:root {
  color-scheme: dark;
  --ink: #f4f8fc;
  --muted: #a7b9c7;
  --canvas: #07131f;
  --surface: #0d202e;
  --surface-raised: #112a3b;
  --line: rgba(198, 226, 239, 0.17);
  --teal: #7de3d0;
  --teal-dark: #154b51;
  --orange: #ff9d2e;
  --red: #ff7f8b;
  --green: #86e6a6;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }
html { min-height: 100%; background: var(--canvas); }
body { min-height: 100vh; margin: 0; background: radial-gradient(circle at 82% -8%, #174358 0, transparent 28rem), var(--canvas); color: var(--ink); }
button, select, input { font: inherit; }
button { cursor: pointer; }

.app-shell { width: min(100%, 42rem); min-height: 100vh; margin: 0 auto; padding: 1.1rem 1rem 2rem; }
.topbar, .brand, .question-meta, .progress-copy, .progress-summary, .dialog-header, .revision-actions, .top-actions { display: flex; align-items: center; }
.topbar { justify-content: space-between; margin-bottom: 1.55rem; }
.brand { gap: .75rem; }
.brand-mark { display: grid; place-items: center; width: 2.8rem; height: 2.8rem; border-radius: .9rem; background: linear-gradient(135deg, var(--orange), #fdc454); color: #162b3a; font-size: 1.75rem; font-weight: 900; box-shadow: 0 .5rem 1.5rem rgba(255,157,46,.19); }
h1, h2, p { margin: 0; }
h1 { font-size: 1.125rem; letter-spacing: -.02em; }
h2 { font-size: 1.5rem; letter-spacing: -.03em; }
.eyebrow { color: var(--teal); font-size: .72rem; font-weight: 800; letter-spacing: .11em; text-transform: uppercase; }
.icon-button { display: grid; place-items: center; width: 2.6rem; height: 2.6rem; padding: 0; border: 1px solid var(--line); border-radius: .8rem; background: rgba(13,32,46,.76); color: var(--ink); font-size: 1.25rem; }
.icon-button:hover { border-color: var(--teal); color: var(--teal); }
.top-actions { gap: .45rem; }
.sync-button { display: inline-flex; align-items: center; gap: .42rem; min-height: 2.6rem; padding: .45rem .65rem; border: 1px solid var(--line); border-radius: .8rem; background: rgba(13,32,46,.76); color: var(--ink); font-size: .78rem; font-weight: 800; }
.sync-button:hover { border-color: var(--teal); }
.sync-dot { width: .55rem; height: .55rem; border-radius: 50%; background: var(--orange); box-shadow: 0 0 0 .18rem rgba(255,157,46,.12); }
.sync-dot.synced { background: var(--green); box-shadow: 0 0 0 .18rem rgba(134,230,166,.12); }

.progress-panel { margin-bottom: 1rem; padding: 1rem; border: 1px solid var(--line); border-radius: 1rem; background: rgba(13,32,46,.73); }
.progress-copy { justify-content: space-between; gap: 1rem; color: var(--muted); font-size: .9rem; }
.progress-copy strong { color: var(--ink); }
.progress-track { height: .4rem; overflow: hidden; margin: .8rem 0; border-radius: 1rem; background: #193446; }
.progress-track span { display: block; width: 0; height: 100%; border-radius: inherit; background: linear-gradient(90deg, var(--teal), #8ab7ff); transition: width .25s ease; }
.progress-summary { justify-content: space-between; color: var(--muted); font-size: .82rem; }
.progress-summary b { color: var(--ink); }
.focus-panel { display: grid; gap: .8rem; margin: 0 0 1rem; padding: 1rem; border: 1px solid rgba(255,157,46,.3); border-radius: 1rem; background: rgba(255,157,46,.06); }
.focus-panel h2 { margin-top: .1rem; font-size: 1rem; }
.focus-list { display: grid; gap: .5rem; }
.focus-item { display: grid; grid-template-columns: 1fr auto; gap: .45rem .75rem; align-items: center; padding: .65rem .7rem; border-radius: .75rem; background: rgba(8,25,36,.62); }
.focus-item strong { font-size: .88rem; }
.focus-item span { color: #ffbf77; font-size: .8rem; font-weight: 800; }
.focus-item small { grid-column: 1 / -1; color: var(--muted); font-size: .78rem; }

.quiz-card, .feedback, .session-complete { border: 1px solid var(--line); border-radius: 1.25rem; background: linear-gradient(145deg, rgba(19,43,59,.96), rgba(11,28,41,.96)); box-shadow: 0 1.5rem 3.5rem rgba(0,0,0,.18); }
.quiz-card { padding: 1.15rem; }
.question-meta { justify-content: space-between; gap: .7rem; margin-bottom: 1.1rem; }
.chip { max-width: 72%; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; padding: .35rem .58rem; border: 1px solid rgba(125,227,208,.26); border-radius: 999px; color: var(--teal); background: rgba(125,227,208,.08); font-size: .72rem; font-weight: 700; }
.question-kind { flex: none; color: var(--muted); font-size: .78rem; }
.question { color: var(--ink); font-size: 1.12rem; line-height: 1.55; }
.question p { margin: 0 0 .65rem; }
.question p:last-child { margin-bottom: 0; }
.audio-row { display: flex; align-items: center; justify-content: space-between; gap: .75rem; margin-top: 1rem; }
.audio-button { display: inline-flex; align-items: center; gap: .62rem; min-height: 2.8rem; padding: .55rem .8rem; border: 1px solid rgba(125,227,208,.36); border-radius: .85rem; background: rgba(125,227,208,.09); color: var(--ink); font-size: .88rem; font-weight: 800; }
.audio-button:hover { border-color: var(--teal); background: rgba(125,227,208,.14); }
.audio-button:disabled { cursor: wait; opacity: .66; }
.audio-icon { display: grid; place-items: center; width: 1.7rem; height: 1.7rem; border-radius: 50%; background: var(--teal); color: #08202d; font-size: .72rem; }
.audio-source { color: var(--muted); font-size: .72rem; white-space: nowrap; }
.answers { display: grid; gap: .65rem; margin: 1.4rem 0 1.15rem; }
.answer { display: flex; align-items: flex-start; gap: .75rem; min-height: 3.5rem; padding: .85rem; border: 1px solid var(--line); border-radius: .9rem; background: rgba(6,18,28,.35); color: var(--ink); line-height: 1.35; transition: border-color .16s ease, transform .16s ease, background .16s ease; }
.answer:hover { border-color: rgba(125,227,208,.68); transform: translateY(-1px); }
.answer:has(input:checked) { border-color: var(--teal); background: rgba(125,227,208,.1); }
.answer input { flex: none; width: 1.15rem; height: 1.15rem; margin: .1rem 0 0; accent-color: var(--teal); }
.answer.correct { border-color: var(--green); background: rgba(134,230,166,.12); }
.answer.incorrect { border-color: var(--red); background: rgba(255,127,139,.11); }
.answer.dimmed { opacity: .62; }

.primary-button, .secondary-button, .text-button { border: 0; border-radius: .85rem; font-weight: 800; }
.primary-button { width: 100%; min-height: 3.3rem; padding: .75rem 1rem; background: linear-gradient(135deg, var(--teal), #91d8e2); color: #08202d; box-shadow: 0 .6rem 1.5rem rgba(125,227,208,.16); }
.primary-button:hover { filter: brightness(1.05); }
.primary-button:disabled { cursor: not-allowed; opacity: .48; }
.feedback { margin-top: 1rem; padding: 1.15rem; }
.feedback-heading { margin-bottom: .85rem; color: var(--green); font-size: 1.18rem; font-weight: 900; }
.feedback-heading.wrong { color: var(--red); }
.answer-recap { margin-bottom: 1rem; color: var(--muted); font-size: .91rem; line-height: 1.45; }
.answer-recap strong { color: var(--ink); }
.explanation { padding: 1rem; border-left: 3px solid var(--orange); background: rgba(255,157,46,.08); color: #deebf4; font-size: .95rem; line-height: 1.55; }
.explanation p + p { margin-top: .7rem; }
.explanation a { color: var(--teal); overflow-wrap: anywhere; }
.revision-actions { gap: .65rem; margin: 1rem 0 .75rem; }
.secondary-button { flex: 1; min-height: 2.9rem; padding: .6rem; border: 1px solid var(--line); background: transparent; color: var(--ink); }
.secondary-button.active-review { border-color: var(--orange); background: rgba(255,157,46,.13); color: #ffbd72; }
.secondary-button.active-mastered { border-color: var(--green); background: rgba(134,230,166,.11); color: var(--green); }
.hidden { display: none !important; }
.session-complete { margin-top: 1rem; padding: 2.4rem 1.2rem; text-align: center; }
.completion-icon { display: grid; place-items: center; width: 3.4rem; height: 3.4rem; margin: 0 auto 1rem; border-radius: 50%; background: rgba(125,227,208,.14); color: var(--teal); font-size: 1.7rem; }
.session-complete h2 { margin: .2rem 0 .65rem; }
.session-complete > p:not(.eyebrow) { margin-bottom: 1.35rem; color: var(--muted); line-height: 1.5; }

dialog { width: min(calc(100% - 2rem), 32rem); max-height: min(46rem, calc(100vh - 2rem)); padding: 0; border: 1px solid var(--line); border-radius: 1.25rem; background: #0d202e; color: var(--ink); box-shadow: 0 2rem 7rem rgba(0,0,0,.64); }
dialog::backdrop { background: rgba(1,7,12,.66); backdrop-filter: blur(3px); }
.settings-panel { display: grid; gap: .85rem; padding: 1.15rem; }
.dialog-header { justify-content: space-between; margin-bottom: .35rem; }
.settings-panel label, legend { color: #d7e5ee; font-size: .9rem; font-weight: 700; }
select { min-height: 3rem; padding: 0 .85rem; border: 1px solid var(--line); border-radius: .75rem; background: #081924; color: var(--ink); }
.auth-fields { display: grid; gap: .65rem; }
.auth-fields input { min-height: 3rem; padding: 0 .85rem; border: 1px solid var(--line); border-radius: .75rem; background: #081924; color: var(--ink); }
.auth-fields input:focus, select:focus { outline: 2px solid rgba(125,227,208,.68); outline-offset: 2px; }
.dialog-copy { color: var(--muted); font-size: .92rem; line-height: 1.45; }
.auth-message { min-height: 1.2rem; margin: 0; color: #ffbf77; font-size: .84rem; line-height: 1.35; }
.signed-in-email { color: var(--teal); font-size: 1rem; font-weight: 800; overflow-wrap: anywhere; }
fieldset { display: grid; gap: .65rem; margin: .2rem 0; padding: .75rem; border: 1px solid var(--line); border-radius: .85rem; }
legend { padding: 0 .3rem; }
.radio-row { display: flex; align-items: center; gap: .65rem; font-weight: 500 !important; }
.radio-row input { width: 1.1rem; height: 1.1rem; accent-color: var(--teal); }
.text-button { padding: .55rem; background: transparent; color: var(--muted); text-decoration: underline; }
.text-button:hover { color: var(--red); }

@media (min-width: 44rem) { .app-shell { padding-top: 2.25rem; } .quiz-card, .feedback { padding: 1.5rem; } }
@media (max-width: 22rem) { .app-shell { padding-inline: .7rem; } .question { font-size: 1.02rem; } .chip { max-width: 65%; } }