:root {
  --bg: #0f1419;
  --card: #1a222c;
  --ink: #f2f5f8;
  --muted: #9aa7b5;
  --line: #2a3542;
  --accent: #3dd68c;
  --accent-ink: #062416;
  --danger: #ff6b6b;
  --warn: #f7d117;
  --pad: max(16px, env(safe-area-inset-left));
  --pad-r: max(16px, env(safe-area-inset-right));
  --pad-b: max(20px, env(safe-area-inset-bottom));
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

* { box-sizing: border-box; }
html, body { margin: 0; min-height: 100%; background: var(--bg); color: var(--ink); }
body { display: flex; flex-direction: column; min-height: 100dvh; }

.top {
  display: flex; align-items: flex-start; justify-content: space-between; gap: 12px;
  padding: 14px var(--pad-r) 8px var(--pad);
  border-bottom: 1px solid var(--line);
  position: sticky; top: 0; background: rgba(15,20,25,.92); backdrop-filter: blur(10px); z-index: 5;
}
.brand h1 { margin: 0; font-size: 1.25rem; letter-spacing: -0.02em; }
.sub { margin: 2px 0 0; color: var(--muted); font-size: 0.8rem; }
.mode { display: inline-flex; background: var(--card); border-radius: 999px; padding: 3px; border: 1px solid var(--line); }
.mode-btn {
  border: 0; background: transparent; color: var(--muted); font-weight: 650;
  padding: 8px 14px; border-radius: 999px; min-height: 40px; cursor: pointer;
}
.mode-btn.is-on { background: var(--accent); color: var(--accent-ink); }

.main { flex: 1; width: min(480px, 100%); margin: 0 auto; padding: 12px var(--pad) var(--pad-b); }
.progress-row { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; }
.progress-track { flex: 1; height: 8px; background: var(--line); border-radius: 999px; overflow: hidden; }
.progress-fill { height: 100%; width: 0; background: var(--accent); border-radius: 999px; transition: width .25s ease; }
.progress-label { margin: 0; font-size: 0.8rem; color: var(--muted); white-space: nowrap; }

.filters-wrap {
  position: relative;
  margin: 0 calc(-1 * var(--pad)) 4px;
  padding: 0 var(--pad);
}
.filters-wrap::after {
  content: "";
  position: absolute; top: 0; right: 0; bottom: 10px; width: 36px;
  pointer-events: none;
  background: linear-gradient(90deg, transparent, var(--bg) 70%);
  opacity: 0; transition: opacity .2s ease;
}
.filters-wrap[data-fade="end"]::after,
.filters-wrap[data-fade="both"]::after { opacity: 1; }
.filters-wrap::before {
  content: "";
  position: absolute; top: 0; left: 0; bottom: 10px; width: 28px;
  pointer-events: none; z-index: 1;
  background: linear-gradient(270deg, transparent, var(--bg) 70%);
  opacity: 0; transition: opacity .2s ease;
}
.filters-wrap[data-fade="start"]::before,
.filters-wrap[data-fade="both"]::before { opacity: 1; }
.filters {
  display: flex; gap: 8px; overflow-x: auto; padding: 0 4px 10px 0;
  -webkit-overflow-scrolling: touch; scrollbar-width: none;
}
.filters::-webkit-scrollbar { display: none; }
.chip {
  flex: 0 0 auto; border: 1px solid var(--line); background: var(--card); color: var(--ink);
  border-radius: 999px; padding: 8px 12px; font-size: 0.8rem; font-weight: 600; min-height: 40px; cursor: pointer;
}
.chip.is-on { border-color: var(--accent); color: var(--accent); }

.card {
  width: 100%; border: 1px solid var(--line); background: var(--card); border-radius: 20px;
  min-height: 340px; padding: 20px 16px; cursor: pointer; text-align: left; color: inherit;
  display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 12px;
  -webkit-tap-highlight-color: transparent;
}
.card:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }
.sign { width: min(220px, 70vw); aspect-ratio: 1; display: grid; place-items: center; }
.sign img, .sign svg { width: 100%; height: 100%; object-fit: contain; filter: drop-shadow(0 8px 18px rgba(0,0,0,.35)); }
.hint { margin: 0; color: var(--muted); font-size: 0.85rem; }
.card-back { width: 100%; }
.cat { margin: 0 0 6px; text-transform: uppercase; letter-spacing: 0.08em; font-size: 0.7rem; color: var(--accent); font-weight: 700; }
.name { margin: 0 0 10px; font-size: 1.45rem; letter-spacing: -0.02em; }
.meaning { margin: 0; line-height: 1.45; color: #d7dee6; font-size: 1rem; }

.actions { display: grid; grid-template-columns: 48px 1fr 1.2fr 48px; gap: 8px; margin-top: 14px; }
.btn {
  border: 1px solid var(--line); background: var(--card); color: var(--ink); border-radius: 14px;
  min-height: 48px; font-weight: 700; font-size: 0.95rem; cursor: pointer; padding: 0 12px;
}
.btn:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
.btn.primary { background: var(--accent); color: var(--accent-ink); border-color: transparent; }
.btn.ghost { font-size: 1.4rem; }
.btn.wide { width: 100%; margin-top: 10px; }
.btn:disabled { opacity: 0.45; cursor: default; }
.known { text-align: center; color: var(--muted); font-size: 0.8rem; margin: 10px 0 0; }

.quiz-sign { width: min(160px, 42vw); margin: 2px auto 8px; aspect-ratio: 1; }
.quiz-sign img, .quiz-sign svg { width: 100%; height: 100%; object-fit: contain; filter: drop-shadow(0 8px 18px rgba(0,0,0,.35)); }
.quiz-prompt { text-align: center; font-weight: 700; margin: 0 0 8px; font-size: 0.95rem; }
.choices { display: grid; gap: 6px; }
.choice {
  text-align: left; border: 1px solid var(--line); background: var(--card); color: var(--ink);
  border-radius: 14px; padding: 11px 12px; min-height: 48px; font-size: 0.88rem; line-height: 1.3; cursor: pointer;
}
.choice.is-correct { border-color: var(--accent); background: rgba(61,214,140,.12); }
.choice.is-wrong { border-color: var(--danger); background: rgba(255,107,107,.1); }
.quiz-feedback { min-height: 0; text-align: center; font-weight: 650; margin: 6px 0 0; font-size: 0.85rem; }
.quiz-feedback:empty { display: none; }
.quiz-feedback.ok { color: var(--accent); }
.quiz-feedback.bad { color: var(--danger); }
#quiz-panel .known { margin: 6px 0 0; }
#quiz-panel .btn.wide { margin-top: 6px; min-height: 44px; }

.foot { padding: 6px var(--pad) var(--pad-b); color: var(--muted); font-size: 0.68rem; line-height: 1.35; text-align: center; max-width: 480px; margin: 0 auto; }
.foot p { margin: 0; }

@media (max-height: 720px) {
  .quiz-sign { width: min(132px, 36vw); margin: 0 auto 6px; }
  .progress-row { margin-bottom: 6px; }
  .filters { padding-bottom: 6px; }
  .filters-wrap::before, .filters-wrap::after { bottom: 6px; }
}

@media (min-width: 720px) {
  .card { min-height: 400px; }
  .sign { width: 260px; }
}

.foot a { color: var(--accent); text-decoration: none; }
.foot a:hover { text-decoration: underline; }