:root {
  --bg: #f6f8fb; --card: #ffffff; --ink: #1f2a37; --muted: #5b6b7d; --line: #dde3ea;
  --brand: #1f6feb; --brand-ink: #ffffff; --ok: #1a7f37; --ok-bg: #e6f4ea; --ng: #c2410c; --ng-bg: #fff1e8;
  --warn: #b42318; --warn-bg: #fdecec; --step: #7c3aed; --step-bg: #f3edff; --radius: 14px;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #0f1520; --card: #172131; --ink: #e6edf5; --muted: #9fb0c3; --line: #2a3a50; --brand: #4c8dff;
    --ok: #4ade80; --ok-bg: #12301f; --ng: #fb923c; --ng-bg: #3a2414; --warn: #f87171; --warn-bg: #3b1717; --step: #b794ff; --step-bg: #2a1f45; }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 16px/1.7 system-ui, -apple-system, "Hiragino Sans", "Yu Gothic UI", "Meiryo", sans-serif; }
a { color: var(--brand); }
.top { display: flex; align-items: center; justify-content: space-between; gap: 8px; padding: 10px 16px; background: var(--card); border-bottom: 1px solid var(--line); position: sticky; top: 0; z-index: 5; }
.brand { display: flex; align-items: center; gap: 8px; font-weight: 700; color: var(--ink); text-decoration: none; font-size: 15px; }
.logo { font-size: 22px; }
#nav { display: flex; gap: 6px; flex-wrap: wrap; justify-content: flex-end; }
main { max-width: 760px; margin: 0 auto; padding: 16px; outline: none; }
.foot { max-width: 760px; margin: 24px auto; padding: 0 16px 32px; color: var(--muted); font-size: 13px; }
h1 { font-size: 22px; margin: 4px 0 12px; } h2 { font-size: 18px; margin: 20px 0 8px; } h3 { font-size: 16px; margin: 12px 0 6px; }
.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px; margin: 12px 0; }
.muted { color: var(--muted); } .small { font-size: 13px; }
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 6px; min-height: 44px; padding: 8px 16px; border-radius: 12px; border: 1px solid var(--line); background: var(--card); color: var(--ink); font: inherit; font-weight: 600; cursor: pointer; text-decoration: none; }
.btn:hover { border-color: var(--brand); }
.btn.primary { background: var(--brand); color: var(--brand-ink); border-color: var(--brand); }
.btn.step { background: var(--step-bg); color: var(--step); border-color: transparent; }
.btn.small { min-height: 36px; padding: 4px 12px; font-size: 14px; }
.btn:disabled { opacity: .5; cursor: default; }
.row { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; }
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 10px; }
label { display: block; font-weight: 600; margin: 10px 0 4px; }
input, select, textarea { width: 100%; min-height: 44px; padding: 8px 12px; border: 1px solid var(--line); border-radius: 10px; background: var(--card); color: var(--ink); font: inherit; }
input:focus, select:focus, textarea:focus { outline: 2px solid var(--brand); outline-offset: 1px; }
.subject { display: flex; flex-direction: column; align-items: flex-start; gap: 2px; padding: 14px; border-radius: var(--radius); border: 1px solid var(--line); background: var(--card); color: var(--ink); text-decoration: none; font: inherit; cursor: pointer; text-align: left; }
.subject .ico { font-size: 26px; } .subject b { font-size: 17px; } .subject:disabled { opacity: .55; cursor: default; }
.badge { display: inline-block; padding: 0 8px; border-radius: 999px; font-size: 12px; font-weight: 700; background: var(--bg); border: 1px solid var(--line); color: var(--muted); }
.badge.A { color: #0b7a4b; } .badge.B { color: #1f6feb; } .badge.C { color: #b42318; }
.problem-body { font-size: 17px; white-space: normal; }
.problem-body p { margin: 0 0 10px; }
.figure { margin: 8px 0; text-align: center; } .figure svg { max-width: 100%; height: auto; }
.answer-line { display: flex; gap: 8px; margin-top: 12px; } .answer-line input { flex: 1; font-size: 18px; }
.choices { display: grid; gap: 8px; margin-top: 12px; }
.result { border-radius: 12px; padding: 12px 14px; margin-top: 12px; font-weight: 600; }
.result.ok { background: var(--ok-bg); color: var(--ok); } .result.ng { background: var(--ng-bg); color: var(--ng); }
.explain { margin-top: 10px; padding: 12px; border-left: 4px solid var(--brand); background: var(--bg); border-radius: 0 10px 10px 0; }
.ladder { border: 2px solid var(--step-bg); border-radius: var(--radius); padding: 14px; margin-top: 14px; background: var(--card); }
.ladder-head { display: flex; justify-content: space-between; align-items: center; gap: 8px; color: var(--step); font-weight: 700; }
.progress { display: flex; gap: 4px; margin: 10px 0; } .progress span { flex: 1; height: 8px; border-radius: 4px; background: var(--line); }
.progress span.done { background: var(--step); } .progress span.now { background: color-mix(in srgb, var(--step) 45%, transparent); }
table { width: 100%; border-collapse: collapse; font-size: 14px; } th, td { padding: 8px 6px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
tr.alert td { background: var(--warn-bg); } .alert-mark { color: var(--warn); font-weight: 700; }
.bar { height: 8px; background: var(--line); border-radius: 4px; overflow: hidden; min-width: 60px; } .bar i { display: block; height: 100%; background: var(--ok); }
.tabs { display: flex; gap: 6px; margin: 8px 0; flex-wrap: wrap; }
.notice { padding: 10px 12px; border-radius: 10px; background: var(--step-bg); color: var(--ink); font-size: 14px; }
.err { color: var(--warn); font-weight: 600; min-height: 1.4em; }
@media (max-width: 520px) {
  .top { padding: 8px 10px; } .brand .full { display: none; } .brand .short { display: inline !important; }
  #nav { flex-wrap: nowrap; gap: 4px; } #nav .btn { min-height: 38px; padding: 4px 7px; font-size: 13px; white-space: nowrap; }
  .brand { white-space: nowrap; font-size: 14px; }
  table.cards thead { display: none; } table.cards tr { display: block; border-bottom: 1px solid var(--line); padding: 8px 0; }
  table.cards td { display: flex; gap: 8px; border: 0; padding: 2px 4px; } table.cards td::before { content: attr(data-l); color: var(--muted); font-size: 12px; min-width: 7.5em; }
  h1 { font-size: 20px; } .table-wrap { overflow-x: auto; }
}
.brand .short { display: none; }
@media print {
  .top, .foot, .no-print { display: none !important; }
  body { background: #fff; color: #000; font-size: 12pt; } main { max-width: none; padding: 0; }
  .card { border: none; padding: 0 0 6mm; margin: 0 0 6mm; border-bottom: 1px dashed #999; border-radius: 0; break-inside: avoid; }
  .print-head { display: flex !important; justify-content: space-between; border-bottom: 2px solid #000; margin-bottom: 6mm; padding-bottom: 2mm; }
  .write-space { display: block !important; height: 28mm; border: 1px solid #bbb; margin-top: 3mm; }
}
.print-head, .write-space { display: none; }
.keypad { display: flex; gap: 6px; flex-wrap: wrap; margin-top: 8px; } .keypad .btn { min-width: 48px; font-size: 18px; }
#sc { grid-template-columns: repeat(auto-fill, minmax(64px, 1fr)); }

/* 過去の入試で出た形(年度の目印) */
.past { margin: 6px 0 0; padding: 6px 10px; border-radius: 10px; background: var(--card); border: 1px solid var(--line); color: var(--muted); line-height: 1.5; }