/* Understand · pre-launch
   1. Fonts   2. Tokens   3. Base   4. Surfaces and layout
   5. Opening   6. Reading columns   7. Glimpse   8. Courses
   9. Beyond and ending   10. Motion   11. 404 */

/* 1. Fonts ---------------------------------------------------------------- */
@font-face {
  font-family: "Bricolage Grotesque";
  src: url("../fonts/bricolage-grotesque.woff2") format("woff2");
  font-weight: 600 800;
  font-display: swap;
}
@font-face {
  font-family: "Figtree";
  src: url("../fonts/figtree.woff2") format("woff2");
  font-weight: 400 600;
  font-display: swap;
}
@font-face {
  font-family: "JetBrains Mono";
  src: url("../fonts/jetbrains-mono.woff2") format("woff2");
  font-weight: 450;
  font-display: swap;
}

/* 2. Tokens --------------------------------------------------------------- */
:root {
  --ink: #17161b;
  --paper: #f6f5f1;
  --signal: #ff6a1f;
  --muted-on-paper: #56545e;
  --muted-on-ink: #a9a7b3;
  --line-on-paper: #dedad0;
  --line-on-ink: #34333b;
  --well: #0f0f12;            /* code sits a step below the ink surface */

  --display: "Bricolage Grotesque", ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  --text: "Figtree", ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "JetBrains Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;

  --size-body: clamp(1.0625rem, 1rem + 0.3vw, 1.1875rem);
  --size-lede: clamp(1.75rem, 1.2rem + 2.6vw, 3rem);
  --size-question: clamp(2.5rem, 1.3rem + 6.2vw, 6.25rem);
  --size-course: clamp(2rem, 1.2rem + 4vw, 4.25rem);

  --gutter: clamp(1.25rem, 5vw, 3rem);
  --measure: 34rem;
  --wide: 68rem;
  --space-section: clamp(5rem, 14vw, 10rem);

  --radius: 10px;
  --ease: cubic-bezier(0.2, 0.7, 0.2, 1);
}

/* 3. Base ----------------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; text-size-adjust: 100%; -webkit-tap-highlight-color: transparent; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 400 var(--size-body)/1.6 var(--text);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
h1, h2, h3, p, ol, pre { margin: 0; }
ol { padding: 0; list-style: none; }
a { color: inherit; }
code, pre { font-family: var(--mono); font-weight: 450; }
p code { font-size: 0.92em; }
::selection { background: var(--signal); color: var(--ink); }
:focus-visible { outline: 2px solid var(--signal); outline-offset: 3px; border-radius: 4px; }

.skip {
  position: absolute; left: var(--gutter); top: -4rem; z-index: 2;
  padding: 0.6rem 0.9rem; border-radius: var(--radius);
  background: var(--paper); color: var(--ink); font-weight: 600; text-decoration: none;
}
.skip:focus { top: 0.75rem; }

/* 4. Surfaces and layout -------------------------------------------------- */
.ink { background: var(--ink); color: var(--paper); }

.mark { width: 1.75rem; height: 1.75rem; flex: none; }
.point { fill: var(--signal); }

.eyebrow {
  font: 600 0.8125rem/1.2 var(--text);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted-on-paper);
}
.ink .eyebrow { color: var(--muted-on-ink); }

.lede {
  font: 700 var(--size-lede)/1.08 var(--display);
  letter-spacing: -0.03em;
  text-wrap: balance;
}
.quiet { color: var(--muted-on-paper); }
.ink .quiet { color: var(--muted-on-ink); }

/* 5. Opening -------------------------------------------------------------- */
.opening {
  min-height: 100vh;
  min-height: 100svh;
  display: grid;
  grid-template-rows: auto 1fr auto;
  padding: max(1.25rem, env(safe-area-inset-top)) max(var(--gutter), env(safe-area-inset-right)) max(1.5rem, env(safe-area-inset-bottom)) max(var(--gutter), env(safe-area-inset-left));
}
.top { display: flex; align-items: center; justify-content: space-between; gap: 1rem; }
.brand {
  display: inline-flex; align-items: center; gap: 0.55rem;
  font: 750 1.2rem/1 var(--display);
  letter-spacing: -0.03em;
  text-decoration: none;
}
.status {
  display: inline-flex; align-items: center; gap: 0.5rem;
  font: 500 0.875rem/1 var(--text);
  color: var(--muted-on-ink);
}
.status-dot { width: 0.4rem; height: 0.4rem; border-radius: 50%; background: var(--signal); }

.question {
  align-self: center;
  justify-self: center;
  width: 100%;
  max-width: var(--wide);
  padding-block: 2rem;
  font: 750 var(--size-question)/0.98 var(--display);
  letter-spacing: -0.04em;
  text-wrap: balance;
}
.question span { display: block; }
.question-before { color: var(--muted-on-ink); }
.question-after { margin-top: 0.12em; }

.continue {
  justify-self: start;
  display: grid; place-items: center;
  width: 3rem; height: 3rem;
  margin-left: -0.75rem;
  border-radius: 50%;
  color: var(--muted-on-ink);
  transition: color 160ms var(--ease), transform 160ms var(--ease);
}
.continue svg { width: 1.5rem; height: 1.5rem; }
.continue:hover { color: var(--paper); transform: translateY(2px); }
.continue:active { transform: translateY(4px); }

/* 6. Reading columns ------------------------------------------------------ */
.column {
  max-width: calc(var(--wide) + 2 * var(--gutter));
  margin-inline: auto;
  padding: var(--space-section) var(--gutter);
}
.column .lede { max-width: 16ch; }
.method .lede { max-width: 18ch; }
.prose { max-width: var(--measure); margin-top: clamp(1.5rem, 4vw, 2.5rem); color: var(--muted-on-paper); }
.prose p + p { margin-top: 1.1em; }
.prose .strong { color: var(--ink); font-weight: 600; }

/* From 56rem the heading and the text sit side by side, like a page spread. */
@media (min-width: 56rem) {
  .column { display: grid; grid-template-columns: minmax(0, 5fr) minmax(0, 6fr); column-gap: 4rem; align-items: start; }
  .column .prose { margin-top: 0.6rem; }
}

/* 7. Glimpse -------------------------------------------------------------- */
.glimpse { padding: var(--space-section) var(--gutter); }
.glimpse-inner { max-width: 38rem; margin-inline: auto; }
.glimpse .lede { margin-top: 0.75rem; }

.quiz { margin-top: clamp(2rem, 6vw, 3.5rem); }
.step + .step { margin-top: clamp(3rem, 9vw, 5rem); }
.turn {
  font: 700 var(--size-lede)/1.08 var(--display);
  letter-spacing: -0.03em;
  margin-bottom: clamp(1.75rem, 5vw, 2.5rem);
  text-wrap: balance;
}
.ask { font-weight: 600; }
.code {
  margin-top: 0.9rem;
  padding: 1.15rem 1.25rem;
  background: var(--well);
  border: 1px solid var(--line-on-ink);
  border-radius: var(--radius);
  font-size: clamp(0.9375rem, 0.85rem + 0.5vw, 1.0625rem);
  line-height: 1.7;
  overflow-x: auto;
  tab-size: 4;
}

.options { display: grid; grid-template-columns: repeat(4, 1fr); gap: 0.6rem; margin-top: 0.9rem; }
.options--wide { grid-template-columns: repeat(3, 1fr); }
@media (max-width: 34rem) { .options--wide { grid-template-columns: 1fr; } }
@media (max-width: 26rem) { .options:not(.options--wide) { grid-template-columns: repeat(2, 1fr); } }
.option {
  min-height: 3.25rem;
  padding: 0.6rem 0.75rem;
  border: 1px solid var(--line-on-ink);
  border-radius: var(--radius);
  background: transparent;
  color: var(--paper);
  font: 450 1rem/1.2 var(--mono);
  white-space: nowrap;
  cursor: pointer;
  transition: border-color 140ms var(--ease), background-color 140ms var(--ease), color 140ms var(--ease), transform 90ms var(--ease);
}
.option:not(:disabled, [aria-disabled="true"]):hover { border-color: var(--muted-on-ink); }
.option:not(:disabled, [aria-disabled="true"]):active { transform: scale(0.98); }
.option:disabled, .option[aria-disabled="true"] { cursor: default; }
/* The chosen answer carries the point, like the mark does. */
.option.is-right { border-color: var(--paper); background: var(--paper); color: var(--ink); }
.option.is-right::before {
  content: ""; display: inline-block; width: 0.5em; height: 0.5em; margin-right: 0.55em;
  border-radius: 50%; background: var(--signal); vertical-align: 0.08em;
}
.option.is-wrong { color: var(--muted-on-ink); text-decoration: line-through; text-decoration-thickness: 1px; }
.step.is-done .option:not(.is-right) { color: var(--muted-on-ink); }

.feedback { margin-top: 1.25rem; color: var(--muted-on-ink); }
.feedback strong, .feedback code { color: var(--paper); }
.feedback strong { font-weight: 600; }
.feedback p + p { margin-top: 1em; }
.coda {
  padding-top: 1.5rem; margin-top: 1.75rem !important;
  border-top: 1px solid var(--line-on-ink);
  color: var(--paper);
  font: 700 clamp(1.25rem, 1rem + 1.2vw, 1.625rem)/1.25 var(--display);
  letter-spacing: -0.02em;
}
/* Sentences break between each other, never inside. */
.coda span, .beyond span { display: inline-block; }

/* Without JavaScript the answers are simply printed. With it, they wait. */
[data-feedback="wrong"] { display: none; }
.js [data-feedback="right"], .js .coda, .js .step[data-step="2"] { display: none; }
.js .step.is-right [data-feedback="right"],
.js .step.is-wrong [data-feedback="wrong"],
.js .step.is-done .coda,
.js .step[data-step="2"].is-open { display: block; }
.js .step.is-right [data-feedback="wrong"] { display: none; }

/* 8. Courses -------------------------------------------------------------- */
.courses {
  max-width: calc(var(--wide) + 2 * var(--gutter));
  margin-inline: auto;
  padding: 0 var(--gutter) var(--space-section);
}
.course-list { margin-top: 1.5rem; border-top: 1px solid var(--line-on-paper); }
.course { padding-block: clamp(1.75rem, 5vw, 3rem); border-bottom: 1px solid var(--line-on-paper); }
.course h3 {
  font: 750 var(--size-course)/1 var(--display);
  letter-spacing: -0.04em;
}
.course p { max-width: 30rem; margin-top: 0.9rem; color: var(--muted-on-paper); }
@media (min-width: 56rem) {
  .course { display: grid; grid-template-columns: minmax(0, 7fr) minmax(0, 5fr); column-gap: 4rem; align-items: end; }
  .course p { margin-top: 0; padding-bottom: 0.35em; }
}

/* 9. Beyond and ending ---------------------------------------------------- */
.beyond {
  max-width: calc(var(--wide) + 2 * var(--gutter));
  margin-inline: auto;
  padding: 0 var(--gutter) var(--space-section);
  font: 700 var(--size-lede)/1.12 var(--display);
  letter-spacing: -0.03em;
}
.beyond span { text-wrap: balance; }

.soon {
  padding: var(--space-section) var(--gutter);
  border-top: 1px solid var(--line-on-paper);
  text-align: center;
}
.soon-lead { max-width: 30rem; margin-inline: auto; color: var(--muted-on-paper); text-wrap: balance; }
.mark--large { width: clamp(4.5rem, 16vw, 6.5rem); height: auto; margin-top: clamp(3rem, 9vw, 5rem); }
.soon-title {
  margin-top: 1.25rem;
  font: 750 clamp(2.25rem, 1.5rem + 4vw, 4rem)/1 var(--display);
  letter-spacing: -0.04em;
}
.soon-status { margin-top: 1rem; font-weight: 600; }
.soon-follow { margin-top: 1.5rem; }
.soon-follow a { font-weight: 600; text-underline-offset: 0.25em; text-decoration-thickness: 1px; }
.soon-follow a:hover { text-decoration-thickness: 2px; }
.soon-domain { margin-top: 0.35rem; color: var(--muted-on-paper); font: 450 0.9375rem/1.4 var(--mono); }

.foot {
  display: flex; flex-wrap: wrap; justify-content: space-between; gap: 0.5rem 2rem;
  max-width: calc(var(--wide) + 2 * var(--gutter));
  margin-inline: auto;
  padding: 1.5rem var(--gutter) max(1.5rem, env(safe-area-inset-bottom));
  color: var(--muted-on-paper);
  font-size: 0.875rem;
}

/* 10. Motion -------------------------------------------------------------- */
@media (prefers-reduced-motion: no-preference) {
  /* The pause before the second line is the point of the page. */
  .question-before { animation: arrive 700ms var(--ease) 150ms both; }
  .question-after { animation: arrive 800ms var(--ease) 1100ms both; }
  .continue { animation: arrive 600ms var(--ease) 2100ms both; }
  .top .point { animation: land 700ms var(--ease) 500ms both; }

  .js [data-reveal] { opacity: 0; transform: translateY(12px); transition: opacity 600ms var(--ease), transform 600ms var(--ease); }
  .js [data-reveal].is-visible { opacity: 1; transform: none; }
  .js [data-reveal="mark"] .point { transform: translateY(-22px); opacity: 0; transition: transform 700ms var(--ease) 250ms, opacity 200ms linear 250ms; }
  .js [data-reveal="mark"].is-visible .point { transform: none; opacity: 1; }

  .js .step.is-right [data-feedback="right"],
  .js .step.is-wrong [data-feedback="wrong"],
  .js .step.is-done .coda { animation: arrive 450ms var(--ease) both; }
  .js .step[data-step="2"].is-open { animation: arrive 600ms var(--ease) 350ms both; }
  .js .step.is-done .coda { animation-delay: 900ms; }
}
@keyframes arrive { from { opacity: 0; transform: translateY(10px); } }
@keyframes land { from { opacity: 0; transform: translateY(-22px); } }

/* 11. 404 ----------------------------------------------------------------- */
.lost {
  min-height: 100vh; min-height: 100svh;
  display: grid; grid-template-rows: auto 1fr;
  padding: max(1.25rem, env(safe-area-inset-top)) var(--gutter) 2rem;
}
.lost-body { align-self: center; max-width: 34rem; }
.lost-body h1 { font: 750 var(--size-lede)/1.05 var(--display); letter-spacing: -0.03em; }
.lost-body p { margin-top: 1rem; color: var(--muted-on-ink); }
.lost-body a { display: inline-block; margin-top: 2rem; font-weight: 600; text-underline-offset: 0.25em; text-decoration-thickness: 1px; }