/* One stylesheet for the whole site. Colors and spacing live in the
   custom properties below so the look can be retuned in one place. */

:root {
  --ink: #22293a;
  --ink-soft: #56607a;
  --paper: #ffffff;
  --paper-tint: #f4f6fa;
  --space: #101830;
  --space-deep: #0a0f22;
  --on-space: #e8ecf7;
  --on-space-soft: #aab4d0;
  --accent: #e2662c;
  --accent-dark: #b84e1c;
  --rule: #dde3ee;
  --serif: Georgia, "Times New Roman", serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --wrap: 62rem;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: var(--sans);
  font-size: 1.0625rem;
  line-height: 1.65;
  color: var(--ink);
  background: var(--paper);
}

h1, h2, h3 { font-family: var(--serif); line-height: 1.25; color: var(--ink); }
h1 { font-size: 2rem; margin: 0 0 0.75rem; }
h2 { font-size: 1.5rem; margin: 2.25rem 0 0.75rem; }
h3 { font-size: 1.15rem; margin: 1.5rem 0 0.5rem; }

a { color: var(--accent-dark); }
a:hover { color: var(--accent); }

img, video { max-width: 100%; height: auto; }

.wrap { max-width: var(--wrap); margin: 0 auto; padding: 0 1.25rem; }

main { padding-bottom: 3rem; }
main > .wrap { padding-top: 2rem; }

.skip-link {
  position: absolute;
  left: -999px;
  background: var(--paper);
  padding: 0.5rem 1rem;
  z-index: 10;
}
.skip-link:focus { left: 0.5rem; top: 0.5rem; }

/* Header and navigation */

.site-header {
  background: var(--space);
  border-bottom: 3px solid var(--accent);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.25rem 1.5rem;
  padding-top: 0.8rem;
  padding-bottom: 0.8rem;
}

.site-name {
  font-family: var(--serif);
  font-size: 1.35rem;
  color: var(--on-space);
  text-decoration: none;
  white-space: nowrap;
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.15rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-nav a {
  display: block;
  padding: 0.35rem 0.7rem;
  color: var(--on-space-soft);
  text-decoration: none;
  border-radius: 6px;
  font-size: 0.97rem;
}

.site-nav a:hover { color: var(--on-space); background: rgba(255, 255, 255, 0.08); }
.site-nav a.active { color: var(--on-space); background: rgba(255, 255, 255, 0.14); }

/* Footer */

.site-footer {
  background: var(--space-deep);
  color: var(--on-space-soft);
  font-size: 0.95rem;
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 1rem 2rem;
  padding-top: 1.75rem;
  padding-bottom: 1.75rem;
}

.site-footer a { color: var(--on-space); }

/* Dark banner used on the home page and as the research hero */

.banner {
  background: var(--space);
  color: var(--on-space);
  padding: 1.4rem 0;
}

.banner h1 { color: #ffffff; font-size: 2.4rem; margin: 0; }
.banner .tagline { color: var(--on-space-soft); font-size: 1.2rem; margin: 0.5rem 0 0; }

/* Banner row within the content column: text left, portrait at the right edge. */
.banner-inner {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}
.banner-text { flex: 1 1 auto; min-width: 0; }
.banner-portrait {
  flex: 0 0 auto;
  width: auto;
  height: clamp(110px, 18vw, 156px);
  border-radius: 8px;
  display: block;
}

.hero {
  background-color: var(--space-deep);
  background-size: cover;
  background-position: center;
  padding: 5.5rem 0;
}

/* Legibility scrim so hero text stays readable over the imagery */
.hero .hero-panel {
  max-width: 34rem;
  background: rgba(8, 12, 28, 0.72);
  padding: 1.5rem 1.75rem;
  border-radius: 10px;
  border-left: 4px solid var(--accent);
}

.hero h1 { color: #ffffff; font-size: 2.4rem; margin: 0 0 0.75rem; }
.hero p { color: var(--on-space); font-size: 1.15rem; margin: 0; }

/* Research page hero: text panel beside the collision image (stacks on phones).
   Both share one black card; the photo is cropped 10% on every edge. */
.research-hero {
  display: flex;
  align-items: stretch;
  margin: 1rem 0 1rem;
  background: #000;
  border-radius: 10px;
  overflow: hidden;
}

.research-hero-text {
  flex: 1 1 42%;
  min-width: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 1.75rem 2rem;
  border-left: 4px solid var(--accent);
}

.research-hero-text h1 { color: #ffffff; font-size: 2.4rem; margin: 0 0 0.75rem; }
.research-hero-text p { color: var(--on-space); font-size: 1.15rem; margin: 0; }

.research-hero-image {
  flex: 1 1 58%;
  min-width: 0;
  align-self: center;
  overflow: hidden;
}

.research-hero-image img {
  display: block;
  width: 100%;
  height: auto;
  transform: scale(1.6667); /* central 60% shows -> 20% cropped off each edge */
  transform-origin: center;
}

/* Tighten the gap between the hero and the first section below it (halved) */
main > .wrap.research-body { padding-top: 1rem; }
.research-body > h2:first-child { margin-top: 1.125rem; }

.about-figure {
  float: right;
  width: 224px;
  max-width: 45%;
  margin: 0.25rem 0 1rem 1.5rem;
}

/* StarSmasher emblem beside the Software section on the research page. */
.starsmasher-badge {
  float: right;
  width: 120px;
  max-width: 30%;
  margin: 0 0 0.75rem 1.5rem;
  transition: opacity 0.2s ease;
}
.starsmasher-badge img { display: block; width: 100%; height: auto; }
.starsmasher-badge:hover { opacity: 0.8; }

/* collAIder logo beside the Software section on the research page. */
.collaider-badge {
  float: left;
  width: 200px;
  max-width: 42%;
  margin: 0.2rem 1.5rem 0.75rem 0;
  transition: opacity 0.2s ease;
}
.collaider-badge img { display: block; width: 100%; height: auto; border-radius: 10px; }
.collaider-badge:hover { opacity: 0.8; }

/* Two photos stacked in a single right-hand column (Beyond physics on the
   About page); text flows down the left and wraps beneath when long enough. */
.beyond-figures {
  float: right;
  width: 224px;
  max-width: 45%;
  margin: 0.25rem 0 1rem 1.5rem;
}
.beyond-figures .about-figure {
  float: none;
  width: 100%;
  max-width: 100%;
  margin: 0 0 1rem;
}
.beyond-figures .about-figure:last-child { margin-bottom: 0; }

/* Contains floated figures so following content (e.g. the footer) never overlaps. */
.clear { clear: both; }

/* Featured videos ("Watch" section of the Favorite Links page) */
.channel-promo {
  margin: 0 0 1.5rem;
  padding: 1.25rem 1.25rem 0.75rem;
  background: var(--paper-tint);
  border-radius: 10px;
}
.channel-promo-title { margin: 0 0 0.3rem; font-size: 1.35rem; }
.channel-promo-note { margin: 0 0 0.5rem; color: var(--ink-soft); font-size: 0.95rem; }
.video-feature-kicker {
  margin: 0 0 0.2rem;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--accent);
}

.video-feature-list { list-style: none; margin: 0; padding: 0; }

.video-feature {
  display: flex;
  gap: 1rem;
  align-items: center;
  padding: 0.85rem 0;
  border-top: 1px solid rgba(0, 0, 0, 0.1);
}
.video-feature:first-child { border-top: 0; padding-top: 0.25rem; }

.video-feature-thumb {
  position: relative;
  flex: 0 0 160px;
  max-width: 40%;
  display: block;
  border-radius: 8px;
  overflow: hidden;
}

.video-feature-thumb img { display: block; width: 100%; height: auto; }

.video-feature-play {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.2rem;
  height: 2.2rem;
  padding-left: 0.15rem;
  font-size: 0.9rem;
  color: #ffffff;
  background: rgba(0, 0, 0, 0.62);
  border-radius: 50%;
}

.video-feature-body { flex: 1 1 auto; min-width: 0; }
.video-feature-title { margin: 0 0 0.3rem; font-size: 1rem; }
.video-feature-note { margin: 0; color: var(--ink-soft); font-size: 0.9rem; }

/* Transient "Copied!" confirmation shown when an email address is clicked. */
.copied-tip {
  position: absolute;
  z-index: 100;
  padding: 0.15rem 0.5rem;
  font-size: 0.8rem;
  color: #ffffff;
  background: #222222;
  border-radius: 6px;
  white-space: nowrap;
  pointer-events: none;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.25);
}

.about-figure img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 10px;
}

.about-figure figcaption {
  margin-top: 0.4rem;
  font-size: 0.85rem;
  color: var(--ink-soft);
  text-align: center;
}

/* Student photo floated beside the Research "For prospective students" text. */
.figure-student {
  float: right;
  width: 18rem;
  max-width: 42%;
  margin: 0.25rem 0 1rem 1.5rem;
}
.figure-student img { display: block; width: 100%; height: auto; border-radius: 10px; }
.figure-student figcaption {
  margin-top: 0.4rem;
  font-size: 0.85rem;
  color: var(--ink-soft);
  text-align: center;
}

/* Figure sized to sit in the text column beside the floated infobox (About page). */
.figure-wide {
  max-width: calc((100% - 19.25rem) * 0.9); /* a touch under the Career text width; leaves the infobox's space free */
  margin: 0.75rem 0 1.5rem;
}
.figure-wide img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 10px;
}
.figure-wide figcaption {
  margin-top: 0.4rem;
  font-size: 0.85rem;
  color: var(--ink-soft);
  text-align: center;
}

/* Card grids (home shortcuts and research papers) */

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  gap: 1.25rem;
  padding: 0;
  margin: 1.5rem 0;
  list-style: none;
}

.card {
  border: 1px solid var(--rule);
  border-radius: 10px;
  background: var(--paper);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

.card-body { padding: 1rem 1.25rem 1.25rem; display: flex; flex-direction: column; gap: 0.5rem; flex: 1; }
.card h3 { margin: 0; }
.card p { margin: 0; color: var(--ink-soft); font-size: 0.98rem; }

.card .figure {
  margin: 0;
  background: #000;
}

.card .figure img { display: block; width: 100%; height: 14rem; object-fit: cover; }

.card .figure figcaption,
.video-item figcaption {
  font-size: 0.85rem;
  color: var(--ink-soft);
  padding: 0.4rem 1.25rem;
  background: var(--paper-tint);
}

.card-links { margin-top: auto; padding-top: 0.5rem; display: flex; gap: 0.6rem; }

.shortcut-card {
  display: block;
  padding: 1.5rem;
  border: 1px solid var(--rule);
  border-radius: 10px;
  text-decoration: none;
  background: var(--paper-tint);
}
.shortcut-card:hover { border-color: var(--accent); }
.shortcut-card h2 { margin: 0 0 0.4rem; font-size: 1.25rem; }
.shortcut-card p { margin: 0; color: var(--ink-soft); font-size: 0.97rem; }

/* Buttons */

.btn {
  display: inline-block;
  padding: 0.45rem 1rem;
  border-radius: 7px;
  border: 1px solid var(--accent-dark);
  color: var(--accent-dark);
  text-decoration: none;
  font-size: 0.95rem;
}
.btn:hover { background: var(--accent); border-color: var(--accent); color: #ffffff; }

.btn-solid {
  background: var(--accent);
  border-color: var(--accent);
  color: #ffffff;
}
.btn-solid:hover { background: var(--accent-dark); border-color: var(--accent-dark); color: #ffffff; }

/* Wikipedia-style infobox on the About page */

.infobox {
  float: right;
  width: 17.5rem;
  margin: 0 0 1.25rem 1.75rem;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: var(--paper-tint);
  font-size: 0.92rem;
  overflow: hidden;
}

.infobox img { display: block; width: 100%; }
.infobox .infobox-title {
  font-family: var(--serif);
  font-size: 1.1rem;
  text-align: center;
  padding: 0.6rem 0.75rem 0;
}
.infobox dl { margin: 0; padding: 0.5rem 0.9rem 0.9rem; }
.infobox dt { font-weight: 600; margin-top: 0.55rem; }
.infobox dd { margin: 0; color: var(--ink-soft); }

/* Video gallery on the research page */

.video-grid {
  display: grid;
  /* Wide enough a laptop shows two columns (larger movie windows); the
     min(…, 100%) lets each card shrink to one column on phones without
     forcing horizontal overflow. */
  grid-template-columns: repeat(auto-fit, minmax(min(24rem, 100%), 1fr));
  gap: 1.25rem;
  margin: 1.5rem 0;
}

.video-item {
  border: 1px solid var(--rule);
  border-radius: 10px;
  overflow: hidden;
  background: var(--paper);
}

.video-item video { display: block; width: 100%; background: #000; }
.video-item h3 { margin: 0; padding: 0.75rem 1.25rem 0.35rem; }

/* Grouped links (Favorite Links page), laid out as a compact card grid so a
   long list of categories stays scannable without filling the whole screen. */

.link-cards {
  list-style: none;
  padding: 0;
  margin: 1rem 0 2rem;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(15rem, 1fr));
  gap: 0.85rem;
}

.link-card {
  padding: 0.85rem 1rem;
  background: var(--paper-tint);
  border: 1px solid var(--rule);
  border-radius: 10px;
}

.link-card > a { font-weight: 600; }

.link-card .link-note {
  display: block;
  margin-top: 0.25rem;
  color: var(--ink-soft);
  font-size: 0.9rem;
}

/* Small helpers */

.lede { font-size: 1.15rem; color: var(--ink-soft); }
.section-note { color: var(--ink-soft); font-size: 0.95rem; }

.pub-list { padding-left: 1.25rem; }
.pub-list li { margin-bottom: 0.6rem; }

@media (max-width: 640px) {
  .banner-inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .banner-portrait {
    width: auto;
    height: 130px;
    max-width: 100%;
  }

  .about-figure { float: none; width: 220px; max-width: 100%; margin: 1rem auto; }
  .beyond-figures { float: none; width: 240px; max-width: 100%; margin: 1rem auto; }
  .starsmasher-badge { float: none; width: 120px; max-width: 40%; margin: 0.25rem 0 0.75rem; }
  .collaider-badge { float: none; width: 220px; max-width: 100%; margin: 0.25rem 0 0.75rem; }
  .infobox { float: none; width: 100%; margin: 1rem 0; }
  .banner h1, .hero h1, .research-hero-text h1 { font-size: 1.9rem; }
  .hero { padding: 3.5rem 0; }
  .research-hero { flex-direction: column; align-items: stretch; }
  .research-hero-image { align-self: stretch; }
  .video-feature-thumb { flex-basis: 120px; }
  .figure-wide { max-width: 100%; }
  .figure-student { float: none; width: auto; max-width: 100%; margin: 1rem 0; }
}