:root {
  --ink: #11273D;
  --ink-soft: #3D5368;
  --paper: #F4F7F9;
  --surface: #FFFFFF;
  --blue: #1C5DA8;        /* potable-water pipe blue */
  --blue-deep: #0F3F78;
  --pink: #D23F7B;        /* DPD chlorine reagent */
  --line: #CAD6E0;
  --ok: #1F7A4D;
  --bad: #B42318;
  --measure: 38rem;
  --radius-control: 6px;
  --radius-panel: 10px;
}

* { box-sizing: border-box; }
/* Layout rules (display: grid/flex) must never override the hidden attribute. */
[hidden] { display: none !important; }

html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } * { transition: none !important; animation: none !important; } }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: "Barlow", system-ui, sans-serif;
  font-size: 1.0625rem;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3 {
  font-family: "Barlow Condensed", "Barlow", sans-serif;
  font-weight: 600;
  line-height: 1.08;
  letter-spacing: -0.005em;
  margin: 0 0 0.5em;
}
h1 { font-size: clamp(2.4rem, 6.5vw, 4.1rem); font-weight: 700; max-width: 17ch; }
h2 { font-size: clamp(1.8rem, 4vw, 2.4rem); }
h3 { font-size: 1.35rem; }
p { margin: 0 0 1em; max-width: var(--measure); }

a { color: var(--blue); }
:focus-visible { outline: 3px solid var(--pink); outline-offset: 2px; }

/* Header */
.site-header {
  display: flex; justify-content: space-between; align-items: center; gap: 1rem;
  padding: 0.85rem clamp(1rem, 4vw, 3rem);
  background: var(--surface);
  border-bottom: 1px solid var(--line);
}
.brand {
  font-family: "Barlow Condensed", sans-serif; font-weight: 700; font-size: 1.45rem;
  color: var(--ink); text-decoration: none;
}
.header-nav { display: flex; align-items: center; gap: 1.25rem; }
.header-link { font-weight: 500; text-decoration: none; }
@media (max-width: 34rem) { .landing .header-nav .header-link { display: none; } }

/* Landing sections are full-bleed; content width comes from inline padding. */
main > section { padding: clamp(2.5rem, 6vw, 5rem) clamp(1rem, 4vw, 3rem); }
.landing main > section { padding-inline: max(clamp(1rem, 4vw, 3rem), calc((100% - 72rem) / 2)); }

/* Hero: the one bold surface, in potable-water blue */
.hero {
  background:
    radial-gradient(60rem 30rem at 85% -10%, rgba(255, 255, 255, 0.09), transparent 60%),
    var(--blue-deep);
  color: #fff;
  border-bottom: 6px solid var(--blue);
}
.hero-inner {
  display: grid; gap: clamp(2rem, 5vw, 4.5rem);
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
  align-items: center;
}
@media (max-width: 52rem) { .hero-inner { grid-template-columns: 1fr; } }
.hero h1 { color: #fff; font-size: clamp(2.6rem, 6.8vw, 4.6rem); max-width: 13ch; margin-bottom: 0.35em; }
.lede { font-size: 1.25rem; color: #D3E2F3; max-width: 34rem; }
.hero-actions { display: flex; flex-wrap: wrap; align-items: center; gap: 1rem 1.5rem; margin: 1.75rem 0 2rem; }
.hero-link { color: #fff; font-weight: 600; text-underline-offset: 3px; }
.hero-facts { list-style: none; padding: 0; margin: 0; display: flex; flex-wrap: wrap; gap: 0.6rem 1.75rem; }
.hero-facts li {
  font-family: "Barlow Condensed", sans-serif; font-size: 1.2rem; font-weight: 600; color: #fff;
  border-left: 3px solid var(--pink); padding-left: 0.6rem;
}

/* Question cards (teaser and quiz share option styles) */
.teaser, .quiz, .results, .diag-intro {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-panel);
  padding: clamp(1.25rem, 3vw, 2rem);
}
.teaser {
  color: var(--ink);
  border: 0; border-top: 6px solid var(--pink);
  box-shadow: 0 24px 48px rgba(4, 22, 48, 0.35), 0 2px 6px rgba(4, 22, 48, 0.2);
}
.teaser-label { font-weight: 600; color: var(--blue); margin-bottom: 0.25rem; }
.teaser-stem, .q-stem {
  font-family: "Barlow Condensed", sans-serif; font-weight: 600;
  font-size: clamp(1.35rem, 2.6vw, 1.6rem); line-height: 1.2; margin-bottom: 1rem;
}
.teaser-options, .q-options { display: grid; gap: 0.6rem; }
.opt {
  display: flex; justify-content: space-between; align-items: center; gap: 1rem;
  font: inherit; text-align: left; cursor: pointer;
  padding: 0.85rem 1rem; min-height: 3rem;
  border: 2px solid var(--line); border-radius: var(--radius-control);
  background: var(--surface); color: var(--ink);
  transition: border-color 120ms ease, background-color 120ms ease;
}
.opt:hover:not(:disabled) { border-color: var(--blue); }
.opt:disabled { cursor: default; }
.opt.is-correct { border-color: var(--ok); background: #E8F4EE; }
.opt.is-wrong { border-color: var(--bad); background: #FBECEA; }
.opt.is-correct::after, .opt.is-wrong::after { flex: none; font-weight: 600; font-size: 0.95rem; }
.opt.is-correct::after { content: "Correct answer"; color: var(--ok); }
.opt.is-wrong::after { content: "Your answer"; color: var(--bad); }

.verdict { font-weight: 600; font-size: 1.15rem; margin: 1.1rem 0 0.4rem; }
.verdict.ok { color: var(--ok); }
.verdict.bad { color: var(--bad); }
.why { color: var(--ink); }
.source { font-size: 0.95rem; color: var(--ink-soft); }
.source a { color: inherit; }

/* Buttons */
.button {
  display: inline-block; font: inherit; font-weight: 600; cursor: pointer;
  padding: 0.85rem 1.4rem; min-height: 3rem;
  border: 0; border-radius: var(--radius-control);
  background: var(--blue); color: #fff; text-decoration: none;
}
.button:hover { background: var(--blue-deep); }
.button-quiet { background: var(--ink); }
.button-buy { background: var(--pink); font-size: 1.15rem; padding: 1rem 1.75rem; }
.button-buy:hover { background: #B32E66; }
.button-light { background: #fff; color: var(--blue-deep); font-size: 1.1rem; }
.button-light:hover { background: #E6EEF8; }
.button-small { padding: 0.55rem 1rem; min-height: 2.5rem; font-size: 0.98rem; }
[data-checkout][aria-disabled=true] { opacity: 0.6; pointer-events: none; }
.link { font: inherit; background: none; border: 0; padding: 0; color: var(--blue); text-decoration: underline; cursor: pointer; }

/* Diagnostic */
.landing .diagnostic { padding-inline: max(clamp(1rem, 4vw, 3rem), calc((100% - 46rem) / 2)); }
.progress { height: 6px; background: var(--paper); border-radius: 3px; margin-bottom: 1rem; overflow: hidden; }
.progress-bar { display: block; height: 100%; width: 0; background: var(--blue); transition: width 200ms ease; }
.q-count { font-weight: 600; margin-bottom: 0; }
.q-area { color: var(--ink-soft); margin-bottom: 0.75rem; }
.resume { margin-top: 1rem; }

/* Results: the DPD comparator */
.score { font-size: clamp(2.2rem, 6vw, 3.2rem); font-weight: 700; margin-bottom: 0.25rem; }
.comparator-title { margin-top: 2rem; }
.comparator-note { color: var(--ink-soft); }
.comparator { list-style: none; padding: 0; margin: 1rem 0 2rem; display: grid; gap: 0.5rem; }
.comparator li {
  display: grid; grid-template-columns: 3.25rem 1fr auto; gap: 0.9rem; align-items: center;
}
.swatch {
  width: 3.25rem; height: 3.25rem; border-radius: 50%;
  border: 2px solid var(--line);
  box-shadow: inset 0 0 0 4px rgba(255, 255, 255, 0.55); /* comparator window */
  /* tint set inline: mix of reagent pink and clear water */
}
.area-name { font-weight: 500; }
.area-score { font-weight: 600; font-variant-numeric: tabular-nums; }
.pitch {
  background: #FDF1F6; border: 1px solid #F3C6D8; border-left: 6px solid var(--pink);
  border-radius: var(--radius-panel); padding: clamp(1.25rem, 3vw, 1.75rem); margin: 0 0 1.5rem;
}
.pitch h3 { font-size: 1.6rem; margin-bottom: 0.35rem; }
.pitch-terms { font-size: 0.95rem; color: var(--ink-soft); margin: 0.75rem 0 0; }
.results-secondary { margin: 0; }

.email-form { margin-top: 2rem; padding-top: 1.5rem; border-top: 1px solid var(--line); }
.email-form label { display: block; font-weight: 600; margin-bottom: 0.5rem; }
.email-row { display: flex; flex-wrap: wrap; gap: 0.6rem; }
.email-row input[type=email] {
  flex: 1 1 14rem; font: inherit; padding: 0.8rem 0.9rem; min-height: 3rem;
  border: 2px solid var(--line); border-radius: var(--radius-control);
}
.form-status { margin-top: 0.5rem; }

/* What the course does */
.inside {
  background: var(--surface);
  display: grid; gap: clamp(2rem, 5vw, 4rem);
  grid-template-columns: minmax(0, 1fr) minmax(0, 0.9fr); align-items: center;
  border-block: 1px solid var(--line);
}
@media (max-width: 52rem) { .inside { grid-template-columns: 1fr; } }
.benefits { margin: 1.5rem 0 0; display: grid; gap: 1.25rem; }
.benefits dt { font-family: "Barlow Condensed", sans-serif; font-weight: 600; font-size: 1.35rem; }
.benefits dd { margin: 0.25rem 0 0; color: var(--ink-soft); max-width: var(--measure); }
.preview { margin: 0; }
.preview-card {
  background: var(--surface); border: 1px solid var(--line); border-top: 6px solid var(--blue);
  border-radius: var(--radius-panel); padding: 1.5rem;
  box-shadow: 0 18px 40px rgba(17, 39, 61, 0.12);
}
.preview-score { font-family: "Barlow Condensed", sans-serif; font-weight: 700; font-size: 2.2rem; margin-bottom: 0.5rem; }
.preview-list { margin: 0.5rem 0 1.25rem; }
.preview-list .swatch { background: color-mix(in srgb, var(--pink) calc(var(--f) * 100%), #fff); width: 2.5rem; height: 2.5rem; }
.preview-list li { grid-template-columns: 2.5rem 1fr auto; }
.preview-cta {
  display: inline-block; margin: 0; padding: 0.6rem 1rem; border-radius: var(--radius-control);
  background: var(--blue); color: #fff; font-weight: 600;
}
.preview figcaption { color: var(--ink-soft); font-size: 0.95rem; margin-top: 0.85rem; }

/* Offer */
.offer {
  max-width: 40rem; margin: 0 auto;
  background: var(--surface); border: 1px solid var(--line); border-top: 6px solid var(--pink);
  border-radius: var(--radius-panel); padding: clamp(1.5rem, 4vw, 2.75rem);
  box-shadow: 0 18px 40px rgba(17, 39, 61, 0.1);
}
.price { display: flex; flex-wrap: wrap; align-items: baseline; gap: 0.25rem 0.9rem; margin: 0.75rem 0 0.25rem; }
.price-now { font-family: "Barlow Condensed", sans-serif; font-size: 4rem; font-weight: 700; line-height: 1; }
.price-note { color: var(--ink-soft); }
.price-compare { font-weight: 600; color: var(--blue-deep); }
.included { list-style: none; padding: 0; margin: 1.5rem 0 2rem; display: grid; gap: 0.7rem; }
.included li { display: grid; grid-template-columns: 1.6rem 1fr; gap: 0.6rem; align-items: start; }
.included li::before {
  content: ""; width: 1.4rem; height: 1.4rem; margin-top: 0.1rem; border-radius: 50%;
  background: var(--blue) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16'%3E%3Cpath d='M3.5 8.5l3 3 6-7' fill='none' stroke='white' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E") center / 0.9rem no-repeat;
}
.offer .button-buy { width: 100%; text-align: center; }
.guarantees { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin: 1.5rem 0 0; }
@media (max-width: 34rem) { .guarantees { grid-template-columns: 1fr; } }
.guarantees p { margin: 0; padding: 0.9rem 1rem; background: var(--paper); border-radius: var(--radius-control); font-size: 0.98rem; }
.offer-foot { margin: 1.5rem 0 0; color: var(--ink-soft); font-size: 0.95rem; }

/* Sticky buy bar (phones) */
.buy-bar {
  position: fixed; inset: auto 0 0 0; z-index: 10;
  display: flex; justify-content: space-between; align-items: center; gap: 1rem;
  padding: 0.7rem 1rem calc(0.7rem + env(safe-area-inset-bottom));
  background: var(--surface); border-top: 1px solid var(--line);
  box-shadow: 0 -8px 24px rgba(17, 39, 61, 0.12);
}
.buy-bar[hidden] { display: none; }
.buy-bar p { margin: 0; display: grid; line-height: 1.25; }
.buy-bar span { color: var(--ink-soft); font-size: 0.92rem; }
.buy-bar .button-buy { padding: 0.7rem 1.4rem; font-size: 1.05rem; }
@media (min-width: 52rem) { .buy-bar { display: none !important; } }
@media (max-width: 52rem) { .landing .site-footer { padding-bottom: 6rem; } }

/* FAQ */
.landing .faq { padding-inline: max(clamp(1rem, 4vw, 3rem), calc((100% - 46rem) / 2)); }
.faq details { border-top: 1px solid var(--line); padding: 1rem 0; }
.faq details:last-of-type { border-bottom: 1px solid var(--line); }
.faq summary { cursor: pointer; font-weight: 600; font-size: 1.1rem; }
.faq details p { margin: 0.75rem 0 0; }

.site-footer {
  padding: 2rem clamp(1rem, 4vw, 3rem) 3rem;
  border-top: 4px solid var(--blue);
  background: var(--surface); color: var(--ink-soft); font-size: 0.95rem;
}
.site-footer a { margin-right: 1rem; }

/* Legal pages */
.legal { max-width: 44rem; margin: 0 auto; padding: 3rem clamp(1rem, 4vw, 3rem); }
.legal h1 { font-size: 2.6rem; max-width: none; }

@media (max-width: 30rem) {
  .opt { flex-direction: column; align-items: flex-start; gap: 0.2rem; }
}

/* ---------- Practice app ---------- */
.app-main { max-width: 46rem; margin: 0 auto; padding: clamp(1.5rem, 4vw, 3rem) clamp(1rem, 4vw, 2rem) 4rem; display: grid; gap: 1.5rem; }
.app-status { color: var(--ink-soft); margin: 0; }
.app-status[hidden] { display: none; }
.panel {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius-panel);
  padding: clamp(1.25rem, 3vw, 2rem);
}
.app-main > section:not(.panel) { display: grid; gap: 1.5rem; padding: 0; }
.app-title { font-size: clamp(2rem, 5vw, 2.8rem); font-weight: 700; margin-bottom: 0.25rem; }
.readiness { border-top: 6px solid var(--blue); }
.app .comparator li { grid-template-columns: 3.25rem 1fr auto auto; }
.practice-area { margin-left: 0.5rem; }
@media (max-width: 30rem) {
  .app .comparator li {
    grid-template-columns: 3.25rem 1fr auto;
    grid-template-areas: "sw name name" "sw score link";
    row-gap: 0.1rem;
  }
  .app .comparator .swatch { grid-area: sw; }
  .app .comparator .area-name { grid-area: name; }
  .app .comparator .area-score { grid-area: score; font-weight: 500; color: var(--ink-soft); }
  .app .comparator .practice-area { grid-area: link; margin-left: 0; }
}
.actions { display: flex; flex-wrap: wrap; gap: 0.75rem; }
.exam-heading { margin-top: 2rem; }
.guarantee ul { padding-left: 1.2rem; display: grid; gap: 0.4rem; }
.small { font-size: 0.95rem; color: var(--ink-soft); }
.welcome { background: #E8F4EE; border: 1px solid #B7DCC8; border-radius: var(--radius-panel); padding: 1rem 1.25rem; }
.welcome h2 { margin-bottom: 0.25rem; }
.stack { display: grid; gap: 0.5rem; max-width: 24rem; margin: 1rem 0 1.5rem; }
.stack label { font-weight: 600; margin-top: 0.5rem; }
.stack input {
  font: inherit; padding: 0.8rem 0.9rem; min-height: 3rem;
  border: 2px solid var(--line); border-radius: var(--radius-control);
}
.stack .button { margin-top: 0.75rem; justify-self: start; }
.run-head { display: flex; justify-content: space-between; align-items: baseline; gap: 1rem; }
.timer { font-family: "Barlow Condensed", sans-serif; font-size: 1.4rem; font-weight: 600; font-variant-numeric: tabular-nums; margin: 0; }
.run-nav { display: flex; flex-wrap: wrap; align-items: center; gap: 0.75rem 1.25rem; margin-top: 1.25rem; }
.opt.is-picked { border-color: var(--blue); background: #EAF1FA; }
.missed { padding-left: 1.4rem; display: grid; gap: 1.25rem; margin-bottom: 2rem; }
.missed-stem { font-weight: 600; margin-bottom: 0.25rem; }