/* Light mode only (Master Specification, requirement 2). */
:root {
  --bg: #f3f5f9;
  --surface: #fff;
  --border: #dde3ec;
  --text: #1b2434;
  --muted: #5b6980;
  --primary: #2b7de9;
  --primary-dark: #1f66c4;
  --soft: #eaf2fd;
  --good: #1d7a46;
  --good-bg: #e3f5ea;
  --warn: #9a5b00;
  --warn-bg: #fff3d9;
  --bad: #b3261e;
  --bad-bg: #fde8e6;
  color-scheme: light;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font: 14px/1.5 "Segoe UI", system-ui, -apple-system, sans-serif;
  color: var(--text);
  background: var(--bg);
  display: grid;
  grid-template: 56px 1fr / 210px 1fr;
  min-height: 100vh;
}
h1 { font-size: 22px; margin: 0; }
h2 { font-size: 16px; margin: 0 0 12px; }
h3 { font-size: 14px; margin: 0 0 8px; }
h4 { font-size: 12px; margin: 0 0 6px; text-transform: uppercase; letter-spacing: .04em; color: var(--muted); }
a { color: var(--primary-dark); }
p { margin: 0 0 10px; }

.topbar {
  grid-column: 1 / -1;
  display: flex; align-items: center; gap: 20px;
  padding: 0 20px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 5;
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 600; font-size: 16px; color: var(--text); text-decoration: none; width: 190px; }
.logo { display: grid; place-items: center; width: 28px; height: 28px; border-radius: 8px; background: var(--primary); color: #fff; font-weight: 700; }
#search { flex: 1; max-width: 420px; }
.who { margin-left: auto; color: var(--muted); display: flex; align-items: center; gap: 8px; }

.sidebar { background: var(--surface); border-right: 1px solid var(--border); padding: 14px 10px; }
.sidebar a {
  display: flex; align-items: center; gap: 10px;
  padding: 8px 10px; border-radius: 8px;
  color: var(--text); text-decoration: none; margin-bottom: 2px;
}
.sidebar a:hover { background: var(--bg); }
.sidebar a.active { background: var(--soft); color: var(--primary-dark); font-weight: 600; }
.sidebar svg { width: 18px; height: 18px; flex: none; }
.sidebar .foot { margin-top: 24px; padding: 10px; font-size: 12px; color: var(--muted); }

main { padding: 24px 28px 60px; min-width: 0; }

input, select, textarea {
  font: inherit; color: inherit;
  padding: 7px 10px;
  border: 1px solid var(--border); border-radius: 8px;
  background: #fff; width: 100%;
}
select { width: auto; }
textarea { resize: vertical; }
input:focus, select:focus, textarea:focus, button:focus-visible { outline: 2px solid var(--primary); outline-offset: 1px; }
input[readonly], textarea[readonly] { background: #f8f9fb; }
input[type=checkbox], input[type=radio] { width: auto; }

.btn {
  font: inherit; font-weight: 500;
  padding: 7px 14px; border-radius: 8px;
  border: 1px solid var(--border); background: #fff; color: var(--text);
  cursor: pointer; white-space: nowrap;
}
.btn:hover { background: var(--bg); }
.btn.primary { background: var(--primary); border-color: var(--primary); color: #fff; }
.btn.primary:hover { background: var(--primary-dark); }
.btn.small { padding: 3px 9px; font-size: 12px; }
.btn.danger { color: var(--bad); }
.btn:disabled { opacity: .5; cursor: default; }

.page-head { display: flex; align-items: flex-end; justify-content: space-between; gap: 16px; margin-bottom: 18px; flex-wrap: wrap; }
.crumb { font-size: 12px; color: var(--muted); text-decoration: none; }
.actions { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.muted { color: var(--muted); }
.card { background: var(--surface); border: 1px solid var(--border); border-radius: 12px; padding: 18px; margin-bottom: 16px; }
.banner { padding: 10px 14px; border-radius: 10px; margin-bottom: 12px; background: var(--soft); border: 1px solid #cfe0f8; }
.banner.warn { background: var(--warn-bg); border-color: #f2dba6; }
.banner.good { background: var(--good-bg); border-color: #bfe5cd; }
.error { color: var(--bad); }

.pill { display: inline-block; padding: 1px 9px; border-radius: 999px; font-size: 12px; background: var(--bg); border: 1px solid var(--border); color: var(--muted); white-space: nowrap; }
.pill.good, .pill.plan, .pill.added { background: var(--good-bg); border-color: #bfe5cd; color: var(--good); }
.pill.warn, .pill.rushed, .pill.changed { background: var(--warn-bg); border-color: #f2dba6; color: var(--warn); }
.pill.bad, .pill.reteach, .pill.removed { background: var(--bad-bg); border-color: #f5c6c2; color: var(--bad); }
.pill.blue { background: var(--soft); border-color: #cfe0f8; color: var(--primary-dark); }

/* Units home */
.home { display: grid; grid-template-columns: 190px 1fr; gap: 24px; }
.rail-group { margin-bottom: 18px; }
.check { display: flex; align-items: center; gap: 8px; padding: 2px 0; cursor: pointer; }
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 14px; }
.unit-card { display: block; color: inherit; text-decoration: none; margin: 0; }
.unit-card:hover { border-color: var(--primary); }
.unit-card h3 { font-size: 15px; }
.unit-card .pills { display: flex; gap: 6px; flex-wrap: wrap; margin-top: 10px; }
.form-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 12px; margin-bottom: 12px; }
.form-row select { width: 100%; }


/* Unit page */
.tabs { display: flex; gap: 4px; border-bottom: 1px solid var(--border); margin-bottom: 16px; }
.tabs a { padding: 8px 14px; text-decoration: none; color: var(--muted); border-bottom: 2px solid transparent; margin-bottom: -1px; }
.tabs a.active { color: var(--primary-dark); border-color: var(--primary); font-weight: 600; }
.save-bar { display: flex; align-items: center; gap: 10px; margin-bottom: 14px; position: sticky; top: 56px; z-index: 3; background: var(--bg); padding: 8px 0; }
.save-bar input { max-width: 300px; }
.unit-layout { display: grid; grid-template-columns: 210px 1fr; gap: 20px; align-items: start; }
.lesson-rail { position: sticky; top: 116px; }
.lesson-rail a { display: flex; gap: 8px; align-items: baseline; padding: 6px 8px; border-radius: 8px; color: var(--text); text-decoration: none; }
.lesson-rail a:hover { background: var(--surface); }
.lesson-rail .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--good); flex: none; }
.lesson-rail .dot.todo { background: #e0a100; }
.lesson-rail small { display: block; color: var(--muted); }

.checklist { margin-bottom: 16px; }
.checklist summary { cursor: pointer; font-weight: 600; }
.checklist ul { margin: 8px 0 0; padding-left: 20px; }
.checklist li.needed { color: var(--bad); font-weight: 500; }
.checklist li.advice { color: var(--muted); }

.field { display: block; margin-bottom: 12px; }
.label { display: block; font-weight: 600; font-size: 12px; margin-bottom: 4px; }
.hint { display: block; font-size: 12px; color: var(--muted); margin-top: 3px; }
.stage-title { display: flex; align-items: center; gap: 10px; }
.stage-num { display: grid; place-items: center; width: 24px; height: 24px; border-radius: 50%; background: var(--soft); color: var(--primary-dark); font-weight: 700; font-size: 12px; }

.chips { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; min-height: 26px; }
.chip { display: inline-flex; align-items: center; gap: 4px; padding: 2px 8px; border-radius: 6px; font-size: 12px; font-weight: 500; border: 1px solid; }
.chip.c0 { background: #f1eafd; border-color: #d9c8f6; color: #5a2ea6; }
.chip.c1 { background: #e3f5ea; border-color: #bfe5cd; color: #1d6a3e; }
.chip.c2 { background: #e6f1fd; border-color: #c4dcf8; color: #1c5aa8; }
.chip.c3 { background: #fff0e0; border-color: #f5d5ae; color: #8a4a00; }
.chip.old { background: var(--bad-bg); border-color: #f5c6c2; color: var(--bad); }
.chip button { border: 0; background: none; cursor: pointer; color: inherit; padding: 0 2px; font-size: 14px; line-height: 1; }
.code-search { margin-top: 6px; position: relative; }
.code-results { border: 1px solid var(--border); border-radius: 8px; background: #fff; margin-top: 4px; overflow: hidden; }
.code-results button { display: block; width: 100%; text-align: left; border: 0; border-bottom: 1px solid var(--border); background: #fff; padding: 6px 10px; font: inherit; cursor: pointer; }
.code-results button:last-child { border-bottom: 0; }
.code-results button:hover { background: var(--soft); }

.sub { border: 1px solid var(--border); border-radius: 10px; padding: 12px; margin-bottom: 10px; background: #fbfcfe; }
.row { display: grid; grid-template-columns: 1fr 90px; gap: 12px; }
.row.three { grid-template-columns: 1fr 1fr auto; align-items: center; }

details.lesson { border: 1px solid var(--border); border-radius: 10px; margin-bottom: 10px; background: #fff; scroll-margin-top: 120px; }
details.lesson > summary { padding: 10px 14px; cursor: pointer; display: flex; gap: 8px; align-items: center; flex-wrap: wrap; font-weight: 600; }
details.lesson[open] > summary { border-bottom: 1px solid var(--border); }
.lesson-body { padding: 14px; }
.section { border-left: 3px solid var(--primary); padding-left: 10px; margin-bottom: 12px; }
.section.block { border-color: #8a5bd6; }
.section-head { display: flex; gap: 8px; align-items: center; margin-bottom: 4px; }
.section-head input { font-weight: 600; border-color: transparent; background: transparent; padding-left: 0; }
.section-head input:hover:not([readonly]) { border-color: var(--border); }
.section.is-hidden { border-color: var(--border); color: var(--muted); display: flex; gap: 10px; align-items: center; }
.tools { display: flex; gap: 4px; }
.after { background: var(--bg); border-radius: 10px; padding: 12px; margin-top: 14px; }
.after .outcomes { display: flex; gap: 8px; flex-wrap: wrap; margin: 8px 0; }
.notes { list-style: none; padding: 0; margin: 8px 0 0; }
.notes li { padding: 4px 0; }

/* History */
.two-col { display: grid; grid-template-columns: repeat(auto-fit, minmax(340px, 1fr)); gap: 16px; align-items: start; }
.timeline { list-style: none; margin: 0; padding: 0 0 0 10px; border-left: 2px solid var(--border); }
.timeline li { position: relative; padding: 0 0 16px 18px; }
.timeline li::before { content: ""; position: absolute; left: -7px; top: 5px; width: 10px; height: 10px; border-radius: 50%; background: #fff; border: 2px solid var(--primary); }
.timeline li:first-child::before { background: var(--primary); }
.timeline .v-head { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; font-weight: 600; }
.timeline .actions { margin-top: 6px; }

/* Compare */
.diff { width: 100%; border-collapse: collapse; margin: 8px 0 4px; table-layout: fixed; }
.diff th, .diff td { border: 1px solid var(--border); padding: 6px 8px; vertical-align: top; text-align: left; white-space: pre-wrap; overflow-wrap: anywhere; }
.diff thead th { background: var(--bg); font-size: 12px; }
.diff th:first-child { width: 150px; font-size: 12px; }
.diff td.del { background: var(--bad-bg); }
.diff td.add { background: var(--good-bg); }
.part-head { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; margin-bottom: 6px; }
.part-head h3 { margin: 0; }
.picks { display: flex; gap: 18px; margin-top: 10px; padding-top: 10px; border-top: 1px solid var(--border); flex-wrap: wrap; }

table.list { width: 100%; border-collapse: collapse; }
table.list th, table.list td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border); vertical-align: top; }
table.list th { font-size: 12px; color: var(--muted); }

#toast {
  position: fixed; bottom: 24px; left: 50%; transform: translateX(-50%);
  background: var(--text); color: #fff; padding: 10px 18px; border-radius: 10px;
  opacity: 0; pointer-events: none; transition: opacity .2s; max-width: 600px; z-index: 10;
}
#toast.show { opacity: 1; }
#toast.bad { background: var(--bad); }

/* Overview screens: dashboard, timeline, map, planner */
.nav-gap { height: 1px; background: var(--border); margin: 10px 6px; }
.inline { display: inline-flex; align-items: center; gap: 6px; color: var(--muted); }
.subject-dot { display: inline-block; width: 10px; height: 10px; border-radius: 50%; margin-right: 6px; flex: none; }
.meter { height: 6px; border-radius: 3px; background: #e6eaf1; overflow: hidden; flex: 1; min-width: 40px; }
.meter span { display: block; height: 100%; border-radius: 3px; background: var(--primary); }
.progress { display: flex; align-items: center; gap: 8px; margin-top: 6px; }
.progress small { color: var(--muted); white-space: nowrap; }
.unit-card { border-top: 4px solid var(--border); }
.unit-card h3 { margin: 4px 0; }

.tiles { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 14px; margin-bottom: 16px; }
.tile { margin: 0; color: inherit; text-decoration: none; display: flex; flex-direction: column; gap: 4px; }
.tile.link:hover { border-color: var(--primary); }
.tile .meter { flex: none; }
.tile-label { font-size: 12px; font-weight: 600; color: var(--muted); }
.tile-value { font-size: 30px; font-weight: 600; line-height: 1.2; }
.quicks { display: grid; grid-template-columns: 1fr 1fr; gap: 6px; margin-top: 4px; }
.quick { display: flex; align-items: center; gap: 6px; padding: 6px 8px; border-radius: 8px; background: var(--soft); color: var(--primary-dark); text-decoration: none; font-weight: 500; font-size: 13px; }
.quick:hover { background: #dbe9fc; }
.quick svg { width: 16px; height: 16px; flex: none; }
.dash { display: grid; grid-template-columns: repeat(auto-fit, minmax(360px, 1fr)); gap: 16px; align-items: start; }
.dash .card { margin: 0; }
.activity { list-style: none; margin: 0; padding: 0; }
.activity li { display: flex; gap: 10px; padding: 7px 0; border-bottom: 1px solid var(--border); }
.activity li:last-child { border-bottom: 0; }
.avatar { display: grid; place-items: center; width: 30px; height: 30px; border-radius: 50%; background: var(--soft); color: var(--primary-dark); font-size: 11px; font-weight: 700; flex: none; }
.row-link { display: flex; gap: 4px; align-items: flex-start; padding: 8px 6px; border-radius: 8px; color: inherit; text-decoration: none; border-bottom: 1px solid var(--border); }
.row-link:last-child { border-bottom: 0; }
.row-link:hover { background: var(--bg); }
.row-link > div { flex: 1; }
.row-link .subject-dot { margin-top: 6px; }
.cover { margin-bottom: 12px; }
.cover-head { display: flex; justify-content: space-between; margin-bottom: 4px; }
.cover-head span:last-child { color: var(--muted); }
.chart { position: relative; }
.chart svg { width: 100%; height: auto; display: block; }
.chart .axis { font-size: 11px; fill: var(--muted); }
.chart rect:focus { outline: none; fill: rgba(43, 125, 233, .08); }
.chart-tip { position: absolute; top: 0; transform: translateX(-50%); background: var(--text); color: #fff; font-size: 12px; padding: 4px 8px; border-radius: 6px; white-space: nowrap; opacity: 0; pointer-events: none; }
.chart-tip.on { opacity: 1; }
.table-view { margin-top: 8px; font-size: 12px; color: var(--muted); }

.timeline-grid { display: grid; grid-template-columns: 150px repeat(4, minmax(0, 1fr)); gap: 8px; align-items: stretch; }
.term-head { font-weight: 600; text-align: center; padding: 4px; border-radius: 6px; }
.term-head.now { background: var(--soft); color: var(--primary-dark); }
.axis-line { grid-column: 2 / -1; display: grid; grid-template-columns: repeat(4, 1fr); height: 14px; background: linear-gradient(var(--border), var(--border)) center / 100% 2px no-repeat; }
.axis-line span { width: 10px; height: 10px; border-radius: 50%; background: #fff; border: 2px solid var(--primary); justify-self: center; align-self: center; }
.lane-label { display: flex; align-items: center; font-weight: 600; font-size: 13px; }
.cell { border: 1px dashed var(--border); border-radius: 10px; padding: 6px; min-height: 84px; }
.cell.now { background: #f7faff; }
.tl-unit { display: block; padding: 8px 10px; border-radius: 8px; background: #fff; border: 1px solid var(--border); border-left: 4px solid; color: inherit; text-decoration: none; }
.tl-unit + .tl-unit { margin-top: 6px; }
.tl-unit:hover { border-color: var(--primary); }
.tl-unit strong { display: block; line-height: 1.3; }
.tl-unit small { color: var(--muted); }

.map-layout { display: grid; grid-template-columns: minmax(0, 1fr) 290px; gap: 16px; align-items: start; }
.map-card { overflow-x: auto; margin: 0; background-image: radial-gradient(#dfe5ee 1px, transparent 1px); background-size: 18px 18px; }
.map-canvas svg { width: 100%; height: auto; min-width: 680px; display: block; }
.map-canvas .link { fill: none; stroke: #b7c0cf; stroke-width: 1.5; }
.map-canvas .node { cursor: pointer; }
.map-canvas .node:focus { outline: none; }
.map-canvas .node:hover circle:first-child, .map-canvas .node:focus circle:first-child, .map-canvas .node.picked circle:first-child { stroke-width: 5; }
.map-canvas .node-label { font-size: 12px; fill: var(--text); font-weight: 500; }
.map-canvas .node.picked .node-label { font-weight: 700; }
.map-canvas .node-sub { fill: var(--muted); font-weight: 400; }
.inspector { margin: 0; position: sticky; top: 76px; }
.insp-row { margin-bottom: 12px; }
.plain { margin: 0; padding-left: 16px; }

.planner { display: grid; grid-template-columns: minmax(0, 1fr) 220px; gap: 16px; align-items: start; }
.board-card { overflow-x: auto; margin: 0; padding: 12px; }
.board { display: grid; grid-auto-flow: column; grid-auto-columns: minmax(150px, 1fr); gap: 8px; min-height: 380px; }
.week { background: var(--bg); border: 1px dashed var(--border); border-radius: 10px; padding: 6px; }
.week.over, .plan-card.over { border-color: var(--primary); background: var(--soft); }
.week-head { font-size: 12px; font-weight: 700; color: var(--muted); text-align: center; padding: 2px 0 6px; }
.plan-card { background: #fff; border: 1px solid var(--border); border-left: 4px solid var(--primary); border-radius: 8px; padding: 8px; margin-bottom: 6px; cursor: grab; display: flex; flex-direction: column; gap: 4px; font-size: 13px; }
.plan-card strong { line-height: 1.3; }
.plan-card.task { border-left-color: #e0a100; background: #fffaf0; }
.plan-card.new { border-style: dashed; border-left-style: solid; }
.plan-card.block { border-left-color: #8a5bd6; }
.plan-tools { display: flex; justify-content: space-between; align-items: center; font-size: 12px; }
.nudge { border: 1px solid var(--border); background: #fff; border-radius: 6px; width: 24px; height: 22px; cursor: pointer; line-height: 1; }
.nudge:disabled { opacity: .4; cursor: default; }
.palette { margin: 0; position: sticky; top: 116px; }

@media (max-width: 900px) {
  .map-layout, .planner { grid-template-columns: 1fr; }
  .timeline-grid { grid-template-columns: 90px repeat(4, minmax(120px, 1fr)); overflow-x: auto; }
  body { grid-template-columns: 1fr; }
  .sidebar { display: flex; overflow-x: auto; border-right: 0; border-bottom: 1px solid var(--border); padding: 6px; }
  .sidebar .foot { display: none; }
  .home, .unit-layout { grid-template-columns: 1fr; }
  .lesson-rail { position: static; }
}

@media print {
  body { display: block; background: #fff; }
  .topbar, .sidebar, .btn, .tabs, .save-bar, .lesson-rail, .after, .code-search, .tools, #toast, .no-print { display: none !important; }
  .unit-layout { display: block; }
  main { padding: 0; }
  .card, details.lesson { break-inside: avoid; }
}