:root {
  color-scheme: light;
  --canvas: #F6F8FB;
  --surface: #FFFFFF;
  --ink: #0A0F16;
  --text: #17212B;
  --muted: #586879;
  --blue: #2F648F;
  --blue-strong: #1E5B8F;
  --blue-deep: #123A63;
  --blue-soft: #DDEAF4;
  --blue-pale: #EDF4F9;
  --blue-line: #B9CDDD;
  --border: #D8E1EA;
  --success: #087A55;
  --warning: #9A5B00;
  --danger: #B42318;
  --shadow: 0 18px 50px rgba(18, 58, 99, 0.10);
  --radius: 1.1rem;
  --content: 1080px;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--text);
  background: var(--canvas);
  scroll-behavior: smooth;
  scroll-padding-top: 5.5rem;
}

* { box-sizing: border-box; }
html, body { margin: 0; min-width: 280px; }
body { overflow-x: hidden; font-size: 18px; line-height: 1.6; background: var(--canvas); }
h1, h2, h3, h4 { color: var(--ink); line-height: 1.12; letter-spacing: -0.02em; }
a { color: inherit; }
button { font: inherit; }
button:focus-visible, a:focus-visible, [tabindex]:focus-visible { outline: 3px solid var(--blue-strong); outline-offset: 4px; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.skip-link { position: absolute; left: 1rem; top: -4rem; padding: .6rem 1rem; border-radius: .5rem; background: var(--ink); color: white; z-index: 10; }
.skip-link:focus { top: 1rem; }

/* Header */
.top { position: sticky; top: 0; z-index: 5; display: flex; align-items: center; justify-content: space-between; gap: 1rem;
  padding: .9rem max(1.25rem, calc((100% - var(--content)) / 2)); border-bottom: 1px solid var(--border); background: rgba(255,255,255,.94); }
.brand { display: inline-flex; align-items: center; gap: .6rem; font-weight: 850; text-decoration: none; color: var(--ink); }
.brand small { display: block; color: var(--muted); font-size: .7rem; font-weight: 600; }
.brand-mark { display: inline-grid; place-items: center; width: 2.1rem; height: 2.1rem; border-radius: 50%; background: var(--ink); color: white; font-weight: 900; }
.top nav { display: flex; gap: 1.4rem; }
.top nav a { color: var(--muted); font-weight: 700; font-size: .95rem; text-decoration: none; }
.top nav a:hover { color: var(--blue-deep); }

/* Layout */
main > section { width: min(calc(100% - 2.5rem), var(--content)); margin: 0 auto; padding: clamp(3.5rem, 7vw, 6rem) 0; }
main > section + section { border-top: 1px solid var(--blue-line); }
.section-title { margin: 0; font-size: clamp(2rem, 3.6vw, 3rem); }
.section-lede { margin: .8rem 0 0; max-width: 720px; color: var(--muted); }

.button { display: inline-flex; align-items: center; justify-content: center; min-height: 3.2rem; padding: .7rem 1.25rem; border: 1px solid transparent;
  border-radius: .65rem; cursor: pointer; font-weight: 800; text-decoration: none; transition: transform 160ms ease, background-color 160ms ease; }
.button:hover { transform: translateY(-1px); }
.button-primary { color: white; background: var(--ink); }
.button-primary:hover { background: var(--blue-deep); }
.button-quiet { border-color: var(--border); color: var(--ink); background: white; }
.button:disabled { cursor: default; opacity: .45; transform: none; }

/* Hero */
.hero { text-align: center; }
.kicker { margin: 0 0 1rem; color: var(--blue-deep); font-size: .78rem; font-weight: 850; letter-spacing: .1em; text-transform: uppercase; }
.hero h1 { max-width: 900px; margin: 0 auto; font-size: clamp(2.7rem, 6.2vw, 5rem); }
.lede { max-width: 720px; margin: 1.4rem auto 2rem; color: var(--muted); font-size: 1.2rem; }
.lede strong { color: var(--text); }

/* Problem */
.story { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; margin: 2rem 0 0; padding: 0; list-style: none; counter-reset: story; }
.story li { position: relative; padding: 1.4rem; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); }
.story li.story-end { border-color: #e7b9b3; background: #fff7f5; }
.story h3 { margin: .8rem 0 .4rem; font-size: 1.2rem; }
.story p { margin: 0; color: var(--muted); }
.story-step, .step-number { display: inline-grid; place-items: center; width: 2rem; height: 2rem; border-radius: 50%; background: var(--blue-soft); color: var(--blue-deep); font-weight: 900; }

/* Demo */
.step { margin-top: 1.6rem; padding: clamp(1.2rem, 3vw, 2rem); border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); box-shadow: var(--shadow); }
.step-head { display: flex; gap: 1rem; align-items: flex-start; }
.step-head h3 { margin: 0; font-size: clamp(1.35rem, 2.4vw, 1.8rem); }
.step-head p { margin: .35rem 0 0; color: var(--muted); }
.step-number { flex: 0 0 auto; width: 2.4rem; height: 2.4rem; background: var(--ink); color: white; }
.step-body { display: grid; grid-template-columns: minmax(200px, 260px) 1fr; gap: 1rem; margin-top: 1.3rem; align-items: start; }
.project { padding: 1rem 1.1rem; border-radius: .8rem; background: var(--blue-pale); }
.project h4 { margin: 0; font-size: 1rem; }
.project-label { margin: .6rem 0 .3rem; color: var(--muted); font-size: .8rem; font-weight: 800; letter-spacing: .06em; text-transform: uppercase; }
.project-deps { margin: 0; padding: 0; list-style: none; font-family: ui-monospace, SFMono-Regular, Consolas, monospace; font-size: .88rem; }
.project-deps li { padding: .15rem 0; }
.memories { display: grid; gap: .7rem; margin: 1.3rem 0 0; padding: 0; list-style: none; }
.step-body .memories { margin-top: 0; }
.memory { padding: .9rem 1.1rem; border: 1px solid var(--border); border-left: 5px solid var(--success); border-radius: .75rem; background: white; transition: background-color 300ms ease, border-color 300ms ease; }
.memory[data-tone="bad"] { border-left-color: var(--danger); background: #fff7f5; }
.memory[data-tone="careful"] { border-left-color: var(--warning); background: #fffaf0; }
.memory[data-tone="gone"] { border-left-color: var(--steel, #718096); background: #F1F4F7; }
.memory[data-tone="neutral"] { border-left-color: var(--blue); }
.memory-top { display: flex; flex-wrap: wrap; align-items: center; gap: .5rem; }
.badge { display: inline-flex; align-items: center; padding: .28rem .65rem; border-radius: 999px; background: #e8f6f0; color: var(--success); font-size: .8rem; font-weight: 850; }
.memory[data-tone="bad"] .badge { background: #fdecea; color: var(--danger); }
.memory[data-tone="careful"] .badge { background: #fff1d6; color: var(--warning); }
.memory[data-tone="gone"] .badge { background: #e2e8ee; color: #3b4a5a; }
.memory-meta { color: var(--muted); font-size: .8rem; }
.memory-text { margin: .45rem 0 0; font-size: 1.08rem; font-weight: 750; color: var(--ink); }
.memory-why { margin: .35rem 0 0; color: var(--text); font-size: .95rem; }
.step-actions { margin-top: 1.2rem; }
.step-result { margin: 1rem 0 0; padding: .85rem 1rem; border-radius: .7rem; background: var(--blue-pale); color: var(--blue-deep); font-weight: 650; }
.demo-footer { margin: 1.4rem 0 0; text-align: center; }
.demo-error { margin: 1rem 0 0; color: var(--danger); font-weight: 700; }

/* How */
.how-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; margin-top: 2rem; }
.how-grid article { padding: 1.4rem; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); }
.how-grid h3 { margin: 0 0 .5rem; font-size: 1.2rem; }
.how-grid p { margin: 0; color: var(--muted); }
.how-note { margin: 1.4rem 0 0; color: var(--blue-deep); font-weight: 700; text-align: center; }

/* More */
.more-links { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1rem; margin-top: 1.6rem; }
.more-card { display: block; padding: 1.3rem 1.4rem; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); text-decoration: none; transition: border-color 160ms ease; }
.more-card:hover { border-color: var(--blue); }
.more-card strong { display: block; color: var(--ink); font-size: 1.15rem; }
.more-card strong::after { content: " →"; color: var(--blue); }
.more-card span { display: block; margin-top: .3rem; color: var(--muted); font-size: .95rem; }

.bottom { display: flex; flex-wrap: wrap; justify-content: space-between; gap: .5rem 1.5rem; padding: 1.6rem max(1.25rem, calc((100% - var(--content)) / 2));
  border-top: 1px solid var(--border); background: white; color: var(--muted); font-size: .9rem; }
.bottom strong { color: var(--ink); }
.noscript { padding: 1rem; text-align: center; }

@media (max-width: 760px) {
  body { font-size: 17px; }
  .top nav { gap: .9rem; }
  .top nav a { font-size: .85rem; }
  .story, .how-grid, .more-links { grid-template-columns: 1fr; }
  .step-body { grid-template-columns: 1fr; }
}
@media (max-width: 420px) {
  .top nav a:first-child { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  :root { scroll-behavior: auto; }
  .button, .memory, .more-card { transition: none; }
}