/* =========================================================================
   RESIDUA — Peptide Research Intelligence
   Design system: cool-clinical base · molecular teal · Spectral / IBM Plex
   ========================================================================= */

/* ---- Design tokens ------------------------------------------------------ */
:root {
  /* Light (default) */
  --bg:           #F6F8F9;
  --surface:      #FFFFFF;
  --surface-2:    #EDF2F4;
  --surface-3:    #E3EAEC;
  --ink:          #0E1C24;
  --ink-soft:     #43545E;
  --ink-faint:    #6C7B84;
  --line:         #D7E0E4;
  --line-strong:  #C2CED4;
  --accent:       #0B7A82;
  --accent-deep:  #075A60;
  --accent-soft:  #E1F0F0;
  --signal:       #B26117;
  --signal-soft:  #F6E9DA;
  --on-accent:    #FFFFFF;
  --shadow:       0 1px 2px rgba(14,28,36,.04), 0 8px 28px -16px rgba(14,28,36,.18);
  --shadow-lift:  0 2px 6px rgba(14,28,36,.06), 0 22px 48px -22px rgba(14,28,36,.28);

  /* Evidence badge hues (light) */
  --ev-meta:      #0B7A82;
  --ev-meta-bg:   #E1F0F0;
  --ev-clinical:  #1E6FA8;
  --ev-clinical-bg:#E2EEF6;
  --ev-pre:       #9A5B12;
  --ev-pre-bg:    #F6EBDB;
  --ev-emerging:  #6B4FB8;
  --ev-emerging-bg:#ECE7F7;
  --ev-editorial: #5A6B74;
  --ev-editorial-bg:#E7ECEE;

  /* Type */
  --serif: "Spectral", Georgia, "Times New Roman", serif;
  --sans:  "IBM Plex Sans", system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  --mono:  "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, monospace;

  /* Scale */
  --step--1: clamp(.78rem, .76rem + .1vw, .84rem);
  --step-0:  clamp(.97rem, .94rem + .14vw, 1.06rem);
  --step-1:  clamp(1.15rem, 1.08rem + .35vw, 1.4rem);
  --step-2:  clamp(1.4rem, 1.25rem + .7vw, 1.9rem);
  --step-3:  clamp(1.85rem, 1.55rem + 1.4vw, 2.85rem);
  --step-4:  clamp(2.4rem, 1.9rem + 2.5vw, 4.1rem);

  --maxw: 1200px;
  --rad: 4px;
  --rad-lg: 8px;
  --gap: clamp(1rem, .7rem + 1.4vw, 1.9rem);
  --pad-x: clamp(1.1rem, .6rem + 2.5vw, 2.5rem);
}

[data-theme="dark"] {
  --bg:           #0A141A;
  --surface:      #0F1D25;
  --surface-2:    #15252E;
  --surface-3:    #1B2E38;
  --ink:          #E7EFF2;
  --ink-soft:     #A6B6BE;
  --ink-faint:    #7B8D96;
  --line:         #213039;
  --line-strong:  #30444E;
  --accent:       #2DC6C1;
  --accent-deep:  #5BD8D3;
  --accent-soft:  #0E2A2B;
  --signal:       #DA9A4C;
  --signal-soft:  #2A2013;
  --on-accent:    #052021;
  --shadow:       0 1px 2px rgba(0,0,0,.4), 0 10px 30px -18px rgba(0,0,0,.7);
  --shadow-lift:  0 2px 6px rgba(0,0,0,.5), 0 26px 52px -24px rgba(0,0,0,.8);

  --ev-meta:      #2DC6C1;  --ev-meta-bg:   #0E2A2B;
  --ev-clinical:  #6FB4E4;  --ev-clinical-bg:#102733;
  --ev-pre:       #D99B4F;  --ev-pre-bg:    #2A2013;
  --ev-emerging:  #A993E8;  --ev-emerging-bg:#1E1A33;
  --ev-editorial: #93A4AD;  --ev-editorial-bg:#1A262C;
}

/* ---- 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: .001ms !important; transition-duration: .001ms !important; }
}
body {
  font-family: var(--sans);
  font-size: var(--step-0);
  line-height: 1.6;
  color: var(--ink);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  transition: background-color .35s ease, color .35s ease;
}
img, svg { max-width: 100%; display: block; }
a { color: var(--accent-deep); text-underline-offset: .18em; text-decoration-thickness: 1px; }
[data-theme="dark"] a { color: var(--accent-deep); }
button { font: inherit; cursor: pointer; color: inherit; }
ul, ol { padding-left: 1.2em; }

:focus-visible {
  outline: 2.5px solid var(--accent);
  outline-offset: 2px;
  border-radius: 2px;
}

.wrap { max-width: var(--maxw); margin-inline: auto; padding-inline: var(--pad-x); }
.skip-link {
  position: absolute; left: 12px; top: -60px; z-index: 200;
  background: var(--accent); color: var(--on-accent);
  padding: .6rem 1rem; border-radius: var(--rad); font-weight: 600;
  transition: top .2s;
}
.skip-link:focus { top: 12px; }

/* ---- Eyebrow / labels --------------------------------------------------- */
.eyebrow {
  font-family: var(--mono);
  font-size: .72rem;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--accent-deep);
  font-weight: 500;
  display: inline-flex; align-items: center; gap: .55rem;
}
.eyebrow::before {
  content: ""; width: 1.6rem; height: 1px; background: var(--accent);
  display: inline-block;
}
.eyebrow.is-plain::before { display: none; }

/* =========================================================================
   Header / nav
   ========================================================================= */
.masthead {
  position: sticky; top: 0; z-index: 100;
  background: color-mix(in srgb, var(--bg) 86%, transparent);
  backdrop-filter: saturate(140%) blur(10px);
  border-bottom: 1px solid var(--line);
}
.masthead__bar {
  display: flex; align-items: center; gap: 1.2rem;
  height: 68px;
}
.brand { display: flex; align-items: center; gap: .7rem; text-decoration: none; color: var(--ink); }
.brand__mark { flex: none; }
.brand__name {
  font-family: var(--serif); font-weight: 600; font-size: 1.32rem;
  letter-spacing: .02em; line-height: 1;
}
.brand__sub {
  display: block; font-family: var(--mono); font-size: .58rem;
  letter-spacing: .22em; text-transform: uppercase; color: var(--ink-faint);
  margin-top: .25rem;
}
.nav { display: flex; align-items: center; gap: .1rem; margin-left: auto; }
.nav a {
  font-size: .92rem; color: var(--ink-soft); text-decoration: none;
  padding: .5rem .72rem; border-radius: var(--rad); font-weight: 500;
  transition: color .18s, background .18s;
}
.nav a:hover { color: var(--ink); background: var(--surface-2); }
.nav a[aria-current="page"] { color: var(--accent-deep); }
.nav a[aria-current="page"]::after {
  content: ""; display: block; height: 2px; background: var(--accent);
  margin-top: .28rem; border-radius: 2px;
}
.tools { display: flex; align-items: center; gap: .4rem; margin-left: .4rem; }
.icon-btn {
  width: 40px; height: 40px; display: grid; place-items: center;
  border: 1px solid var(--line); border-radius: var(--rad);
  background: var(--surface); color: var(--ink-soft);
  transition: background .18s, color .18s, border-color .18s;
}
.icon-btn:hover { color: var(--ink); border-color: var(--line-strong); }
.icon-btn svg { width: 18px; height: 18px; }
.theme-toggle .moon { display: none; }
[data-theme="dark"] .theme-toggle .sun { display: none; }
[data-theme="dark"] .theme-toggle .moon { display: block; }
.nav-toggle { display: none; }

@media (max-width: 880px) {
  .nav {
    position: fixed; inset: 68px 0 auto 0;
    flex-direction: column; align-items: stretch; gap: 0;
    background: var(--surface); border-bottom: 1px solid var(--line);
    padding: .5rem var(--pad-x) 1rem;
    transform: translateY(-130%); transition: transform .3s ease;
    box-shadow: var(--shadow);
  }
  .nav.open { transform: translateY(0); }
  .nav a { padding: .85rem .4rem; border-bottom: 1px solid var(--line); }
  .nav a[aria-current="page"]::after { display: none; }
  .nav-toggle { display: grid; }
}

/* =========================================================================
   Buttons
   ========================================================================= */
.btn {
  display: inline-flex; align-items: center; gap: .5rem;
  font-weight: 600; font-size: .92rem; text-decoration: none;
  padding: .7rem 1.15rem; border-radius: var(--rad);
  border: 1px solid transparent; transition: transform .15s, background .18s, border-color .18s, color .18s;
}
.btn:active { transform: translateY(1px); }
.btn--primary { background: var(--accent); color: var(--on-accent); }
.btn--primary:hover { background: var(--accent-deep); }
.btn--ghost { background: transparent; border-color: var(--line-strong); color: var(--ink); }
.btn--ghost:hover { background: var(--surface-2); }
.btn svg { width: 16px; height: 16px; }

/* =========================================================================
   Hero
   ========================================================================= */
.hero { position: relative; padding: clamp(2.5rem, 1rem + 7vw, 6rem) 0 clamp(2rem,1rem+4vw,4rem); overflow: hidden; }
.hero__grid { display: grid; grid-template-columns: 1.1fr .9fr; gap: clamp(1.5rem,1rem+4vw,4rem); align-items: center; }
.hero h1 {
  font-family: var(--serif); font-weight: 500;
  font-size: var(--step-4); line-height: 1.04; letter-spacing: -.015em;
  margin: 1.1rem 0 0;
}
.hero h1 em { font-style: italic; color: var(--accent-deep); }
.hero__lede { font-size: var(--step-1); color: var(--ink-soft); margin-top: 1.3rem; max-width: 40ch; line-height: 1.5; }
.hero__actions { display: flex; flex-wrap: wrap; gap: .7rem; margin-top: 1.8rem; }
.hero__stats { display: flex; gap: 2rem; margin-top: 2.4rem; flex-wrap: wrap; }
.stat__num { font-family: var(--serif); font-size: 1.7rem; font-weight: 600; color: var(--ink); line-height: 1; }
.stat__label { font-family: var(--mono); font-size: .68rem; letter-spacing: .12em; text-transform: uppercase; color: var(--ink-faint); margin-top: .4rem; }
.hero__viz {
  border: 1px solid var(--line); border-radius: var(--rad-lg);
  background: var(--surface); padding: 1.4rem; box-shadow: var(--shadow);
}
.hero__viz figcaption { font-family: var(--mono); font-size: .68rem; letter-spacing: .08em; color: var(--ink-faint); margin-top: 1rem; text-transform: uppercase; }

@media (max-width: 820px) {
  .hero__grid { grid-template-columns: 1fr; }
  .hero__viz { order: -1; }
}

/* peptide backbone svg residues */
.residue circle { fill: var(--surface-2); stroke: var(--accent); }
.residue text { fill: var(--accent-deep); font-family: var(--mono); font-weight: 500; }
.bond { stroke: var(--line-strong); }
.bond--peptide { stroke: var(--accent); }

/* =========================================================================
   Section scaffolding
   ========================================================================= */
.section { padding: clamp(2.4rem, 1.4rem + 4vw, 4.6rem) 0; }
.section--tint { background: var(--surface-2); border-block: 1px solid var(--line); }
.section__head { display: flex; align-items: flex-end; justify-content: space-between; gap: 1rem; margin-bottom: 1.8rem; flex-wrap: wrap; }
.section__title { font-family: var(--serif); font-weight: 500; font-size: var(--step-2); letter-spacing: -.01em; margin-top: .55rem; }
.section__head p { color: var(--ink-soft); max-width: 52ch; margin-top: .4rem; }
.link-more { font-family: var(--mono); font-size: .8rem; letter-spacing: .04em; text-decoration: none; color: var(--accent-deep); white-space: nowrap; display: inline-flex; align-items: center; gap: .4rem; }
.link-more:hover { text-decoration: underline; }

.divider-helix { height: 26px; margin: 0; }
.divider-helix path { stroke: var(--line-strong); fill: none; }
.divider-helix .accent { stroke: var(--accent); }

/* =========================================================================
   Article cards
   ========================================================================= */
.card-grid { display: grid; gap: var(--gap); grid-template-columns: repeat(auto-fill, minmax(290px, 1fr)); }
.card {
  display: flex; flex-direction: column;
  background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--rad-lg); padding: 1.4rem; text-decoration: none; color: inherit;
  transition: transform .2s, box-shadow .2s, border-color .2s;
  position: relative; overflow: hidden;
}
.card::before {
  content: ""; position: absolute; left: 0; top: 0; bottom: 0; width: 3px;
  background: var(--accent); transform: scaleY(0); transform-origin: top;
  transition: transform .25s ease;
}
.card:hover { transform: translateY(-3px); box-shadow: var(--shadow-lift); border-color: var(--line-strong); }
.card:hover::before { transform: scaleY(1); }
.card__meta { display: flex; align-items: center; gap: .6rem; flex-wrap: wrap; margin-bottom: .85rem; }
.card__cat { font-family: var(--mono); font-size: .68rem; letter-spacing: .1em; text-transform: uppercase; color: var(--ink-faint); }
.card__title { font-family: var(--serif); font-weight: 600; font-size: var(--step-1); line-height: 1.18; letter-spacing: -.01em; }
.card__summary { color: var(--ink-soft); font-size: .94rem; margin-top: .6rem; flex: 1; }
.card__foot { display: flex; align-items: center; gap: .6rem; margin-top: 1.1rem; font-size: .82rem; color: var(--ink-faint); }
.card__foot .dot { width: 3px; height: 3px; border-radius: 50%; background: var(--ink-faint); }
.card--feature { grid-column: span 2; flex-direction: row; gap: 1.6rem; }
.card--feature .card__title { font-size: var(--step-2); }
.card--feature .card__art { flex: 0 0 42%; border-radius: var(--rad); overflow: hidden; background: var(--surface-2); display: grid; place-items: center; }
@media (max-width: 720px) {
  .card--feature { grid-column: span 1; flex-direction: column; }
  .card--feature .card__art { flex: none; aspect-ratio: 16/9; width: 100%; }
}

/* tags */
.tags { display: flex; flex-wrap: wrap; gap: .4rem; }
.tag {
  font-family: var(--mono); font-size: .7rem; letter-spacing: .03em;
  background: var(--surface-2); border: 1px solid var(--line);
  color: var(--ink-soft); padding: .2rem .5rem; border-radius: 100px; text-decoration: none;
}
a.tag:hover { border-color: var(--accent); color: var(--accent-deep); }

/* evidence badge */
.badge {
  font-family: var(--mono); font-size: .66rem; font-weight: 500;
  letter-spacing: .06em; text-transform: uppercase;
  padding: .24rem .55rem; border-radius: 100px; white-space: nowrap;
  border: 1px solid transparent;
}
.badge[data-ev="meta"]      { color: var(--ev-meta); background: var(--ev-meta-bg); }
.badge[data-ev="clinical"]  { color: var(--ev-clinical); background: var(--ev-clinical-bg); }
.badge[data-ev="preclinical"]{ color: var(--ev-pre); background: var(--ev-pre-bg); }
.badge[data-ev="emerging"]  { color: var(--ev-emerging); background: var(--ev-emerging-bg); }
.badge[data-ev="editorial"] { color: var(--ev-editorial); background: var(--ev-editorial-bg); border-style: dashed; border-color: currentColor; }

/* =========================================================================
   Research feed (list rows)
   ========================================================================= */
.feed { display: grid; gap: .2rem; }
.feed__row {
  display: grid; grid-template-columns: auto 1fr auto; gap: 1rem; align-items: center;
  padding: 1rem .4rem; border-bottom: 1px solid var(--line); text-decoration: none; color: inherit;
  transition: background .15s;
}
.feed__row:hover { background: var(--surface-2); }
.feed__date { font-family: var(--mono); font-size: .78rem; color: var(--ink-faint); white-space: nowrap; }
.feed__main strong { font-weight: 600; font-size: 1rem; }
.feed__main span { display: block; color: var(--ink-soft); font-size: .86rem; margin-top: .15rem; }
.feed__src { font-family: var(--mono); font-size: .72rem; color: var(--accent-deep); white-space: nowrap; }
@media (max-width: 640px) {
  .feed__row { grid-template-columns: 1fr; gap: .35rem; }
  .feed__src { justify-self: start; }
}

/* =========================================================================
   Trending peptides
   ========================================================================= */
.trend-grid { display: grid; gap: var(--gap); grid-template-columns: repeat(auto-fill, minmax(220px,1fr)); }
.trend {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--rad-lg);
  padding: 1.2rem; position: relative;
}

/* compound structure thumbnail (PubChem image, falls back to helix glyph) */
.struct {
  display: inline-flex; align-items: center; justify-content: center;
  border: 1px solid var(--line); border-radius: var(--rad);
  background: #fff; overflow: hidden; flex: none; line-height: 0;
}
.struct img { width: 100%; height: 100%; object-fit: contain; display: block; padding: 5px; box-sizing: border-box; }
.struct__glyph { color: var(--accent); }
.struct--fallback { background: var(--surface-2); }

/* trend card variant that leads with the structure thumbnail */
.trend--struct { display: flex; align-items: center; gap: .9rem; text-decoration: none; color: inherit; }
.trend--struct .trend__txt { display: flex; flex-direction: column; gap: .15rem; min-width: 0; }
.trend--struct .trend__name { margin-top: 0; }
.trend__rank { font-family: var(--mono); font-size: .72rem; color: var(--ink-faint); }
.trend__name { font-family: var(--serif); font-size: 1.25rem; font-weight: 600; margin-top: .3rem; display: flex; align-items: baseline; gap: .5rem; }
.trend__class { font-family: var(--mono); font-size: .68rem; letter-spacing: .08em; text-transform: uppercase; color: var(--signal); }
.trend__seq {
  font-family: var(--mono); font-size: .76rem; color: var(--ink-soft);
  background: var(--surface-2); border: 1px solid var(--line);
  padding: .5rem .6rem; border-radius: var(--rad); margin-top: .8rem;
  word-break: break-all; line-height: 1.5;
}
.trend__note { font-size: .85rem; color: var(--ink-soft); margin-top: .7rem; }
.spark { display: flex; align-items: flex-end; gap: 3px; height: 26px; margin-top: .9rem; }
.spark i { flex: 1; background: var(--accent-soft); border-radius: 1px; }
.spark i.hot { background: var(--accent); }

/* =========================================================================
   Footer
   ========================================================================= */
.site-foot { border-top: 1px solid var(--line); background: var(--surface); margin-top: 2rem; }
.foot__grid { display: grid; grid-template-columns: 1.6fr repeat(3, 1fr); gap: 2rem; padding: 3rem 0 2rem; }
.foot__grid h4 { font-family: var(--mono); font-size: .72rem; letter-spacing: .14em; text-transform: uppercase; color: var(--ink-faint); margin-bottom: .9rem; font-weight: 500; }
.foot__grid ul { list-style: none; padding: 0; display: grid; gap: .5rem; }
.foot__grid a { color: var(--ink-soft); text-decoration: none; font-size: .9rem; }
.foot__grid a:hover { color: var(--ink); }
.foot__about p { color: var(--ink-soft); font-size: .9rem; max-width: 34ch; margin-top: .8rem; }
.foot__legal {
  border-top: 1px solid var(--line); padding: 1.3rem 0 2.4rem;
  display: flex; justify-content: space-between; gap: 1rem; flex-wrap: wrap;
  font-size: .8rem; color: var(--ink-faint);
}
.foot__legal .disclaimer { max-width: 60ch; }
@media (max-width: 760px) { .foot__grid { grid-template-columns: 1fr 1fr; } }
@media (max-width: 460px) { .foot__grid { grid-template-columns: 1fr; } }

/* =========================================================================
   Disclaimer / callout banners
   ========================================================================= */
.notice {
  display: flex; gap: .85rem; align-items: flex-start;
  border: 1px solid var(--line-strong); border-left: 3px solid var(--signal);
  background: var(--signal-soft); color: var(--ink);
  padding: 1rem 1.1rem; border-radius: var(--rad); font-size: .9rem;
}
.notice svg { flex: none; width: 20px; height: 20px; color: var(--signal); margin-top: 1px; }
.notice strong { font-weight: 600; }
.notice--info { border-left-color: var(--accent); background: var(--accent-soft); }
.notice--info svg { color: var(--accent-deep); }

/* =========================================================================
   Page header (interior pages)
   ========================================================================= */
.page-head { padding: clamp(2.2rem,1.4rem+3vw,3.8rem) 0 1.6rem; border-bottom: 1px solid var(--line); }
.page-head h1 { font-family: var(--serif); font-weight: 500; font-size: var(--step-3); letter-spacing: -.015em; margin-top: .7rem; }
.page-head p { color: var(--ink-soft); font-size: var(--step-1); max-width: 56ch; margin-top: .8rem; line-height: 1.5; }

/* filter bar */
.filters { display: flex; gap: .5rem; flex-wrap: wrap; align-items: center; margin: 1.6rem 0 2rem; }
.chip {
  font-family: var(--mono); font-size: .76rem; letter-spacing: .04em;
  border: 1px solid var(--line-strong); background: var(--surface);
  color: var(--ink-soft); padding: .45rem .8rem; border-radius: 100px;
  transition: all .15s;
}
.chip:hover { border-color: var(--accent); color: var(--accent-deep); }
.chip[aria-pressed="true"] { background: var(--accent); color: var(--on-accent); border-color: var(--accent); }

/* =========================================================================
   Article (post) layout
   ========================================================================= */
.article { padding: clamp(2rem,1rem+4vw,3.5rem) 0; }
.article__grid { display: grid; grid-template-columns: minmax(0,1fr) 240px; gap: clamp(1.5rem,1rem+3vw,3.5rem); align-items: start; }
.article__head { max-width: 70ch; }
.article__title { font-family: var(--serif); font-weight: 500; font-size: var(--step-3); line-height: 1.1; letter-spacing: -.015em; margin: 1rem 0; }
.byline { display: flex; align-items: center; gap: .8rem; flex-wrap: wrap; color: var(--ink-soft); font-size: .9rem; margin: 1.2rem 0; }
.byline .avatar { width: 38px; height: 38px; border-radius: 50%; background: var(--accent-soft); display: grid; place-items: center; font-family: var(--serif); font-weight: 600; color: var(--accent-deep); }
.byline b { color: var(--ink); font-weight: 600; }

.prose { max-width: 70ch; font-size: 1.08rem; line-height: 1.75; color: var(--ink); }
.prose > * + * { margin-top: 1.25rem; }
.prose h2 { font-family: var(--serif); font-weight: 600; font-size: var(--step-2); margin-top: 2.6rem; letter-spacing: -.01em; }
.prose h3 { font-family: var(--serif); font-weight: 600; font-size: var(--step-1); margin-top: 2rem; }
.prose p { color: var(--ink); }
.prose strong { font-weight: 600; }
.prose a { color: var(--accent-deep); }
.prose blockquote {
  border-left: 3px solid var(--accent); padding: .3rem 0 .3rem 1.3rem;
  font-family: var(--serif); font-style: italic; font-size: 1.2rem; color: var(--ink-soft);
}
.prose code { font-family: var(--mono); font-size: .88em; background: var(--surface-2); padding: .1em .4em; border-radius: 3px; }
.prose figure { margin: 1.6rem 0; }
.prose figcaption { font-size: .82rem; color: var(--ink-faint); margin-top: .5rem; font-family: var(--mono); }
.prose .seq-callout {
  font-family: var(--mono); font-size: .92rem; background: var(--surface-2);
  border: 1px solid var(--line); border-radius: var(--rad); padding: 1rem 1.1rem;
  line-height: 1.7; word-break: break-all;
}

.toc { position: sticky; top: 90px; font-size: .88rem; }
.toc h4 { font-family: var(--mono); font-size: .7rem; letter-spacing: .14em; text-transform: uppercase; color: var(--ink-faint); margin-bottom: .8rem; }
.toc ol { list-style: none; padding: 0; display: grid; gap: .55rem; border-left: 1px solid var(--line); }
.toc a { display: block; padding-left: 1rem; margin-left: -1px; border-left: 2px solid transparent; color: var(--ink-soft); text-decoration: none; }
.toc a:hover { color: var(--ink); }
.toc a.active { color: var(--accent-deep); border-left-color: var(--accent); }
@media (max-width: 900px) { .article__grid { grid-template-columns: 1fr; } .toc { display: none; } }

/* references */
.references { margin-top: 3rem; padding-top: 2rem; border-top: 1px solid var(--line); max-width: 75ch; }
.references h2 { font-family: var(--serif); font-weight: 600; font-size: var(--step-2); }
.references ol { list-style: none; counter-reset: ref; padding: 0; margin-top: 1.2rem; display: grid; gap: 1rem; }
.ref { counter-increment: ref; display: grid; grid-template-columns: auto 1fr; gap: .9rem; font-size: .92rem; }
.ref::before { content: counter(ref); font-family: var(--mono); font-size: .8rem; color: var(--accent-deep); background: var(--accent-soft); width: 1.7rem; height: 1.7rem; border-radius: var(--rad); display: grid; place-items: center; font-weight: 500; }
.ref__title { font-weight: 600; color: var(--ink); }
.ref__cite { color: var(--ink-soft); }
.ref__links { display: flex; gap: .8rem; margin-top: .35rem; font-family: var(--mono); font-size: .76rem; }
.ref__links a { text-decoration: none; color: var(--accent-deep); }
.ref__links a:hover { text-decoration: underline; }
.ref__type { font-family: var(--mono); font-size: .66rem; letter-spacing: .06em; text-transform: uppercase; color: var(--ink-faint); }

/* =========================================================================
   Research sources / databases
   ========================================================================= */
.db-grid { display: grid; gap: var(--gap); grid-template-columns: repeat(auto-fill,minmax(250px,1fr)); }
.db {
  display: flex; flex-direction: column; gap: .6rem;
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--rad-lg);
  padding: 1.3rem; text-decoration: none; color: inherit; transition: border-color .2s, transform .2s;
}
.db:hover { border-color: var(--accent); transform: translateY(-2px); }
.db__name { font-family: var(--serif); font-weight: 600; font-size: 1.15rem; display: flex; align-items: center; gap: .5rem; }
.db__name svg { width: 18px; height: 18px; color: var(--accent-deep); }
.db__desc { color: var(--ink-soft); font-size: .9rem; flex: 1; }
.db__go { font-family: var(--mono); font-size: .74rem; color: var(--accent-deep); letter-spacing: .04em; }

/* API / code block */
.endpoint { display: grid; gap: 1.2rem; }
.api-card { border: 1px solid var(--line); border-radius: var(--rad-lg); overflow: hidden; background: var(--surface); }
.api-card__head { display: flex; align-items: center; gap: .8rem; padding: .9rem 1.1rem; border-bottom: 1px solid var(--line); background: var(--surface-2); flex-wrap: wrap; }
.method { font-family: var(--mono); font-size: .72rem; font-weight: 600; letter-spacing: .08em; padding: .25rem .55rem; border-radius: var(--rad); background: var(--accent-soft); color: var(--accent-deep); }
.api-card__path { font-family: var(--mono); font-size: .9rem; color: var(--ink); }
.api-card__desc { padding: .8rem 1.1rem; color: var(--ink-soft); font-size: .9rem; }
.code {
  font-family: var(--mono); font-size: .82rem; line-height: 1.65;
  background: var(--surface-2); color: var(--ink); padding: 1.1rem 1.2rem;
  overflow-x: auto; border-top: 1px solid var(--line); margin: 0;
  white-space: pre;
}
.code .k { color: var(--accent-deep); }
.code .s { color: var(--signal); }
.code .c { color: var(--ink-faint); font-style: italic; }
.api-live {
  display: grid; gap: .8rem; border: 1px solid var(--line); border-radius: var(--rad-lg);
  padding: 1.3rem; background: var(--surface);
}
.api-live__out {
  font-family: var(--mono); font-size: .8rem; background: var(--surface-2);
  border: 1px solid var(--line); border-radius: var(--rad); padding: 1rem;
  min-height: 80px; white-space: pre-wrap; word-break: break-word; color: var(--ink-soft); max-height: 360px; overflow:auto;
}

/* =========================================================================
   About / mission
   ========================================================================= */
.lede-block { max-width: 60ch; }
.lede-block p { font-size: var(--step-1); line-height: 1.6; color: var(--ink-soft); }
.principles { display: grid; gap: var(--gap); grid-template-columns: repeat(auto-fit,minmax(240px,1fr)); margin-top: 2rem; }
.principle { border-top: 2px solid var(--accent); padding-top: 1rem; }
.principle h3 { font-family: var(--serif); font-size: 1.2rem; font-weight: 600; }
.principle p { color: var(--ink-soft); font-size: .92rem; margin-top: .5rem; }
.principle .num { font-family: var(--mono); font-size: .72rem; color: var(--accent-deep); letter-spacing: .1em; }

.signature-row { display: grid; grid-template-columns: repeat(auto-fit,minmax(150px,1fr)); gap: 1rem; margin-top: 1.5rem; }
.src-pill { font-family: var(--mono); font-size: .8rem; border: 1px solid var(--line); border-radius: 100px; padding: .5rem .9rem; text-align: center; color: var(--ink-soft); background: var(--surface); }

/* utility */
.muted { color: var(--ink-soft); }
.center { text-align: center; }
.mt-1 { margin-top: .5rem; } .mt-2 { margin-top: 1rem; } .mt-3 { margin-top: 1.5rem; } .mt-4 { margin-top: 2.5rem; }
.flow > * + * { margin-top: 1.1rem; }
.hidden { display: none !important; }
.placeholder-flag {
  font-family: var(--mono); font-size: .64rem; letter-spacing: .08em; text-transform: uppercase;
  color: var(--signal); border: 1px dashed var(--signal); border-radius: 100px; padding: .15rem .5rem;
}