:root {
  --paper: #FCFCF8;
  --grid: #DCE6EE;
  --ink: #1F2A44;
  --ink-soft: #5B6578;
  --leaf: #1E7A4C;
  --leaf-bg: #E4F3EA;
  --marigold: #F2B632;
  --marigold-bg: #FFF4D6;
  --clay: #C4442A;
  --clay-bg: #FBE7E2;
  --line: #C9D3DD;
  --radius: 6px;
  --sans: "Atkinson Hyperlegible", "Segoe UI", system-ui, sans-serif;
  --display: "Fraunces", Georgia, serif;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: var(--sans);
  color: var(--ink);
  background-color: var(--paper);
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 24px 24px;
  line-height: 1.5;
  font-size: 17px;
}
button { font: inherit; }
h1, h2, h3 { font-family: var(--display); font-weight: 800; line-height: 1.15; margin: 0 0 .4em; }
h1 { font-size: 2.2rem; }
h2 { font-size: 1.5rem; }
h3 { font-size: 1.15rem; }
p { margin: 0 0 .9em; max-width: 68ch; }

.topbar {
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  padding: 12px 20px; background: var(--ink); color: #fff;
}
.brand { color: #fff; text-decoration: none; font-family: var(--display); font-weight: 800; font-size: 1.15rem; }
.brand span { font-family: var(--sans); font-weight: 400; opacity: .75; font-size: .9rem; margin-left: 8px; }
.topbar nav { display: flex; align-items: center; gap: 18px; font-size: .95rem; }
.topbar nav a { color: #fff; text-decoration: none; border-bottom: 2px solid transparent; }
.topbar nav a:hover, .topbar nav a:focus-visible { border-color: var(--marigold); }
.who { opacity: .75; }
.linkbtn { background: none; border: 1px solid rgba(255,255,255,.5); color: #fff; padding: 4px 10px; border-radius: var(--radius); cursor: pointer; }
.linkbtn:hover { border-color: #fff; }

main { max-width: 780px; margin: 0 auto; padding: 32px 20px 80px; }
.sheet { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 28px; box-shadow: 0 1px 0 var(--line); }
.sheet + .sheet { margin-top: 20px; }

/* login */
.login { max-width: 400px; margin: 48px auto; }
.login label { display: block; font-weight: 700; margin: 14px 0 4px; }
.login input { width: 100%; padding: 10px 12px; font: inherit; border: 1.5px solid var(--line); border-radius: var(--radius); }
.login input:focus { outline: 2px solid var(--marigold); border-color: var(--ink); }
.error { color: var(--clay); background: var(--clay-bg); padding: 8px 12px; border-radius: var(--radius); margin: 10px 0; }

.btn { background: var(--ink); color: #fff; border: 0; padding: 10px 18px; border-radius: var(--radius); cursor: pointer; font-weight: 700; }
.btn:hover { background: #2c3a5c; }
.btn:disabled { opacity: .45; cursor: not-allowed; }
.btn.secondary { background: #fff; color: var(--ink); border: 1.5px solid var(--ink); }
.btn.secondary:hover { background: var(--marigold-bg); }
.btn:focus-visible, .opt:focus-visible, .chip:focus-visible, .slot:focus-visible { outline: 3px solid var(--marigold); outline-offset: 2px; }

/* section list */
.sections { list-style: none; padding: 0; margin: 20px 0 0; display: grid; gap: 12px; }
.sections li { border: 1px solid var(--line); border-radius: var(--radius); padding: 16px 18px; background: #fff; display: grid; grid-template-columns: 1fr auto; gap: 8px 16px; align-items: center; }
.sections .meta { color: var(--ink-soft); font-size: .92rem; grid-column: 1 / -1; }
.sections .score-pill { font-weight: 700; padding: 3px 10px; border-radius: 999px; background: var(--marigold-bg); }
.sections .score-pill.good { background: var(--leaf-bg); color: var(--leaf); }
.sections .score-pill.low { background: var(--clay-bg); color: var(--clay); }
.total { display: flex; align-items: baseline; gap: 14px; margin-top: 8px; }
.total .big { font-family: var(--display); font-size: 3rem; font-weight: 800; line-height: 1; }
.total .sub { color: var(--ink-soft); }

/* quiz */
.progress { display: flex; align-items: center; gap: 12px; color: var(--ink-soft); font-size: .92rem; margin-bottom: 18px; }
.progress .bar { flex: 1; height: 6px; background: var(--grid); border-radius: 3px; overflow: hidden; }
.progress .bar i { display: block; height: 100%; background: var(--leaf); transition: width .3s; }
.prompt { font-size: 1.15rem; font-weight: 700; margin: 0 0 16px; max-width: 70ch; }
.scenario { background: var(--marigold-bg); border-left: 4px solid var(--marigold); padding: 12px 16px; margin-bottom: 18px; border-radius: 0 var(--radius) var(--radius) 0; }
.scenario p { margin: 0; }

.opts { display: grid; gap: 10px; margin: 0; padding: 0; list-style: none; }
.opt { text-align: left; width: 100%; padding: 12px 14px; border: 1.5px solid var(--line); border-radius: var(--radius); background: #fff; cursor: pointer; color: var(--ink); }
.opt:hover { border-color: var(--ink); }
.opt.selected { border-color: var(--ink); background: var(--marigold-bg); }
.opt.correct { border-color: var(--leaf); background: var(--leaf-bg); }
.opt.wrong { border-color: var(--clay); background: var(--clay-bg); }

/* match & sort (drag and drop) */
.dnd { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
@media (max-width: 640px) { .dnd { grid-template-columns: 1fr; } }
.pool, .slots { display: grid; gap: 8px; align-content: start; }
.pool { padding: 10px; border: 1.5px dashed var(--line); border-radius: var(--radius); min-height: 60px; background: #fafbfc; }
.chip { padding: 10px 12px; background: #fff; border: 1.5px solid var(--ink); border-radius: var(--radius); cursor: grab; user-select: none; touch-action: none; }
.chip.dragging, .chip.picked { background: var(--marigold-bg); box-shadow: 0 2px 8px rgba(31,42,68,.2); }
.slot { border: 1.5px solid var(--line); border-radius: var(--radius); padding: 8px 10px; background: #fff; min-height: 64px; }
.slot .term { font-weight: 700; margin-bottom: 6px; }
.slot .drop { min-height: 40px; border: 1.5px dashed var(--line); border-radius: 4px; display: grid; gap: 6px; padding: 4px; }
.slot.over .drop { border-color: var(--leaf); background: var(--leaf-bg); }
.slot.correct { border-color: var(--leaf); background: var(--leaf-bg); }
.slot.wrong { border-color: var(--clay); background: var(--clay-bg); }
.slot .drop .chip { cursor: grab; }
.hint { color: var(--ink-soft); font-size: .92rem; margin: -6px 0 12px; }

/* feedback */
.feedback { margin-top: 18px; padding: 14px 16px; border-radius: var(--radius); border-left: 5px solid; }
.feedback.ok { background: var(--leaf-bg); border-color: var(--leaf); }
.feedback.no { background: var(--clay-bg); border-color: var(--clay); }
.feedback h3 { margin-bottom: 6px; }
.feedback ul { margin: 6px 0 0; padding-left: 20px; }
.feedback li { margin-bottom: 6px; }
.actions { display: flex; gap: 12px; margin-top: 20px; flex-wrap: wrap; }

/* data table */
table.data { border-collapse: collapse; margin: 0 0 18px; font-size: .95rem; }
table.data caption { font-weight: 700; text-align: left; padding-bottom: 6px; }
table.data th, table.data td { border: 1px solid var(--ink); padding: 5px 12px; text-align: left; }
table.data th { background: var(--grid); }
table.data td:last-child { text-align: right; }

/* graphs */
.graph-wrap { margin: 0 0 16px; }
.graph { width: 100%; max-width: 640px; height: auto; display: block; touch-action: none; user-select: none; }
.graph .gridline { stroke: var(--grid); stroke-width: 1; }
.graph .axis { stroke: var(--ink); stroke-width: 2; }
.graph text { font-family: var(--sans); fill: var(--ink); }
.graph .tick { font-size: 13px; }
.graph .axislabel { font-size: 14px; font-weight: 700; }
.graph .gtitle { font-family: var(--display); font-size: 17px; font-weight: 800; }
.graph .hit { fill: transparent; cursor: crosshair; }
.graph .pt { fill: var(--ink); stroke: #fff; stroke-width: 2; cursor: pointer; }
.graph .pt.good { fill: var(--leaf); }
.graph .pt.bad { fill: var(--clay); }
.graph .pt.ghost { fill: none; stroke: var(--leaf); stroke-dasharray: 3 3; pointer-events: none; }
.graph .pline { fill: none; stroke: var(--ink); stroke-width: 2; }
.graph .bar { fill: var(--marigold); stroke: var(--ink); stroke-width: 1.5; cursor: ns-resize; }
.graph .bar.good { fill: var(--leaf); }
.graph .bar.bad { fill: var(--clay); }
.graph .bar-hit { fill: transparent; cursor: ns-resize; }
.graph .val { font-size: 13px; font-weight: 700; text-anchor: middle; }
.graph .target { stroke: var(--leaf); stroke-width: 2; stroke-dasharray: 4 3; }
.graph .cat { font-size: 12px; text-anchor: middle; }
.graph .hover { fill: var(--ink-soft); font-size: 12px; pointer-events: none; }
.static-chart .bar { cursor: default; }

/* grades */
table.grades { width: 100%; border-collapse: collapse; margin-top: 12px; font-size: .95rem; }
table.grades th, table.grades td { text-align: left; padding: 8px 6px; border-bottom: 1px solid var(--line); }
table.grades th { color: var(--ink-soft); font-weight: 700; }
.empty { color: var(--ink-soft); }

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

/* hints, video, fun */
.hintbox { margin-top: 18px; padding: 12px 14px; background: var(--marigold-bg); border: 1px dashed var(--marigold); border-radius: var(--radius); }
.hints { margin: 0 0 10px; padding-left: 20px; }
.hints li { margin-bottom: 6px; }
.nudge { color: var(--ink-soft); font-size: .92rem; margin: 0 0 8px; }
.btn.small { padding: 6px 12px; font-size: .92rem; }
.video { margin: 0 0 16px; border: 1px solid var(--line); border-radius: var(--radius); background: #fff; }
.video summary { cursor: pointer; padding: 10px 14px; font-weight: 700; list-style: none; }
.video summary::before { content: "\25B6"; margin-right: 8px; font-size: .8em; color: var(--clay); }
.video[open] summary::before { content: "\25BC"; }
.video-frame { padding: 0 14px; }
.video-frame iframe { width: 100%; aspect-ratio: 16 / 9; border: 0; border-radius: 4px; }
.video .hint { padding: 6px 14px 10px; margin: 0; }
.streak { color: var(--leaf); font-family: var(--sans); font-weight: 700; font-size: .85em; margin-left: 6px; }
.score-pill.mastered { background: var(--ink); color: var(--marigold); }

/* stats & review */
.misses { display: grid; gap: 10px; margin: 6px 0 12px; }
.miss { border-left: 4px solid var(--clay); background: var(--clay-bg); padding: 10px 14px; border-radius: 0 var(--radius) var(--radius) 0; }
.miss-q { font-weight: 700; margin-bottom: 4px; }
.miss p { margin: 0 0 4px; }
.weak { margin: 14px 0 4px; }
.weak ul { margin: 0; padding-left: 20px; }
.linkbtn.dark { color: var(--ink); border-color: var(--ink); }
table.grades tr.detail td { background: #fafbfc; padding: 12px; }