/* Layout: a Maths exercise book. Quiet paper, blue-biro ink for interaction, red pen only for
   "potentially at risk". Form column on the left, a sticky squared-paper result sheet on the right. */
:root {
  --paper: #f6f7f9;
  --sheet: #ffffff;
  --ink: #1a2132;
  --muted: #687185;
  --rule: #dfe3ea;
  --grid: #e9edf3;
  --biro: #2347c8;
  --biro-wash: #eaefff;
  --redpen: #c8372c;
  --redpen-wash: #fdeceb;

  --display: "Bricolage Grotesque", "Avenir Next", "Segoe UI", system-ui, sans-serif;
  --body: "Atkinson Hyperlegible", "Segoe UI", system-ui, -apple-system, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;

  --step--1: 0.8125rem;
  --step-0: 1rem;
  --step-1: 1.25rem;
  --step-2: clamp(1.6rem, 1.2rem + 1.6vw, 2.25rem);
  --step-big: clamp(4rem, 3rem + 4vw, 6rem);
  --radius: 10px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #0d1220; --sheet: #141a2a; --ink: #e5e8f0; --muted: #929ab0; --rule: #263049; --grid: #1b2336;
    --biro: #86a6ff; --biro-wash: #1c2950; --redpen: #ff8174; --redpen-wash: #3a1d1f; color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #0d1220; --sheet: #141a2a; --ink: #e5e8f0; --muted: #929ab0; --rule: #263049; --grid: #1b2336;
  --biro: #86a6ff; --biro-wash: #1c2950; --redpen: #ff8174; --redpen-wash: #3a1d1f; color-scheme: dark;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font: 400 var(--step-0)/1.55 var(--body);
  padding-inline: clamp(16px, 4vw, 48px); padding-block: 0 72px;
}
h1, h2 { font-family: var(--display); font-weight: 800; letter-spacing: -0.02em; text-wrap: balance; margin: 0; }
h1 { font-size: var(--step-2); line-height: 1.1; }
h2 { font-size: var(--step-1); margin-block: 32px 12px; }
p { margin: 0; }
button, input { font: inherit; color: inherit; }
:focus-visible { outline: 2px solid var(--biro); outline-offset: 2px; border-radius: 6px; }
.visually-hidden { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.eyebrow { font: 500 var(--step--1)/1.2 var(--mono); letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted); }

/* ---------- header ---------- */
.top {
  display: flex; align-items: center; justify-content: space-between; gap: 16px; flex-wrap: wrap;
  max-width: 1180px; margin-inline: auto; padding-block: 22px;
}
.brand { display: flex; align-items: center; gap: 10px; }
.mark {
  display: grid; place-items: center; width: 34px; height: 34px; border-radius: 50%;
  border: 1.5px solid var(--redpen); color: var(--redpen);
  font: 600 0.8rem/1 var(--mono); transform: rotate(-8deg);
}
.name { font: 800 1.15rem/1 var(--display); letter-spacing: -0.01em; }
.views { display: flex; gap: 4px; }
.views button {
  border: 0; background: none; padding: 8px 12px; border-radius: 999px; cursor: pointer; color: var(--muted);
}
.views button[aria-selected="true"] { color: var(--ink); background: var(--sheet); box-shadow: inset 0 0 0 1px var(--rule); }
.views button:hover { color: var(--ink); }

main { max-width: 1180px; margin-inline: auto; }

/* ---------- student view ---------- */
.student {
  display: grid; grid-template-columns: minmax(0, 1fr) minmax(300px, 400px);
  grid-template-areas: "intro sheet" "form sheet"; column-gap: clamp(24px, 5vw, 72px); row-gap: 28px;
  align-items: start;
}
.student .intro { grid-area: intro; }
.intro { display: grid; gap: 10px; max-width: 62ch; padding-block: 16px 0; }
.intro p { color: var(--muted); }
.form { grid-area: form; display: grid; gap: 36px; min-width: 0; }

.group { display: grid; gap: 4px; border: 0; padding: 0; margin: 0; min-width: 0; }
.group > legend { padding: 0 0 8px; }
.row {
  display: grid; grid-template-columns: 190px minmax(0, 1fr); gap: 8px 20px; align-items: center;
  padding-block: 10px; border-top: 1px solid var(--rule);
}
.row > .label { font-size: 0.95rem; }
.row > .label small { display: block; color: var(--muted); font: 400 0.75rem/1.3 var(--mono); }

/* pills: one choice from a short list */
.pills { display: flex; flex-wrap: wrap; gap: 6px; border: 0; margin: 0; padding: 0; min-width: 0; }
.pills label, .seg label, .flags label { position: relative; cursor: pointer; }
.pills input, .seg input, .flags input { position: absolute; opacity: 0; inset: 0; margin: 0; cursor: pointer; }
.pills span {
  display: inline-block; padding: 5px 12px; border-radius: 999px; border: 1px solid var(--rule);
  background: var(--sheet); font-size: 0.9rem; line-height: 1.3; transition: border-color .15s, background .15s, color .15s;
}
.pills label:hover span { border-color: var(--muted); }
.pills input:checked + span { border-color: var(--biro); color: var(--biro); background: var(--biro-wash); }
.pills input:focus-visible + span, .seg input:focus-visible + span, .flags input:focus-visible + span,
.scale input:focus-visible + span { outline: 2px solid var(--biro); outline-offset: 2px; }

/* 1–5 rating scale */
.scale { display: grid; gap: 4px; border: 0; margin: 0; padding: 0; min-width: 0; }
.scale .dots { display: flex; gap: 8px; }
.scale label { position: relative; cursor: pointer; }
.scale input { position: absolute; opacity: 0; inset: 0; margin: 0; cursor: pointer; }
.scale .dots span {
  display: grid; place-items: center; width: 34px; height: 34px; border-radius: 50%;
  border: 1px solid var(--rule); background: var(--sheet); font: 500 0.85rem/1 var(--mono);
  transition: border-color .15s, background .15s, color .15s;
}
.scale .dots label:hover span { border-color: var(--muted); }
.scale .dots input:checked + span { border-color: var(--biro); background: var(--biro); color: var(--sheet); }
.scale .ends { display: flex; justify-content: space-between; gap: 12px; width: calc(5 * 34px + 4 * 8px); }
.scale .ends span { font: 400 0.72rem/1.2 var(--mono); color: var(--muted); white-space: nowrap; }

/* stepper for whole numbers */
.stepper { display: inline-flex; align-items: center; border: 1px solid var(--rule); border-radius: 999px; background: var(--sheet); }
.stepper button { width: 34px; height: 34px; border: 0; background: none; border-radius: 50%; cursor: pointer; font-size: 1.1rem; color: var(--muted); }
.stepper button:hover { color: var(--biro); }
.stepper input {
  width: 3.5ch; border: 0; background: none; text-align: center; font: 500 1rem/1 var(--mono);
  font-variant-numeric: tabular-nums; -moz-appearance: textfield; appearance: textfield;
}
.stepper input::-webkit-outer-spin-button, .stepper input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.range-note { margin-left: 10px; font: 400 0.75rem/1 var(--mono); color: var(--muted); }

/* yes/no flags as on/off chips */
.flags { display: flex; flex-wrap: wrap; gap: 8px; padding-top: 12px; border-top: 1px solid var(--rule); }
.flags span {
  display: inline-flex; align-items: center; gap: 8px; padding: 6px 12px 6px 10px; border-radius: 999px;
  border: 1px solid var(--rule); background: var(--sheet); font-size: 0.9rem; transition: border-color .15s, background .15s, color .15s;
}
.flags span::before { content: ""; width: 9px; height: 9px; border-radius: 50%; border: 1.5px solid var(--muted); }
.flags label:hover span { border-color: var(--muted); }
.flags input:checked + span { border-color: var(--biro); color: var(--biro); background: var(--biro-wash); }
.flags input:checked + span::before { background: var(--biro); border-color: var(--biro); }
.flags-hint { font: 400 0.75rem/1.3 var(--mono); color: var(--muted); padding-top: 4px; }

/* ---------- result sheet ---------- */
.sheet {
  grid-area: sheet; position: sticky; top: calc(env(safe-area-inset-top, 0px) + 20px);
  display: grid; gap: 22px; padding: 26px 24px 24px; border-radius: 16px;
  background-color: var(--sheet);
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 16px 16px; background-position: -1px -1px;
  box-shadow: 0 0 0 1px var(--rule), 0 18px 40px -28px rgba(20, 30, 60, .35);
  margin-top: 16px;
}
.knows { display: grid; gap: 8px; }
.seg { display: grid; grid-template-columns: 1fr 1fr; padding: 3px; border-radius: 999px; background: var(--paper); box-shadow: inset 0 0 0 1px var(--rule); }
.seg span { display: block; text-align: center; padding: 6px 10px; border-radius: 999px; font-size: 0.85rem; color: var(--muted); transition: background .15s, color .15s; }
.seg input:checked + span { background: var(--sheet); color: var(--ink); box-shadow: 0 0 0 1px var(--rule); }

.readout { display: grid; gap: 6px; justify-items: start; }
.grade { display: flex; align-items: baseline; gap: 10px; font-family: var(--display); font-variant-numeric: tabular-nums; }
#grade { font-size: var(--step-big); font-weight: 800; line-height: 0.95; letter-spacing: -0.04em; }
.of { font-size: 1.4rem; color: var(--muted); font-weight: 400; }
.chip {
  display: inline-flex; align-items: center; gap: 8px; padding: 4px 12px; border-radius: 999px;
  font: 500 0.8rem/1.4 var(--mono); letter-spacing: 0.02em; border: 1px solid var(--rule); color: var(--muted); background: var(--sheet);
}
.chip.ok { color: var(--ink); border-color: var(--ink); }
.chip.risk { color: var(--sheet); background: var(--redpen); border-color: var(--redpen); }
.sheet.is-risk #grade { color: var(--redpen); }

.ruler { width: 100%; height: auto; overflow: visible; }
.ruler .below { fill: var(--redpen-wash); }
.ruler .band { fill: var(--biro-wash); }
.ruler .tick { stroke: var(--muted); stroke-width: 1; }
.ruler .tick.major { stroke: var(--ink); }
.ruler .num { fill: var(--muted); font: 500 13px var(--mono); text-anchor: middle; }
.ruler .pass { stroke: var(--redpen); stroke-width: 1.5; stroke-dasharray: 3 3; }
.ruler .pass-label { fill: var(--redpen); font: 600 13px var(--mono); text-anchor: middle; }
.ruler .marker line { stroke: var(--biro); stroke-width: 2.5; }
.ruler .marker circle { fill: var(--sheet); stroke: var(--biro); stroke-width: 2.5; }
.sheet.is-risk .ruler .marker line, .sheet.is-risk .ruler .marker circle { stroke: var(--redpen); }
#marker, #band { transition: transform .45s cubic-bezier(.2, .8, .2, 1); }
.legend { display: flex; gap: 8px; align-items: flex-start; font: 400 0.75rem/1.4 var(--mono); color: var(--muted); margin-top: -12px; }
.key { flex: none; width: 14px; height: 10px; margin-top: 2px; border-radius: 2px; }
.key-band { background: var(--biro-wash); box-shadow: inset 0 0 0 1px var(--biro); }

.advice { font-size: 0.95rem; }
.facts { display: grid; gap: 8px; margin: 0; padding-top: 16px; border-top: 1px solid var(--rule); }
.facts div { display: flex; justify-content: space-between; gap: 16px; }
.facts dt { color: var(--muted); font-size: 0.85rem; }
.facts dd { margin: 0; font: 500 0.85rem/1.4 var(--mono); text-align: right; font-variant-numeric: tabular-nums; white-space: nowrap; }
.warn { font-size: 0.85rem; color: var(--redpen); }

.mini { display: none; }

/* ---------- other views ---------- */
.panel { display: grid; gap: 22px; padding-block: 16px 0; max-width: 900px; }
.actions { display: flex; flex-wrap: wrap; gap: 10px; }
.btn {
  display: inline-flex; align-items: center; padding: 9px 18px; border-radius: 999px; cursor: pointer;
  font-size: 0.95rem; border: 1px solid var(--rule); background: var(--sheet); color: var(--ink); justify-self: start;
}
.btn:hover { border-color: var(--muted); }
.btn.solid { background: var(--biro); border-color: var(--biro); color: var(--sheet); }
.btn.solid:hover { filter: brightness(1.08); }
.summary { color: var(--muted); }
.summary strong { color: var(--ink); }
.table-wrap { overflow-x: auto; min-width: 0; }
.table { width: 100%; border-collapse: collapse; font-size: 0.92rem; }
.table th { text-align: left; font: 500 var(--step--1)/1.3 var(--mono); letter-spacing: 0.04em; text-transform: uppercase; color: var(--muted); padding: 10px 12px; border-bottom: 1px solid var(--ink); white-space: nowrap; }
.table td { padding: 10px 12px; border-bottom: 1px solid var(--rule); vertical-align: top; }
.table .num { text-align: right; font-family: var(--mono); font-variant-numeric: tabular-nums; }
.table td.notes { color: var(--muted); font-size: 0.85rem; min-width: 16ch; }
.table .chip { white-space: nowrap; }
.compare th:first-child, .compare td:first-child { color: var(--muted); }
.compare td { font-family: var(--mono); font-variant-numeric: tabular-nums; }
.compare thead th { text-transform: none; letter-spacing: 0; font-size: 0.9rem; color: var(--ink); font-family: var(--body); font-weight: 700; }
.note { color: var(--muted); font-size: 0.9rem; max-width: 70ch; }
.limits { margin: 0; padding-left: 1.1rem; display: grid; gap: 8px; max-width: 70ch; }
.limits li::marker { color: var(--redpen); }

.foot { max-width: 1180px; margin: 56px auto 0; padding-top: 16px; border-top: 1px solid var(--rule); color: var(--muted); font: 400 0.8rem/1.4 var(--mono); }

/* ---------- narrow screens ---------- */
@media (max-width: 860px) {
  .student { grid-template-columns: minmax(0, 1fr); grid-template-areas: "intro" "sheet" "form"; }
  .sheet { position: static; margin-top: 0; }
  .row { grid-template-columns: minmax(0, 1fr); }
  .mini {
    display: flex; position: fixed; left: 50%; transform: translateX(-50%);
    bottom: calc(env(safe-area-inset-bottom, 0px) + 14px); gap: 10px; align-items: center;
    padding: 8px 16px; border-radius: 999px; background: var(--ink); color: var(--paper);
    font: 600 1rem/1 var(--mono); font-variant-numeric: tabular-nums; box-shadow: 0 10px 30px -12px rgba(0,0,0,.5);
  }
  .mini #mini-status { font-weight: 400; font-size: 0.8rem; opacity: .8; }
  .mini.is-risk { background: var(--redpen); }
  .mini:not(.away), .mini[data-hidden="true"] { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; }
}