/* components.css — reusable pieces built from tokens.css. Every component
   reads var(--accent), which templates set per page; nothing here names a
   category directly. */

/* ---------------------------------------------------------------------- */
/* Utilities */

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

/* Keyboard users land on this before the header; it stays off-screen until
   focused rather than being hidden from the accessibility tree. */
.skip-link {
  position: absolute;
  top: var(--space);
  left: var(--space);
  z-index: 300;
  transform: translateY(-200%);
  padding: 0.6em 1.1em;
  background: var(--accent);
  color: var(--text-on-accent);
  font: 600 0.9375rem var(--font-ui);
  text-decoration: none;
  border-radius: var(--radius-sm);
  box-shadow: var(--panel-lift-high);
  transition: transform var(--motion-hover) var(--ease-standard);
}

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

/* ---------------------------------------------------------------------- */
/* Glass panel */

.panel {
  background: var(--panel-fill);
  backdrop-filter: blur(var(--panel-blur));
  -webkit-backdrop-filter: blur(var(--panel-blur));
  border: var(--border) solid var(--panel-border);
  border-radius: var(--radius-md);
  box-shadow: var(--panel-lift);
}

.panel--raised {
  background: var(--panel-fill-raised);
  border-color: var(--panel-border-bright);
  box-shadow: var(--panel-lift-high);
}

/* ---------------------------------------------------------------------- */
/* Recessed surface — inputs, code blocks */

.recess {
  background: var(--recess-fill);
  border-radius: var(--radius-sm);
  border: var(--border) solid var(--panel-border);
  box-shadow: inset 0 1px 0 rgba(0, 0, 0, 0.4);
}

/* ---------------------------------------------------------------------- */
/* Site header — a floating glass island, same width as the content below */

.site-header {
  position: sticky;
  top: calc(var(--space) * 1.5);
  z-index: 100;
  width: min(100% - var(--gutter) * 2, var(--wrap));
  margin: calc(var(--space) * 1.5) auto 0;
  display: flex;
  align-items: center;
  gap: calc(var(--space) * 3);
  padding: calc(var(--space) * 1.25) calc(var(--space) * 2);
  background: var(--panel-fill);
  backdrop-filter: blur(var(--panel-blur));
  -webkit-backdrop-filter: blur(var(--panel-blur));
  border: var(--border) solid var(--panel-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--panel-lift);
  transition: backdrop-filter var(--motion-base) var(--ease-standard),
    background var(--motion-base) var(--ease-standard),
    border-color var(--motion-base) var(--ease-standard),
    box-shadow var(--motion-base) var(--ease-standard);
}

.site-header.is-scrolled {
  background: var(--panel-fill-raised);
  backdrop-filter: blur(calc(var(--panel-blur) * 1.6));
  -webkit-backdrop-filter: blur(calc(var(--panel-blur) * 1.6));
  border-color: var(--panel-border-bright);
  box-shadow: var(--panel-lift-high);
}

/* ---------------------------------------------------------------------- */
/* Brand */

.brand {
  display: inline-flex;
  align-items: center;
  gap: calc(var(--space) * 1.25);
  flex: 0 0 auto;
  font: bold 1.0625rem/1.1 var(--font-ui);
  letter-spacing: -0.01em;
  color: var(--text-primary);
  text-decoration: none;
}

.brand__mark {
  flex: 0 0 auto;
  transition: transform var(--motion-hover) var(--ease-entrance),
    filter var(--motion-hover) var(--ease-standard);
}

.brand:hover .brand__mark,
.brand:focus-visible .brand__mark {
  transform: translateY(-2px);
  filter: drop-shadow(0 3px 10px rgba(77, 217, 232, 0.45));
}

/* ---------------------------------------------------------------------- */
/* Nav — Home, Categories, About Me, and search, all visible on desktop */

.nav {
  display: flex;
  align-items: center;
  gap: calc(var(--space) * 3);
  margin-left: auto;
}

.nav__list {
  display: flex;
  align-items: center;
  gap: calc(var(--space) * 3);
  list-style: none;
  margin: 0;
  padding: 0;
}

/* A nav item is text and a 2px rule, nothing more. The rule is transparent
   at rest, the accent under the cursor, and the accent permanently on the
   current section, so the marker survives a touch screen and a keyboard. */
.nav__link {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 0.35em;
  font: 600 0.9375rem var(--font-ui);
  color: var(--text-primary);
  text-decoration: none;
  padding: 0.5em 0.15em;
  border-bottom: 2px solid transparent;
  white-space: nowrap;
  transition: color var(--motion-hover) var(--ease-standard),
    border-color var(--motion-hover) var(--ease-standard);
}

.nav__link:hover,
.nav__link:focus-visible {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

.nav__link[aria-current],
.dropdown[data-current] > .dropdown__summary {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

.nav__toggle {
  display: none;
  align-items: center;
  gap: 0.5em;
  margin-left: auto;
  font: 600 0.9375rem var(--font-ui);
  color: var(--text-primary);
  background: var(--panel-fill);
  border: var(--border) solid var(--panel-border);
  border-radius: var(--radius-pill);
  padding: 0.5em 0.9em;
  cursor: pointer;
}

/* ---------------------------------------------------------------------- */
/* Categories dropdown — a <details> element, so it opens, closes, and is
   keyboard-operable with the script absent. site.js only adds the
   click-outside and Escape conveniences. */

.dropdown {
  position: relative;
}

.dropdown__summary {
  list-style: none;
  cursor: pointer;
}

.dropdown__summary::-webkit-details-marker {
  display: none;
}

.dropdown__summary::after {
  content: "";
  width: 0.42em;
  height: 0.42em;
  margin-left: 0.15em;
  border: solid currentColor;
  border-width: 0 2px 2px 0;
  transform: translateY(-0.15em) rotate(45deg);
  transition: transform var(--motion-hover) var(--ease-standard);
}

.dropdown[open] > .dropdown__summary::after {
  transform: translateY(0.1em) rotate(-135deg);
}

.dropdown__panel {
  position: absolute;
  top: calc(100% + var(--space) * 1.5);
  left: 50%;
  transform: translateX(-50%);
  z-index: 200;
  width: max-content;
  max-width: min(90vw, 34rem);
  padding: var(--space);
  /* The glass film sits over a near-opaque canvas base rather than over the
     page: a menu floating across display type has to stay readable whether
     or not the browser gives us the backdrop blur. */
  background:
    linear-gradient(rgba(255, 255, 255, 0.07), rgba(255, 255, 255, 0.07)),
    color-mix(in srgb, var(--canvas) 93%, transparent);
  backdrop-filter: blur(calc(var(--panel-blur) * 1.8));
  -webkit-backdrop-filter: blur(calc(var(--panel-blur) * 1.8));
  border: var(--border) solid var(--panel-border-bright);
  border-radius: var(--radius-md);
  box-shadow: var(--panel-lift-high);
  animation: dropdown-in var(--motion-base) var(--ease-standard) both;
}

@keyframes dropdown-in {
  from {
    opacity: 0;
    transform: translate(-50%, -8px);
  }
  to {
    opacity: 1;
    transform: translate(-50%, 0);
  }
}

.dropdown__list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 2px calc(var(--space) * 2);
  list-style: none;
  margin: 0;
  padding: 0;
}

/* The category's own colour sits on the dot at rest, so the colour key is
   readable without a cursor. Hover moves the label, not the panel. */
.dropdown__link {
  display: flex;
  align-items: center;
  gap: 0.65em;
  padding: 0.6em 0.75em;
  border-radius: var(--radius-sm);
  font: 0.9375rem var(--font-ui);
  color: var(--text-primary);
  text-decoration: none;
  white-space: nowrap;
  transition: background var(--motion-hover) var(--ease-standard),
    color var(--motion-hover) var(--ease-standard);
}

.dropdown__link::before {
  content: "";
  flex: 0 0 auto;
  width: 0.55em;
  height: 0.55em;
  border-radius: 50%;
  background: var(--accent);
}

.dropdown__link:hover,
.dropdown__link:focus-visible,
.dropdown__link[aria-current] {
  color: var(--accent);
  background: rgba(255, 255, 255, 0.06);
}

/* ---------------------------------------------------------------------- */
/* Header search */

.site-search {
  display: flex;
  align-items: center;
  gap: calc(var(--space) * 0.75);
}

.site-search__field {
  position: relative;
  display: flex;
  align-items: center;
}

/* The magnifier is the submit control rather than a decoration beside one,
   so the field carries a visible affordance without a second button. */
.site-search__submit {
  position: absolute;
  left: 0.35em;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.9em;
  height: 1.9em;
  padding: 0;
  color: var(--text-secondary);
  background: none;
  border: 0;
  border-radius: 50%;
  cursor: pointer;
  transition: color var(--motion-hover) var(--ease-standard);
}

.site-search__submit:hover,
.site-search__field:focus-within .site-search__submit {
  color: var(--accent);
}

.site-search__input {
  width: clamp(9rem, 15vw, 15rem);
  padding: 0.55em 0.9em 0.55em 2.4em;
  font: 0.9375rem var(--font-ui);
  color: var(--text-primary);
  background: var(--recess-fill);
  border: var(--border) solid var(--panel-border);
  border-radius: var(--radius-pill);
  box-shadow: inset 0 1px 0 rgba(0, 0, 0, 0.4);
  transition: border-color var(--motion-hover) var(--ease-standard),
    background var(--motion-hover) var(--ease-standard);
}

.site-search__input::placeholder {
  color: var(--text-secondary);
}

.site-search__field:hover .site-search__input,
.site-search__input:focus {
  border-color: var(--panel-border-bright);
}

/* ---------------------------------------------------------------------- */
/* Mobile chrome — everything stays reachable, nothing moves to an overflow */

@media (max-width: 960px) {
  .site-header {
    flex-wrap: wrap;
    row-gap: calc(var(--space) * 1.5);
  }

  .nav__toggle {
    display: inline-flex;
  }

  .nav {
    display: none;
    flex-basis: 100%;
    flex-direction: column;
    align-items: stretch;
    gap: calc(var(--space) * 2);
    margin-left: 0;
    padding-top: calc(var(--space) * 1.5);
    border-top: var(--border) solid var(--panel-border);
  }

  .nav.is-open {
    display: flex;
  }

  .nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: calc(var(--space) * 0.5);
  }

  .nav__link {
    padding: 0.6em 0.15em;
    font-size: 1rem;
  }

  /* The dropdown becomes an in-flow accordion rather than an overlay. */
  .dropdown__panel {
    position: static;
    transform: none;
    width: auto;
    max-width: none;
    margin-top: var(--space);
    animation: none;
  }

  .dropdown__list {
    grid-template-columns: 1fr;
  }

  .site-search {
    width: 100%;
  }

  .site-search__field {
    flex: 1 1 auto;
  }

  .site-search__input {
    width: 100%;
  }
}

/* ---------------------------------------------------------------------- */
/* Category badge */

/* The category label is a dot and a word in the region's colour rather than
   a filled pill: on a listing of a dozen cards, a dozen bright fills shout
   over the titles. Every accent clears the contrast floor as text (the
   build gate in tools/check_contrast.py is what guarantees it). */
.category-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5em;
  color: var(--accent);
  font: 600 0.875rem var(--font-ui);
  letter-spacing: 0.02em;
}

.category-badge::before {
  content: "";
  width: 0.55em;
  height: 0.55em;
  border-radius: 50%;
  background: currentColor;
}

/* ---------------------------------------------------------------------- */
/* Category chip — a compact link carrying its region's colour at rest */

.category-chips {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: calc(var(--space) * 1.25);
  list-style: none;
  margin: 0;
  padding: 0;
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 0.55em;
  font: 600 0.9375rem var(--font-ui);
  color: var(--text-primary);
  text-decoration: none;
  padding: 0.55em 1.05em;
  background: var(--panel-fill);
  border: var(--border) solid var(--panel-border);
  border-radius: var(--radius-pill);
  transition: transform var(--motion-hover) var(--ease-standard),
    border-color var(--motion-hover) var(--ease-standard),
    background var(--motion-hover) var(--ease-standard),
    box-shadow var(--motion-hover) var(--ease-standard);
}

.chip::before {
  content: "";
  width: 0.55em;
  height: 0.55em;
  border-radius: 50%;
  background: var(--accent);
}

.chip:hover,
.chip:focus-visible {
  transform: translateY(-2px);
  color: var(--accent);
  border-color: color-mix(in srgb, var(--accent) 55%, transparent);
  box-shadow: var(--panel-lift);
}

/* ---------------------------------------------------------------------- */
/* Card — article listing on the front page, category pages, and search */

.card {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  background: var(--panel-fill);
  backdrop-filter: blur(var(--panel-blur));
  -webkit-backdrop-filter: blur(var(--panel-blur));
  border: var(--border) solid var(--panel-border);
  border-radius: var(--radius-md);
  box-shadow: var(--panel-lift);
  padding: calc(var(--space) * 3);
  overflow: hidden;
  transition: transform var(--motion-hover) var(--ease-standard),
    box-shadow var(--motion-hover) var(--ease-standard),
    border-color var(--motion-hover) var(--ease-standard);
}

/* The badge carries the accent at rest, not only on hover — the colour
   system must clear the multi-channel floor without relying on state. */
.card .category-badge {
  margin-bottom: calc(var(--space) * 2);
}

.card__title {
  font-size: 1.4375rem;
  line-height: 1.2;
  margin: 0 0 0.35em;
}

.card__title a {
  color: var(--text-primary);
  text-decoration: none;
  transition: color var(--motion-hover) var(--ease-standard);
}

/* Stretched link: the whole card is the hit target, and the anchor stays a
   real anchor for the keyboard and the status bar. */
.card__title a::after {
  content: "";
  position: absolute;
  inset: 0;
}

.card__subtitle {
  font: 1rem/1.5 var(--font-ui);
  color: var(--text-secondary);
  margin: 0 0 0.75em;
}

.card__summary {
  font-size: 1rem;
  line-height: 1.6;
  margin: 0 0 calc(var(--space) * 2);
}

.card__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5em;
  margin: auto 0 0;
  font: 0.875rem var(--font-ui);
  color: var(--text-secondary);
}

/* A thin accent edge along the top of the card, dark at rest and lit under
   the cursor. This is the whole of the card's decoration. */
.card::after {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 2px;
  background: var(--accent);
  opacity: 0.35;
  pointer-events: none;
  transition: opacity var(--motion-hover) var(--ease-standard);
}

.card:hover,
.card:focus-within {
  transform: translateY(-4px);
  box-shadow: var(--panel-lift-high);
  border-color: color-mix(in srgb, var(--accent) 45%, var(--panel-border-bright));
}

.card:hover .card__title a,
.card:focus-within .card__title a {
  color: var(--accent);
}

.card:hover::after,
.card:focus-within::after {
  opacity: 1;
}

/* ---------------------------------------------------------------------- */
/* Glow — wide, soft, low-opacity accent wash. Decorative only; never sits
   behind body text or a data figure. */

.glow {
  position: relative;
  isolation: isolate;
}

.glow::before {
  content: "";
  position: absolute;
  inset: -20% -10%;
  background: radial-gradient(50% 50% at 50% 30%, var(--accent) 0%, transparent 70%);
  opacity: 0.1;
  z-index: -1;
  pointer-events: none;
}

/* ---------------------------------------------------------------------- */
/* Buttons */

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5em;
  font: 600 0.9375rem var(--font-ui);
  color: var(--text-primary);
  text-decoration: none;
  background: var(--panel-fill);
  border: var(--border) solid var(--panel-border);
  border-radius: var(--radius-pill);
  padding: 0.65em 1.25em;
  cursor: pointer;
  transition: transform var(--motion-hover) var(--ease-standard),
    box-shadow var(--motion-hover) var(--ease-standard),
    border-color var(--motion-hover) var(--ease-standard),
    background var(--motion-hover) var(--ease-standard),
    opacity var(--motion-hover) var(--ease-standard);
}

.button:hover {
  transform: translateY(-2px);
  border-color: var(--panel-border-bright);
  box-shadow: var(--panel-lift);
}

.button:active {
  transform: translateY(0) scale(0.97);
}

.button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.button:disabled,
.button[aria-disabled="true"] {
  opacity: 0.45;
  cursor: not-allowed;
  filter: saturate(0.4);
  transform: none;
}

.button--primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--text-on-accent);
}

.button--primary:hover {
  box-shadow: var(--panel-lift-high);
  filter: brightness(1.08);
}

.button--primary:disabled,
.button--primary[aria-disabled="true"] {
  filter: saturate(0.3) brightness(0.9);
}