:root {
  --ink: #152139;
  --muted: #5b6474;
  --paper: #fffdf7;
  --cream: #f7f2e8;
  --white: #ffffff;
  --blue: #173b8e;
  --blue-2: #2a66cf;
  --cyan: #4fc6e8;
  --lime: #b9e900;
  --yellow: #ffd84d;
  --pink: #ef4b9b;
  --orange: #ff7043;
  --line: #dfe4ea;
  --shadow: 0 24px 70px rgba(21, 33, 57, .13);
  --radius-lg: 34px;
  --radius-md: 22px;
  --container: 1180px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 90px;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: "Aptos", "Segoe UI", system-ui, -apple-system, sans-serif;
  font-size: 17px;
  line-height: 1.68;
  text-rendering: optimizeLegibility;
}

body.menu-open { overflow: hidden; }

img { display: block; max-width: 100%; height: auto; }
a { color: inherit; }
button, input { font: inherit; }
button { color: inherit; }

h1, h2, h3, p, ul, ol, dl, figure, blockquote { margin-top: 0; }
h1, h2, h3 { line-height: 1.08; letter-spacing: -.035em; text-wrap: balance; }
h1 { font-size: clamp(2.65rem, 5.3vw, 5.75rem); }
h2 { font-size: clamp(2rem, 3.6vw, 3.55rem); }
h3 { font-size: clamp(1.35rem, 2vw, 1.9rem); }
p { text-wrap: pretty; }

.container { width: min(calc(100% - 40px), var(--container)); margin-inline: auto; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }

.skip-link {
  position: fixed;
  z-index: 999;
  top: 10px;
  left: 10px;
  transform: translateY(-180%);
  padding: 10px 16px;
  border-radius: 10px;
  background: var(--ink);
  color: #fff;
}

.skip-link:focus { transform: translateY(0); }

.reading-progress {
  position: fixed;
  z-index: 120;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: transparent;
}

.reading-progress span {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--pink), var(--yellow), var(--lime));
}

.site-header {
  position: sticky;
  z-index: 100;
  top: 0;
  border-bottom: 1px solid rgba(21, 33, 57, .09);
  background: rgba(255, 253, 247, .92);
  backdrop-filter: blur(18px);
}

.header-inner { min-height: 74px; display: flex; align-items: center; justify-content: space-between; gap: 24px; }

.lab-brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  color: var(--ink);
  text-decoration: none;
  line-height: 1;
}

.brand-logo {
  width: auto;
  height: 45px;
  object-fit: contain;
}

.lab-brand strong { display: block; font-size: .98rem; letter-spacing: .08em; }
.lab-brand small { display: block; margin-top: 5px; color: var(--muted); font-size: .66rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; }

.main-nav { display: flex; align-items: center; gap: 26px; }
.main-nav a { text-decoration: none; font-size: .88rem; font-weight: 750; }
.main-nav a:not(.nav-cta):hover { color: var(--blue-2); }
.main-nav .language-switch { display: inline-flex; align-items: center; gap: 6px; min-height: 36px; padding: 5px 9px; border: 2px solid var(--ink); border-radius: 999px; background: #fff; color: var(--ink); line-height: 1; }
.flag-icon { position: relative; display: inline-block; flex: 0 0 auto; width: 24px; height: 16px; overflow: hidden; border: 1px solid rgba(21, 33, 57, .28); border-radius: 2px; }
.flag-it { background: linear-gradient(90deg, #009246 0 33.33%, #fff 33.33% 66.66%, #ce2b37 66.66% 100%); }
.flag-us { background: repeating-linear-gradient(to bottom, #b22234 0 1.23px, #fff 1.23px 2.46px); }
.flag-us::after { position: absolute; top: 0; left: 0; width: 10px; height: 8px; background: #3c3b6e; content: ""; }
.nav-cta { padding: 10px 17px; border: 2px solid var(--ink); border-radius: 999px; background: var(--yellow); box-shadow: 3px 3px 0 var(--ink); }

.menu-button {
  display: none;
  width: 45px;
  height: 42px;
  padding: 10px;
  border: 0;
  background: transparent;
}

.menu-button i { display: block; height: 2px; margin: 5px 0; background: var(--ink); transition: transform .2s ease, opacity .2s ease; }

.hero {
  position: relative;
  min-height: 690px;
  overflow: hidden;
  border-bottom: 1px solid var(--line);
  background:
    radial-gradient(circle at 14% 20%, rgba(185, 233, 0, .19) 0 5%, transparent 5.2%),
    linear-gradient(120deg, #fffdf7 0%, #fffdf7 38%, #f1f9ff 72%, #dff6ff 100%);
}

.hero::before,
.hero::after {
  position: absolute;
  content: "";
  width: 220px;
  height: 220px;
  border: 34px solid rgba(239, 75, 155, .1);
  border-radius: 50%;
}

.hero::before { top: 110px; left: -150px; }
.hero::after { right: 30%; bottom: -170px; border-color: rgba(42, 102, 207, .09); }

.hero-art {
  position: absolute;
  inset: 0 0 0 auto;
  width: 65%;
}

.hero-art::after {
  position: absolute;
  inset: 0;
  content: "";
  background: linear-gradient(90deg, var(--paper) 0%, rgba(255, 253, 247, .93) 9%, rgba(255, 253, 247, .18) 42%, transparent 65%);
}

.hero-art img { width: 100%; height: 100%; object-fit: cover; object-position: 56% center; }
.hero-inner { position: relative; z-index: 2; display: flex; align-items: center; min-height: 690px; padding-block: 70px; }
.hero-copy { width: min(55%, 650px); }

.eyebrow,
.section-label,
.topic-number {
  margin-bottom: 16px;
  color: var(--blue);
  font-size: .76rem;
  font-weight: 900;
  letter-spacing: .13em;
  text-transform: uppercase;
}

.eyebrow span { display: inline-block; padding: 5px 9px; border-radius: 99px; background: var(--lime); color: var(--ink); }
.hero h1 { max-width: 670px; margin-bottom: 24px; }
.hero h1 em { position: relative; color: var(--blue-2); font-style: normal; white-space: nowrap; }
.hero h1 em::after { position: absolute; right: 0; bottom: -4px; left: 0; height: 8px; content: ""; border-radius: 100%; background: var(--yellow); transform: rotate(-1deg); z-index: -1; }
.hero-lead { max-width: 620px; margin-bottom: 30px; color: #3c4657; font-size: clamp(1.07rem, 1.5vw, 1.25rem); line-height: 1.65; }

.hero-actions, .book-actions { display: flex; align-items: center; flex-wrap: wrap; gap: 18px; }

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 11px;
  min-height: 54px;
  padding: 13px 23px;
  border: 2px solid var(--ink);
  border-radius: 999px;
  color: var(--ink);
  font-weight: 850;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  box-shadow: 4px 4px 0 var(--ink);
  transition: transform .17s ease, box-shadow .17s ease;
}

.button:hover { transform: translate(2px, 2px); box-shadow: 2px 2px 0 var(--ink); }
.button:active { transform: translate(4px, 4px); box-shadow: none; }
.button-primary { background: var(--lime); }
.button-dark { background: var(--ink); color: #fff; border-color: var(--ink); box-shadow: 4px 4px 0 var(--cyan); }
.button-yellow { background: var(--yellow); }

.text-button {
  padding: 8px 2px;
  border: 0;
  border-bottom: 2px solid currentColor;
  background: transparent;
  color: var(--blue);
  font-weight: 800;
  cursor: pointer;
}

.share-button { display: inline-flex; align-items: center; gap: 9px; }
.share-button svg { flex: 0 0 auto; overflow: visible; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }

.hero-facts { display: flex; gap: 0; margin: 42px 0 0; }
.hero-facts div { min-width: 125px; padding-right: 22px; }
.hero-facts div + div { padding-left: 22px; border-left: 1px solid #cdd6df; }
.hero-facts dt { color: var(--muted); font-size: .69rem; font-weight: 850; letter-spacing: .12em; text-transform: uppercase; }
.hero-facts dd { margin: 3px 0 0; font-size: .95rem; font-weight: 850; }

.quick-answer { padding-block: 70px; background: var(--blue); color: #fff; }
.answer-grid { display: grid; grid-template-columns: .8fr 1.2fr; gap: clamp(40px, 8vw, 110px); align-items: start; }
.quick-answer .section-label { color: var(--lime); }
.quick-answer h2 { margin-bottom: 0; font-size: clamp(2rem, 3.3vw, 3.3rem); }
.answer-copy { padding-left: 34px; border-left: 4px solid var(--lime); }
.answer-copy p:last-child { margin-bottom: 0; color: #d8e2fb; }

.article-layout { display: grid; grid-template-columns: 220px minmax(0, 1fr); gap: clamp(45px, 7vw, 90px); padding-block: 90px 130px; }
.article { min-width: 0; }

.toc { position: relative; }
.toc-inner { position: sticky; top: 108px; padding-top: 6px; }
.toc p { margin-bottom: 15px; font-size: .72rem; font-weight: 900; letter-spacing: .13em; text-transform: uppercase; }
.toc ol { margin: 0; padding: 0; list-style: none; counter-reset: toc; }
.toc li { counter-increment: toc; border-top: 1px solid var(--line); }
.toc li:last-child { border-bottom: 1px solid var(--line); }
.toc a { display: block; padding: 11px 2px; color: var(--muted); font-size: .82rem; font-weight: 700; line-height: 1.35; text-decoration: none; }
.toc li a::before { content: "0" counter(toc) " "; margin-right: 4px; color: var(--blue-2); font-size: .68rem; }
.toc a:hover, .toc a.active { color: var(--blue); }
.toc-download { margin-top: 18px; color: var(--blue) !important; font-size: .8rem !important; }

.safety-box {
  display: grid;
  grid-template-columns: 58px 1fr;
  gap: 24px;
  margin-bottom: 110px;
  padding: clamp(28px, 4vw, 44px);
  border: 2px solid var(--ink);
  border-radius: var(--radius-md);
  background: #fff5cf;
  box-shadow: 8px 8px 0 var(--yellow);
}

.safety-icon { display: grid; place-items: center; width: 54px; height: 54px; border: 2px solid var(--ink); border-radius: 50%; background: var(--yellow); font-size: 1.6rem; font-weight: 950; }
.safety-box h2 { margin-bottom: 23px; font-size: clamp(1.7rem, 3vw, 2.6rem); }
.check-list { margin: 0; padding: 0; list-style: none; }
.check-list li { position: relative; padding-left: 30px; }
.check-list li + li { margin-top: 12px; }
.check-list li::before { position: absolute; top: 0; left: 0; content: "✓"; color: var(--blue); font-weight: 950; }

.topic-section { margin-bottom: 130px; }
.topic-heading { display: grid; grid-template-columns: minmax(0, 1fr) 260px; gap: 42px; align-items: end; margin-bottom: 40px; }
.topic-number { margin-bottom: 14px; color: var(--pink); }
.topic-heading h2 { margin-bottom: 22px; }
.topic-intro { margin-bottom: 0; color: var(--muted); font-size: 1.03rem; }

.say-it {
  position: relative;
  padding: 24px;
  border: 2px solid var(--ink);
  border-radius: 42% 58% 48% 52% / 52% 45% 55% 48%;
  background: #dff5ff;
  box-shadow: 6px 6px 0 var(--cyan);
  transform: rotate(1deg);
}

.say-it::after { position: absolute; right: 22px; bottom: -15px; width: 26px; height: 26px; border-right: 2px solid var(--ink); border-bottom: 2px solid var(--ink); background: inherit; content: ""; transform: rotate(45deg); }
.say-it span { display: block; margin-bottom: 7px; font-size: .66rem; font-weight: 900; letter-spacing: .11em; text-transform: uppercase; }
.say-it p { margin: 0; font-size: .94rem; font-weight: 800; line-height: 1.45; }
.say-it-pink { background: #ffe5f2; box-shadow-color: var(--pink); }
.say-it-lime { background: #f0f9cb; box-shadow-color: var(--lime); }

.topic-figure { margin: 0 0 55px; }
.topic-figure img { width: 100%; border: 2px solid var(--ink); border-radius: var(--radius-lg); box-shadow: 9px 9px 0 var(--ink); }
.topic-figure figcaption { margin: 17px 8px 0; color: var(--muted); font-size: .8rem; font-style: italic; text-align: center; }

.experiment-list { display: grid; gap: 28px; }
.experiment {
  position: relative;
  padding: clamp(29px, 5vw, 52px);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--white);
  box-shadow: var(--shadow);
}

.experiment.compact { box-shadow: none; }
.experiment-topline { display: flex; justify-content: space-between; gap: 15px; margin-bottom: 18px; color: var(--muted); font-size: .72rem; font-weight: 800; letter-spacing: .06em; text-transform: uppercase; }
.experiment-id { color: var(--blue); }
.experiment h3 { margin-bottom: 14px; }
.experiment-goal { max-width: 780px; margin: 0 0 22px; color: #344050; font-size: .96rem; }
.materials { margin-bottom: 18px; padding: 17px 19px; border-left: 4px solid var(--yellow); background: #fff9e5; font-size: .9rem; }
.materials h4 { margin: 0 0 10px; color: var(--ink); font-size: .76rem; letter-spacing: .08em; text-transform: uppercase; }
.materials ul { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 6px 28px; margin: 0; padding-left: 19px; }
.materials li { padding-left: 2px; }
.preparation { margin: 0 0 24px; padding: 15px 18px; border: 1px solid #d9e0e8; border-radius: 12px; background: #fbfcfd; color: #3b4654; font-size: .91rem; }
.steps { margin: 0 0 24px; padding: 0; list-style: none; counter-reset: steps; }
.steps li { position: relative; min-height: 36px; padding-left: 50px; counter-increment: steps; }
.steps li + li { margin-top: 14px; }
.steps li::before { position: absolute; top: -3px; left: 0; display: grid; place-items: center; width: 34px; height: 34px; border: 2px solid var(--ink); border-radius: 50%; background: var(--lime); content: counter(steps); font-size: .8rem; font-weight: 900; }
.result, .science-note { margin-top: 17px; padding: 18px 20px; border-radius: 14px; font-size: .93rem; }
.result { background: #e7f7ff; }
.science-note { border: 1px dashed #95a2b3; background: #f6f7f9; }
.experiment-tip { margin-top: 17px; padding: 16px 19px; border-left: 4px solid var(--pink); background: #fff2f6; font-size: .91rem; }
.ask { margin: 22px 0 0; color: var(--blue); font-size: .93rem; }

.mid-funnel {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 35px;
  align-items: center;
  margin: -45px 0 130px;
  padding: 36px 40px;
  border: 2px solid var(--ink);
  border-radius: var(--radius-md);
  background: var(--cyan);
  box-shadow: 8px 8px 0 var(--ink);
}

.mid-funnel .section-label { margin-bottom: 8px; color: var(--ink); }
.mid-funnel h2 { margin-bottom: 10px; font-size: clamp(1.65rem, 3vw, 2.65rem); }
.mid-funnel p:last-child { margin-bottom: 0; }

.method-section {
  margin: -15px 0 115px;
  padding: clamp(35px, 6vw, 65px);
  border-radius: var(--radius-lg);
  background: var(--ink);
  color: #fff;
}

.method-heading { max-width: 690px; }
.method-heading .section-label { color: var(--lime); }
.method-heading h2 { margin-bottom: 17px; }
.method-heading > p:last-child { color: #c8d1df; }
.method-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; margin: 42px 0 0; padding: 0; list-style: none; }
.method-grid li { padding: 23px 19px; border: 1px solid rgba(255, 255, 255, .2); border-radius: 18px; background: rgba(255, 255, 255, .05); }
.method-grid li > span { display: grid; place-items: center; width: 36px; height: 36px; margin-bottom: 18px; border-radius: 50%; background: var(--lime); color: var(--ink); font-weight: 950; }
.method-grid strong { display: block; margin-bottom: 7px; font-size: 1.1rem; }
.method-grid p { margin: 0; color: #c8d1df; font-size: .8rem; line-height: 1.5; }
.method-section blockquote { position: relative; margin: 48px 0 0; padding: 30px 0 0 75px; border-top: 1px solid rgba(255, 255, 255, .22); }
.method-section blockquote::before { position: absolute; top: 15px; left: 0; color: var(--yellow); content: "“"; font-family: Georgia, serif; font-size: 5rem; line-height: 1; }
.method-section blockquote p { max-width: 700px; margin: 0; font-family: Georgia, serif; font-size: clamp(1.2rem, 2vw, 1.6rem); font-style: italic; }

.printable {
  display: grid;
  grid-template-columns: .9fr 1.1fr;
  gap: 50px;
  align-items: center;
  margin-bottom: 125px;
  padding: clamp(30px, 5vw, 55px);
  border: 2px solid var(--ink);
  border-radius: var(--radius-lg);
  background: #ecf4ff;
  box-shadow: 10px 10px 0 var(--blue);
}

.printable h2 { margin-bottom: 18px; font-size: clamp(1.8rem, 3vw, 2.8rem); }
.printable-copy > p:not(.section-label) { color: var(--muted); }
.resource-gate-form { display: grid; gap: 14px; margin-top: 24px; }
.resource-gate-form > label:not(.resource-consent) { display: grid; gap: 7px; color: var(--ink); font-size: .78rem; font-weight: 850; }
.resource-gate-form input[type="email"] { width: 100%; min-height: 48px; padding: 10px 13px; border: 2px solid var(--ink); border-radius: 10px; background: #fff; color: var(--ink); font: inherit; }
.resource-gate-form input[type="email"]:focus-visible { outline: 4px solid rgba(31, 111, 235, .25); outline-offset: 2px; }
.resource-consent { display: grid; grid-template-columns: auto 1fr; gap: 10px; align-items: start; color: #485266; font-size: .68rem; line-height: 1.5; }
.resource-consent input { width: 18px; height: 18px; margin-top: 2px; accent-color: var(--blue); }
.resource-consent a { color: inherit; font-weight: 800; text-underline-offset: 3px; }
.resource-gate-form .button { justify-self: start; }
.resource-gate-form .button[disabled] { cursor: wait; opacity: .65; }
.resource-form-trap { position: absolute !important; left: -10000px !important; width: 1px !important; height: 1px !important; overflow: hidden !important; }
.resource-gate-status { min-height: 1.4em; margin: 0; font-size: .75rem; font-weight: 800; }
.resource-gate-status.is-success { color: #126238; }
.resource-gate-status.is-error { color: #a61932; }
.resource-gate-form.is-complete > :not(.resource-gate-status) { display: none; }
.resource-unlocked { margin-top: 20px; padding: 18px; border: 2px solid #126238; border-radius: 14px; background: #effbf4; }
.resource-unlocked[hidden] { display: none; }
.resource-unlocked strong { display: block; color: #126238; font-size: 1rem; }
.resource-unlocked p { margin: 6px 0 15px; color: var(--muted); font-size: .75rem; }
.resource-unlocked:focus-visible { outline: 4px solid rgba(18, 98, 56, .25); outline-offset: 4px; }
.sheet-preview { padding: 25px 27px; border: 1px solid #c8d1df; background: #fff; box-shadow: 0 16px 35px rgba(21, 33, 57, .12); transform: rotate(2deg); }
.sheet-preview span { display: block; margin-bottom: 18px; color: var(--blue); font-size: .63rem; font-weight: 900; letter-spacing: .12em; }
.sheet-preview strong { display: block; margin-top: 10px; font-size: .72rem; }
.sheet-preview i { display: block; height: 25px; border-bottom: 1px solid #acb7c5; }

.faq-section { margin-bottom: 105px; }
.faq-heading { max-width: 760px; margin-bottom: 42px; }
.faq-heading > p:last-child { color: var(--muted); }
.faq-list { border-top: 2px solid var(--ink); }
.faq-list details { border-bottom: 1px solid #bfc8d3; }
.faq-list summary { position: relative; padding: 24px 54px 24px 0; font-size: 1.07rem; font-weight: 850; line-height: 1.35; list-style: none; cursor: pointer; }
.faq-list summary::-webkit-details-marker { display: none; }
.faq-list summary::after { position: absolute; top: 22px; right: 5px; display: grid; place-items: center; width: 32px; height: 32px; border: 1px solid var(--ink); border-radius: 50%; content: "+"; font-size: 1.3rem; font-weight: 500; transition: transform .2s ease, background .2s ease; }
.faq-list details[open] summary::after { background: var(--lime); content: "−"; transform: rotate(180deg); }
.faq-list details > div { max-width: 760px; padding: 0 45px 24px 0; color: var(--muted); }
.faq-list details p { margin: 0; }
.faq-list details strong { color: var(--ink); }

.sources { padding-top: 34px; border-top: 1px solid var(--line); color: var(--muted); font-size: .85rem; }
.sources h2 { margin-bottom: 16px; color: var(--ink); font-size: 1.35rem; }
.sources a { color: var(--blue); font-weight: 750; }
.source-note { margin-bottom: 0; font-size: .76rem; }

.book-funnel { position: relative; overflow: hidden; padding-block: 90px; background: var(--blue); color: #fff; }
.book-funnel::before { position: absolute; top: -150px; right: -110px; width: 420px; height: 420px; border: 78px solid rgba(185, 233, 0, .14); border-radius: 50%; content: ""; }
.book-grid { position: relative; display: grid; grid-template-columns: .68fr .6fr 1fr; gap: clamp(30px, 5vw, 70px); align-items: center; }
.teacher-art { align-self: end; margin-bottom: -92px; }
.teacher-art img { max-height: 650px; margin-inline: auto; object-fit: contain; }
.book-cover-wrap { position: relative; }
.book-cover-wrap > img { width: min(100%, 320px); margin-inline: auto; border-radius: 5px 12px 12px 5px; box-shadow: 0 30px 60px rgba(0, 0, 0, .4); transform: rotate(3deg); }
.book-badge { position: absolute; z-index: 2; top: -20px; right: -12px; display: grid; place-items: center; width: 86px; height: 86px; border: 3px solid var(--ink); border-radius: 50%; background: var(--lime); color: var(--ink); font-size: .77rem; font-weight: 950; transform: rotate(8deg); }
.book-copy .section-label { color: var(--lime); }
.book-copy h2 { margin-bottom: 22px; }
.book-copy > p, .book-copy li { color: #d8e2fb; }
.book-copy ul { margin: 24px 0 30px; padding: 0; list-style: none; }
.book-copy li { position: relative; padding-left: 28px; }
.book-copy li + li { margin-top: 8px; }
.book-copy li::before { position: absolute; left: 0; color: var(--lime); content: "✦"; }
.book-link { color: #fff; font-weight: 750; text-underline-offset: 5px; }
.affiliate-note { margin: 20px 0 0; font-size: .7rem; }

.site-footer { padding-block: 45px; background: #0e182a; color: #d4d9e1; }
.footer-inner { display: grid; grid-template-columns: 1fr auto; gap: 25px; align-items: center; }
.footer-inner strong { color: #fff; letter-spacing: .08em; }
.footer-inner p { margin: 4px 0 0; font-size: .82rem; }
.footer-links { display: flex; align-items: center; gap: 22px; }
.footer-links a, .footer-links button { border: 0; background: transparent; color: inherit; font-size: .78rem; text-decoration: underline; text-underline-offset: 4px; cursor: pointer; }
.copyright { grid-column: 1 / -1; padding-top: 20px; border-top: 1px solid rgba(255, 255, 255, .1); color: #8791a1; }

.mobile-funnel { display: none; }
.print-sheet { display: none; }

:focus-visible { outline: 4px solid var(--pink); outline-offset: 4px; }

@media (max-width: 1040px) {
  .main-nav { gap: 15px; }
  .main-nav a { font-size: .8rem; }
  .hero { min-height: 750px; }
  .hero-inner { min-height: 750px; align-items: flex-start; padding-top: 90px; }
  .hero-copy { width: 62%; }
  .hero-art { width: 70%; }
  .hero-art::after { background: linear-gradient(90deg, var(--paper) 0%, rgba(255,253,247,.96) 15%, rgba(255,253,247,.5) 50%, transparent 75%); }
  .article-layout { grid-template-columns: 180px minmax(0, 1fr); gap: 50px; }
  .topic-heading { grid-template-columns: 1fr; }
  .say-it { width: min(100%, 500px); border-radius: 22px; transform: none; }
  .method-grid { grid-template-columns: repeat(2, 1fr); }
  .book-grid { grid-template-columns: .6fr .75fr 1.2fr; gap: 30px; }
}

@media (max-width: 820px) {
  body { font-size: 16px; }
  .container { width: min(calc(100% - 30px), var(--container)); }
  .menu-button { display: block; }
  .main-nav {
    position: fixed;
    inset: 74px 0 auto;
    display: grid;
    gap: 0;
    padding: 15px 20px 30px;
    border-bottom: 2px solid var(--ink);
    background: var(--paper);
    transform: translateY(-140%);
    transition: transform .25s ease;
  }
  .main-nav.open { transform: translateY(0); }
  .main-nav a { padding: 15px 5px; border-bottom: 1px solid var(--line); }
  .main-nav .nav-cta { margin-top: 14px; border-bottom: 2px solid var(--ink); text-align: center; }
  .menu-button[aria-expanded="true"] i:nth-of-type(1) { transform: translateY(7px) rotate(45deg); }
  .menu-button[aria-expanded="true"] i:nth-of-type(2) { opacity: 0; }
  .menu-button[aria-expanded="true"] i:nth-of-type(3) { transform: translateY(-7px) rotate(-45deg); }

  .hero { display: flex; min-height: auto; flex-direction: column-reverse; }
  .hero-art { position: relative; width: 100%; height: auto; aspect-ratio: 1.55 / 1; }
  .hero-art::after { background: linear-gradient(0deg, var(--paper) 0%, transparent 27%); }
  .hero-art img { object-position: 54% center; }
  .hero-inner { min-height: auto; padding-block: 55px 25px; }
  .hero-copy { width: 100%; }
  .hero h1 { font-size: clamp(2.7rem, 12vw, 4.7rem); }
  .hero-lead { font-size: 1.05rem; }
  .answer-grid { grid-template-columns: 1fr; gap: 28px; }
  .answer-copy { padding: 0 0 0 22px; }
  .article-layout { display: block; padding-block: 65px 100px; }
  .toc { display: none; }
  .safety-box { margin-bottom: 90px; }
  .topic-section { margin-bottom: 105px; }
  .mid-funnel { grid-template-columns: 1fr; margin-bottom: 105px; }
  .printable { grid-template-columns: 1fr; }
  .book-grid { grid-template-columns: .7fr 1fr; }
  .teacher-art { display: none; }
  .book-copy { grid-column: 1 / -1; padding-top: 20px; }
  .book-cover-wrap { grid-column: 1 / -1; }
  .book-cover-wrap > img { width: 240px; }
}

@media (max-width: 560px) {
  body { line-height: 1.62; }
  h2 { font-size: clamp(2rem, 10vw, 2.7rem); }
  .lab-brand small { display: none; }
  .hero-inner { padding-top: 44px; }
  .hero-art { aspect-ratio: 1.08 / 1; }
  .hero-art img { object-position: 67% center; }
  .hero h1 { margin-bottom: 20px; }
  .hero h1 em { white-space: normal; }
  .hero-actions { align-items: stretch; flex-direction: column; }
  .hero-actions .button { width: 100%; }
  .hero-actions .text-button { align-self: center; }
  .hero-facts { justify-content: space-between; gap: 0; }
  .hero-facts div { min-width: 0; padding-right: 11px; }
  .hero-facts div + div { padding-left: 11px; }
  .hero-facts dd { font-size: .8rem; }
  .quick-answer { padding-block: 55px; }
  .article-layout { padding-top: 55px; }
  .safety-box { grid-template-columns: 1fr; gap: 16px; padding: 26px 22px; box-shadow: 5px 5px 0 var(--yellow); }
  .topic-heading { gap: 28px; }
  .topic-figure { margin-inline: -15px; }
  .topic-figure img { border-right: 0; border-left: 0; border-radius: 0; box-shadow: 0 7px 0 var(--ink); }
  .topic-figure figcaption { padding-inline: 15px; }
  .experiment { padding: 27px 20px; border-radius: 22px; }
  .experiment-topline { align-items: flex-start; flex-direction: column; gap: 5px; }
  .materials ul { grid-template-columns: 1fr; gap: 6px; }
  .steps li { padding-left: 43px; }
  .mid-funnel { padding: 28px 22px; box-shadow: 5px 5px 0 var(--ink); }
  .method-section { margin-inline: -15px; padding: 40px 22px; border-radius: 0; }
  .method-grid { grid-template-columns: 1fr; }
  .method-section blockquote { padding-left: 48px; }
  .method-section blockquote::before { font-size: 4rem; }
  .printable { padding: 29px 22px; box-shadow: 6px 6px 0 var(--blue); }
  .sheet-preview { display: none; }
  .faq-list summary { font-size: 1rem; }
  .book-funnel { padding-block: 70px 95px; }
  .book-grid { display: block; }
  .book-cover-wrap { margin-bottom: 55px; }
  .book-copy h2 { font-size: 2.5rem; }
  .book-actions { align-items: stretch; flex-direction: column; }
  .book-actions .button { width: 100%; }
  .book-link { text-align: center; }
  .footer-inner { display: block; }
  .footer-links { margin-top: 25px; flex-wrap: wrap; }
  .copyright { margin-top: 24px !important; }

  .mobile-funnel {
    position: fixed;
    z-index: 90;
    right: 10px;
    bottom: 10px;
    left: 10px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    padding: 11px 13px 11px 17px;
    border: 2px solid var(--ink);
    border-radius: 16px;
    background: var(--yellow);
    color: var(--ink);
    box-shadow: 4px 4px 0 var(--ink);
    font-size: .78rem;
    font-weight: 850;
    opacity: 0;
    pointer-events: none;
    transform: translateY(140%);
    transition: opacity .25s ease, transform .25s ease;
  }
  .mobile-funnel.visible { opacity: 1; pointer-events: auto; transform: translateY(0); }
  .mobile-funnel a { padding: 7px 11px; border-radius: 10px; background: var(--ink); color: #fff; text-decoration: none; white-space: nowrap; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; animation-duration: .01ms !important; }
}

@media print {
  @page { size: A4; margin: 14mm; }
  body > * { display: none !important; }
  .print-sheet {
    display: grid !important;
    grid-template-rows: auto repeat(6, minmax(0, 1fr)) auto;
    width: 100%;
    height: 258mm;
    overflow: hidden;
    color: #111;
    font-family: Arial, sans-serif;
    line-height: 1.25;
    page-break-inside: avoid;
    break-inside: avoid;
  }
  .print-sheet header { padding: 6mm 8mm 5mm; border: 2px solid #111; border-radius: 6mm 6mm 0 0; background: #eef6ff !important; }
  .print-sheet header span { font-size: 8pt; font-weight: 900; letter-spacing: 1.5px; }
  .print-sheet h2 { margin: 2mm 0 3mm; font-size: 20pt; line-height: 1.05; }
  .print-sheet header p { margin: 0; font-size: 9pt; }
  .print-sheet > div { min-height: 0; padding: 3mm 7mm; border-right: 2px solid #111; border-bottom: 2px solid #111; border-left: 2px solid #111; break-inside: avoid; }
  .print-sheet h3 { margin: 0 0 1mm; font-size: 11pt; }
  .print-sheet div p { margin: 0; font-size: 9pt; }
  .print-sheet i { display: block; height: 5.5mm; border-bottom: 1px solid #777; }
  .print-sheet footer { padding: 2.5mm; border: 2px solid #111; border-top: 0; border-radius: 0 0 4mm 4mm; font-size: 9pt; font-weight: 900; letter-spacing: 1.5px; text-align: center; }
}