:root {
  --bg: #111827; --panel: #1f2937; --line: #374151; --text: #f3f4f6; --muted: #9ca3af;
  --accent: #fbbf24; --good: #34d399; --warn: #fbbf24; --bad: #f87171;
  color-scheme: dark;
}
@media (prefers-color-scheme: light) {
  :root { --bg: #f9fafb; --panel: #fff; --line: #d1d5db; --text: #111827; --muted: #6b7280; --accent: #b45309; --good: #047857; --warn: #b45309; --bad: #b91c1c; color-scheme: light; }
}
/* Japanese typefaces, from fonts already on the device (no downloads, works offline). unicode-range limits each
   to kana/kanji/fullwidth, so Latin text keeps the system font. A style whose fonts are missing fails to load;
   app.js detects that and leaves it out of the toggle. */
@font-face { font-family: "ja-gothic"; unicode-range: U+3000-30FF, U+3400-9FFF, U+FF00-FFEF;
  src: local("Hiragino Sans W3"), local("HiraginoSans-W3"), local("Hiragino Kaku Gothic ProN W3"), local("HiraKakuProN-W3"),
       local("Yu Gothic"), local("YuGothic-Regular"), local("Meiryo"), local("Noto Sans CJK JP"), local("NotoSansCJKjp-Regular"),
       local("Noto Sans JP"), local("IPAexGothic"), local("IPAGothic"), local("TakaoGothic"); }
@font-face { font-family: "ja-mincho"; unicode-range: U+3000-30FF, U+3400-9FFF, U+FF00-FFEF;
  src: local("Hiragino Mincho ProN W3"), local("HiraMinProN-W3"), local("Yu Mincho"), local("YuMincho-Regular"), local("MS Mincho"),
       local("Noto Serif CJK JP"), local("NotoSerifCJKjp-Regular"), local("Noto Serif JP"), local("IPAexMincho"), local("IPAMincho"), local("TakaoMincho"); }
@font-face { font-family: "ja-kyokasho"; unicode-range: U+3000-30FF, U+3400-9FFF, U+FF00-FFEF;
  src: local("UD Digi Kyokasho NK-R"), local("UDDigiKyokashoNK-R"), local("UD Digi Kyokasho N-R"), local("Klee Medium"), local("Klee-Medium"),
       local("Klee One"), local("HGKyokashotai"), local("Kyokasho ICA"); }

:root { --ja: "ja-gothic"; }
:root[data-font="mincho"] { --ja: "ja-mincho"; }
:root[data-font="kyokasho"] { --ja: "ja-kyokasho"; }
* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }
html, body { margin: 0; background: var(--bg); color: var(--text); }
body { font: 17px/1.55 var(--ja), system-ui, -apple-system, "Hiragino Sans", "Noto Sans JP", sans-serif; min-height: 100dvh; padding-bottom: env(safe-area-inset-bottom); }
.bar { position: sticky; top: 0; z-index: 2; display: flex; justify-content: space-between; align-items: center; padding: calc(8px + env(safe-area-inset-top)) 16px 8px; background: var(--panel); border-bottom: 1px solid var(--line); }
.brand { background: none; border: 0; color: var(--text); font-size: 1.1rem; font-weight: 700; padding: 8px 0; }
.brand span { color: var(--muted); font-weight: 400; font-size: .85rem; margin-left: 4px; }
.bar-end { display: flex; align-items: center; }
.font-btn { font-size: 1.15rem; font-weight: 600; }
.icon-btn { background: none; border: 0; color: var(--text); font-size: 1.4rem; width: 44px; height: 44px; }
main { max-width: 640px; margin: 0 auto; padding: 16px; }
h1, h2, h3 { line-height: 1.25; margin: 0 0 .5rem; }
p { margin: 0 0 .75rem; }
.muted { color: var(--muted); } .small { font-size: .8rem; }
.card { background: var(--panel); border: 1px solid var(--line); border-radius: 14px; padding: 16px; margin-bottom: 12px; }
button { font: inherit; min-height: 48px; padding: 0 18px; border-radius: 12px; border: 1px solid var(--line); background: var(--panel); color: var(--text); }
button.primary { background: var(--accent); border-color: var(--accent); color: #111827; font-weight: 700; }
button.danger { color: var(--bad); }
button.block { width: 100%; }
button:active { transform: scale(.98); }
button:disabled { opacity: .5; }
.prompt { font-size: 1.35rem; font-weight: 600; }
textarea, #answer { width: 100%; font: inherit; font-size: 1.25rem; padding: 12px; border-radius: 12px; border: 1px solid var(--line); background: var(--bg); color: var(--text); resize: vertical; }
textarea:focus { outline: 2px solid var(--accent); border-color: transparent; }
.chip { display: inline-block; font-size: .75rem; padding: 2px 10px; border-radius: 99px; border: 1px solid var(--line); color: var(--muted); margin-right: 6px; }
.verdict { font-weight: 700; font-size: 1.1rem; }
.verdict.correct { color: var(--good); } .verdict.close { color: var(--warn); } .verdict.wrong { color: var(--bad); }
.ja { font-size: 1.3rem; }
.diff-row { margin: .35rem 0; } .diff-row small { display: block; color: var(--muted); }
.explain p, .explain li { font-size: .95rem; }
.explain ul { padding-left: 1.2rem; margin: 0 0 .75rem; }
.explain strong { color: var(--accent); }
.pattern-title { font-size: 1.4rem; font-weight: 700; }
.row { display: flex; gap: 8px; margin: 12px 0; } .row > * { flex: 1; }
dialog { width: min(92vw, 480px); border: 1px solid var(--line); border-radius: 16px; background: var(--panel); color: var(--text); padding: 16px; }
dialog::backdrop { background: rgba(0,0,0,.6); }
.list-item { display: flex; justify-content: space-between; gap: 8px; padding: 10px 0; border-top: 1px solid var(--line); }
.list-item:first-child { border-top: 0; }
.confusion { border-color: var(--warn); border-width: 2px; }
.context { font-size: .9rem; color: var(--muted); font-style: italic; margin: -.25rem 0 .75rem; }
.context b { font-style: normal; font-weight: 600; }
.more-examples { margin-top: .75rem; }
.more-examples summary { cursor: pointer; min-height: 44px; display: flex; align-items: center; color: var(--accent); font-weight: 600; }
.examples { list-style: none; padding: 0; margin: 0; }
.examples .example { padding: 8px 0; border-top: 1px solid var(--line); }
.examples .example:first-child { border-top: 0; }
.examples .ja { font-size: 1.1rem; }
.context-inline { font-style: italic; }