/* 学び（共通UI）— スマホ最優先。色だけで正誤を示さない（記号＋文字を必ず併記）。 */
:root {
  --bg: #f7f7f4; --card: #ffffff; --ink: #1d1d1b; --sub: #55554f; --line: #d9d9d2;
  --accent: #1f5fa8; --accent-ink: #ffffff; --ok: #1b7a3d; --ok-bg: #e7f5ec; --ng: #b3261e; --ng-bg: #fdecea;
  --sel: #e6eefa; --focus: #f0a500; --blank: #fff7d6;
  --radius: 12px; --tap: 48px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #151514; --card: #22221f; --ink: #f1f1ec; --sub: #b9b9b0; --line: #3b3b36;
    --accent: #7fb2ec; --accent-ink: #0d1b2b; --ok: #7fd49a; --ok-bg: #16301f; --ng: #ff8a80; --ng-bg: #3a1a18;
    --sel: #1f2d40; --focus: #ffc93c; --blank: #3a3520;
  }
}
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 17px/1.7 system-ui, -apple-system, "Hiragino Sans", "Noto Sans JP", "Yu Gothic UI", sans-serif; overflow-wrap: anywhere; }
.wrap { width: 100%; max-width: 760px; margin: 0 auto; padding: 0 16px; }
a { color: var(--accent); }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; }
[tabindex="-1"]:focus { outline: none; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.skip { position: absolute; left: -9999px; display: inline-block; min-height: 44px; padding: 12px; }
.skip:focus { left: 8px; top: 8px; z-index: 10; background: var(--card); }

.top { background: var(--card); border-bottom: 1px solid var(--line); }
.bar { display: flex; align-items: center; justify-content: space-between; gap: 8px; flex-wrap: wrap; }
.brand { font-weight: 700; color: var(--ink); text-decoration: none; display: inline-block; padding: 12px 0; min-height: var(--tap); }
.menu { display: flex; gap: 4px; }
.menu a { display: inline-block; padding: 12px 10px; min-height: var(--tap); text-decoration: none; font-size: 15px; }

main { padding-top: 16px; padding-bottom: 32px; min-height: 60vh; }
main:focus { outline: none; }
h1 { font-size: 22px; line-height: 1.4; margin: 8px 0 12px; }
h2 { font-size: 18px; margin: 20px 0 8px; }
p { margin: 8px 0; }
.sub { color: var(--sub); font-size: 15px; }
.loading { color: var(--sub); }
.panel { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px; margin: 12px 0; }
.note { background: var(--blank); border-radius: 8px; padding: 10px 12px; font-size: 15px; }
.err { border-color: var(--ng); }

.btn { display: inline-flex; align-items: center; justify-content: center; min-height: var(--tap); padding: 10px 18px; border-radius: 10px;
  border: 2px solid var(--accent); background: var(--accent); color: var(--accent-ink); font: inherit; font-weight: 700; cursor: pointer; text-decoration: none; }
.btn.ghost { background: transparent; color: var(--accent); }
.btn.small { min-height: 44px; padding: 6px 12px; font-size: 15px; font-weight: 600; }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btns { display: flex; flex-wrap: wrap; gap: 10px; margin: 16px 0; }
.btns .btn { flex: 1 1 200px; }

.levels { list-style: none; padding: 0; margin: 0; display: grid; gap: 10px; grid-template-columns: 1fr; }
@media (min-width: 560px) { .levels { grid-template-columns: 1fr 1fr; } }
.card { display: block; background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 14px 16px; color: var(--ink); text-decoration: none; min-height: var(--tap); }
a.card:hover { border-color: var(--accent); }
.card .t { font-weight: 700; font-size: 18px; }
.card .d { color: var(--sub); font-size: 15px; }
.card.off { opacity: .55; }
.links { list-style: none; padding: 0; display: grid; gap: 8px; grid-template-columns: 1fr 1fr; }
.links a { display: flex; align-items: center; min-height: var(--tap); padding: 8px 12px; background: var(--card); border: 1px solid var(--line); border-radius: 10px; text-decoration: none; }

fieldset { border: 0; padding: 0; margin: 0 0 16px; min-width: 0; }
legend { font-weight: 700; margin-bottom: 8px; padding: 0; }
.opts { display: grid; gap: 8px; grid-template-columns: 1fr; }
.opts.row { grid-template-columns: repeat(3, 1fr); }
.opts.two { grid-template-columns: 1fr 1fr; }
.opt { position: relative; }
.opt input { position: absolute; inset: 0; width: 100%; height: 100%; margin: 0; opacity: 0; pointer-events: none; }
.opt label { display: flex; align-items: center; justify-content: space-between; gap: 8px; min-height: var(--tap); padding: 10px 14px;
  background: var(--card); border: 2px solid var(--line); border-radius: 10px; cursor: pointer; }
.opt input:checked + label { border-color: var(--accent); background: var(--sel); font-weight: 700; }
.opt input:checked + label::before { content: "✓"; margin-right: 4px; }
.opt input:focus-visible + label { outline: 3px solid var(--focus); outline-offset: 2px; }
.opt .c { color: var(--sub); font-size: 14px; font-weight: 400; }

.qhead { display: flex; align-items: center; justify-content: space-between; gap: 8px; flex-wrap: wrap; }
.prog { width: 100%; height: 8px; background: var(--line); border-radius: 4px; overflow: hidden; margin: 6px 0 12px; }
.prog > span { display: block; height: 100%; background: var(--accent); }
.fav { min-height: 44px; min-width: 44px; padding: 6px 10px; border-radius: 10px; border: 2px solid var(--line); background: var(--card); color: var(--ink); font: inherit; font-size: 15px; cursor: pointer; }
.fav[aria-pressed="true"] { border-color: var(--focus); }
.instr { color: var(--sub); font-size: 15px; margin: 4px 0; }
.passage { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 0 14px; margin: 8px 0 12px; }
.passage summary { min-height: var(--tap); display: flex; align-items: center; cursor: pointer; font-weight: 700; }
.passage .ptitle { font-weight: 700; margin-top: 4px; }
.passage p { margin: 0 0 12px; font-size: 17px; line-height: 1.8; }
.stem { font-size: 19px; line-height: 1.75; margin: 8px 0 14px; }
.blank { display: inline-block; min-width: 3.5em; border-bottom: 2px solid var(--ink); background: var(--blank); text-align: center; }
.seg { text-decoration: underline; text-decoration-thickness: 2px; text-underline-offset: 4px; }
.seg-l { font-size: 12px; font-weight: 700; vertical-align: super; margin-right: 2px; color: var(--accent); text-decoration: none; display: inline-block; }
.choices { display: grid; gap: 10px; margin: 8px 0 16px; }
.choice { display: flex; align-items: flex-start; gap: 10px; width: 100%; min-height: 52px; padding: 12px 14px; text-align: left;
  background: var(--card); color: var(--ink); border: 2px solid var(--line); border-radius: 12px; font: inherit; font-size: 18px; cursor: pointer; }
.choice .num { flex: 0 0 auto; display: inline-flex; align-items: center; justify-content: center; width: 28px; height: 28px; border-radius: 50%; background: var(--line); font-size: 15px; font-weight: 700; margin-top: 1px; }
.choice .txt { flex: 1 1 auto; min-width: 0; }
.choice .tag { flex: 0 0 auto; font-size: 14px; font-weight: 700; padding: 2px 8px; border-radius: 6px; }
.choice[aria-pressed="true"] { border-color: var(--accent); background: var(--sel); }
.choice.is-ok { border-color: var(--ok); background: var(--ok-bg); }
.choice.is-ok .tag { color: var(--ok); }
.choice.is-ng { border-color: var(--ng); background: var(--ng-bg); }
.choice.is-ng .tag { color: var(--ng); }
.choice:disabled { cursor: default; opacity: 1; }
.inputrow { display: flex; gap: 8px; flex-wrap: wrap; margin: 8px 0 16px; }
.inputrow label { flex: 1 1 100%; font-size: 15px; color: var(--sub); }
.inputrow input { flex: 1 1 180px; min-height: 52px; font: inherit; font-size: 19px; padding: 8px 12px; border: 2px solid var(--line); border-radius: 10px; background: var(--card); color: var(--ink); }
.fb { border-radius: var(--radius); padding: 14px 16px; margin: 8px 0 16px; border: 2px solid var(--line); background: var(--card); }
.fb.ok { border-color: var(--ok); }
.fb.ng { border-color: var(--ng); }
.fb .res { font-size: 20px; font-weight: 700; margin: 0 0 6px; }
.fb.ok .res { color: var(--ok); }
.fb.ng .res { color: var(--ng); }
.fb .lbl { font-weight: 700; font-size: 15px; margin-top: 10px; }
.pt { background: var(--blank); border-radius: 8px; padding: 8px 10px; }

.score { font-size: 28px; font-weight: 800; margin: 4px 0; }
table { width: 100%; border-collapse: collapse; font-size: 15px; }
th, td { border-bottom: 1px solid var(--line); padding: 8px 6px; text-align: left; vertical-align: top; }
td.n { text-align: right; white-space: nowrap; }
.rlist { list-style: none; padding: 0; margin: 0; display: grid; gap: 10px; }
.rlist > li { background: var(--card); border: 1px solid var(--line); border-radius: 10px; padding: 12px 14px; }
.rlist .mk { font-weight: 700; }
.rlist .mk.ok { color: var(--ok); }
.rlist .mk.ng { color: var(--ng); }
.rlist details summary { min-height: 44px; display: flex; align-items: center; cursor: pointer; color: var(--accent); }
.rowline { display: flex; justify-content: space-between; align-items: center; gap: 8px; flex-wrap: wrap; }
.rowline a { display: inline-block; padding: 10px 0; min-height: 44px; }

.foot { border-top: 1px solid var(--line); color: var(--sub); font-size: 14px; padding: 12px 0 28px; }
.foot a { display: inline-block; padding: 10px 0; min-height: 44px; }
.foot p { margin: 4px 0; }

/* 2026-10-02 使いやすさ改善: 学習の状況・今日の10問・学び方の入口 */
.stats { list-style: none; padding: 0; margin: 8px 0 12px; display: grid; gap: 8px; grid-template-columns: 1fr 1fr; }
@media (min-width: 560px) { .stats { grid-template-columns: repeat(4, 1fr); } }
.stats li { background: var(--card); border: 1px solid var(--line); border-radius: 10px; padding: 8px 12px; }
.stats .k { display: block; color: var(--sub); font-size: 14px; line-height: 1.4; }
.stats .v { display: block; font-weight: 700; font-size: 19px; }
.hero { border: 2px solid var(--accent); }
.hero h2, .panel > h2:first-child { margin-top: 0; }
.row2 { display: flex; flex-wrap: wrap; gap: 10px; margin: 12px 0 4px; }
.lvpick { flex: 1 1 180px; display: flex; min-height: var(--tap); }
.lvpick select { width: 100%; min-height: var(--tap); font: inherit; padding: 8px 10px; border: 2px solid var(--line); border-radius: 10px; background: var(--card); color: var(--ink); }
.row2 .btn { flex: 1 1 140px; }
.modes { list-style: none; padding: 0; margin: 0; display: grid; gap: 10px; grid-template-columns: 1fr; }
@media (min-width: 560px) { .modes { grid-template-columns: repeat(3, 1fr); } }
.mode { display: block; width: 100%; height: 100%; min-height: var(--tap); padding: 12px 16px; text-align: left; background: var(--card); color: var(--ink);
  border: 1px solid var(--line); border-radius: var(--radius); font: inherit; text-decoration: none; cursor: pointer; }
.mode:hover { border-color: var(--accent); }
.mode .t { display: block; font-weight: 700; color: var(--accent); }
.mode .d { display: block; color: var(--sub); font-size: 15px; }
.badge { display: inline-block; margin: 0 6px; padding: 0 8px; border-radius: 6px; background: var(--sel); color: var(--accent); font-size: 14px; font-weight: 700; vertical-align: middle; }
.score.rec { font-size: 24px; line-height: 1.4; }
details.panel > summary { min-height: var(--tap); display: flex; align-items: center; cursor: pointer; color: var(--accent); font-weight: 700; }
/* 2026-10-02: 勉強用BGM（ヘッダーのボタンとパネル） */
.menu-b { min-height: var(--tap); padding: 12px 10px; font: inherit; font-size: 15px; color: var(--accent); background: none; border: 0; cursor: pointer; }
.bgm-row { display: flex; flex-wrap: wrap; align-items: center; gap: 4px 12px; margin: 10px 0; }
.bgm-row label { flex: 0 0 auto; min-width: 5.5em; }
.bgm-row select { flex: 1 1 160px; min-height: var(--tap); font: inherit; padding: 8px 10px; border: 2px solid var(--line); border-radius: 10px; background: var(--card); color: var(--ink); }
.bgm-row input[type=range] { flex: 1 1 160px; min-height: var(--tap); margin: 0; accent-color: var(--accent); }