/* =============================================================
   comphy-lab.org site header, ported for the talks pages.
   Source: comphy-lab/comphy-lab.github.io (see SOURCE.md):
   assets/css/styles.css section 6 "Header & navigation" and its
   Menu drawer media query, with the legacy colour variables it reads
   (styles.css :root and [data-theme="dark"]) resolved to values.
   Trimmed to what the talks pages use; changes are marked "talks:".
   Loads after ../ds/tokens.css.
   ============================================================= */

/* talks: comphy-lab.org's bridge.css lifts the dark surfaces off the
   tokens' near-black; the whole page shares them so header, footer and
   body match the main site in dark mode. */
:root[data-theme="dark"] {
  --c-paper: #1b1814;
  --c-paper-tint: #241f18;
  --c-surface-strong: #2b251d;
  --c-surface-glass: rgba(43, 37, 29, 0.78);
  --c-border: rgba(248, 244, 236, 0.14);
  --c-border-strong: rgba(248, 244, 236, 0.22);
}

:root {
  --header-h: 80px;
  --s-header-bg: rgba(104, 35, 109, 0.15);
  --s-header-shadow: rgba(104, 35, 109, 0.2);
  --s-nav-item-bg: rgba(255, 255, 255, 0.25);
  --s-nav-item-color: #1a1a1a;
  --s-nav-item-hover-bg: rgba(255, 255, 255, 0.35);
  --s-mobile-nav-bg: rgba(255, 255, 255, 0.95);
  --s-mobile-nav-shadow: rgba(0, 0, 0, 0.1);
  --s-mobile-nav-item-hover-bg: rgba(255, 255, 255, 0.35);
  --s-icon-github: #1a1a1a;
  --s-icon-bluesky: #0085ff;
  --s-transition: all 0.3s ease;
}

:root[data-theme="dark"] {
  --s-header-bg: rgba(40, 15, 45, 0.75);
  --s-header-shadow: rgba(0, 0, 0, 0.4);
  --s-nav-item-bg: rgba(30, 30, 30, 0.6);
  --s-nav-item-color: #fff;
  --s-nav-item-hover-bg: rgba(40, 40, 40, 0.8);
  --s-mobile-nav-bg: rgba(30, 30, 35, 0.95);
  --s-mobile-nav-shadow: rgba(0, 0, 0, 0.3);
  --s-mobile-nav-item-hover-bg: rgba(60, 60, 70, 0.5);
  --s-icon-github: #fff;
  --s-icon-bluesky: #fff;
}

/* talks: the header is fixed, as on comphy-lab.org; content starts below it
   and in-page targets scroll clear of it. */
html {
  scroll-padding-top: var(--header-h);
}

body {
  padding-top: var(--header-h);
}

.s-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--header-h);
  background: var(--s-header-bg);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  z-index: 100;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 30px;
  box-shadow: 0 4px 16px var(--s-header-shadow);
  transition: var(--s-transition);
}

.s-header__logo {
  height: 65px;
  flex: none;
}

.s-header__logo a {
  border-bottom: 0; /* the tokens' prose-link underline; comphy-lab.org shows none */
}

.s-header__logo img {
  height: 100%;
  max-height: 65px;
  width: auto;
}

/* Menu toggle (shown below the breakpoint). talks: a <button>, not a link. */
.s-header__menu-toggle {
  display: none;
  align-items: center;
  gap: 10px;
  margin: 0;
  padding: 0;
  border: 0;
  background: none;
  color: var(--fg-1);
  font: inherit;
  cursor: pointer;
}

.s-header__menu-text {
  font-size: 16px;
}

.s-header__menu-icon {
  position: relative;
  display: block;
  width: 24px;
  height: 2px;
  background-color: currentColor;
}

.s-header__menu-icon::before,
.s-header__menu-icon::after {
  content: "";
  position: absolute;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: currentColor;
  transition: transform 0.3s ease;
}

.s-header__menu-icon::before {
  transform: translateY(-8px);
}

.s-header__menu-icon::after {
  transform: translateY(8px);
}

/* Navigation */
.s-header__nav {
  display: flex;
  align-items: center;
}

.s-header__nav-list {
  display: flex;
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 0;
  align-items: center;
}

.s-header__nav-list li {
  display: flex;
  align-items: center;
  height: 100%;
}

.s-header__nav-list a {
  display: flex;
  align-items: center;
  height: 40px;
  padding: 8px 16px;
  border: 0;
  border-radius: 5px;
  background: var(--s-nav-item-bg);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  color: var(--s-nav-item-color);
  font-size: 16px;
  white-space: nowrap; /* never wrap a label (comphy-lab.org has the same rule since its Talks link) */
  text-decoration: none;
  transition: var(--s-transition);
}

.s-header__nav-list a:hover {
  background: var(--s-nav-item-hover-bg);
  color: var(--s-nav-item-color);
  transform: translateY(-2px);
}

/* Icon links: Google Scholar, GitHub, Bluesky (inline SVG; the main site
   uses icon fonts at 1.75em). */
.s-header__nav-list .s-header__item--icon a {
  justify-content: center;
  width: 40px;
  height: 40px;
  padding: 0;
  background: none;
}

.s-header__icon {
  display: block;
  height: 1.75em;
  width: auto;
  fill: currentColor;
  transition: transform 0.3s ease, color 0.3s ease;
}

.s-header__nav-list a:hover .s-header__icon {
  transform: translateY(-2px);
  opacity: 0.9;
}

.s-header__icon--github {
  color: var(--s-icon-github);
}

.s-header__icon--bluesky {
  color: var(--s-icon-bluesky);
}

/* talks: the page's own section, marked aria-current="page" on the talks
   index (the page the link opens) and aria-current="true" on a talk page
   (inside that section). The main site has no current-item style; this is
   the lightest one that reads as such. */
.s-header__nav-list a[aria-current="page"],
.s-header__nav-list a[aria-current="true"] {
  background: var(--s-nav-item-hover-bg);
  text-decoration: underline;
  text-decoration-thickness: 2px;
  text-underline-offset: 6px;
}

/* Native Close button inside the menu, shared with the main site. */
.s-header__nav-close-btn {
  display: none;
  position: absolute;
  top: 20px;
  right: 20px;
  margin: 0 0 0 8px;
  padding: 8px 16px;
  border: 0;
  border-radius: 5px;
  background: var(--s-nav-item-bg);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  color: var(--s-nav-item-color);
  font: inherit;
  font-size: 16px;
  cursor: pointer;
  transition: var(--s-transition);
}

.s-header__nav-close-btn:hover {
  background: var(--s-nav-item-hover-bg);
  color: var(--s-nav-item-color);
  transform: translateY(-2px);
}

/* Native theme toggle shared with the main site. */
.theme-toggle {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  margin: 0;
  padding: 0;
  border: 0;
  border-radius: 50%;
  background: var(--s-nav-item-bg);
  color: var(--fg-1);
  font: inherit;
  cursor: pointer;
  transition: var(--s-transition);
}

.theme-toggle:hover {
  background: var(--s-nav-item-hover-bg);
  transform: translateY(-2px);
}

.theme-toggle-icon {
  position: absolute;
  width: 24px;
  height: 24px;
  transition: opacity 0.3s ease, transform 0.5s ease;
  pointer-events: none;
}

.theme-toggle-icon.moon {
  opacity: 1;
}

.theme-toggle-icon.sun {
  opacity: 0;
  transform: rotate(90deg);
}

:root[data-theme="dark"] .theme-toggle-icon.moon {
  opacity: 0;
  transform: rotate(-90deg);
}

:root[data-theme="dark"] .theme-toggle-icon.sun {
  opacity: 1;
  transform: rotate(0);
}

/* ---------- Menu below the breakpoint ----------
   Same breakpoint as comphy-lab.org (max-width 1119px), so the header keeps
   its form when moving between the two sites. The talks bar (no
   command-palette button) needs only about 1003 px, so it always fits. */
@media (max-width: 1119px) {
  .s-header__menu-toggle {
    display: flex;
    z-index: 90;
  }

  .s-header__nav {
    position: fixed;
    top: 0;
    right: -300px;
    width: 300px;
    height: 100vh;
    height: 100dvh;
    padding: 20px;
    flex-direction: column;
    align-items: flex-start;
    background: var(--s-mobile-nav-bg);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    box-shadow: -2px 0 10px var(--s-mobile-nav-shadow);
    z-index: 100;
    /* talks: scrolls on short screens; hidden (so out of the tab order and
       the accessibility tree) once it has slid out. */
    overflow-y: auto;
    overscroll-behavior: contain;
    visibility: hidden;
    transition: right 0.3s ease, visibility 0s linear 0.3s;
  }

  .s-header__nav.is-active {
    right: 0;
    visibility: visible;
    transition: right 0.3s ease, visibility 0s linear 0s;
  }

  .s-header__nav-close-btn {
    display: block;
  }

  .s-header__nav-list {
    flex-direction: column;
    width: 100%;
    align-items: flex-start;
  }

  .s-header__nav-list li {
    width: 100%;
    height: auto;
    margin: 10px 0;
  }

  .s-header__nav-list a {
    width: 100%;
    height: auto;
    padding: 10px 0;
    justify-content: center;
    text-align: center;
    font-size: 18px;
    background: none;
  }

  .s-header__nav-list a:hover {
    background: var(--s-mobile-nav-item-hover-bg);
  }

  .s-header__nav-list .s-header__item--icon {
    justify-content: center;
  }

  .s-header__nav-list .s-header__item--icon a {
    width: auto;
  }
}

@media (prefers-reduced-motion: reduce) {
  .s-header,
  .s-header *,
  .s-header *::before,
  .s-header *::after {
    transition: none !important;
  }

  .s-header__nav-list a:hover,
  .s-header__nav-list a:hover .s-header__icon,
  .s-header__nav-close-btn:hover,
  .theme-toggle:hover {
    transform: none;
  }
}