/* ------------------------------------------------------------------
   tgy1221.github.io — v2
   Type: IBM Plex Serif (display) / IBM Plex Sans (text) / IBM Plex Mono (data)
   ------------------------------------------------------------------ */

:root {
  --bg:        #ffffff;
  --bg-soft:   #f4f4f5;
  --ink:       #101013;
  --ink-2:     #35353a;
  --muted:     #6b6b72;
  --rule:      rgba(0, 0, 0, 0.11);
  --rule-soft: rgba(0, 0, 0, 0.06);
  --accent:    #0b62d6;

  /* mark treatments: raster black-on-white vs. flat-color vector */
  --mark-invert: 0;
  --mark-white: none;

  --serif: "IBM Plex Serif", Georgia, "Times New Roman", serif;
  --sans:  "IBM Plex Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --mono:  "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;

  --pad: clamp(20px, 5vw, 40px);
  --max: 1060px;

  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg:        #08080a;
    --bg-soft:   #131316;
    --ink:       #f4f4f6;
    --ink-2:     #cfcfd4;
    --muted:     #8a8a92;
    --rule:      rgba(255, 255, 255, 0.15);
    --rule-soft: rgba(255, 255, 255, 0.08);
    --accent:    #4d9dff;
    --mark-invert: 1;
    --mark-white: brightness(0) invert(1);
    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --bg:        #08080a;
  --bg-soft:   #131316;
  --ink:       #f4f4f6;
  --ink-2:     #cfcfd4;
  --muted:     #8a8a92;
  --rule:      rgba(255, 255, 255, 0.15);
  --rule-soft: rgba(255, 255, 255, 0.08);
  --accent:    #4d9dff;
  --mark-invert: 1;
  --mark-white: brightness(0) invert(1);
  color-scheme: dark;
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 92px;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17.5px;
  line-height: 1.58;
  letter-spacing: -0.004em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }
img { max-width: 100%; display: block; }
h1, h2, h3 { margin: 0; font-weight: 600; letter-spacing: -0.018em; }

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

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

.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: color-mix(in srgb, var(--bg) 80%, transparent);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.25s ease;
}
.nav[data-stuck="true"] { border-bottom-color: var(--rule-soft); }

.nav-inner {
  height: 58px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.nav-mark {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 15px;
  font-weight: 600;
  color: var(--ink);
}
.nav-mark img { width: 26px; height: 26px; border-radius: 50%; object-fit: cover; }
.nav-mark span { white-space: nowrap; }
.nav-mark:hover { text-decoration: none; opacity: 0.62; }

.nav-right { display: flex; align-items: center; gap: clamp(14px, 2.6vw, 28px); }

.nav-links {
  display: flex;
  gap: clamp(14px, 2.6vw, 28px);
  font-size: 14.5px;
  color: var(--muted);
}
.nav-links a { color: inherit; }
.nav-links a:hover { color: var(--ink); text-decoration: none; }

.theme-toggle {
  appearance: none;
  border: 1px solid var(--rule);
  background: transparent;
  color: var(--ink-2);
  width: 34px;
  height: 34px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  cursor: pointer;
  padding: 0;
  flex: none;
  transition: border-color 0.2s ease, color 0.2s ease;
}
.theme-toggle:hover { border-color: var(--ink); color: var(--ink); }
.theme-toggle svg { width: 16px; height: 16px; }
.theme-toggle .moon { display: none; }
:root[data-theme="dark"] .theme-toggle .moon { display: block; }
:root[data-theme="dark"] .theme-toggle .sun  { display: none; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .theme-toggle .moon { display: block; }
  :root:not([data-theme="light"]) .theme-toggle .sun  { display: none; }
}

@media (max-width: 700px) { .nav-links a[data-optional] { display: none; } }
@media (max-width: 520px) { .nav-mark span { display: none; } }

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

.hero {
  padding-top: clamp(44px, 8vw, 84px);
  padding-bottom: clamp(48px, 9vw, 88px);
  display: grid;
  grid-template-columns: minmax(0, 1fr) 306px;
  gap: clamp(32px, 6vw, 64px);
  align-items: start;
}
@media (max-width: 880px) { .hero { grid-template-columns: 1fr; gap: 34px; } }

.avatar {
  width: 132px;
  height: 132px;
  border-radius: 50%;
  object-fit: cover;
  margin-bottom: 24px;
  background: var(--bg-soft);
}

.eyebrow {
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 16px;
}

h1 {
  font-family: var(--serif);
  font-size: clamp(2.7rem, 6.6vw, 4.15rem);
  font-weight: 600;
  line-height: 1.04;
  letter-spacing: -0.024em;
  margin-bottom: 24px;
}

.roles {
  margin: 0 0 28px;
  padding: 0 0 0 17px;
  list-style: none;
  border-left: 2px solid var(--rule);
  display: grid;
  gap: 9px;
}
.roles li { font-size: 16.5px; color: var(--ink-2); line-height: 1.45; }
.roles strong { font-weight: 600; color: var(--ink); }
.roles .sub {
  display: block;
  font-size: 15px;
  color: var(--muted);
  margin-top: 1px;
}
.roles .sub a { color: var(--muted); }
.roles .sub a:hover { color: var(--accent); text-decoration: none; }

.lede {
  font-size: clamp(1.3rem, 2.15vw, 1.6rem);
  line-height: 1.42;
  letter-spacing: -0.014em;
  color: var(--ink);
  margin: 0 0 28px;
  max-width: 32ch;
}

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0 0 32px;
  padding: 0;
  list-style: none;
}
.tags li {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ink-2);
  border: 1px solid var(--rule);
  border-radius: 100px;
  padding: 5px 12px;
}

.links { display: flex; flex-wrap: wrap; gap: 22px; font-size: 15.5px; }
.links a { color: var(--ink-2); display: inline-flex; align-items: center; gap: 6px; }
.links a:hover { color: var(--accent); text-decoration: none; }
.links .arw { font-size: 11px; opacity: 0.5; }

/* ---------- availability ------------------------------------------- */

.avail {
  border: 1px solid var(--rule);
  border-radius: 16px;
  padding: 24px;
  background: var(--bg-soft);
}
.avail-title {
  display: flex;
  align-items: center;
  gap: 9px;
  font-size: 14.5px;
  font-weight: 600;
  margin-bottom: 7px;
}
.dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: #2fbf5b;
  box-shadow: 0 0 0 3px color-mix(in srgb, #2fbf5b 22%, transparent);
  flex: none;
}
.avail-body { font-size: 15px; color: var(--muted); margin: 0 0 20px; line-height: 1.5; }

.btn {
  display: inline-block;
  background: var(--ink);
  color: var(--bg);
  font-size: 15px;
  font-weight: 500;
  padding: 10px 22px;
  border-radius: 100px;
  transition: opacity 0.2s ease;
}
.btn:hover { opacity: 0.82; text-decoration: none; }

.avail-mail {
  display: block;
  margin-top: 13px;
  font-family: var(--mono);
  font-size: 13px;
  color: var(--muted);
  word-break: break-all;
}
.avail-mail:hover { color: var(--accent); text-decoration: none; }

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

section { padding-block: clamp(52px, 8vw, 84px); }
section + section { border-top: 1px solid var(--rule-soft); }

.sec-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 20px;
  margin-bottom: clamp(28px, 4vw, 44px);
}
.sec-label {
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--muted);
}
.sec-note { font-size: 14.5px; color: var(--muted); }

/* ---------- research ------------------------------------------------ */

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(20px, 3vw, 34px);
}
@media (max-width: 780px) { .grid-3 { grid-template-columns: 1fr; gap: 28px; } }

.topic .num {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--muted);
  display: block;
  border-top: 1px solid var(--rule);
  padding-top: 13px;
  margin-bottom: 13px;
}
.topic h3 { font-size: 21px; letter-spacing: -0.016em; margin-bottom: 9px; }
.topic p { margin: 0; font-size: 16px; line-height: 1.52; color: var(--muted); }

/* ---------- publications -------------------------------------------- */

.pubs { display: grid; }

.pub {
  display: grid;
  grid-template-columns: 42px 232px minmax(0, 1fr);
  gap: clamp(16px, 2.6vw, 30px);
  padding-block: 32px;
  border-top: 1px solid var(--rule);
  align-items: start;
}
.pub:last-child { border-bottom: 1px solid var(--rule); }
@media (max-width: 760px) {
  .pub { grid-template-columns: 36px minmax(0, 1fr); }
  .pub-thumb { display: none; }
}

.pub-num { font-family: var(--mono); font-size: 13px; color: var(--muted); padding-top: 3px; }

.pub-thumb {
  aspect-ratio: 16 / 10;
  border-radius: 10px;
  overflow: hidden;
  background: var(--bg-soft);
  border: 1px solid var(--rule-soft);
  padding: 5px;
}
.pub-thumb img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  border-radius: 5px;
  transition: transform 0.45s cubic-bezier(0.22, 1, 0.36, 1);
}
.pub:hover .pub-thumb img { transform: scale(1.045); }

.pub-venue {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 10px;
}
.pub-venue b { color: var(--ink); font-weight: 600; }

.pub-title {
  font-size: 21px;
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: -0.017em;
  margin-bottom: 9px;
}
.pub-title a { color: var(--ink); }
.pub-title a:hover { color: var(--accent); text-decoration: none; }

.pub-authors { font-size: 15.5px; color: var(--muted); margin: 0 0 11px; line-height: 1.5; }
.pub-authors .me { color: var(--ink); font-weight: 600; }
.pub-authors a { color: var(--muted); }
.pub-authors a:hover { color: var(--ink); text-decoration: none; }

.pub-desc { font-size: 16px; line-height: 1.55; color: var(--ink-2); margin: 0 0 14px; max-width: 62ch; }

.pub-links { display: flex; flex-wrap: wrap; gap: 7px; font-size: 13px; }
.pub-links a {
  color: var(--ink-2);
  border: 1px solid var(--rule);
  border-radius: 100px;
  padding: 4px 13px;
  transition: border-color 0.18s ease, color 0.18s ease;
}
.pub-links a:hover { color: var(--accent); border-color: var(--accent); text-decoration: none; }

/* ---------- education / experience ----------------------------------- */

.entries { display: grid; }

.entry {
  display: grid;
  grid-template-columns: 132px 148px minmax(0, 1fr);
  gap: clamp(16px, 3vw, 32px);
  align-items: start;
  padding-block: 26px;
  border-top: 1px solid var(--rule);
}
.entry:last-child { border-bottom: 1px solid var(--rule); }

.entry-mark { height: 58px; display: flex; align-items: center; }
.entry-mark img {
  max-width: 100%;
  max-height: 58px;
  width: auto;
  height: auto;
  object-fit: contain;
}
/* black artwork on an opaque white plate — straight inversion */
.entry-mark img.tone-mono { filter: invert(var(--mark-invert)); }
/* flat-color vector on transparency — force to white */
.entry-mark img.tone-flat { filter: var(--mark-white); }
/* the CMU red chip and Intel blue keep their brand color in both themes */
.entry-mark img.chip { border-radius: 3px; }

.entry-when {
  font-family: var(--mono);
  font-size: 13px;
  color: var(--muted);
  padding-top: 3px;
  white-space: nowrap;
}

.entry-body h3 { font-size: 19px; letter-spacing: -0.016em; margin-bottom: 4px; }
.entry-org { font-size: 16px; color: var(--ink-2); margin: 0; }
.entry-note { font-size: 15px; color: var(--muted); margin: 4px 0 0; }
.entry-note a { color: var(--muted); }
.entry-note a:hover { color: var(--accent); text-decoration: none; }

@media (max-width: 780px) {
  .entry { grid-template-columns: minmax(0, 1fr); gap: 12px; }
  .entry-mark { height: 40px; justify-content: flex-start; }
  .entry-mark img { max-height: 40px; max-width: 160px; }
  .entry-when { padding-top: 0; }
}

/* ---------- teaching ------------------------------------------------ */

.units { display: grid; }
.unit {
  display: grid;
  grid-template-columns: 96px minmax(0, 1fr) auto;
  gap: 18px;
  align-items: baseline;
  padding-block: 13px;
  border-bottom: 1px solid var(--rule-soft);
  font-size: 16px;
}
.unit:first-child { border-top: 1px solid var(--rule-soft); }
.unit code { font-family: var(--mono); font-size: 13.5px; color: var(--muted); }
.unit .lvl {
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--muted);
}
@media (max-width: 540px) {
  .unit { grid-template-columns: 86px minmax(0, 1fr); }
  .unit .lvl { grid-column: 2; }
}

/* ---------- service --------------------------------------------------- */

.service {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(24px, 4vw, 48px);
}
@media (max-width: 720px) { .service { grid-template-columns: 1fr; gap: 30px; } }

.svc-label {
  display: block;
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--muted);
  padding-bottom: 13px;
  border-bottom: 1px solid var(--rule);
}
.svc ul { list-style: none; margin: 0; padding: 0; }
.svc li {
  font-size: 16px;
  color: var(--ink-2);
  padding-block: 12px;
  border-bottom: 1px solid var(--rule-soft);
}

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

footer { border-top: 1px solid var(--rule-soft); padding-block: 44px 56px; }
.foot-inner {
  display: flex;
  flex-wrap: wrap;
  gap: 16px 28px;
  align-items: baseline;
  justify-content: space-between;
}
.foot-links { display: flex; flex-wrap: wrap; gap: 20px; font-size: 15px; }
.foot-links a { color: var(--ink-2); }
.foot-links a:hover { color: var(--accent); text-decoration: none; }
.colophon { font-size: 13px; color: var(--muted); }

.visitors { margin-top: 34px; }
.visitors-label {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--muted);
  display: block;
  margin-bottom: 12px;
}
.visitors-map {
  max-width: 260px;
  opacity: 0.85;
  filter: saturate(0.85);
}
.visitors-map img { border-radius: 8px; }

/* ---------- motion --------------------------------------------------- */

.rise {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.7s cubic-bezier(0.22, 1, 0.36, 1),
              transform 0.7s cubic-bezier(0.22, 1, 0.36, 1);
}
.rise.in { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .rise { opacity: 1; transform: none; transition: none; }
  .pub:hover .pub-thumb img { transform: none; }
}

/* ---------- print ---------------------------------------------------- */

@media print {
  .nav, .avatar, .avail .btn, .colophon, .visitors { display: none; }
  body { font-size: 10.5pt; color: #000; background: #fff; }
  a { color: #000; }
  section { padding-block: 12pt; break-inside: avoid; }
  .pub, .entry { break-inside: avoid; }
}