/* ==========================================================================
   Dexter DCL — Open Data Systems for the United Kingdom
   Design system
   ========================================================================== */

/* ---------- Tokens ---------- */
:root {
  /* Surfaces */
  --paper:        #FBFAF7;
  --surface:      #FFFFFF;
  --surface-2:    #F3F2ED;
  --surface-3:    #E8E6DE;

  /* Ink */
  --ink:          #12151C;
  --ink-2:        #3A414F;
  --ink-3:        #6B7280;
  --ink-faint:    #9AA1AC;

  /* Line */
  --line:         #DEDCD3;
  --line-strong:  #C4C1B4;

  /* Brand */
  --accent:       #1D4ED8;
  --accent-2:     #0E7490;
  --accent-soft:  #E8EEFC;
  --accent-ink:   #1E3A8A;

  /* Semantic */
  --hot:          #B42318;
  --hot-soft:     #FEE4E2;
  --warm:         #B54708;
  --warm-soft:    #FEF0C7;
  --cool:         #067647;
  --cool-soft:    #DCFAE6;

  /* Data viz sequence */
  --d1: #1D4ED8;
  --d2: #0E7490;
  --d3: #B54708;
  --d4: #6D28D9;
  --d5: #047857;
  --d6: #B42318;

  /* Type */
  --sans: "IBM Plex Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  --serif: "Newsreader", Iowan Old Style, Palatino, "Palatino Linotype", Georgia, serif;
  --mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;

  /* Space */
  --gut: clamp(1.25rem, 4vw, 2.5rem);
  --maxw: 1240px;
  --readw: 74ch;

  /* Motion */
  --ease: cubic-bezier(.2, .7, .3, 1);
}

:root:not([data-theme="light"]) {
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper:       #0C0E13;
    --surface:     #12151C;
    --surface-2:   #181C25;
    --surface-3:   #222833;

    --ink:         #ECEEF2;
    --ink-2:       #B4BAC6;
    --ink-3:       #8A91A0;
    --ink-faint:   #666D7C;

    --line:        #242A35;
    --line-strong: #333B49;

    --accent:      #7DA2FF;
    --accent-2:    #4FD1D9;
    --accent-soft: #16203A;
    --accent-ink:  #A9C2FF;

    --hot:         #FF9B94;
    --hot-soft:    #3A1714;
    --warm:        #FFC46B;
    --warm-soft:   #33220A;
    --cool:        #6EE7A8;
    --cool-soft:   #08251A;

    --d1: #7DA2FF; --d2: #4FD1D9; --d3: #FFC46B;
    --d4: #C4A6FF; --d5: #6EE7A8; --d6: #FF9B94;

    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --paper:       #0C0E13;
  --surface:     #12151C;
  --surface-2:   #181C25;
  --surface-3:   #222833;
  --ink:         #ECEEF2;
  --ink-2:       #B4BAC6;
  --ink-3:       #8A91A0;
  --ink-faint:   #666D7C;
  --line:        #242A35;
  --line-strong: #333B49;
  --accent:      #7DA2FF;
  --accent-2:    #4FD1D9;
  --accent-soft: #16203A;
  --accent-ink:  #A9C2FF;
  --hot:         #FF9B94;  --hot-soft:  #3A1714;
  --warm:        #FFC46B;  --warm-soft: #33220A;
  --cool:        #6EE7A8;  --cool-soft: #08251A;
  --d1: #7DA2FF; --d2: #4FD1D9; --d3: #FFC46B;
  --d4: #C4A6FF; --d5: #6EE7A8; --d6: #FF9B94;
  color-scheme: dark;
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .01ms !important; transition-duration: .01ms !important; }
}

body {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 1.0625rem;
  line-height: 1.65;
  font-feature-settings: "kern", "liga", "cv05", "ss01";
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

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

::selection { background: var(--accent); color: var(--paper); }

:focus-visible {
  outline: 2.5px solid var(--accent);
  outline-offset: 3px;
  border-radius: 3px;
}

/* ---------- Layout ---------- */
.wrap {
  width: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: var(--gut);
}
.wrap--narrow { max-width: 860px; }

.section { padding-block: clamp(3.5rem, 9vw, 7rem); }
.section--tight { padding-block: clamp(2.5rem, 6vw, 4.5rem); }
.section--alt { background: var(--surface-2); }
.section--ink {
  background: var(--ink);
  color: var(--paper);
}
.section--ink h2, .section--ink h3 { color: var(--paper); }

/* ---------- Type ---------- */
h1, h2, h3, h4 {
  line-height: 1.1;
  letter-spacing: -0.022em;
  font-weight: 640;
  text-wrap: balance;
}

.display {
  font-size: clamp(2.5rem, 6.4vw, 4.75rem);
  line-height: 1.02;
  letter-spacing: -0.035em;
  font-weight: 680;
}

h2 { font-size: clamp(1.75rem, 3.4vw, 2.6rem); }
h3 { font-size: clamp(1.2rem, 2vw, 1.5rem); letter-spacing: -0.015em; }
h4 { font-size: 1.0625rem; letter-spacing: -0.005em; font-weight: 660; }

p { text-wrap: pretty; }
.lede {
  font-size: clamp(1.15rem, 1.9vw, 1.4rem);
  line-height: 1.5;
  color: var(--ink-2);
  max-width: 62ch;
  font-weight: 420;
}

.prose { max-width: var(--readw); }
.prose > * + * { margin-top: 1.1em; }
.prose h3 { margin-top: 2.4em; }
.prose h4 { margin-top: 2em; }
.prose ul, .prose ol { padding-left: 1.35em; }
.prose li + li { margin-top: .45em; }
.prose a { color: var(--accent); text-underline-offset: 3px; text-decoration-thickness: 1.5px; }
.prose strong { font-weight: 645; color: var(--ink); }

.eyebrow {
  font-family: var(--mono);
  font-size: .7rem;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 550;
  display: inline-flex;
  align-items: center;
  gap: .6em;
}
/* Section labels on system pages are headings, so the page has a real outline
   for crawlers and screen readers. The class keeps their appearance; this keeps
   their box identical to the div they replaced. */
h2.eyebrow, h3.eyebrow { line-height: inherit; text-wrap: initial; }

/* Footer column headings are h2 so the page outline has no gap. The class
   restores the smaller size they had as h4. */
.foot h2 { font-size: 1.0625rem; letter-spacing: -0.005em; font-weight: 660; }

/* Available to assistive technology, absent from the visual design. Used for a
   heading that labels a column the design shows as a continuation. */
.visually-hidden {
  position: absolute; width: 1px; height: 1px; padding: 0;
  margin: -1px; overflow: hidden; clip: rect(0 0 0 0);
  white-space: nowrap; border: 0;
}

.eyebrow::before {
  content: "";
  width: 1.6em; height: 1.5px;
  background: currentColor;
  opacity: .55;
}
.section--ink .eyebrow { color: var(--accent-2); }

.muted { color: var(--ink-3); }
.small { font-size: .875rem; line-height: 1.55; }
.tiny  { font-size: .78rem; line-height: 1.5; }

/* ---------- Nav ---------- */
.nav {
  position: sticky; top: 0; z-index: 100;
  background: color-mix(in srgb, var(--paper) 88%, transparent);
  backdrop-filter: saturate(1.6) blur(14px);
  -webkit-backdrop-filter: saturate(1.6) blur(14px);
  border-bottom: 1px solid var(--line);
}
.nav__inner {
  display: flex; align-items: center; gap: 1.5rem;
  height: 62px;
}
.brand {
  display: inline-flex; align-items: center; gap: .6rem;
  font-weight: 660; letter-spacing: -.02em;
  text-decoration: none; font-size: .98rem;
  white-space: nowrap;
}
.brand__mark {
  width: 26px; height: 26px; flex: none;
  border-radius: 6px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  display: grid; place-items: center;
  color: #fff; font-family: var(--mono);
  font-size: .68rem; font-weight: 700; letter-spacing: -.04em;
}
.brand__sub {
  color: var(--ink-3); font-weight: 450;
  border-left: 1px solid var(--line-strong);
  padding-left: .6rem; margin-left: .1rem;
  font-size: .85rem;
}
.nav__links {
  margin-left: auto;
  display: flex; align-items: center; gap: .35rem;
}
.nav__links a {
  text-decoration: none; font-size: .875rem;
  color: var(--ink-2); padding: .42rem .68rem;
  border-radius: 7px; font-weight: 500;
  transition: background .16s var(--ease), color .16s var(--ease);
  white-space: nowrap;
}
.nav__links a:hover { background: var(--surface-2); color: var(--ink); }
.nav__links a.is-cta {
  background: var(--ink); color: var(--paper);
}
.nav__links a.is-cta:hover { background: var(--accent); color: #fff; }
@media (max-width: 900px) { .nav__links .hide-sm { display: none; } }

/* On a phone the brand (228px) and the remaining links (305px) did not fit a
   375px bar, and the whole page scrolled sideways. The links stay in the markup
   and stay reachable -- they are the site's primary internal links -- so the row
   scrolls instead of the page, and the brand drops its sub-label. */
@media (max-width: 560px) {
  .nav__inner { gap: .75rem; }
  .brand__sub { display: none; }
  .nav__links {
    min-width: 0;
    overflow-x: auto;
    scrollbar-width: none;
    -webkit-overflow-scrolling: touch;
  }
  .nav__links::-webkit-scrollbar { display: none; }
}

.themetoggle {
  width: 34px; height: 34px; flex: none;
  display: grid; place-items: center;
  background: transparent; border: 1px solid var(--line);
  border-radius: 8px; cursor: pointer; color: var(--ink-2);
  transition: background .16s var(--ease);
}
.themetoggle:hover { background: var(--surface-2); }

/* ---------- Hero ---------- */
.hero {
  position: relative;
  padding-block: clamp(3.5rem, 10vw, 7.5rem) clamp(3rem, 7vw, 5rem);
  overflow: hidden;
}
.hero::before {
  content: "";
  position: absolute; inset: 0;
  background:
    radial-gradient(60% 55% at 78% 8%, color-mix(in srgb, var(--accent) 13%, transparent), transparent 68%),
    radial-gradient(45% 45% at 8% 88%, color-mix(in srgb, var(--accent-2) 11%, transparent), transparent 70%);
  pointer-events: none;
}
.hero__grid {
  position: absolute; inset: 0;
  background-image:
    linear-gradient(to right, var(--line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--line) 1px, transparent 1px);
  background-size: 64px 64px;
  opacity: .4;
  mask-image: radial-gradient(70% 60% at 50% 30%, #000 20%, transparent 78%);
  -webkit-mask-image: radial-gradient(70% 60% at 50% 30%, #000 20%, transparent 78%);
  pointer-events: none;
}
.hero > * { position: relative; }

.hero__title { margin-top: 1.4rem; }
.hero__title em {
  font-style: normal;
  color: var(--accent);
}
.hero__lede { margin-top: 1.6rem; }
.hero__cta { display: flex; flex-wrap: wrap; gap: .75rem; margin-top: 2.4rem; }

.btn {
  display: inline-flex; align-items: center; gap: .5rem;
  padding: .7rem 1.2rem; border-radius: 9px;
  font-size: .9rem; font-weight: 570; text-decoration: none;
  border: 1px solid transparent; cursor: pointer;
  transition: transform .16s var(--ease), background .16s var(--ease), border-color .16s var(--ease);
}
.btn:hover { transform: translateY(-1.5px); }
.btn--primary { background: var(--ink); color: var(--paper); }
.btn--primary:hover { background: var(--accent); color: #fff; }
.btn--ghost { border-color: var(--line-strong); color: var(--ink); }
.btn--ghost:hover { background: var(--surface-2); border-color: var(--ink-3); }

/* ---------- Stat band ---------- */
.statband {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.stat {
  padding: 1.6rem var(--gut) 1.6rem 0;
  border-right: 1px solid var(--line);
}
.stat:last-child { border-right: 0; }
.stat__num {
  font-size: clamp(1.7rem, 3.2vw, 2.4rem);
  font-weight: 680; letter-spacing: -.035em;
  line-height: 1; color: var(--ink);
  font-variant-numeric: tabular-nums;
}
.stat__num sup { font-size: .5em; color: var(--accent); top: -.7em; }
.stat__label { margin-top: .5rem; font-size: .83rem; color: var(--ink-3); line-height: 1.45; }

/* ---------- Cards ---------- */
.grid {
  display: grid;
  gap: 1.15rem;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
}
.grid--2 { grid-template-columns: repeat(auto-fit, minmax(340px, 1fr)); }
.grid--3 { grid-template-columns: repeat(auto-fit, minmax(228px, 1fr)); }

.card {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 1.5rem;
  text-decoration: none; color: inherit;
  display: flex; flex-direction: column;
  transition: border-color .18s var(--ease), transform .18s var(--ease), box-shadow .18s var(--ease);
  overflow: hidden;
}
a.card:hover {
  border-color: var(--accent);
  transform: translateY(-3px);
  box-shadow: 0 12px 32px -14px color-mix(in srgb, var(--accent) 45%, transparent);
}
.card__num {
  font-family: var(--mono); font-size: .74rem; font-weight: 600;
  color: var(--accent); letter-spacing: .06em;
}
.card__title { margin-top: .7rem; font-size: 1.16rem; letter-spacing: -.018em; }
.card__desc { margin-top: .6rem; color: var(--ink-2); font-size: .9rem; line-height: 1.55; flex: 1; }
.card__foot {
  margin-top: 1.1rem; padding-top: .9rem;
  border-top: 1px solid var(--line);
  display: flex; flex-wrap: wrap; gap: .4rem; align-items: center;
}

.tag {
  font-size: .715rem; font-weight: 540;
  padding: .22rem .55rem; border-radius: 5px;
  background: var(--surface-2); color: var(--ink-3);
  border: 1px solid var(--line);
  white-space: nowrap;
}
.tag--accent { background: var(--accent-soft); color: var(--accent-ink); border-color: transparent; }
.tag--hot   { background: var(--hot-soft);  color: var(--hot);  border-color: transparent; }
.tag--warm  { background: var(--warm-soft); color: var(--warm); border-color: transparent; }
.tag--cool  { background: var(--cool-soft); color: var(--cool); border-color: transparent; }

/* ---------- Tables ---------- */
.tablewrap {
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface);
}
table { border-collapse: collapse; width: 100%; font-size: .875rem; min-width: 560px; }
thead th {
  text-align: left; font-weight: 600; font-size: .74rem;
  letter-spacing: .07em; text-transform: uppercase;
  color: var(--ink-3);
  padding: .8rem 1rem;
  border-bottom: 1px solid var(--line-strong);
  background: var(--surface-2);
  white-space: nowrap;
}
tbody td {
  padding: .8rem 1rem;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
  line-height: 1.5;
}
tbody tr:last-child td { border-bottom: 0; }
tbody tr:hover { background: var(--surface-2); }
td code, .prose code {
  font-family: var(--mono); font-size: .84em;
  background: var(--surface-2); padding: .12em .4em;
  border-radius: 4px; border: 1px solid var(--line);
}

/* ---------- Callouts ---------- */
.note {
  background: var(--accent-soft);
  border: 1px solid color-mix(in srgb, var(--accent) 26%, transparent);
  padding: 1.1rem 1.3rem;
  border-radius: 10px;
  font-size: .92rem; line-height: 1.6;
}
.note--warn { background: var(--warm-soft); border-color: color-mix(in srgb, var(--warm) 26%, transparent); }
.note--hot  { background: var(--hot-soft);  border-color: color-mix(in srgb, var(--hot) 26%, transparent); }
.note__title {
  font-weight: 640; margin-bottom: .35rem;
  font-size: .76rem; letter-spacing: .07em; text-transform: uppercase;
  color: var(--accent-ink);
}
.note--warn .note__title { color: var(--warm); }
.note--hot .note__title  { color: var(--hot); }

/* ---------- System detail page ---------- */
.sysHead {
  padding-block: clamp(2.5rem, 6vw, 4rem) 2.5rem;
  border-bottom: 1px solid var(--line);
  position: relative; overflow: hidden;
}
.sysHead::before {
  content: ""; position: absolute; inset: 0;
  background: radial-gradient(52% 100% at 88% 0%, color-mix(in srgb, var(--accent) 12%, transparent), transparent 70%);
  pointer-events: none;
}
.sysHead > * { position: relative; }
.backlink {
  display: inline-flex; align-items: center; gap: .45rem;
  font-size: .84rem; color: var(--ink-3); text-decoration: none;
  margin-bottom: 1.5rem;
}
.backlink:hover { color: var(--accent); }

.sysLayout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 3rem;
  align-items: start;
}
/* A grid item defaults to min-width:auto, so it refuses to shrink below the
   min-content width of what it holds. On a phone that pushed the whole column
   to 562px inside a 375px viewport and scrolled the page sideways. */
.sysLayout > * { min-width: 0; }
@media (min-width: 1080px) {
  .sysLayout { grid-template-columns: minmax(0,1fr) 250px; gap: 4rem; }
  .sysLayout__aside { position: sticky; top: 86px; }
}
.toc { border-left: 2px solid var(--line); padding-left: 1rem; }
.toc__title {
  font-family: var(--mono); font-size: .68rem; letter-spacing: .13em;
  text-transform: uppercase; color: var(--ink-faint); margin-bottom: .8rem;
}
.toc a {
  display: block; font-size: .84rem; color: var(--ink-3);
  text-decoration: none; padding: .28rem 0; line-height: 1.4;
}
.toc a:hover, .toc a.is-active { color: var(--accent); }

.specrow {
  display: grid; grid-template-columns: 1fr; gap: .3rem;
  padding: .85rem 0; border-bottom: 1px solid var(--line);
}
@media (min-width: 620px) { .specrow { grid-template-columns: 168px 1fr; gap: 1.5rem; } }
.specrow__k {
  font-size: .76rem; text-transform: uppercase; letter-spacing: .07em;
  color: var(--ink-faint); font-weight: 560; padding-top: .12rem;
}
.specrow__v { font-size: .93rem; line-height: 1.55; }

/* Feature list */
.feat { display: grid; gap: .9rem; }
.feat__item {
  display: grid; grid-template-columns: 26px 1fr; gap: .85rem;
  align-items: start;
}
.feat__ico {
  width: 22px; height: 22px; border-radius: 6px; margin-top: .12rem;
  background: var(--accent-soft); color: var(--accent-ink);
  display: grid; place-items: center;
  font-family: var(--mono); font-size: .64rem; font-weight: 700;
}
.feat__t { font-weight: 615; font-size: .95rem; }
.feat__d { font-size: .885rem; color: var(--ink-2); line-height: 1.55; margin-top: .18rem; }

/* Impact metrics */
.impact { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px,1fr)); gap: 1px; background: var(--line); border: 1px solid var(--line); border-radius: 12px; overflow: hidden; }
.impact__cell { background: var(--surface); padding: 1.2rem; }
.impact__n { font-size: 1.6rem; font-weight: 680; letter-spacing: -.03em; color: var(--accent); font-variant-numeric: tabular-nums; line-height: 1.1; }
.impact__l { font-size: .8rem; color: var(--ink-3); margin-top: .4rem; line-height: 1.45; }

/* Architecture diagram */
.arch { width: 100%; height: auto; }
.arch text { font-family: var(--sans); }

/* Pipeline / phases */
.phases { display: grid; gap: 0; counter-reset: ph; }
.phase {
  display: grid; grid-template-columns: 34px 1fr; gap: 1.1rem;
  padding-bottom: 1.6rem; position: relative;
}
.phase:not(:last-child)::before {
  content: ""; position: absolute; left: 16px; top: 34px; bottom: 0;
  width: 1.5px; background: var(--line);
}
.phase__n {
  width: 34px; height: 34px; border-radius: 50%; flex: none;
  border: 1.5px solid var(--accent); color: var(--accent);
  display: grid; place-items: center;
  font-family: var(--mono); font-size: .78rem; font-weight: 650;
  background: var(--paper); position: relative; z-index: 1;
}
.phase__t { font-weight: 630; font-size: 1rem; }
.phase__meta { font-size: .76rem; color: var(--ink-faint); font-family: var(--mono); margin-top: .2rem; }
.phase__d { font-size: .89rem; color: var(--ink-2); margin-top: .45rem; line-height: 1.6; }

/* Sources */
.srcs { display: grid; gap: .55rem; }
.src {
  display: grid; grid-template-columns: 24px 1fr; gap: .7rem;
  font-size: .84rem; line-height: 1.5; align-items: start;
}
.src__n { font-family: var(--mono); font-size: .72rem; color: var(--ink-faint); padding-top: .12rem; }
.src a { color: var(--accent); text-decoration: none; word-break: break-word; }
.src a:hover { text-decoration: underline; }

/* Filters */
.filters { display: flex; flex-wrap: wrap; gap: .45rem; margin-bottom: 1.75rem; }
.filter {
  font-size: .82rem; padding: .4rem .82rem; border-radius: 999px;
  border: 1px solid var(--line-strong); background: transparent;
  color: var(--ink-2); cursor: pointer; font-weight: 520;
  transition: all .15s var(--ease); font-family: inherit;
}
.filter:hover { border-color: var(--ink-3); }
.filter.is-on { background: var(--ink); color: var(--paper); border-color: var(--ink); }

/* Footer */
.foot {
  border-top: 1px solid var(--line);
  padding-block: 3rem 2.5rem;
  background: var(--surface-2);
}
.foot__grid {
  display: grid; gap: 2rem;
  grid-template-columns: repeat(auto-fit, minmax(200px,1fr));
}
.foot h4 { font-size: .78rem; text-transform: uppercase; letter-spacing: .09em; color: var(--ink-faint); margin-bottom: .8rem; }
.foot a { display: block; font-size: .875rem; color: var(--ink-2); text-decoration: none; padding: .2rem 0; }
.foot a:hover { color: var(--accent); }
.foot__bottom {
  margin-top: 2.5rem; padding-top: 1.5rem; border-top: 1px solid var(--line);
  display: flex; flex-wrap: wrap; gap: 1rem; justify-content: space-between;
  font-size: .8rem; color: var(--ink-faint);
}

/* Utilities */
.mt-0 { margin-top: 0; }
.mt-1 { margin-top: .5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }
.mt-5 { margin-top: 3rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }
.hr { height: 1px; background: var(--line); border: 0; margin-block: 2.5rem; }
.flexrow { display: flex; flex-wrap: wrap; gap: .5rem; align-items: center; }