/* ============================================================
   bryantduong.github.io — single-page academic site
   Layout in the spirit of the classic REAL-lab personal pages,
   implemented from scratch. Palette: University of Pennsylvania.
   Light/dark themes via CSS custom properties; the toggle in the
   nav is injected by /assets/js/theme.js and sets [data-theme].
   ============================================================ */

:root {
  --penn-blue: #103a78;   /* headings, name — Penn Blue #011f5b lifted ~9 points
                             in lightness, same 216deg navy hue (11:1 on white) */
  --penn-blue-2: #1d4f9c; /* secondary navy for subheads (7.9:1 on white) */
  --penn-red: #990000;    /* links / accent */
  --penn-red-2: #c23b3b;  /* link hover */
  --ink: #3d3d3d;         /* body text */
  --grey: #5a5a5a;        /* muted text */
  --line: #e4e4e4;        /* dividers */
  --gold: #b7860b;        /* highlights (awards etc.) */
  --bg: #ffffff;
  --code-bg: #f3f3f3;     /* inline code chips */
  --toggle-track: #e9edf4;
  color-scheme: light;
}

/* ---------- dark theme (Penn palette, night shift) ---------- */
[data-theme="dark"] {
  --penn-blue: #a9c4f5;   /* headings flip to light Penn blue */
  --penn-blue-2: #7fa3e0;
  --penn-red: #e58a8a;    /* Penn red needs lightening on dark */
  --penn-red-2: #f2aaa9;
  --ink: #d3d8e2;
  --grey: #9aa4b5;
  --line: #2a3450;
  --gold: #d5a72e;
  --bg: #0e1524;          /* near-black navy keeps the Penn identity */
  --code-bg: #1b2437;
  --toggle-track: #223050;
  color-scheme: dark;
}

* { box-sizing: border-box; }

html {
  font-size: 100%;
}

@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
  body { transition: background-color 0.25s ease, color 0.25s ease; }
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: "Source Sans 3", "Source Sans Pro", "Segoe UI", sans-serif;
  font-weight: 300;
  letter-spacing: 0.3px;
  line-height: 1.55;
}

a {
  color: var(--penn-red);
  text-decoration: none;
}
a:hover { color: var(--penn-red-2); }
a:focus-visible {
  outline: 2px solid var(--penn-blue-2);
  outline-offset: 2px;
  border-radius: 2px;
}

b, strong { font-weight: 600; }
strong { color: var(--gold); }

.wrap {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 1.25rem 3rem;
}

/* ---------- top nav ---------- */
nav.site-nav {
  display: flex;
  align-items: center;
  justify-content: space-around;
  flex-wrap: wrap;
  gap: 0.5rem 1rem;
  padding: 1.4rem 0 1rem;
  font-size: 1.05rem;
}
nav.site-nav a { color: var(--penn-red); }
nav.site-nav a.current { color: var(--penn-blue); font-weight: 600; }

/* ---------- dark-mode toggle ----------
   One canonical control: a 52x26 pill living as the last item in nav.site-nav,
   with inline SVG sun/moon icons and a sliding knob. Wired by theme.js. */
.theme-toggle {
  position: relative;
  flex: 0 0 auto;
  width: 52px;
  height: 26px;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--toggle-track);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: space-around;
}
.theme-toggle svg {
  width: 13px;
  height: 13px;
  display: block;
  fill: none;
  stroke: var(--grey);
  stroke-width: 2.2;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.theme-toggle .tt-knob {
  position: absolute;
  top: 2px;
  left: 2px;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: #ffffff;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.35);
}
[data-theme="dark"] .theme-toggle .tt-knob { transform: translateX(26px); }
.theme-toggle::after {           /* invisible 44px-tall hit area for touch */
  content: "";
  position: absolute;
  inset: -9px -6px;
}
.theme-toggle:focus-visible {
  outline: 2px solid var(--penn-blue-2);
  outline-offset: 2px;
}
@media (prefers-reduced-motion: no-preference) {
  .theme-toggle .tt-knob { transition: transform 0.18s ease; }
}

/* ---------- section headings ---------- */
h1.section-title {
  font-size: 1.9rem;
  font-weight: 500;
  color: var(--penn-blue);
  margin: 2.4rem 0 1rem;
}
.divider {
  border: 0;
  border-top: 1px solid var(--line);
  margin: 2.2rem 0 0;
}

/* ---------- profile ---------- */
.profile {
  display: flex;
  gap: 2.2rem;
  align-items: flex-start;
  margin-top: 1.6rem;
}
.profile-pic { flex: 0 0 300px; }
.profile-pic img {
  width: 100%;
  border-radius: 6px;
  display: block;
}
.profile-pic .credit {
  font-size: 0.85rem;
  color: var(--grey);
  margin-top: 0.4rem;
}
.profile-intro { flex: 1; }
.profile-name {
  font-size: 2.1rem;
  font-weight: 600;
  color: var(--penn-blue);
  line-height: 1.15;
}
.profile-email {
  color: var(--grey);
  margin: 0.15rem 0 1rem;
}
.profile-intro p { margin: 0 0 0.9rem; }
.links-row {
  margin-top: 1.1rem;
  font-size: 1.02rem;
}
.links-row .sep { color: var(--grey); padding: 0 0.35rem; }

/* ---------- updates ---------- */
ul.updates {
  list-style: none;
  margin: 0;
  padding: 0;
}
ul.updates li {
  padding: 0.28rem 0;
}
ul.updates .date {
  font-weight: 600;
  color: var(--penn-blue);
  margin-right: 0.45rem;
  white-space: nowrap;
}

/* ---------- project / research entries ---------- */
h2.group-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--penn-blue-2);
  margin: 1.6rem 0 0.6rem;
}
.entry {
  display: flex;
  gap: 1.4rem;
  align-items: flex-start;
  margin: 1.1rem 0 1.6rem;
}
.entry-thumb {
  flex: 0 0 300px;
}
.entry-thumb img,
.entry-thumb video {
  width: 100%;
  border-radius: 6px;
  display: block;
  border: 1px solid var(--line);
}
.entry-body { flex: 1; }
.entry-title {
  font-size: 1.12rem;
  font-weight: 600;
  color: var(--penn-blue);
  display: block;
  margin-bottom: 0.35rem;
}
a.entry-title:hover { color: var(--penn-red-2); }
.entry-body p { margin: 0.2rem 0; color: var(--ink); }
.entry-meta { color: var(--grey); font-size: 0.95rem; }

/* ---------- publications ---------- */
.pub-authors { font-size: 0.98rem; margin: 0.15rem 0 0.1rem; }
.pub-authors .me { font-weight: 600; color: var(--penn-blue-2); }
.pub-venue { font-size: 0.95rem; color: var(--grey); font-style: italic; margin: 0.1rem 0; }
.pub-links { font-size: 0.95rem; margin-top: 0.35rem; }
.pub-links .sep { color: var(--grey); padding: 0 0.3rem; }
.pub-note {
  font-size: 0.92rem;
  color: var(--grey);
  border-left: 2px solid var(--line);
  border-radius: 0;
  padding: 0.1rem 0 0.1rem 0.8rem;
  margin: 0.4rem 0 1.4rem;
}

ul.poster-list { list-style: none; margin: 0.6rem 0 0; padding: 0; }
ul.poster-list li {
  font-size: 0.98rem;
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--line);
}
ul.poster-list li:last-child { border-bottom: 0; }
ul.poster-list b { color: var(--penn-blue); font-weight: 600; }
ul.poster-list .pub-venue { display: inline; }

/* ---------- blog listing ---------- */
.post-list { list-style: none; margin: 0; padding: 0; }
.post-list li {
  display: flex;
  gap: 1.2rem;
  align-items: baseline;
  padding: 0.7rem 0;
  border-bottom: 1px solid var(--line);
}
.post-list .date {
  flex: 0 0 7.2rem;
  font-weight: 600;
  color: var(--penn-blue);
  white-space: nowrap;
}
.post-list .post-link { font-size: 1.08rem; font-weight: 600; }
.post-list .blurb {
  display: block;
  color: var(--grey);
  font-size: 0.95rem;
  font-weight: 300;
  margin-top: 0.15rem;
}

/* ---------- article / post pages ---------- */
article.post, article.page {
  max-width: 760px;
  margin: 0 auto;
}
article .post-title {
  font-size: 2rem;
  font-weight: 600;
  color: var(--penn-blue);
  line-height: 1.2;
  margin: 1.8rem 0 0.3rem;
}
article .post-meta {
  color: var(--grey);
  font-size: 0.95rem;
  margin-bottom: 1.6rem;
}
article h2 {
  font-size: 1.45rem;
  font-weight: 600;
  color: var(--penn-blue);
  margin: 2rem 0 0.6rem;
}
article h3 {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--penn-blue-2);
  margin: 1.4rem 0 0.4rem;
}
article p { margin: 0 0 1rem; }
article ul, article ol { margin: 0 0 1rem; padding-left: 1.4rem; }
article li { margin: 0.35rem 0; }
article figure { margin: 1.6rem 0; }
article figure img {
  max-width: 100%;
  border-radius: 6px;
  border: 1px solid var(--line);
  display: block;
}
article figcaption {
  font-size: 0.88rem;
  color: var(--grey);
  margin-top: 0.45rem;
}
.back-link { display: inline-block; margin-top: 1.2rem; font-size: 0.98rem; }

/* ---------- inline code ---------- */
article code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.88em;
  background: var(--code-bg);
  padding: 0.1em 0.35em;
  border-radius: 4px;
}

/* ---------- footer ---------- */
footer.site-footer {
  margin-top: 3rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--line);
  color: var(--grey);
  font-size: 0.88rem;
  text-align: center;
}

/* soften bright screenshots/photos on the dark background */
[data-theme="dark"] article figure img,
[data-theme="dark"] .profile-pic img,
[data-theme="dark"] .entry-thumb img { filter: brightness(0.88); }

/* ---------- responsive ---------- */
@media (max-width: 760px) {
  nav.site-nav { font-size: 0.98rem; gap: 0.35rem 0.7rem; justify-content: center; }
  .profile { flex-direction: column; gap: 1.2rem; }
  .profile-pic { flex-basis: auto; max-width: 320px; }
  .entry { flex-direction: column; gap: 0.7rem; }
  .entry-thumb { flex-basis: auto; max-width: 420px; width: 100%; }
  .post-list li { flex-direction: column; gap: 0.15rem; }
  .post-list .date { flex-basis: auto; }
}