:root{
    --page:#FFFFFF; --ink:#1F2430; --ink-soft:#6B7280;
    --accent:#7DD13B; --tint:#F1FAE8; --shadow:rgba(125,209,59,.26); --deep:#3E7A1E;
    --display:"Bricolage Grotesque",system-ui,sans-serif; --hand:"Caveat",cursive; --ui:"Chivo",system-ui,sans-serif;
  }
  *{box-sizing:border-box;-webkit-tap-highlight-color:transparent}
  [hidden]{display:none !important}
  body{margin:0; min-height:100svh; font-family:var(--ui); color:var(--ink); background:var(--page);
    display:flex; flex-direction:column; align-items:center;
    padding:max(10px,env(safe-area-inset-top)) 16px max(28px,env(safe-area-inset-bottom))}
  header,main{width:100%; max-width:640px}
  .topbar{display:flex; align-items:center; justify-content:space-between; gap:12px; margin-bottom:2px}
  .home{font-family:var(--hand); font-size:21px; color:var(--ink-soft); text-decoration:none}
  .eyebrow{font-size:11px; letter-spacing:.18em; text-transform:uppercase; color:var(--deep); margin:0 0 2px; font-weight:700}
  h1{font-family:var(--display); font-weight:800; font-size:clamp(32px,8.5vw,46px); letter-spacing:-.03em; margin:0 0 6px; line-height:1}
  .lead{font-size:15.5px; color:var(--ink-soft); margin:0 0 18px; line-height:1.5; max-width:48ch}

  /* jump links */
  .jump{display:flex; gap:7px; flex-wrap:wrap; margin-bottom:20px}
  .jump a{text-decoration:none; font-size:12.5px; font-weight:700; color:var(--deep); background:var(--tint); padding:7px 12px; border-radius:99px}

  section{margin:0 0 30px}
  h2{font-family:var(--display); font-weight:800; font-size:24px; letter-spacing:-.02em; margin:0 0 4px; color:var(--deep)}
  h2 .n{font-family:var(--hand); font-weight:600; font-size:20px; color:var(--ink-soft); margin-right:6px}
  .sub{font-family:var(--hand); font-size:20px; color:var(--ink-soft); margin:0 0 12px}
  p{line-height:1.5; margin:0 0 10px; text-wrap:pretty}
  b{color:var(--deep)}

  /* the words */
  .toggle{display:flex; gap:8px; margin:0 0 12px}
  .toggle button{border:0; cursor:pointer; font-family:var(--ui); font-size:12.5px; font-weight:700; padding:7px 12px; border-radius:99px; color:var(--deep); background:var(--tint)}
  .toggle button[aria-selected="true"]{color:#fff; background:var(--accent)}
  .words{display:grid; gap:10px}
  .wordcard{background:#fff; border-radius:18px; padding:14px 16px; box-shadow:0 8px 20px var(--shadow)}
  .wordcard .w{font-family:var(--display); font-weight:800; font-size:21px; letter-spacing:-.02em; color:var(--deep); margin:0 0 4px}
  .wordcard .d{margin:0 0 6px; font-size:15.5px}
  .wordcard .ex{margin:0; font-size:13.5px; color:var(--ink-soft)}
  .wordcard .ex b{color:var(--ink-soft); font-weight:700}
  .wordcard .note{margin:6px 0 0; font-family:var(--hand); font-size:17px; color:#C2410C}
  .blank{display:inline-block; min-width:5.5em; border-bottom:3px dashed var(--accent); color:transparent; cursor:pointer; border-radius:3px; padding:0 4px; position:relative; transition:color .15s}
  .blank::after{content:"tap"; position:absolute; left:0; right:0; top:0; text-align:center; font-family:var(--hand); font-size:14px; color:var(--ink-soft); pointer-events:none}
  .blank.on{color:var(--deep); font-weight:700; border-bottom-style:solid}
  .blank.on::after{display:none}

  /* the design process */
  .strip{display:grid; grid-template-columns:repeat(6,1fr); gap:6px; margin:8px 0 12px}
  .stepbtn{border:0; cursor:pointer; border-radius:14px; padding:10px 4px 8px; color:#fff; background:var(--c); font-family:var(--ui);
    display:flex; flex-direction:column; align-items:center; gap:2px; box-shadow:0 8px 18px var(--cs); transition:transform .12s}
  .stepbtn .l{font-family:var(--display); font-weight:800; font-size:26px; line-height:1}
  .stepbtn .nm{font-size:11px; font-weight:700; letter-spacing:.02em}
  .stepbtn[aria-selected="true"]{transform:translateY(-3px); outline:3px solid var(--ink); outline-offset:2px}
  .stepdetail{background:var(--tint); border-radius:18px; padding:14px 16px; min-height:90px}
  .stepdetail .t{font-family:var(--display); font-weight:800; font-size:20px; margin:0 0 4px; color:var(--deep)}
  .stepdetail p{margin:0 0 6px}
  .stepdetail .ex{font-family:var(--hand); font-size:18px; color:var(--ink-soft); margin:0}
  .mnemonic{display:flex; flex-wrap:wrap; gap:6px 10px; margin:12px 0 0; font-family:var(--hand); font-size:22px; color:var(--ink-soft)}
  .mnemonic span::first-letter{color:var(--deep); font-weight:700; font-size:1.25em}
  .arrows{font-size:14px; color:var(--ink-soft); margin:10px 0 0; line-height:1.6}
  .arrows b{color:var(--ink)}

  /* why test */
  .bullets{margin:0; padding:0; list-style:none; display:grid; gap:8px}
  .bullets li{background:#fff; border-radius:14px; padding:11px 14px; box-shadow:0 6px 16px var(--shadow); font-size:15px; line-height:1.45}

  /* benefits and risks */
  .pairs{display:grid; gap:10px}
  .pair{background:#fff; border-radius:16px; padding:12px 14px; box-shadow:0 6px 16px var(--shadow)}
  .pair .thing{font-family:var(--display); font-weight:800; font-size:18px; margin:0 0 8px}
  .pair .cols{display:grid; grid-template-columns:1fr 1fr; gap:10px; font-size:14px}
  .pair .col b{display:block; font-size:11px; letter-spacing:.14em; text-transform:uppercase; margin-bottom:4px}
  .pair .good b{color:#1B7A57} .pair .bad b{color:#C2410C}
  .pair .col span{display:block; line-height:1.4}
  .helps{display:flex; flex-wrap:wrap; gap:7px; margin:10px 0 0}
  .helps span{background:var(--tint); color:var(--deep); font-weight:700; font-size:13px; padding:7px 12px; border-radius:99px}

  /* review questions */
  details{background:#fff; border-radius:16px; padding:12px 14px; box-shadow:0 6px 16px var(--shadow); margin-bottom:8px}
  details summary{cursor:pointer; font-weight:700; font-size:15.5px; list-style:none; display:flex; gap:8px; align-items:flex-start}
  details summary::-webkit-details-marker{display:none}
  details summary::before{content:"?"; flex:none; width:24px; height:24px; border-radius:50%; background:var(--tint); color:var(--deep); display:grid; place-items:center; font-family:var(--display); font-weight:800}
  details[open] summary::before{content:"✓"; background:var(--accent); color:#fff}
  details p{margin:10px 0 0 32px; font-size:15px; color:var(--ink)}
  .hint{font-family:var(--hand); font-size:19px; color:var(--ink-soft); margin:0 0 10px}

  .go{display:inline-block; margin-top:4px; text-decoration:none; font-family:var(--ui); font-size:16px; font-weight:700; color:#fff; background:var(--accent);
    border-radius:99px; padding:13px 24px; box-shadow:0 8px 18px var(--shadow)}
  .go.alt{background:#fff; color:var(--deep); margin-left:8px}

  @media (max-width:420px){
    .strip{grid-template-columns:repeat(3,1fr)}
    .pair .cols{grid-template-columns:1fr}
  }
  @media (min-width:700px){
    body{padding-left:24px; padding-right:24px}
    .words{grid-template-columns:1fr 1fr}
  }