/* ==========================================================================
   First Response Lab — design system
   A technical publication, not an affiliate blog.
   One stylesheet, no framework, no build step, no webfont requests that block.
   ========================================================================== */

/* --- tokens ------------------------------------------------------------- */
:root {
  /* Ink and paper. Warm-neutral paper, near-black ink: reads as print, not SaaS. */
  --paper:        #fbfaf8;
  --paper-raised: #ffffff;
  --paper-sunk:   #f3f1ed;
  --ink:          #16161a;
  --ink-soft:     #4a4a52;
  --ink-faint:    #67676f;
  --rule:         #e2ded7;
  --rule-strong:  #cdc8bf;

  /* One accent. Instrument blue — used for measurement, never for decoration. */
  --accent:       #1f4ed8;
  --accent-soft:  #eef2ff;
  --accent-ink:   #1a3fb0;

  /* Evidence semantics. These carry meaning and are defined once. */
  --verified:     #166534;
  --verified-bg:  #e8f5ec;
  --tested:       #1f4ed8;
  --tested-bg:    #eef2ff;
  --claim:        #854d0e;
  --claim-bg:     #fdf4e3;
  --unknown:      #5b5b66;
  --unknown-bg:   #eeedea;

  --measure: 42rem;        /* article text column */
  --wide:    74rem;        /* page shell */

  --step--1: clamp(0.82rem, 0.80rem + 0.10vw, 0.88rem);
  --step-0:  clamp(1.00rem, 0.97rem + 0.16vw, 1.09rem);
  --step-1:  clamp(1.19rem, 1.12rem + 0.33vw, 1.38rem);
  --step-2:  clamp(1.42rem, 1.29rem + 0.62vw, 1.75rem);
  --step-3:  clamp(1.69rem, 1.47rem + 1.06vw, 2.22rem);
  --step-4:  clamp(2.02rem, 1.65rem + 1.73vw, 2.81rem);

  --radius: 6px;
  --gutter: clamp(1rem, 0.6rem + 2vw, 2rem);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper:        #141416;
    --paper-raised: #1c1c20;
    --paper-sunk:   #1f1f24;
    --ink:          #f2f1ee;
    --ink-soft:     #b9b8b4;
    --ink-faint:    #989793;
    --rule:         #2e2e34;
    --rule-strong:  #41414a;
    --accent:       #8ba6ff;
    --accent-soft:  #1b2340;
    --accent-ink:   #a9beff;
    --verified:     #6ee7a0;
    --verified-bg:  #11291b;
    --tested:       #8ba6ff;
    --tested-bg:    #1b2340;
    --claim:        #e8c37a;
    --claim-bg:     #2d2414;
    --unknown:      #a3a3ad;
    --unknown-bg:   #26262b;
  }
}
:root[data-theme="dark"] {
  --paper: #141416; --paper-raised: #1c1c20; --paper-sunk: #1f1f24;
  --ink: #f2f1ee; --ink-soft: #b9b8b4; --ink-faint: #989793;
  --rule: #2e2e34; --rule-strong: #41414a;
  --accent: #8ba6ff; --accent-soft: #1b2340; --accent-ink: #a9beff;
  --verified: #6ee7a0; --verified-bg: #11291b;
  --tested: #8ba6ff; --tested-bg: #1b2340;
  --claim: #e8c37a; --claim-bg: #2d2414;
  --unknown: #a3a3ad; --unknown-bg: #26262b;
}

/* --- 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; }
}
img, svg, video { display: block; max-width: 100%; height: auto; }
input, button, textarea, select { font: inherit; color: inherit; }

body {
  background: var(--paper);
  color: var(--ink);
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: var(--step-0);
  line-height: 1.6;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

/* --- typography --------------------------------------------------------- */
h1, h2, h3, h4 { line-height: 1.18; font-weight: 650; letter-spacing: -0.015em; text-wrap: balance; }
h1 { font-size: var(--step-4); }
h2 { font-size: var(--step-2); margin-block-start: 2.4em; }
h3 { font-size: var(--step-1); margin-block-start: 1.9em; }
h4 { font-size: var(--step-0); margin-block-start: 1.6em; }
p, ul, ol, table, figure, pre { margin-block-start: 1em; }
p { text-wrap: pretty; }
ul, ol { padding-inline-start: 1.3em; }
.prose li + li, .callout li + li, .verdict li + li { margin-block-start: .35em; }
strong { font-weight: 650; }
small { font-size: var(--step--1); }

a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { color: var(--accent-ink); }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 2px; }

code, kbd, .mono {
  font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.9em;
  font-variant-numeric: tabular-nums;
}

.skip-link {
  position: absolute; left: -9999px; top: 0; z-index: 100;
  background: var(--ink); color: var(--paper); padding: .6rem 1rem; border-radius: 0 0 var(--radius) 0;
}
.skip-link:focus { left: 0; }

/* --- layout ------------------------------------------------------------- */
.shell { width: min(100% - (var(--gutter) * 2), var(--wide)); margin-inline: auto; }
.prose { width: min(100%, var(--measure)); }
.stack > * + * { margin-block-start: var(--flow, 1rem); }

/* --- masthead ----------------------------------------------------------- */
.masthead {
  border-block-end: 1px solid var(--rule);
  background: var(--paper);
  position: sticky; top: 0; z-index: 30;
  backdrop-filter: saturate(180%) blur(8px);
}
.masthead__inner { display: flex; align-items: center; gap: 1.5rem; min-height: 60px; }
.wordmark {
  display: inline-flex; align-items: baseline; gap: .5rem;
  font-weight: 700; letter-spacing: -0.02em; color: var(--ink); text-decoration: none;
  font-size: 1.02rem; white-space: nowrap;
}
.wordmark__mark {
  display: inline-grid; place-items: center;
  inline-size: 1.45rem; block-size: 1.45rem; border-radius: 4px;
  background: var(--ink); color: var(--paper);
  font-size: .68rem; font-weight: 700; letter-spacing: 0; transform: translateY(2px);
}
.masthead nav { margin-inline-start: auto; }
.masthead ul { display: flex; align-items: center; align-content: center; gap: 1.35rem; list-style: none; padding: 0; margin: 0; flex-wrap: nowrap; line-height: 1; }
.masthead nav li { display: flex; align-items: center; }
.masthead a:not(.wordmark) {
  color: var(--ink-soft); text-decoration: none; font-size: var(--step--1); font-weight: 520;
  padding-block: .4rem; border-block-end: 2px solid transparent; white-space: nowrap;
}
.masthead a:not(.wordmark):hover,
.masthead a[aria-current="page"] { color: var(--ink); border-block-end-color: var(--accent); }

@media (max-width: 54rem) {
  .masthead__inner { flex-wrap: wrap; padding-block: .6rem; gap: .4rem; }
  .masthead nav { margin-inline-start: 0; inline-size: 100%; overflow-x: auto; }
  .masthead ul { gap: 1.05rem; padding-block-end: .25rem; flex-wrap: nowrap; }
  .masthead { position: static; }
}

/* --- badges: the evidence vocabulary ------------------------------------ */
.badge {
  display: inline-flex; align-items: center; gap: .32rem;
  font-size: .70rem; font-weight: 640; letter-spacing: .055em; text-transform: uppercase;
  padding: .18rem .48rem; border-radius: 3px; white-space: nowrap;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}
.badge--verified { background: var(--verified-bg); color: var(--verified); }
.badge--tested   { background: var(--tested-bg);   color: var(--tested); }
.badge--claim    { background: var(--claim-bg);    color: var(--claim); }
.badge--unknown  { background: var(--unknown-bg);  color: var(--unknown); }
.badge--untested { background: var(--unknown-bg);  color: var(--unknown); }

/* --- hero --------------------------------------------------------------- */
.hero { padding-block: clamp(3rem, 1.5rem + 6vw, 5.5rem) clamp(2rem, 1rem + 4vw, 3.5rem); }
.hero__eyebrow {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: .72rem; letter-spacing: .14em; text-transform: uppercase; color: var(--ink-faint);
  margin-block-end: 1.1rem;
}
.hero h1 { max-width: 20ch; }
.hero__lede { font-size: var(--step-1); color: var(--ink-soft); max-width: 46ch; margin-block-start: 1.2rem; }

/* --- the measurement strip (homepage proof bar) ------------------------- */
.strip {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(10.5rem, 1fr));
  gap: 1px; background: var(--rule);
  border: 1px solid var(--rule); border-radius: var(--radius); overflow: hidden;
  margin-block-start: 2.5rem;
}
.strip__cell { background: var(--paper-raised); padding: 1.1rem 1.15rem; }
.strip__k {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: .68rem; letter-spacing: .1em; text-transform: uppercase; color: var(--ink-faint);
}
.strip__v { font-size: var(--step-2); font-weight: 680; letter-spacing: -0.02em; margin-block-start: .3rem; font-variant-numeric: tabular-nums; }
.strip__n { font-size: var(--step--1); color: var(--ink-soft); margin-block-start: .2rem; }

/* --- cards -------------------------------------------------------------- */
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(15.5rem, 1fr)); gap: 1rem; margin-block-start: 1.5rem; }
.card {
  background: var(--paper-raised); border: 1px solid var(--rule); border-radius: var(--radius);
  padding: 1.25rem; display: flex; flex-direction: column; gap: .5rem;
  transition: border-color .15s ease, transform .15s ease;
}
a.card { text-decoration: none; color: inherit; }
a.card:hover { border-color: var(--rule-strong); transform: translateY(-1px); }
.card__kicker {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: .68rem; letter-spacing: .1em; text-transform: uppercase; color: var(--ink-faint);
}
.card h3 { font-size: var(--step-1); margin: 0; }
.card p { color: var(--ink-soft); font-size: var(--step--1); margin: 0; }
.card__foot { margin-block-start: auto; padding-block-start: .6rem; font-size: var(--step--1); color: var(--accent); font-weight: 560; }

/* --- section headers ---------------------------------------------------- */
.section { padding-block: clamp(2.5rem, 1.5rem + 3vw, 4rem); }
.section--sunk { background: var(--paper-sunk); border-block: 1px solid var(--rule); }
.section__head { display: flex; align-items: baseline; justify-content: space-between; gap: 1rem; flex-wrap: wrap; border-block-end: 1px solid var(--rule); padding-block-end: .8rem; }
.section__head h2 { margin: 0; font-size: var(--step-2); }
.section__head p { margin: 0; color: var(--ink-soft); font-size: var(--step--1); max-width: 48ch; }

/* --- tables ------------------------------------------------------------- */
.table-wrap { overflow-x: auto; margin-block-start: 1.25rem; border: 1px solid var(--rule); border-radius: var(--radius); background: var(--paper-raised); }
table { border-collapse: collapse; inline-size: 100%; font-size: var(--step--1); }
caption { text-align: left; padding: .9rem 1rem; color: var(--ink-soft); font-size: var(--step--1); border-block-end: 1px solid var(--rule); }
th, td { text-align: left; padding: .7rem .9rem; border-block-end: 1px solid var(--rule); vertical-align: top; }
thead th {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: .68rem; letter-spacing: .08em; text-transform: uppercase; color: var(--ink-faint); font-weight: 640;
  background: var(--paper-sunk); position: sticky; top: 0;
}
tbody tr:last-child td { border-block-end: 0; }
tbody tr:hover { background: var(--paper-sunk); }
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; }

/* --- callouts ----------------------------------------------------------- */
.callout {
  border: 1px solid var(--rule); border-left: 3px solid var(--rule-strong);
  background: var(--paper-raised); border-radius: 0 var(--radius) var(--radius) 0;
  padding: 1rem 1.1rem; margin-block-start: 1.5rem; font-size: var(--step--1);
}
.callout__title { font-weight: 650; margin-block-end: .3rem; display: flex; align-items: center; gap: .5rem; }
.callout--note     { border-left-color: var(--accent); }
.callout--untested { border-left-color: var(--unknown); background: var(--unknown-bg); }
.callout--money    { border-left-color: var(--claim); background: var(--claim-bg); }
.callout p { margin-block-start: .4rem; }
.callout p:first-of-type { margin-block-start: 0; }

/* --- verdict block ------------------------------------------------------ */
.verdict {
  border: 1px solid var(--rule-strong); border-radius: var(--radius);
  background: var(--paper-raised); padding: 1.3rem 1.4rem; margin-block-start: 1.8rem;
}
.verdict h2 { margin-block-start: 0; font-size: var(--step-1); }
.verdict dl { display: grid; grid-template-columns: auto 1fr; gap: .45rem 1rem; margin-block-start: .9rem; font-size: var(--step--1); }
.verdict dt { color: var(--ink-faint); font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: .7rem; letter-spacing: .07em; text-transform: uppercase; padding-block-start: .18rem; }
.verdict dd { margin: 0; }

/* --- pick list (alternatives articles) ---------------------------------- */
.pick { border-block-start: 1px solid var(--rule); padding-block: 1.6rem; }
.pick__head { display: flex; align-items: flex-start; gap: .85rem; flex-wrap: wrap; }
.pick__n {
  display: inline-grid; place-items: center; inline-size: 1.7rem; block-size: 1.7rem; flex: none;
  border-radius: 4px; background: var(--ink); color: var(--paper);
  font-family: ui-monospace, monospace; font-size: .8rem; font-weight: 700;
}
.pick__title { font-size: var(--step-1); font-weight: 650; margin: 0; }
.pick__for { color: var(--ink-soft); font-size: var(--step--1); margin: .1rem 0 0; }
.pick__badges { display: flex; gap: .4rem; flex-wrap: wrap; margin-block-start: .55rem; }

/* --- CTA ---------------------------------------------------------------- */
.btn {
  display: inline-flex; align-items: center; gap: .45rem;
  background: var(--ink); color: var(--paper); text-decoration: none;
  padding: .6rem 1.05rem; border-radius: var(--radius); font-size: var(--step--1); font-weight: 580;
  border: 1px solid var(--ink);
}
.btn:hover { background: transparent; color: var(--ink); }
.btn--ghost { background: transparent; color: var(--ink); border-color: var(--rule-strong); }
.btn--ghost:hover { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.btn__note { font-size: var(--step--1); color: var(--ink-faint); margin-block-start: .5rem; }

/* --- disclosure --------------------------------------------------------- */
.disclosure {
  font-size: var(--step--1); color: var(--ink-soft);
  background: var(--paper-sunk); border: 1px solid var(--rule);
  border-radius: var(--radius); padding: .75rem .95rem; margin-block-start: 1.5rem;
}
.disclosure strong { color: var(--ink); }

/* --- article meta ------------------------------------------------------- */
.article-head { padding-block: clamp(2rem, 1rem + 4vw, 3.5rem) 0; }
.article-meta {
  display: flex; gap: 1rem 1.6rem; flex-wrap: wrap; align-items: center;
  font-size: var(--step--1); color: var(--ink-faint);
  border-block: 1px solid var(--rule); padding-block: .75rem; margin-block-start: 1.6rem;
}
.article-meta__item { display: flex; gap: .4rem; align-items: center; }
.article-body { padding-block-end: 3rem; }
.article-body h2 { scroll-margin-top: 5rem; }

/* --- breadcrumbs -------------------------------------------------------- */
.crumbs { font-size: var(--step--1); color: var(--ink-faint); padding-block-start: 1.4rem; }
.crumbs ol { display: flex; flex-wrap: wrap; gap: .4rem; list-style: none; padding: 0; margin: 0; }
.crumbs li::after { content: "/"; margin-inline-start: .4rem; color: var(--rule-strong); }
.crumbs li:last-child::after { content: ""; }
.crumbs a { color: var(--ink-faint); text-decoration: none; }
.crumbs a:hover { color: var(--ink); text-decoration: underline; }

/* --- TOC ---------------------------------------------------------------- */
.toc { border: 1px solid var(--rule); border-radius: var(--radius); padding: 1rem 1.2rem; background: var(--paper-raised); margin-block-start: 1.75rem; }
.toc__title { font-family: ui-monospace, monospace; font-size: .68rem; letter-spacing: .1em; text-transform: uppercase; color: var(--ink-faint); }
.toc ol { margin-block-start: .5rem; padding-inline-start: 1.1rem; font-size: var(--step--1); }
.toc a { text-decoration: none; }
.toc a:hover { text-decoration: underline; }

/* --- footer ------------------------------------------------------------- */
.footer { border-block-start: 1px solid var(--rule); background: var(--paper-sunk); padding-block: 2.5rem 3rem; margin-block-start: 3rem; }
.footer__grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(13rem, 1fr)); gap: 2rem; }
.footer h2 { font-size: .7rem; font-family: ui-monospace, monospace; letter-spacing: .1em; text-transform: uppercase; color: var(--ink-faint); margin: 0 0 .7rem; font-weight: 640; }
.footer ul { list-style: none; padding: 0; margin: 0; font-size: var(--step--1); }
.footer li + li { margin-block-start: .4rem; }
.footer a { color: var(--ink-soft); text-decoration: none; }
.footer a:hover { color: var(--ink); text-decoration: underline; }
.footer__legal { margin-block-start: 2.5rem; padding-block-start: 1.25rem; border-block-start: 1px solid var(--rule); font-size: var(--step--1); color: var(--ink-faint); max-width: 60ch; }

/* --- status dashboard --------------------------------------------------- */
.status-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(13rem, 1fr)); gap: 1rem; margin-block-start: 1.5rem; }
.status-col { border: 1px solid var(--rule); border-radius: var(--radius); background: var(--paper-raised); padding: 1rem; }
.status-col h3 { margin: 0 0 .7rem; font-size: .7rem; font-family: ui-monospace, monospace; letter-spacing: .09em; text-transform: uppercase; color: var(--ink-faint); }
.status-col ul { list-style: none; padding: 0; margin: 0; font-size: var(--step--1); }
.status-col li { padding-block: .35rem; border-block-end: 1px dashed var(--rule); }
.status-col li:last-child { border-block-end: 0; }

/* --- print -------------------------------------------------------------- */
@media print {
  .masthead, .footer, .btn { display: none; }
  body { background: #fff; color: #000; }
  a::after { content: " (" attr(href) ")"; font-size: .8em; color: #555; }
}