/**
 * Reset, document defaults, motion and shared utilities.
 *
 * Deliberately small: the design is not built on a utility framework, so this
 * file only sets what every element needs and gets out of the way.
 */

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  height: auto;
  min-height: 100%;
  /* Keep an anchored or focused element clear of the sticky header above and
     the mobile action bar below, so focus is never parked underneath either. */
  scroll-padding-top: 96px;
  scroll-padding-bottom: 72px;
}

body {
  height: auto;
  min-height: 100%;
  margin: 0;
  background: var(--dk-white);
  color: var(--dk-text);
  font-family: var(--dk-font-body);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--dk-blue);
  text-decoration: none;
}

a:hover {
  color: var(--dk-blue-hover);
}

img,
svg {
  display: block;
  max-width: 100%;
}

/**
 * `hidden` must actually hide.
 *
 * The user-agent rule for `[hidden]` is `display: none`, but any author rule
 * that sets `display` — and several components here need `display: flex` — wins
 * on specificity and silently reveals the element again. This is the one place
 * `!important` is the correct tool: `hidden` is not a hint.
 */
[hidden] {
  display: none !important;
}

input,
textarea,
button {
  font-family: inherit;
}

a,
button {
  transition:
    background-color var(--dk-speed-fast) ease,
    color var(--dk-speed-fast) ease,
    border-color var(--dk-speed-fast) ease,
    transform var(--dk-speed-fast) ease;
}

/* A single visible focus ring for every interactive element. Keyboard-only, so
   it never appears on a mouse click but is always there for tab navigation. */
a:focus-visible,
button:focus-visible,
input:focus-visible,
textarea:focus-visible,
summary:focus-visible,
[tabindex]:focus-visible {
  outline: 2px solid var(--dk-focus-ring, var(--dk-blue));
  outline-offset: 3px;
  border-radius: 1px;
}

/**
 * The brand blue only reaches 2.96:1 against the navy bands, below the 3:1 that
 * WCAG 1.4.11 asks of a focus indicator. Dark surfaces switch the ring to white
 * (17.5:1). The ring is painted only on :focus-visible, so nothing changes for
 * a visitor who is not tabbing — this costs zero pixels at rest.
 */
.dk-dark,
footer,
.dk-topbar {
  --dk-focus-ring: var(--dk-on-dark);
}

/**
 * Windows High Contrast collapses the border colours several controls rely on
 * as their only affordance. Restoring a system-coloured border keeps them
 * visible. `forced-color-adjust: none` is deliberately not used — overriding
 * the user's chosen palette is the problem, not the fix.
 */
@media (forced-colors: active) {
  .dk-iconbtn,
  .dk-social,
  .dk-chip,
  .dk-faq__mark,
  .dk-card__go,
  .dk-fab a {
    border: 1px solid ButtonBorder;
  }
}

/* ---------------------------------------------------------------- motion */

@keyframes dk-fade {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

@keyframes dk-rise {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

/**
 * Scroll-linked reveal.
 *
 * `animation-timeline: view()` ties progress to the element entering the
 * viewport. Where it is unsupported the declaration is dropped and the same
 * animation simply plays once on load — which is the degradation the original
 * design has, so the two behave identically in every browser.
 */
[data-anim] {
  animation: dk-rise 0.7s var(--dk-ease) both;
  animation-timeline: view();
  animation-range: entry 0% cover 22%;
}

.dk-fade-in {
  animation: dk-fade 0.35s ease both;
}

/* ------------------------------------------------------------- utilities */

/**
 * Skip link: off-screen until focused, then pinned to the top-left above the
 * sticky header so a keyboard visitor can jump past the navigation.
 */
.dk-skip {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 100;
  padding: 12px 18px;
  border-radius: var(--dk-radius-sm);
  background: var(--dk-blue);
  color: var(--dk-on-dark);
  font: 600 14px/1 var(--dk-font-display);
  letter-spacing: var(--dk-track-button);
  text-transform: uppercase;
  transform: translateY(-200%);
  transition: transform var(--dk-speed) ease;
}

.dk-skip:focus-visible {
  transform: none;
  color: var(--dk-on-dark);
}

/** Visually hidden but available to assistive technology. */
.dk-sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

/** The monospaced `[ photo: … ]` markers standing in for real photography. */
.dk-placeholder {
  position: absolute;
  left: var(--dk-gutter);
  bottom: 16px;
  margin: 0;
  font: 400 11px/1 var(--dk-font-mono);
  letter-spacing: 0.08em;
  color: rgba(255, 255, 255, 0.42);
}

/** The 64x2 rule under every section heading. */
.dk-rule {
  width: 64px;
  height: 2px;
  background: var(--dk-blue);
  margin: 20px 0 28px;
}

.dk-rule--center {
  margin-left: auto;
  margin-right: auto;
}

/* --------------------------------------------------------- reduced motion */

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  [data-anim],
  .dk-fade-in {
    animation: none !important;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}