/* Click Split · graph-paper lab */

:root {
  --ink: #1B2A4A;
  --pen: #2458E6;
  --marker: #E8503A;
  --hi: #FFD84D;
  --green: #2E9E63;
  --gray: #8A97AC;
  --paper: #FDFEFF;
  --grid-line: #DCE8F5;
  --card: #FFFFFF;
  --display: "Bricolage Grotesque", system-ui, sans-serif;
  --body: "IBM Plex Sans", system-ui, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, monospace;
  --serif: "IBM Plex Serif", Georgia, serif;
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  color: var(--ink);
  font-family: var(--body);
  font-size: 16px;
  line-height: 1.55;
  background-color: var(--paper);
  background-image:
    linear-gradient(var(--grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);
  background-size: 24px 24px;
}

.wrap { max-width: 1120px; margin: 0 auto; padding: 0 24px; }

/* ---------- header ---------- */

.site-header { padding: 72px 0 40px; }

.eyebrow {
  font-family: var(--mono);
  font-size: 13px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--pen);
  margin: 0 0 8px;
}

.wordmark {
  font-family: var(--display);
  font-weight: 800;
  font-size: clamp(56px, 9vw, 104px);
  line-height: 0.95;
  letter-spacing: -0.02em;
  margin: 0 0 20px;
}
.wordmark-gap { display: inline-block; width: 0.25em; }

/* the signature: a fraction bar that splits when clicked */
.split-bar {
  display: flex;
  width: min(560px, 100%);
  height: 44px;
  padding: 0;
  border: 2.5px solid var(--ink);
  border-radius: 8px;
  overflow: hidden;
  background: var(--card);
  cursor: pointer;
  box-shadow: 5px 5px 0 rgba(27, 42, 74, 0.12);
}
.split-bar:hover { transform: translate(-1px, -1px); box-shadow: 6px 6px 0 rgba(27, 42, 74, 0.14); }
.split-bar:active { transform: translate(1px, 1px); box-shadow: 3px 3px 0 rgba(27, 42, 74, 0.12); }
.split-bar > span {
  flex: 1;
  background: var(--hi);
  border-right: 2px solid var(--ink);
}
.split-bar > span:last-child { border-right: none; }
.split-bar > span:nth-child(even) { background: #FFE68A; }

.split-caption {
  font-family: var(--mono);
  font-size: 14px;
  color: var(--gray);
  margin: 10px 0 28px;
}
.split-caption strong { color: var(--ink); }

.lede { max-width: 620px; font-size: 17px; margin: 0; }

/* ---------- sections & grid ---------- */

.band { margin: 56px 0 0; }

.band-head {
  display: flex;
  align-items: baseline;
  gap: 16px;
  border-bottom: 2.5px solid var(--ink);
  padding-bottom: 8px;
  margin-bottom: 24px;
}
.band-head h2 {
  font-family: var(--display);
  font-weight: 800;
  font-size: clamp(24px, 3.4vw, 34px);
  letter-spacing: -0.01em;
  margin: 0;
}
.band-head .grades {
  font-family: var(--mono);
  font-size: 13px;
  color: var(--pen);
  white-space: nowrap;
}

.grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
}
@media (max-width: 900px) {
  .grid { grid-template-columns: 1fr; }
}

/* ---------- cards ---------- */

.card {
  background: var(--card);
  border: 2px solid var(--ink);
  border-radius: 10px;
  box-shadow: 6px 6px 0 rgba(27, 42, 74, 0.10);
  padding: 20px 20px 22px;
  display: flex;
  flex-direction: column;
  min-height: 380px;
}

.card-head { display: flex; gap: 12px; align-items: baseline; margin-bottom: 4px; }
.card-index {
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 600;
  color: var(--card);
  background: var(--ink);
  border-radius: 6px;
  padding: 2px 7px;
  flex: none;
}
.card h3 {
  font-family: var(--display);
  font-weight: 800;
  font-size: 21px;
  margin: 0;
  letter-spacing: -0.01em;
}
.card .prompt { font-size: 14px; color: var(--gray); margin: 2px 0 14px; }

.stage { flex: 1; display: flex; flex-direction: column; gap: 12px; }
.stage svg { width: 100%; height: auto; display: block; touch-action: none; }
.stage .loading { font-family: var(--mono); font-size: 13px; color: var(--gray); }

/* ---------- controls ---------- */

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
  align-items: center;
}

.slider { display: flex; align-items: center; gap: 8px; font-size: 13px; }
.slider-label { font-weight: 600; white-space: nowrap; }
.slider-value {
  font-family: var(--mono);
  font-size: 13px;
  min-width: 44px;
  color: var(--pen);
}

input[type="range"] {
  appearance: none;
  -webkit-appearance: none;
  width: 120px;
  height: 22px;
  background: transparent;
  cursor: pointer;
}
input[type="range"]::-webkit-slider-runnable-track {
  height: 4px; border-radius: 2px; background: var(--ink);
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px; height: 18px; border-radius: 50%;
  background: var(--marker);
  border: 2.5px solid var(--ink);
  margin-top: -7px;
}
input[type="range"]::-moz-range-track {
  height: 4px; border-radius: 2px; background: var(--ink);
}
input[type="range"]::-moz-range-thumb {
  width: 13px; height: 13px; border-radius: 50%;
  background: var(--marker);
  border: 2.5px solid var(--ink);
}

input[type="number"], select {
  font-family: var(--mono);
  font-size: 14px;
  color: var(--ink);
  border: 2px solid var(--ink);
  border-radius: 6px;
  padding: 4px 8px;
  background: var(--card);
  max-width: 110px;
}

button.btn {
  font-family: var(--body);
  font-weight: 600;
  font-size: 13px;
  color: var(--ink);
  background: var(--hi);
  border: 2px solid var(--ink);
  border-radius: 7px;
  padding: 6px 12px;
  cursor: pointer;
  box-shadow: 3px 3px 0 rgba(27, 42, 74, 0.14);
}
button.btn:hover { transform: translate(-1px, -1px); box-shadow: 4px 4px 0 rgba(27, 42, 74, 0.16); }
button.btn:active { transform: translate(1px, 1px); box-shadow: 1px 1px 0 rgba(27, 42, 74, 0.14); }
button.btn:disabled { opacity: 0.35; cursor: not-allowed; transform: none; box-shadow: 3px 3px 0 rgba(27, 42, 74, 0.08); }
button.btn.quiet { background: var(--card); }

label.check { display: inline-flex; gap: 6px; align-items: center; font-size: 13px; font-weight: 600; cursor: pointer; }
label.check input { accent-color: var(--pen); width: 16px; height: 16px; }

:focus-visible { outline: 3px solid var(--pen); outline-offset: 2px; border-radius: 4px; }

/* ---------- readouts ---------- */

.readout {
  font-family: var(--mono);
  font-size: 15px;
  background: rgba(220, 232, 245, 0.45);
  border-left: 4px solid var(--pen);
  border-radius: 0 6px 6px 0;
  padding: 8px 12px;
}
.readout .good { color: var(--green); font-weight: 600; }
.readout .bad { color: var(--marker); font-weight: 600; }
.readout .warn { color: #B78A00; font-weight: 600; }

.formula {
  font-family: var(--serif);
  font-style: italic;
  font-size: 17px;
}

.worksheet {
  font-family: var(--mono);
  font-size: 16px;
  line-height: 1.45;
  background: rgba(220, 232, 245, 0.45);
  border-radius: 8px;
  padding: 12px 16px;
  margin: 0;
  overflow-x: auto;
  min-height: 150px;
}
.worksheet .hot { background: var(--hi); border-radius: 3px; }

.step-caption { font-size: 14px; min-height: 42px; margin: 0; }
.step-caption strong { color: var(--pen); }

/* ---------- svg conventions ---------- */

.handle { cursor: grab; }
.handle:active { cursor: grabbing; }

/* ---------- footer ---------- */

.site-footer {
  margin-top: 80px;
  border-top: 2.5px solid var(--ink);
  padding: 28px 0 48px;
  font-size: 14px;
}

.noscript { font-family: var(--mono); color: var(--marker); padding: 40px 0; }