:root {
    --font-ja-heading: "M PLUS Rounded 1c", "Hiragino Sans", "Yu Gothic", sans-serif;
    --font-ja-body: "Noto Sans JP", "Hiragino Sans", "Yu Gothic", sans-serif;
    --font-en-heading: "Nunito", "Nunito Sans", system-ui, sans-serif;
    --font-en-body: "Nunito Sans", "Nunito", system-ui, sans-serif;
    --font-ko-heading: "Jua", "Noto Sans KR", "Apple SD Gothic Neo", "Malgun Gothic", sans-serif;
    --font-ko-body: "Noto Sans KR", "Apple SD Gothic Neo", "Malgun Gothic", sans-serif;
    --font-body: var(--font-ja-body);
    --font-ui: "Nunito", "Nunito Sans", "M PLUS Rounded 1c", "Jua", sans-serif;
    --paper: #F7F5F0;
    --card: #FFFFFF;
    --ink: #1F2733;
    --ink-soft: #5A6373;
    --line: #E3DFD6;
    --accent: #2B5CAF;
    --accent-soft: #E7EDF8;
    --red: #C0392F;
    --red-soft: #F7E7E5;
    --gold: #C9971F;
    --gold-soft: #F7EFDC;
    --green: #2E7D4F;
    --green-soft: #E4F0E9;
    --shadow: 0 1px 3px rgba(31,39,51,.08), 0 4px 14px rgba(31,39,51,.06);
  }
  @media (prefers-color-scheme: dark) {
    :root {
      --paper: #14181F;
      --card: #1D232D;
      --ink: #E8EAF0;
      --ink-soft: #9AA3B2;
      --line: #2C3440;
      --accent: #7FA6E8;
      --accent-soft: #22304A;
      --red: #E0766C;
      --red-soft: #3D2523;
      --gold: #D9AE4A;
      --gold-soft: #3A3122;
      --green: #6FBF92;
      --green-soft: #1F3529;
      --shadow: 0 1px 3px rgba(0,0,0,.4), 0 4px 14px rgba(0,0,0,.3);
    }
  }
  :root[data-theme="dark"] {
    --paper: #14181F;
    --card: #1D232D;
    --ink: #E8EAF0;
    --ink-soft: #9AA3B2;
    --line: #2C3440;
    --accent: #7FA6E8;
    --accent-soft: #22304A;
    --red: #E0766C;
    --red-soft: #3D2523;
    --gold: #D9AE4A;
    --gold-soft: #3A3122;
    --green: #6FBF92;
    --green-soft: #1F3529;
    --shadow: 0 1px 3px rgba(0,0,0,.4), 0 4px 14px rgba(0,0,0,.3);
  }
  :root[data-theme="light"] {
    --paper: #F7F5F0;
    --card: #FFFFFF;
    --ink: #1F2733;
    --ink-soft: #5A6373;
    --line: #E3DFD6;
    --accent: #2B5CAF;
    --accent-soft: #E7EDF8;
    --red: #C0392F;
    --red-soft: #F7E7E5;
    --gold: #C9971F;
    --gold-soft: #F7EFDC;
    --green: #2E7D4F;
    --green-soft: #E4F0E9;
    --shadow: 0 1px 3px rgba(31,39,51,.08), 0 4px 14px rgba(31,39,51,.06);
  }

  * { box-sizing: border-box; }
  html, body { margin: 0; padding: 0; }
  body {
    background: var(--paper);
    color: var(--ink);
    font-family: var(--font-body);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
  }

  :lang(ja), .jp { font-family: var(--font-ja-body); }
  :lang(en), .en { font-family: var(--font-en-body); }
  :lang(ko) { font-family: var(--font-ko-body); }
  .ko { font-family: var(--font-ko-heading); }
  .roma,
  .lyric-roma,
  .sub,
  .tap,
  .label,
  .count {
    font-family: var(--font-en-body);
  }

  h1, h2, h3, summary,
  button, .btn, .chip, .mode-btn, .persona-btn,
  .stat .num, .stat .label, .word-status, .song-title {
    font-family: var(--font-ui);
  }
  h4, h5, 
  .choice,
  .big-ko,
  .mode-btn .icon,
  .song-title .ko {
    font-family: var(--font-ko-body);
    font-weight: bold;
  }
  .ko-ex,
  .ex .ko,
  .lyric-ko,
  .tok-info .w {
    font-family: var(--font-ko-body);
  }

  .app { max-width: 720px; margin: 0 auto; padding: 0 16px 96px; }

  header.top {
    display: flex; align-items: baseline; justify-content: space-between;
    padding: 22px 4px 14px;
    border-bottom: 2px solid var(--ink);
    margin-bottom: 20px;
  }
  header.top h1 {
    font-size: 1.5rem; margin: 0; letter-spacing: .02em;
  }
  header.top h1 .ko { color: var(--accent); }
  header.top .sub { font-size: .78rem; color: var(--ink-soft); letter-spacing: .08em; text-transform: uppercase; }

  nav.tabs {
    position: fixed; bottom: 0; left: 0; right: 0; z-index: 50;
    background: var(--card);
    border-top: 1px solid var(--line);
    display: flex; justify-content: center;
  }
  nav.tabs .inner { display: flex; width: 100%; max-width: 720px; }
  nav.tabs button {
    flex: 1; background: none; border: none; cursor: pointer;
    padding: 9px 1px 11px; color: var(--ink-soft);
    font-size: .7rem; line-height: 1.3;
    display: flex; flex-direction: column; align-items: center; gap: 2px;
    border-top: 3px solid transparent;
  }
  nav.tabs button .ko { font-size: 1.04rem; font-weight: 700; }
  nav.tabs button.active { color: var(--accent); border-top-color: var(--accent); }
  nav.tabs button:focus-visible { outline: 2px solid var(--accent); outline-offset: -2px; }

  .screen { display: none; }
  .screen.active { display: block; animation: rise .25s ease; }
  @keyframes rise { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }
  @media (prefers-reduced-motion: reduce) {
    .screen.active { animation: none; }
    .flip-inner { transition: none !important; }
  }

  h2.section {
    font-size: 1.25rem; margin: 28px 0 12px; text-wrap: balance;
  }
  h2.section .ko { color: var(--accent); margin-right: .4em; }
  .hint { font-size: .85rem; color: var(--ink-soft); margin: 4px 0 14px; }

  .card {
    background: var(--card); border: 1px solid var(--line); border-radius: 10px;
    padding: 18px 20px; box-shadow: var(--shadow); margin-bottom: 14px;
  }

  .stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
  .stat {
    background: var(--card); border: 1px solid var(--line); border-radius: 10px;
    padding: 14px 14px 12px; box-shadow: var(--shadow);
  }
  .stat .num { font-size: 1.7rem; font-weight: 800; font-variant-numeric: tabular-nums; line-height: 1.2; }
  .stat .num small { font-size: .85rem; font-weight: 600; color: var(--ink-soft); }
  .stat .label { font-size: .74rem; color: var(--ink-soft); letter-spacing: .05em; }
  .stat .sub-label { display: block; margin-top: 3px; font-size: .66rem; color: var(--ink-soft); letter-spacing: 0; line-height: 1.35; }
  .stat .sub-label .accent-num { color: var(--accent); font-weight: 800; }
  .stat.accent .num { color: var(--accent); }
  .stat.gold .num { color: var(--gold); }
  .stat.green .num { color: var(--green); }

  .exam-table { width: 100%; border-collapse: collapse; font-size: .88rem; }
  .exam-table th, .exam-table td { text-align: left; padding: 7px 10px; border-bottom: 1px solid var(--line); }
  .exam-table th { font-size: .74rem; letter-spacing: .06em; color: var(--ink-soft); text-transform: uppercase; }
  .exam-table td.n { font-variant-numeric: tabular-nums; }

  .btn {
    display: inline-flex; align-items: center; gap: 8px; justify-content: center;
    background: var(--accent); color: var(--card); border: none; border-radius: 8px;
    font-size: .95rem; font-weight: 700;
    padding: 11px 20px; cursor: pointer;
  }
  .btn:hover { filter: brightness(1.08); }
  .btn:focus-visible { outline: 2px solid var(--ink); outline-offset: 2px; }
  .btn.ghost { background: none; color: var(--accent); border: 1.5px solid var(--accent); }
  .btn.quiet { background: none; color: var(--ink-soft); border: 1.5px solid var(--line); }
  .btn.small { padding: 7px 14px; font-size: .85rem; }
  .btn.danger { background: none; color: var(--red); border: 1.5px solid var(--red); }

  .gq-actions {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 8px;
  }

  .chips { display: flex; flex-wrap: wrap; gap: 8px; margin: 12px 0 14px; }
  .chip {
    background: var(--card); border: 1.5px solid var(--line); border-radius: 999px;
    padding: 6px 14px; font-size: .84rem; color: var(--ink);
    cursor: pointer;
  }
  .chip.active { border-color: var(--accent); background: var(--accent-soft); color: var(--accent); font-weight: 700; }
  .chip:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }
  .chip .count { color: var(--ink-soft); font-size: .76rem; font-variant-numeric: tabular-nums; }


  .flip-wrap { margin: 14px 0; }
  .flip {
    position: relative; width: 100%; cursor: pointer;
    background: none; border: none; padding: 0; display: block; text-align: inherit;
  }
  .flip:focus-visible .flip-inner { outline: 2px solid var(--accent); outline-offset: 3px; }
  .flip-inner { position: relative; width: 100%; }
  .face {
    background: var(--card); border: 1px solid var(--line); border-radius: 14px;
    box-shadow: var(--shadow); display: flex; flex-direction: column;
    align-items: center; justify-content: center; gap: 6px; padding: 20px 22px;
    min-height: 320px; animation: rise .2s ease;
  }
  .face.back { justify-content: flex-start; padding-top: 26px; display: none; }
  .flip.flipped .face.front { display: none; }
  .flip.flipped .face.back { display: flex; }
  .fc-nav {
    position: absolute; top: 50%; transform: translateY(-50%); z-index: 2;
    width: 38px; height: 58px; border: 1px solid var(--line); border-radius: 10px;
    background: color-mix(in srgb, var(--card) 88%, transparent); color: var(--accent);
    font-size: 1.4rem; font-weight: 800; cursor: pointer; box-shadow: var(--shadow);
    display: flex; align-items: center; justify-content: center;
  }
  .fc-nav.prev { left: 10px; }
  .fc-nav.next { right: 10px; }
  .fc-nav:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
  .word-row {
    display: flex; align-items: center; justify-content: center;
    max-width: calc(100% - 88px); width: 100%;
  }
  .face .big-ko { font-size: 2.5rem; font-weight: 800; color: var(--ink); line-height: 1.25; text-align: center; }
  .face .big-jp { font-size: 1.85rem; font-weight: 800; color: var(--ink); line-height: 1.35; text-align: center; }
  .face .roma { color: var(--accent); font-weight: 700; font-size: .95rem; }
  .face .jp { font-size: 1.35rem; font-weight: 700; color: var(--ink); text-align: center; line-height: 1.4; }
  .face .en { font-size: .9rem; color: var(--ink-soft); text-align: center; }
  .face .tap { font-size: .74rem; color: var(--ink-soft); margin-top: 8px; letter-spacing: .06em; }
  .word-status { font-size: .74rem; font-weight: 700; border-radius: 999px; padding: 2px 10px; }
  .word-status.known { background: var(--green-soft); color: var(--green); }
  .word-status.new { background: var(--accent-soft); color: var(--accent); }

  .fc-ex {
    width: calc(100% - 96px); max-width: 100%; margin: 12px auto 0; border-top: 1px dashed var(--line); padding-top: 10px;
    display: flex; gap: 10px; align-items: flex-start; text-align: left;
  }
  .fc-ex .lines { flex: 1; }
  .fc-ex .label { font-size: .68rem; letter-spacing: .08em; color: var(--ink-soft); text-transform: uppercase; }
  .fc-ex-line { display: flex; align-items: center; justify-content: flex-start; gap: 8px; }
  .fc-ex .ko-ex { flex: 0 1 auto; min-width: 0; font-weight: 700; font-size: 1.0rem; line-height: 1.5; }
  .fc-ex .jp-ex { color: var(--ink-soft); font-size: .84rem; line-height: 1.55; margin-top: 3px; }
  .fc-tip {
    width: 100%; margin-top: 10px; background: var(--gold-soft); border-radius: 8px;
    padding: 8px 12px; font-size: .82rem; text-align: left; line-height: 1.5;
  }
  .fc-tip .label { font-weight: 800; color: var(--gold); margin-right: 6px; }

  .fc-controls { display: flex; flex-direction: column; gap: 8px; justify-content: center; margin-top: 10px; }
  .fc-controls .btn { width: 100%; }
  .progress-track { height: 6px; background: var(--line); border-radius: 3px; overflow: hidden; margin: 10px 0 4px; }
  .progress-fill { height: 100%; background: var(--accent); border-radius: 3px; transition: width .3s; }
  .fc-meta { display: flex; justify-content: space-between; font-size: .8rem; color: var(--ink-soft); font-variant-numeric: tabular-nums; }
  .fc-filter { display: flex; align-items: center; gap: 6px; font-size: .82rem; color: var(--ink-soft); margin-bottom: 6px; }
  .fc-filter input { accent-color: var(--accent); width: 16px; height: 16px; }
  .fc-autoplay-row { display: flex; justify-content: center; margin: 8px 0 2px; }
  #fc-autoplay.playing { background: var(--accent); color: #fff; border-color: var(--accent); }

  .speak-btn {
    background: var(--accent-soft); color: var(--accent); border: none; border-radius: 999px;
    width: 42px; height: 42px; font-size: 1.15rem; cursor: pointer; flex-shrink: 0;
  }
  .speak-btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
  .speak-btn.inline { width: 32px; height: 32px; font-size: .95rem; }

  details.gram {
    background: var(--card); border: 1px solid var(--line); border-radius: 10px;
    margin-bottom: 10px; box-shadow: var(--shadow); overflow: hidden;
  }
  details.gram summary {
    cursor: pointer; padding: 14px 18px; font-weight: 700; list-style: none;
    display: flex; align-items: baseline; gap: 10px;
  }
  details.gram summary::-webkit-details-marker { display: none; }
  details.gram summary .pat { color: var(--accent); font-size: 1.05rem; }
  details.gram summary .mean { color: var(--ink-soft); font-weight: 500; font-size: .88rem; }
  details.gram[open] summary { border-bottom: 1px solid var(--line); }
  .gram-body { padding: 14px 18px 16px; font-size: .92rem; }
  .gram-body .expl { margin: 0 0 10px; }
  .gram-body .en-note { color: var(--ink-soft); font-size: .84rem; margin: 0 0 12px; }
  .ex {
    border-left: 3px solid var(--accent); padding: 6px 0 6px 14px; margin: 10px 0;
    display: flex; align-items: center; gap: 10px;
  }
  .ex .lines { flex: 1; }
  .ex .ko { font-weight: 700; font-size: 1.02rem; }
  .ex .jp { font-size: .88rem; }
  .ex .en { font-size: .8rem; color: var(--ink-soft); }

  .quiz-modes { display: grid; gap: 10px; }
  .mode-btn {
    background: var(--card); border: 1.5px solid var(--line); border-radius: 10px;
    padding: 16px 18px; text-align: left; cursor: pointer;
    display: flex; align-items: center; gap: 14px; box-shadow: var(--shadow);
  }
  .mode-btn:hover { border-color: var(--accent); }
  .mode-btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
  .mode-btn .icon {
    width: clamp(48px, 8vw, 56px); height: 44px; border-radius: 10px; background: var(--accent-soft);
    color: var(--accent); display: flex; align-items: center; justify-content: center;
    font-size: clamp(.78rem, 2.5vw, .92rem); font-weight: 800; flex-shrink: 0;
    line-height: 1; white-space: nowrap;
  }
  .mode-btn .t { font-weight: 700; color: var(--ink); }
  .mode-btn .d { font-size: .8rem; color: var(--ink-soft); }
  .mock-overview { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 10px; }
  .mock-overview div { border: 1px solid var(--line); border-radius: 8px; padding: 10px; }
  .mock-overview strong { display: block; font-size: 1.1rem; color: var(--accent); }
  .mock-overview span { display: block; font-size: .78rem; color: var(--ink-soft); margin-top: 3px; }
  .mock-passage {
    margin: 14px auto 0; max-width: 560px; text-align: left; white-space: pre-line;
    font-size: .96rem; line-height: 1.7; color: var(--ink); background: var(--card);
    border: 1px solid var(--line); border-radius: 8px; padding: 12px;
  }

  .q-head { display: flex; justify-content: space-between; align-items: center; font-size: .85rem; color: var(--ink-soft); font-variant-numeric: tabular-nums; }
  .q-prompt { text-align: center; padding: 26px 10px 20px; }
  .q-prompt .main { font-size: 2.0rem; font-weight: 800; line-height: 1.3; }
  .q-prompt .instr { font-size: .82rem; color: var(--ink-soft); letter-spacing: .04em; }
  .choices { display: grid; gap: 10px; }
  .choice {
    background: var(--card); border: 1.5px solid var(--line); border-radius: 10px;
    padding: 13px 16px; font-size: 1.0rem; text-align: left;
    cursor: pointer; color: var(--ink);
  }
  .choice:hover { border-color: var(--accent); }
  .choice:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }
  .choice.selected { border-color: var(--accent); background: var(--accent-soft); font-weight: 700; }
  .choice.correct { border-color: var(--green); background: var(--green-soft); color: var(--green); font-weight: 700; }
  .choice.wrong { border-color: var(--red); background: var(--red-soft); color: var(--red); }
  .choice:disabled { cursor: default; }

  .result-score { text-align: center; padding: 12px 0 4px; }
  .result-score .big { font-size: 3rem; font-weight: 800; font-variant-numeric: tabular-nums; color: var(--accent); line-height: 1.1; }
  .result-score .of { color: var(--ink-soft); }
  .review-item { display: flex; gap: 10px; align-items: center; padding: 8px 0; border-bottom: 1px solid var(--line); font-size: .92rem; }
  .review-item:last-child { border-bottom: none; }
  .review-item .mark { font-weight: 800; width: 20px; text-align: center; }
  .review-item .mark.ok { color: var(--green); }
  .review-item .mark.ng { color: var(--red); }
  .review-item .k { font-weight: 700; }
  .review-item .m { color: var(--ink-soft); font-size: .84rem; }

  /* K-POP lyrics */
  .song-card { margin-bottom: 18px; }
  .song-title { font-size: 1.15rem; font-weight: 800; margin: 0; }
  .song-title .ko { color: var(--accent); margin-right: 8px; }
  .song-sub { font-size: .78rem; color: var(--ink-soft); margin: 2px 0 12px; }
  .lyric-line { border-top: 1px dashed var(--line); padding: 12px 0 4px; }
  .lyric-line:first-of-type { border-top: none; }
  .lyric-ko { font-size: 1.08rem; font-weight: 700; line-height: 2.0; }
  .tok {
    background: none; border: none; font: inherit; color: inherit; cursor: pointer;
    padding: 1px 2px; border-radius: 5px; border-bottom: 2px solid var(--accent-soft);
    margin-right: 2px;
  }
  .tok:hover, .tok.on { background: var(--accent-soft); border-bottom-color: var(--accent); color: var(--accent); }
  .tok:focus-visible { outline: 2px solid var(--accent); }
  .lyric-roma { font-size: .78rem; color: var(--accent); }
  .lyric-jp { font-size: .88rem; color: var(--ink-soft); margin-bottom: 6px; }
  .tok-info {
    background: var(--accent-soft); border-radius: 8px; padding: 9px 13px; margin: 6px 0 8px;
    font-size: .86rem; line-height: 1.55;
  }
  .tok-info .w { font-weight: 800; font-size: 1.0rem; }
  .tok-info .dict { color: var(--accent); font-weight: 700; }
  .tok-info .note { color: var(--ink-soft); font-size: .8rem; display: block; }
  .lyric-tools { display: flex; gap: 8px; margin: 10px 0 2px; }

  /* Chat */
  .persona-pick { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin-bottom: 14px; }
  .persona-btn {
    background: var(--card); border: 1.5px solid var(--line); border-radius: 12px;
    padding: 14px; cursor: pointer; text-align: center; box-shadow: var(--shadow);
  }
  .persona-btn .face-emoji { font-size: 2rem; }
  .persona-btn .nm { font-weight: 800; color: var(--ink);}
  .persona-btn .tg { font-size: .72rem; color: var(--ink-soft); }
  .persona-btn.active { border-color: var(--accent); background: var(--accent-soft); }
  .persona-btn:focus-visible { outline: 2px solid var(--accent); }

  .chat-box {
    background: var(--card); border: 1px solid var(--line); border-radius: 12px;
    box-shadow: var(--shadow); padding: 14px; min-height: 300px; max-height: 460px;
    overflow-y: auto; display: flex; flex-direction: column; gap: 10px; margin-bottom: 10px;
  }
  .msg { max-width: 86%; padding: 9px 13px; border-radius: 14px; font-size: .92rem; line-height: 1.55; }
  .msg.bot { background: var(--accent-soft); border-bottom-left-radius: 4px; align-self: flex-start; }
  .msg.user { background: var(--green-soft); border-bottom-right-radius: 4px; align-self: flex-end; }
  .msg .who { font-size: .7rem; font-weight: 800; color: var(--accent); display: block; }
  .msg.user .who { color: var(--green); }
  .msg .jp-sub { display: block; font-size: .78rem; color: var(--ink-soft); margin-top: 3px; }
  .msg .fb { display: block; margin-top: 4px; }
  .msg .fb.ok { color: var(--green); }
  .msg .fb.ng { color: var(--red); }
  .msg .model { display: block; margin-top: 6px; padding-top: 6px; border-top: 1px dashed var(--line); font-size: .84rem; }
  .msg .model b { color: var(--accent); }
  .chat-input { display: flex; gap: 8px; }
  .chat-input textarea {
    flex: 1; resize: none; font-family: inherit; font-size: 1rem; padding: 10px 12px;
    border: 1.5px solid var(--line); border-radius: 10px; background: var(--card); color: var(--ink);
    min-height: 48px;
  }
  .chat-input textarea:focus-visible { outline: 2px solid var(--accent); }
  .chat-tools { display: flex; gap: 8px; margin-top: 8px; flex-wrap: wrap; }

  .tts-note { font-size: .78rem; color: var(--ink-soft); background: var(--card); border: 1px dashed var(--line); border-radius: 8px; padding: 8px 12px; margin-top: 10px; }
  .footer-note { text-align: center; font-size: .74rem; color: var(--ink-soft); margin-top: 36px; }
  .disclaimer { font-size: .76rem; color: var(--ink-soft); background: var(--card); border: 1px dashed var(--line); border-radius: 8px; padding: 8px 12px; margin: 4px 0 14px; }

  .gdoc details.gram summary { font-size: .95rem; }
  .gdoc h4 { margin: 18px 0 8px; font-size: 1.0rem; color: var(--accent); }
  .gdoc h5 { margin: 14px 0 6px; font-size: .9rem; }
  .gdoc p { margin: 6px 0; font-size: .9rem; }
  .gdoc .tbl { overflow-x: auto; }
  .gdoc table { width: 100%; border-collapse: collapse; font-size: .85rem; margin: 8px 0; }
  .gdoc th, .gdoc td { border-bottom: 1px solid var(--line); padding: 5px 8px; text-align: left; }
  .gdoc th { color: var(--ink-soft); font-size: .75rem; }
  .gdoc ul { margin: 6px 0; padding-left: 20px; font-size: .9rem; }
  .gdoc li { margin: 5px 0; }
  .gdoc blockquote { border-left: 3px solid var(--gold); margin: 8px 0; padding: 4px 12px; color: var(--ink-soft); font-size: .86rem; }
  .gdoc .say { background: var(--accent-soft); color: var(--accent); border: none; border-radius: 999px; width: 24px; height: 24px; font-size: .68rem; cursor: pointer; margin-right: 6px; vertical-align: middle; flex-shrink: 0; }
  .gdoc .say:focus-visible { outline: 2px solid var(--accent); }

  @media (max-width: 480px) {
    .stats { grid-template-columns: 1fr 1fr; }
    .face .big-ko { font-size: 2.0rem; }
    .q-prompt .main { font-size: 1.6rem; }
    .persona-pick { grid-template-columns: 1fr; }
  }

  /* ================= MOBILE RESPONSIVE ================= */
  html {
    -webkit-text-size-adjust: 100%;
    text-size-adjust: 100%;
    overflow-x: hidden;
  }

  body {
    min-width: 0;
    overflow-x: hidden;
    padding-top: env(safe-area-inset-top);
  }

  img, svg, video, canvas, audio {
    max-width: 100%;
  }

  input, textarea, select {
    font: inherit;
  }

  button {
    font-family: var(--font-ui);
  }

  button, .chip, .choice, .mode-btn, .persona-btn, .tok {
    touch-action: manipulation;
    -webkit-tap-highlight-color: transparent;
  }

  .app {
    width: 100%;
    min-width: 0;
    padding-left: max(16px, env(safe-area-inset-left));
    padding-right: max(16px, env(safe-area-inset-right));
    padding-bottom: calc(104px + env(safe-area-inset-bottom));
  }

  nav.tabs {
    padding-left: env(safe-area-inset-left);
    padding-right: env(safe-area-inset-right);
    padding-bottom: env(safe-area-inset-bottom);
  }

  nav.tabs .inner {
    min-width: 0;
  }

  nav.tabs button {
    min-width: 0;
    min-height: 58px;
  }

  .card,
  .stat,
  .mode-btn,
  .choice,
  details.gram,
  .song-card,
  .chat-box {
    min-width: 0;
    overflow-wrap: anywhere;
  }

  .gdoc .tbl,
  .exam-table {
    max-width: 100%;
  }

  .gdoc .tbl {
    -webkit-overflow-scrolling: touch;
  }

  .gdoc table,
  .exam-table {
    min-width: 520px;
  }

  .lyric-ko,
  .lyric-roma,
  .lyric-jp,
  .tok-info,
  .msg,
  .q-prompt .main {
    overflow-wrap: anywhere;
    word-break: normal;
  }

  .tok {
    min-height: 34px;
  }

  @media (max-width: 600px) {
    .app {
      padding-left: max(12px, env(safe-area-inset-left));
      padding-right: max(12px, env(safe-area-inset-right));
    }

    header.top {
      align-items: flex-start;
      gap: 8px;
      padding: 15px 2px 11px;
      margin-bottom: 14px;
    }

    header.top h1 {
      font-size: clamp(1.15rem, 5vw, 1.4rem);
      line-height: 1.25;
    }

    header.top .sub {
      flex-shrink: 0;
      padding-top: 3px;
      font-size: .64rem;
      letter-spacing: .04em;
      text-align: right;
    }

    h2.section {
      margin: 21px 0 9px;
      font-size: 1.12rem;
      line-height: 1.4;
    }

    .hint {
      margin-bottom: 11px;
      font-size: .8rem;
      line-height: 1.55;
    }

    .card {
      padding: 14px;
      margin-bottom: 11px;
      border-radius: 12px;
    }

    .stats {
      grid-template-columns: repeat(3, minmax(0, 1fr));
      gap: 7px;
    }

    .stat {
      padding: 10px 8px 9px;
      border-radius: 10px;
    }

    .stat .num {
      font-size: clamp(1.15rem, 6vw, 1.45rem);
      white-space: nowrap;
    }

    .stat .num small {
      font-size: .65rem;
    }

    .stat .label {
      margin-top: 3px;
      font-size: .61rem;
      line-height: 1.35;
      letter-spacing: 0;
    }

    .btn {
      min-height: 44px;
      padding: 10px 14px;
      font-size: .9rem;
    }

    .btn.small {
      min-height: 40px;
      padding: 8px 12px;
      font-size: .82rem;
    }

    /* ホーム画面の横並びカードをスマホでは縦並びにする */
    #scr-home .card[style*="justify-content:space-between"] {
      flex-direction: column;
      align-items: stretch !important;
    }

    #scr-home .card[style*="justify-content:space-between"] .btn {
      width: 100%;
    }

    #scr-home .card > div[style*="display:flex"] {
      display: grid !important;
      grid-template-columns: repeat(2, minmax(0, 1fr));
      gap: 8px !important;
    }

    #scr-home .card > div[style*="display:flex"] .btn {
      width: 100%;
    }

    .chips {
      flex-wrap: nowrap;
      overflow-x: auto;
      overscroll-behavior-inline: contain;
      -webkit-overflow-scrolling: touch;
      scrollbar-width: none;
      margin: 9px -12px 12px;
      padding: 2px 12px 5px;
    }

    .chips::-webkit-scrollbar {
      display: none;
    }

    .chip {
      flex: 0 0 auto;
      min-height: 40px;
      padding: 7px 12px;
      white-space: nowrap;
    }

    .flip-wrap {
      margin: 10px 0;
    }

    .face {
      min-height: 270px;
      padding: 17px 14px;
    }

    .face.back {
      padding-top: 20px;
    }

    .face .big-ko {
      font-size: clamp(1.8rem, 9vw, 2.25rem);
    }

    .face .big-jp {
      font-size: clamp(1.28rem, 6.5vw, 1.7rem);
    }

    .word-row {
      max-width: calc(100% - 76px);
    }

    .face > .speak-btn.inline,
    .fc-ex-line .speak-btn {
      width: 38px;
      height: 38px;
      font-size: .98rem;
    }

    .fc-nav {
      width: 32px;
      height: 50px;
      font-size: 1.15rem;
    }

    .fc-nav.prev { left: 8px; }
    .fc-nav.next { right: 8px; }

    .face .jp {
      font-size: 1.15rem;
    }

    .fc-ex {
      width: calc(100% - 72px);
    }

    .fc-controls {
      gap: 8px;
    }

    .fc-controls .btn {
      width: 100%;
    }

    details.gram summary {
      padding: 12px 13px;
      gap: 7px;
      align-items: flex-start;
      line-height: 1.45;
    }

    .gram-body {
      padding: 11px 13px 14px;
    }

    .gdoc ul {
      padding-left: 17px;
    }

    .gdoc li[style*="margin-left:-20px"] {
      margin-left: -12px !important;
    }

    .gdoc .say {
      width: 30px;
      height: 30px;
      min-width: 30px;
    }

    .mode-btn {
      min-height: 74px;
      padding: 13px;
      gap: 11px;
    }

    .mode-btn .icon {
      width: clamp(46px, 13vw, 52px);
      height: 40px;
      font-size: clamp(.72rem, 3.4vw, .86rem);
    }

    .mock-overview {
      grid-template-columns: 1fr;
    }

    .q-prompt {
      padding: 20px 3px 15px;
    }

    .q-prompt .main {
      font-size: clamp(1.3rem, 6.7vw, 1.7rem);
    }

    .choice {
      min-height: 48px;
      padding: 12px 13px;
      font-size: .95rem;
      line-height: 1.45;
    }

    .review-item {
      align-items: flex-start;
    }

    .song-card {
      padding: 14px 12px;
    }

    .song-title {
      font-size: 1.05rem;
      line-height: 1.4;
    }

    .lyric-line {
      padding: 11px 0 3px;
    }

    .lyric-ko {
      font-size: 1rem;
      line-height: 2.15;
    }

    .lyric-roma {
      font-size: .72rem;
      line-height: 1.5;
    }

    .lyric-jp {
      font-size: .82rem;
      line-height: 1.55;
    }

    .tok {
      padding: 4px 3px;
      margin-right: 1px;
    }

    .tok-info {
      padding: 9px 10px;
      font-size: .82rem;
    }

    .lyric-tools {
      flex-wrap: wrap;
    }

    .lyric-tools .btn {
      flex: 1 1 120px;
    }

    .persona-pick {
      grid-template-columns: repeat(2, minmax(0, 1fr));
      gap: 8px;
    }

    .persona-btn {
      min-height: 92px;
      padding: 11px 8px;
    }

    .chat-box {
      min-height: 260px;
      max-height: min(52vh, 430px);
      padding: 10px;
    }

    .msg {
      max-width: 92%;
      padding: 8px 10px;
      font-size: .88rem;
    }

    .chat-input {
      align-items: stretch;
    }

    .chat-input textarea {
      min-width: 0;
      min-height: 52px;
      font-size: 16px; /* iOS Safariの入力時自動ズームを防止 */
    }

    .chat-input .btn,
    .chat-input button {
      flex: 0 0 auto;
      min-width: 64px;
      padding-left: 11px;
      padding-right: 11px;
    }

    .chat-tools .btn {
      flex: 1 1 135px;
    }

    nav.tabs button {
      min-height: 64px;
      padding: 7px 0 8px;
      font-size: .6rem;
      gap: 1px;
    }

    nav.tabs button .ko {
      font-size: .84rem;
    }
  }

  @media (max-width: 380px) {
    .app {
      padding-left: max(9px, env(safe-area-inset-left));
      padding-right: max(9px, env(safe-area-inset-right));
    }

    header.top .sub {
      display: none;
    }

    .stats {
      grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .stats .stat:last-child {
      grid-column: 1 / -1;
    }

    #scr-home .card > div[style*="display:flex"] {
      grid-template-columns: 1fr;
    }

    .persona-pick {
      grid-template-columns: 1fr;
    }

    .fc-controls {
      gap: 7px;
    }

    nav.tabs button {
      font-size: .54rem;
    }

    nav.tabs button .ko {
      font-size: .76rem;
    }
  }

  @media (min-width: 721px) {
    .app {
      padding-left: 20px;
      padding-right: 20px;
    }
  }