; cursor: pointer; color: var(--text); }

@media (max-width: 860px) {
  .nav-toggle { display: block; }
  .nav-links {
    display: none; position: absolute; top: 72px; left: 0; right: 0; flex-direction: column; gap: 0;
    background: var(--paper); border-bottom: 1px solid var(--hairline); padding: 8px;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 13px 14px; }
}

/* ---------------- Announcement banner ---------------- */
.notice { background: var(--accent); color: #fff; }
.notice .wrap { display: flex; gap: 14px; align-items: center; justify-content: center; padding: 11px 24px; font-size: 14px; text-align: center; flex-wrap: wrap; }
.notice a { color: #fff; text-decoration: underline; }
.notice a:hover { opacity: .75; }
.notice .pill { font-family: var(--mono); font-size: 10.5px; letter-spacing: 2px; text-transform: uppercase; background: rgba(255,255,255,.16); padding: 3px 9px; border-radius: 999px; }

/* ---------------- Hero ---------------- */
.hero { position: relative; overflow: hidden; padding: 68px 0 62px; background: var(--paper-2); border-bottom: 1px solid var(--hairline); }
.hero-grid {
  position: absolute; inset: 0; pointer-events: none;
  background-image:
    linear-gradient(var(--hairline) 1px, transparent 1px),
    linear-gradient(90deg, var(--hairline) 1px, transparent 1px);
  background-size: 64px 64px;
  -webkit-mask-image: radial-gradient(700px 400px at 70% 30%, #000, transparent 75%);
          mask-image: radial-gradient(700px 400px at 70% 30%, #000, transparent 75%);
}
.hero .wrap { position: relative; z-index: 2; }
.hero h1 { font-size: clamp(32px, 5.4vw, 58px); line-height: 1.04; margin: 14px 0 16px; letter-spacing: -1.4px; color: var(--ink); }
.hero h1 .accent { color: var(--text-faint); }
.hero p { font-size: clamp(16px, 2.1vw, 20px); color: var(--text-dim); max-width: 680px; margin: 0 0 22px; }
.hero-emblem { width: 104px; height: auto; display: block; margin-bottom: 20px; }
.hero-inner { display: grid; grid-template-columns: 1.05fr .95fr; gap: 40px; align-items: center; }
@media (max-width: 900px) { .hero-inner { grid-template-columns: 1fr; gap: 28px; } }
.hero-media .video-embed { box-shadow: var(--shadow); }
.video-thumbs { display: flex; gap: 10px; margin-top: 12px; flex-wrap: wrap; }
.vthumb { padding: 0; border: 2px solid transparent; border-radius: 9px; overflow: hidden; cursor: pointer; background: none; width: 110px; flex: 0 0 auto; line-height: 0; transition: border-color .15s ease; }
.vthumb img { width: 100%; height: auto; display: block; }
.vthumb:hover { border-color: var(--hairline-2); }
.vthumb.active { border-color: var(--ink); }
.btn-row { display: flex; gap: 13px; flex-wrap: wrap; }
.btn { display: inline-block; padding: 13px 24px; border-radius: 11px; font-weight: 700; font-size: 15px; transition: all .15s ease; }
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: var(--accent-dark); color: #fff; opacity: 1; }
.btn-ghost { background: transparent; color: var(--accent); border: 1px solid var(--hairline-2); }
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); opacity: 1; }

/* ---------------- Quick links ---------------- */
.quicklinks { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 28px; }
.quicklinks a { display: inline-flex; align-items: center; gap: 9px; border: 1px solid var(--hairline-2); border-radius: 10px; padding: 9px 15px; font-size: 14px; font-weight: 600; color: var(--ink); background: var(--paper); transition: border-color .15s ease, color .15s ease; }
.quicklinks a:hover { border-color: var(--accent); color: var(--accent); opacity: 1; }
.quicklinks a .ext { font-family: var(--mono); font-size: 11px; color: var(--text-faint); }

/* ---------------- Sections ---------------- */
section { padding: 52px 0; }
.section-soft { background: var(--paper-2); }
.section-head { max-width: 720px; margin: 0 0 26px; }
.section-head h2 { font-size: clamp(26px, 3.6vw, 38px); margin: 8px 0 8px; letter-spacing: -.7px; color: var(--ink); }
.section-head p { color: var(--text-dim); font-size: 16.5px; margin: 0; }

.page-title { padding: 48px 0 6px; position: relative; }
.page-title h1 { font-size: clamp(30px, 4.8vw, 46px); margin: 8px 0 8px; letter-spacing: -.8px; color: var(--ink); }
.page-title p { color: var(--text-dim); font-size: 17.5px; margin: 0; max-width: 720px; }

/* ---------------- Cards / Grid ---------------- */
.grid { display: grid; gap: 18px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 940px) { .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 640px) { .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; } }

.card {
  position: relative; background: var(--paper); border: 1px solid var(--hairline);
  border-radius: var(--radius); padding: 24px; overflow: hidden;
  transition: transform .18s ease, border-color .18s ease, box-shadow .18s ease;
}
.card::before { content: ""; position: absolute; top: 0; left: 0; width: 40px; height: 2px; background: var(--accent); opacity: 1; }
.card:hover { transform: translateY(-4px); border-color: var(--hairline-2); box-shadow: var(--shadow); }
.card .tag { display: inline-block; font-family: var(--mono); font-size: 11px; font-weight: 600; letter-spacing: 1.5px; text-transform: uppercase; color: var(--accent); margin-bottom: 14px; }
.card h3 { margin: 0 0 10px; font-size: 20px; letter-spacing: -.3px; color: var(--ink); }
.card p { margin: 0; color: var(--text-dim); font-size: 15px; line-height: 1.5; }
.card .partner { margin-top: 14px; font-family: var(--mono); font-size: 11.5px; letter-spacing: 1px; color: var(--text-faint); text-transform: uppercase; }

/* ---------------- PI block ---------------- */
.pi { display: grid; grid-template-columns: 230px 1fr; gap: 36px; align-items: start; }
@media (max-width: 640px) { .pi { grid-template-columns: 1fr; } }
.pi .frame { position: relative; }
.pi .frame img { width: 230px; border-radius: var(--radius); border: 1px solid var(--hairline); }
.pi .frame::after { content: ""; position: absolute; inset: -8px; border: 1px solid var(--hairline); border-radius: 22px; pointer-events: none; }
.pi h3 { margin: 6px 0 4px; font-size: 26px; letter-spacing: -.5px; color: var(--ink); }
.pi .role { color: var(--text-dim); font-weight: 700; margin: 0 0 16px; }

/* ---------------- People ---------------- */
.people { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
@media (max-width: 940px) { .people { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 560px) { .people { grid-template-columns: 1fr; } }
.person { background: var(--paper); border: 1px solid var(--hairline); border-radius: var(--radius); overflow: hidden; transition: transform .18s ease, border-color .18s ease, box-shadow .18s ease; }
.person:hover { transform: translateY(-4px); border-color: var(--accent); box-shadow: var(--shadow); }
.person .photo { aspect-ratio: 1/1; background: var(--paper-3); overflow: hidden; }
.person .photo img { width: 100%; height: 100%; object-fit: cover; transition: transform .2s ease; }
.person:hover .photo img { transform: scale(1.03); }
.person .photo.placeholder { display: grid; place-items: center; background: var(--paper-3); color: var(--text-faint); font-size: 40px; font-weight: 800; font-family: var(--mono); }
.person .body { padding: 17px 19px; }
.person .body b { font-size: 16px; color: var(--ink); }
.person .body p { margin: 5px 0 0; font-size: 13px; color: var(--text-dim); }
.person .body .topic { font-family: var(--mono); font-size: 11.5px; color: var(--text-dim); letter-spacing: .3px; margin-top: 7px; }

.name-list { display: flex; flex-wrap: wrap; gap: 10px; }
.name-list span { background: var(--paper); border: 1px solid var(--hairline); border-radius: 999px; padding: 9px 17px; font-weight: 600; font-size: 14.5px; color: var(--text-dim); }
.name-list span:hover { border-color: var(--hairline-2); color: var(--text); }

.subhead { font-family: var(--mono); font-size: 12px; letter-spacing: 2.5px; text-transform: uppercase; color: var(--text-faint); font-weight: 600; margin: 34px 0 16px; display: flex; align-items: center; gap: 14px; }
.subhead::after { content: ""; flex: 1; height: 1px; background: var(--hairline); }

/* ---------------- Publications ---------------- */
.pub-tabs { display: flex; gap: 8px; margin-bottom: 26px; flex-wrap: wrap; }
.pub-tabs button { border: 1px solid var(--hairline); background: var(--paper); color: var(--text-dim); padding: 9px 20px; border-radius: 999px; font-weight: 600; font-size: 14px; cursor: pointer; font-family: var(--sans); transition: all .15s ease; }
.pub-tabs button:hover { color: var(--text); border-color: var(--hairline-2); }
.pub-tabs button.active { background: var(--accent); color: #fff; border-color: var(--accent); }
.pub { display: flex; gap: 18px; padding: 15px 0; border-bottom: 1px solid var(--hairline); }
.pub .id { flex: 0 0 auto; font-family: var(--mono); font-weight: 700; color: var(--accent); background: var(--accent-tint); border: 1px solid var(--accent-tint); border-radius: 8px; padding: 5px 11px; height: fit-content; font-size: 12.5px; }
.pub .meta p { margin: 0; font-size: 15px; color: var(--text); }
.pub .meta .venue { color: var(--text-faint); font-size: 13.5px; margin-top: 5px; }
.pub .meta .venue .award { color: var(--accent); font-weight: 700; }
.pub .meta a.pdf { font-family: var(--mono); font-size: 12px; font-weight: 700; letter-spacing: .5px; }

/* ---------------- Contact ---------------- */
.contact-grid { display: grid; grid-template-columns: 1.1fr .9fr; gap: 26px; }
@media (max-width: 720px) { .contact-grid { grid-template-columns: 1fr; } }
.info-row { display: flex; gap: 14px; padding: 16px 0; border-bottom: 1px solid var(--hairline); }
.info-row .ic { flex: 0 0 auto; width: 38px; height: 38px; border-radius: 10px; background: var(--accent-tint); border: 1px solid var(--accent-tint); display: grid; place-items: center; color: var(--accent); }
.info-row .k { font-family: var(--mono); font-size: 11px; letter-spacing: 1.5px; text-transform: uppercase; color: var(--text-faint); }
.info-row .v { font-size: 15.5px; color: var(--text); }

/* ---------------- Video embed ---------------- */
.video-embed { position: relative; width: 100%; aspect-ratio: 16 / 9; border-radius: var(--radius); overflow: hidden; border: 1px solid var(--hairline); background: #000; box-shadow: var(--shadow); }
.video-embed iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }

/* ---------------- News ---------------- */
.news { display: grid; gap: 0; }
.news .item { display: flex; gap: 22px; padding: 15px 2px; border-bottom: 1px solid var(--hairline); align-items: baseline; }
.news .item:hover { opacity: 1; }
.news .item:hover .t { text-decoration: underline; }
.news .date { font-family: var(--mono); font-size: 11.5px; letter-spacing: 1px; color: var(--text-faint); flex: 0 0 88px; text-transform: uppercase; }
.news .t { color: var(--text); font-size: 16.5px; font-weight: 600; letter-spacing: -.2px; }
.news .t .src { display: block; color: var(--text-faint); font-weight: 500; font-size: 12.5px; font-family: var(--mono); letter-spacing: .5px; margin-top: 3px; text-decoration: none; }
@media (max-width: 560px) { .news .item { flex-direction: column; gap: 4px; } }

/* ---------------- Method visualizations (animations) ---------------- */
.viz-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
@media (max-width: 920px) { .viz-grid { grid-template-columns: 1fr; max-width: 520px; margin: 0 auto; } }
.viz { background: var(--paper); border: 1px solid var(--hairline); border-radius: var(--radius); padding: 22px; }
.viz .tag { display: inline-block; font-family: var(--mono); font-size: 11px; font-weight: 600; letter-spacing: 1.5px; text-transform: uppercase; color: var(--accent); margin-bottom: 12px; }
.viz h3 { margin: 0 0 8px; font-size: 19px; letter-spacing: -.3px; color: var(--ink); }
.viz .stage { width: 100%; height: auto; display: block; background: var(--paper-2); border: 1px solid var(--hairline); border-radius: 12px; }
.viz .cap { color: var(--text-dim); font-size: 14px; margin: 12px 0 0; }
.viz .v-tube   { stroke: var(--accent-tint); stroke-width: 26; fill: none; stroke-linecap: round; opacity: .8; }
.viz .v-sample { stroke: var(--hairline-2); stroke-width: 1.2; fill: none; opacity: .7; stroke-dasharray: 5 5; animation: vflow 3s linear infinite; }
.viz .v-mean   { stroke: var(--ink); stroke-width: 2.5; fill: none; }
.viz .v-obst   { fill: var(--paper-3); stroke: var(--text-faint); stroke-width: 1.2; }
.viz .v-node   { fill: var(--ink); }
.viz .v-goal   { fill: var(--paper); stroke: var(--ink); stroke-width: 2; }
.viz .v-ell    { fill: var(--accent-tint); stroke: var(--ink); stroke-width: 1.2; opacity: .85; }
.viz .v-orbit  { stroke: var(--hairline-2); stroke-width: 1.2; fill: none; }
.viz .v-agent  { fill: var(--ink); }
.viz .v-target { fill: var(--ink); }
.viz .v-pulse  { stroke: var(--text-faint); stroke-width: 1.4; fill: none; }
.viz .v-wire   { stroke: var(--ink); stroke-width: 1.4; fill: none; }
.viz .v-lbl    { fill: var(--text-faint); font-family: var(--mono); font-size: 9px; letter-spacing: 1px; text-transform: uppercase; }
@keyframes vflow { to { stroke-dashoffset: -60; } }
@media (prefers-reduced-motion: reduce) { .viz .v-sample { animation: none; } }

/* ---------------- Alumni list ---------------- */
.alumni { display: grid; gap: 0; max-width: 760px; }
.alumni .row { display: flex; flex-wrap: wrap; gap: 6px 12px; align-items: baseline; padding: 13px 0; border-bottom: 1px solid var(--hairline); }
.alumni .row b { color: var(--ink); font-size: 16px; }
.alumni .row .deg { font-family: var(--mono); font-size: 11.5px; letter-spacing: .5px; text-transform: uppercase; color: var(--text-faint); }
.alumni .row .now { color: var(--text-dim); font-size: 14.5px; }
.alumni .row .now::before { content: "→ "; color: var(--accent); }

/* ---------------- Blog (article list) ---------------- */
.postlist { max-width: 760px; }
.post-entry { padding: 22px 0; border-bottom: 1px solid var(--hairline); }
.post-entry:first-child { padding-top: 0; }
.post-entry .meta { font-family: var(--mono); font-size: 11.5px; letter-spacing: 1.5px; text-transform: uppercase; color: var(--text-faint); margin-bottom: 7px; }
.post-entry h3 { margin: 0 0 6px; font-size: 21px; letter-spacing: -.3px; }
.post-entry h3 a { color: var(--ink); }
.post-entry p { margin: 0; color: var(--text-dim); font-size: 15.5px; }
.post-entry .more { display: inline-block; margin-top: 8px; font-weight: 600; font-size: 14px; }

/* ---------------- Footer ---------------- */
.site-footer { border-top: 1px solid var(--hairline); background: var(--paper-2); padding: 44px 0; margin-top: 50px; }
.site-footer .wrap { display: flex; justify-content: space-between; gap: 20px; flex-wrap: wrap; align-items: center; }
.site-footer .lab { color: var(--ink); font-weight: 700; }
.site-footer .sub { color: var(--text-faint); font-size: 13.5px; margin-top: 3px; font-family: var(--mono); letter-spacing: .5px; }
.site-footer a { color: var(--accent); }
.site-footer .right { font-family: var(--mono); font-size: 12.5px; color: var(--text-faint); letter-spacing: 1px; }