/* ---------------------------------------------------------------------------
 * Shared header/footer chrome for pages Quarto renders (labs/*.qmd, hw/*.qmd).
 *
 * This is a DELIBERATELY NARROW subset of assets/css/main.css -- just the
 * rules the site-header/site-footer markup needs, plus the page background,
 * copied over rather than loading main.css wholesale. main.css also has
 * `a { color: inherit }`, which would bleed into Quarto's own Bootstrap/
 * cosmo content styling and make every link inside a rendered lab invisible
 * against body text -- deliberately left out here. Keep new rules scoped to
 * .site-header/.site-footer/.skip-link/body background, not text/links.
 *
 * If you change the header/footer markup or its styling in main.css, update
 * the matching rule here too -- there's no single source of truth linking
 * the two.
 * --------------------------------------------------------------------------- */

/* Quarto's own site-level footer (repeats "Edit this page" / "Report an
   issue" for mobile). Our relocated .site-footer (see _includes/site-footer
   .html) replaces it entirely -- left in place it shows as an empty-looking
   light band between the article content and our real footer. */
footer.footer {
  display: none;
}

:root {
  --navy-950: #00143f;
  --navy-900: #001a57;
  --navy-800: #072866;
  --blue-600: #0064a8;
  --blue-100: #dcebf3;
  --ink-900: #142033;
  --ink-700: #3b4858;
  --ink-500: #596574;
  --paper: #f7f4ec;
  --paper-deep: #efeadf;
  --white: #fff;
  --gold-500: #d3a446;
  --gold-300: #f4c96f;
  --line: #d8d3c8;
  --line-dark: rgba(255, 255, 255, 0.22);
  --font-display: "Titillium Web", "Helvetica Neue", Arial, sans-serif;
  --font-body: "Open Sans", Helvetica, Arial, sans-serif;
  --page-width: 1180px;
  --reading-width: 760px;
  --gutter: clamp(1.25rem, 4vw, 3.5rem);
  --section-space: clamp(5rem, 10vw, 9rem);
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

body {
  background: var(--paper);
}

body::before {
  position: fixed;
  z-index: 10;
  top: 0;
  right: 0;
  left: 0;
  height: 4px;
  background: var(--gold-500);
  content: "";
}

.site-header a,
.site-footer a,
.site-nav summary,
.skip-link {
  color: inherit;
}

.site-header a:focus-visible,
.site-footer a:focus-visible,
.site-nav summary:focus-visible,
.skip-link:focus-visible {
  border-radius: 2px;
  outline: 3px solid var(--white);
  outline-offset: 2px;
  box-shadow: 0 0 0 6px var(--navy-900);
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 0.8rem;
  left: 1rem;
  padding: 0.7rem 1rem;
  color: var(--navy-950);
  background: var(--white);
  font-weight: 700;
  transform: translateY(-180%);
  transition: transform 180ms ease;
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: relative;
  z-index: 20;
  color: var(--white);
  background: var(--navy-900);
}

.site-header__inner {
  display: flex;
  width: min(100% - (2 * var(--gutter)), var(--page-width));
  min-height: 88px;
  margin: 0 auto;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
}

.site-brand {
  display: inline-flex;
  min-height: 48px;
  align-items: center;
  gap: 0.9rem;
  text-decoration: none;
}

.site-brand__mark {
  display: grid;
  width: 45px;
  height: 45px;
  border: 1px solid rgba(255, 255, 255, 0.42);
  color: var(--gold-300);
  font-family: var(--font-display);
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  place-items: center;
}

.site-brand__text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.site-brand__text strong {
  font-family: var(--font-display);
  font-size: 1.08rem;
  font-weight: 600;
  letter-spacing: 0.08em;
}

.site-brand__text span {
  margin-top: 0.18rem;
  color: rgba(255, 255, 255, 0.68);
  font-size: 0.72rem;
  letter-spacing: 0.02em;
}

.site-nav {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: clamp(0.8rem, 2vw, 1.75rem);
}

.site-nav > a,
.site-nav__menu > summary {
  position: relative;
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  color: inherit;
  cursor: pointer;
  font-family: var(--font-display);
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.11em;
  list-style: none;
  text-decoration: none;
  text-transform: uppercase;
  user-select: none;
  white-space: nowrap;
}

.site-nav > a,
.site-nav__menu {
  flex: 0 0 auto;
}

.site-nav__menu > summary::-webkit-details-marker {
  display: none;
}

.site-nav > a::after,
.site-nav__menu > summary::before {
  position: absolute;
  right: 0;
  bottom: 8px;
  left: 0;
  height: 2px;
  background: var(--gold-300);
  content: "";
  transform: scaleX(0);
  transform-origin: right;
  transition: transform 220ms var(--ease);
}

.site-nav > a:hover::after,
.site-nav > a:focus-visible::after,
.site-nav > a[aria-current="page"]::after,
.site-nav__menu > summary:hover::before,
.site-nav__menu > summary:focus-visible::before,
.site-nav__menu[open] > summary::before,
.site-nav__menu--current > summary::before {
  transform: scaleX(1);
  transform-origin: left;
}

.site-nav__menu {
  position: relative;
}

.site-nav__chevron {
  margin-left: 0.38rem;
  color: var(--gold-300);
  font-size: 0.78rem;
  transition: transform 180ms var(--ease);
}

.site-nav__menu[open] .site-nav__chevron {
  transform: rotate(180deg);
}

.site-nav__dropdown {
  position: absolute;
  z-index: 30;
  top: calc(100% + 0.65rem);
  right: -0.65rem;
  min-width: 14rem;
  margin: 0;
  padding: 0.45rem;
  border: 1px solid rgba(0, 26, 87, 0.14);
  border-top: 3px solid var(--gold-500);
  color: var(--navy-900);
  background: var(--white);
  box-shadow: 0 18px 40px rgba(0, 20, 63, 0.2);
  list-style: none;
}

.site-nav__dropdown a {
  display: flex;
  min-height: 44px;
  padding: 0.65rem 0.8rem;
  align-items: center;
  color: var(--navy-900);
  font-family: var(--font-display);
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.025em;
  line-height: 1.25;
  text-decoration: none;
  text-transform: none;
  white-space: nowrap;
}

.site-nav__dropdown a:hover,
.site-nav__dropdown a:focus-visible {
  background: var(--paper);
}

.site-nav__dropdown a[aria-current="page"] {
  color: var(--navy-950);
  background: var(--blue-100);
  font-weight: 700;
}

.site-footer {
  color: rgba(255, 255, 255, 0.72);
  background: var(--navy-950);
}

.site-footer__inner {
  display: grid;
  width: min(100% - (2 * var(--gutter)), var(--page-width));
  margin: 0 auto;
  padding: clamp(3rem, 6vw, 5rem) 0;
  align-items: end;
  gap: 2rem;
  grid-template-columns: 1.2fr 1fr auto;
}

.site-footer p {
  margin: 0;
  font-size: 0.82rem;
  line-height: 1.6;
}

.site-footer__course {
  margin-bottom: 0.55rem !important;
  color: var(--white);
  font-family: var(--font-display);
  font-size: 1rem !important;
  font-weight: 700;
  letter-spacing: 0.12em;
}

.site-footer__affiliation {
  color: rgba(255, 255, 255, 0.52);
}

.back-to-top {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  gap: 0.7rem;
  color: var(--white);
  font-family: var(--font-display);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.3rem;
  text-transform: uppercase;
}

@media (max-width: 760px) {
  .site-header__inner {
    min-height: 80px;
    align-items: center;
  }

  .site-brand__text span {
    display: none;
  }

  .site-nav {
    gap: 0.6rem;
  }

  .site-nav > a,
  .site-nav__menu > summary {
    padding: 0 0.15rem;
    font-size: 0.69rem;
  }

  .site-footer__inner {
    align-items: start;
    grid-template-columns: 1fr 1fr;
  }

  .back-to-top {
    grid-column: 1 / -1;
  }
}

@media (max-width: 560px) {
  :root {
    --gutter: 1.15rem;
  }

  .site-header__inner {
    min-height: auto;
    padding: 0.75rem 0 0.45rem;
    align-items: flex-start;
    flex-direction: column;
    gap: 0.25rem;
  }

  .site-brand {
    min-height: 45px;
  }

  .site-nav {
    width: 100%;
    border-top: 1px solid rgba(255, 255, 255, 0.16);
    align-items: center;
    justify-content: flex-start;
    column-gap: 0.85rem;
    flex-wrap: wrap;
    row-gap: 0;
  }

  .site-nav > a,
  .site-nav__menu > summary {
    min-height: 44px;
  }

  .site-nav__dropdown {
    right: 0;
  }

  .site-footer__inner {
    grid-template-columns: 1fr;
  }

  .back-to-top {
    grid-column: auto;
  }
}

@media (max-width: 400px) {
  .site-nav__dropdown {
    right: auto;
    left: 0;
  }
}