/* Layout: one centered column (max 760px) for phone-first practice; Emma (coral, left) asks and
   Sam (blue, right) answers, the same pair and colors as the course videos. */
:root {
  --bg: #f6f4ef;
  --card: #ffffff;
  --ink: #1f2547;
  --ink-2: #5b6080;
  --line: #e4e1d8;
  --yellow: #ffc531;
  --ink-on-yellow: #1f2547;
  --coral: #e5533d;
  --coral-soft: #fde6e1;
  --blue: #2d6be4;
  --blue-soft: #e1eafc;
  --good: #1f9d63;
  --good-soft: #dcf3e7;
  --bad: #d23c2a;
  --bad-soft: #fbe2de;
  --hl: #fff0b8;
  --shadow: 0 1px 0 rgba(31, 37, 71, .06), 0 6px 18px rgba(31, 37, 71, .06);
  --font: "Be Vietnam Pro", "Segoe UI", system-ui, -apple-system, sans-serif;
  --font-ipa: "Noto Sans", "Segoe UI", "Lucida Grande", system-ui, sans-serif;
  --r: 16px;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #151829; --card: #1e2238; --ink: #eef0fa; --ink-2: #a7acc8; --line: #2e3350;
    --yellow: #ffcb45; --ink-on-yellow: #1f2547; --coral: #ff7a63; --coral-soft: #3a2328;
    --blue: #6b9bff; --blue-soft: #1f2c4d; --good: #3fcf8e; --good-soft: #17352a;
    --bad: #ff7a69; --bad-soft: #3d2124; --hl: #4a4020;
    --shadow: 0 1px 0 rgba(0, 0, 0, .3), 0 6px 18px rgba(0, 0, 0, .25);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #151829; --card: #1e2238; --ink: #eef0fa; --ink-2: #a7acc8; --line: #2e3350;
  --yellow: #ffcb45; --ink-on-yellow: #1f2547; --coral: #ff7a63; --coral-soft: #3a2328;
  --blue: #6b9bff; --blue-soft: #1f2c4d; --good: #3fcf8e; --good-soft: #17352a;
  --bad: #ff7a69; --bad-soft: #3d2124; --hl: #4a4020;
  --shadow: 0 1px 0 rgba(0, 0, 0, .3), 0 6px 18px rgba(0, 0, 0, .25);
  color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  background: var(--bg); color: var(--ink); font: 400 16px/1.55 var(--font);
  -webkit-text-size-adjust: 100%;
}
body::before { content: ""; position: fixed; inset: 0 0 auto; height: env(safe-area-inset-top, 0px); z-index: 30; background: var(--card); }
button, select, input, textarea { font: inherit; color: inherit; }
button { cursor: pointer; }
:focus-visible { outline: 3px solid var(--blue); outline-offset: 2px; }
[hidden] { display: none !important; }
.wrap {
  max-width: 760px; margin: 0 auto;
  padding-left: max(16px, env(safe-area-inset-left, 0px));
  padding-right: max(16px, env(safe-area-inset-right, 0px));
}

/* ---------- top bar ---------- */
.bar { position: sticky; top: env(safe-area-inset-top, 0px); z-index: 20; background: var(--card); border-bottom: 1px solid var(--line); }
.bar-in {
  max-width: 760px; margin: 0 auto; display: flex; align-items: center; gap: 14px; padding-block: 10px;
  padding-left: max(16px, env(safe-area-inset-left, 0px)); padding-right: max(16px, env(safe-area-inset-right, 0px));
}
.brand { display: flex; align-items: center; gap: 8px; text-decoration: none; color: var(--ink); font-weight: 600; letter-spacing: .04em; font-size: 15px; white-space: nowrap; }
.brand svg { width: 32px; height: 32px; }
.brand b { font-weight: 800; }
.overall { flex: 1; min-width: 0; display: flex; align-items: center; gap: 10px; font-size: 13px; color: var(--ink-2); }
.overall .meter { flex: 1; max-width: 220px; }
.icon-btn { width: 40px; height: 40px; border-radius: 12px; border: 1px solid var(--line); background: var(--card); display: grid; place-items: center; color: var(--ink); }
.icon-btn svg { width: 22px; height: 22px; }
.settings {
  max-width: 760px; margin: 0 auto 10px; display: grid; gap: 4px;
  padding-left: max(16px, env(safe-area-inset-left, 0px)); padding-right: max(16px, env(safe-area-inset-right, 0px));
}
.set-row { display: flex; justify-content: space-between; align-items: center; gap: 12px; padding: 10px 14px; background: var(--bg); border-radius: 12px; font-size: 15px; }
.set-row select { padding: 6px 10px; border-radius: 10px; border: 1px solid var(--line); background: var(--card); }
.set-row input[type=checkbox] { width: 22px; height: 22px; accent-color: var(--blue); }

.meter { height: 8px; border-radius: 99px; background: var(--line); overflow: hidden; }
.meter i { display: block; height: 100%; background: var(--good); border-radius: inherit; transition: width .4s; }

main { padding-block: 22px 40px; min-height: 70vh; }
.foot { color: var(--ink-2); font-size: 13px; padding-block: 18px 36px; text-align: center; }

/* ---------- home ---------- */
.hero { padding: 18px 0 8px; }
.eyebrow { font-size: 12px; font-weight: 700; letter-spacing: .14em; text-transform: uppercase; color: var(--coral); }
.hero h1 { font-size: clamp(30px, 7vw, 46px); line-height: 1.08; margin: 8px 0 10px; font-weight: 800; letter-spacing: -.02em; text-wrap: balance; }
.hero h1 em { font-style: normal; color: var(--blue); }
.hero p { margin: 0; color: var(--ink-2); max-width: 54ch; }

.stats { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin: 22px 0 28px; }
.stat {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--r); padding: 14px 16px; text-align: left;
  display: grid; gap: 2px; text-decoration: none; color: var(--ink); box-shadow: var(--shadow);
}
.stat b { font-size: 18px; font-weight: 700; }
.stat span { font-size: 13px; color: var(--ink-2); }
.stat.go { background: var(--yellow); border-color: transparent; color: var(--ink-on-yellow); }
.stat.go span { color: var(--ink-on-yellow); opacity: .75; }
.stat.dim { opacity: .65; }
.stat .meter { margin-top: 6px; }

.sec-title { display: flex; align-items: baseline; justify-content: space-between; margin: 6px 0 12px; }
.sec-title h2 { font-size: 20px; margin: 0; font-weight: 700; }
.sec-title span { font-size: 13px; color: var(--ink-2); }

.topics { display: grid; grid-template-columns: repeat(auto-fill, minmax(min(100%, 330px), 1fr)); gap: 12px; }
.topic {
  display: grid; grid-template-columns: auto 1fr auto; align-items: center; gap: 14px;
  background: var(--card); border: 1px solid var(--line); border-radius: var(--r); padding: 14px 16px;
  text-decoration: none; color: var(--ink); box-shadow: var(--shadow); transition: transform .15s, border-color .15s;
}
.topic:hover { transform: translateY(-1px); border-color: var(--blue); }
.topic .num { width: 44px; height: 44px; border-radius: 12px; display: grid; place-items: center; font-weight: 800; font-variant-numeric: tabular-nums; background: var(--blue-soft); color: var(--blue); }
.topic.done .num { background: var(--good-soft); color: var(--good); }
.topic .t { min-width: 0; }
.topic .t b { display: block; font-weight: 700; }
.topic .t small { color: var(--ink-2); font-size: 13px; }
.badge { font-size: 12px; font-weight: 700; padding: 4px 10px; border-radius: 99px; background: var(--bg); color: var(--ink-2); white-space: nowrap; }
.badge.ok { background: var(--good-soft); color: var(--good); }

/* ---------- topic ---------- */
.back { display: inline-flex; align-items: center; gap: 6px; color: var(--ink-2); text-decoration: none; font-size: 14px; font-weight: 600; margin-bottom: 10px; }
.thead h1 { font-size: clamp(26px, 6vw, 36px); margin: 4px 0 6px; line-height: 1.15; font-weight: 800; text-wrap: balance; }
.thead p { margin: 0 0 18px; color: var(--ink-2); font-size: 14px; }
.modes { display: grid; grid-template-columns: repeat(auto-fill, minmax(min(100%, 220px), 1fr)); gap: 12px; }
.mode {
  display: flex; flex-direction: column; gap: 4px; padding: 16px 18px 18px; border-radius: var(--r); text-decoration: none; color: #fff;
  min-height: 136px; background: var(--m); box-shadow: var(--shadow); position: relative;
}
.mode svg { width: 30px; height: 30px; flex: none; margin-bottom: auto; }
.mode b { margin-top: 14px; }
.mode b { font-size: 17px; font-weight: 700; }
.mode span { font-size: 13px; opacity: .9; }
.mode.plain { background: var(--card); color: var(--ink); border: 1px solid var(--line); }
.mode.plain span { color: var(--ink-2); opacity: 1; }
.mode .score { position: absolute; top: 16px; right: 16px; font-size: 12px; font-weight: 700; background: rgba(255,255,255,.22); padding: 3px 9px; border-radius: 99px; }

/* ---------- exercise shell ---------- */
.ex-top { display: flex; align-items: center; gap: 12px; margin-bottom: 18px; }
.ex-top .meter { flex: 1; }
.ex-top .count { font-size: 13px; color: var(--ink-2); font-variant-numeric: tabular-nums; white-space: nowrap; }
.ex-title { font-size: 13px; font-weight: 700; letter-spacing: .12em; text-transform: uppercase; color: var(--ink-2); margin: 0 0 8px; }
.prompt { font-size: 15px; color: var(--ink-2); margin: 0 0 12px; }

.bubble {
  background: var(--card); border: 2px solid var(--c, var(--line)); border-radius: 22px; padding: 16px 18px; box-shadow: var(--shadow);
  position: relative; max-width: 620px;
}
.bubble.q { --c: var(--coral); border-bottom-left-radius: 6px; }
.bubble.a { --c: var(--blue); border-bottom-right-radius: 6px; margin-left: auto; }
.who { font-size: 12px; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--c); margin-bottom: 4px; display: flex; align-items: center; gap: 8px; }
.en { font-size: clamp(20px, 4.6vw, 24px); font-weight: 600; line-height: 1.35; }
.en.small { font-size: 18px; }
.ipa { font-family: var(--font-ipa); color: var(--ink-2); font-size: 15px; margin-top: 6px; }
.vi { color: var(--ink-2); font-size: 15px; margin-top: 6px; }
.hl { background: var(--hl); border-radius: 6px; padding: 0 2px; margin: 0 -2px; -webkit-box-decoration-break: clone; box-decoration-break: clone; }
.w-ok { color: var(--good); }
.w-miss { color: var(--ink-2); opacity: .55; text-decoration: underline wavy var(--bad); text-underline-offset: 4px; }
.w-bad { color: var(--bad); }
.stack { display: grid; gap: 14px; }

.row { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; }
.btn {
  border: 1px solid var(--line); background: var(--card); color: var(--ink); border-radius: 14px; padding: 11px 16px;
  font-weight: 600; display: inline-flex; align-items: center; gap: 8px; min-height: 46px;
}
.btn svg { width: 20px; height: 20px; flex: none; }
.btn.primary { background: var(--ink); color: var(--card); border-color: var(--ink); }
.btn.yellow { background: var(--yellow); color: var(--ink-on-yellow); border-color: var(--yellow); }
.btn.good { background: var(--good); border-color: var(--good); color: #fff; }
.btn.ghost { background: transparent; }
.btn:disabled { opacity: .45; cursor: default; }
.btn.playing { border-color: var(--blue); color: var(--blue); }

.mic {
  width: 84px; height: 84px; border-radius: 50%; border: 0; background: var(--coral); color: #fff; display: grid; place-items: center;
  box-shadow: 0 8px 22px color-mix(in srgb, var(--coral) 40%, transparent);
}
.mic svg { width: 36px; height: 36px; }
.mic.on { animation: pulse 1.2s ease-in-out infinite; }
@keyframes pulse { 0%, 100% { box-shadow: 0 0 0 0 color-mix(in srgb, var(--coral) 45%, transparent); } 50% { box-shadow: 0 0 0 16px transparent; } }
.mic-zone { display: grid; justify-items: center; gap: 10px; padding: 12px 0 4px; text-align: center; }
.mic-zone small { color: var(--ink-2); font-size: 14px; }
.heard { font-size: 15px; color: var(--ink-2); }
.heard b { color: var(--ink); font-weight: 600; }

.result { border-radius: 14px; padding: 12px 16px; font-weight: 600; display: flex; align-items: center; gap: 10px; }
.result.good { background: var(--good-soft); color: var(--good); }
.result.mid { background: var(--hl); color: var(--ink); }
.result.bad { background: var(--bad-soft); color: var(--bad); }
.note { font-size: 14px; color: var(--ink-2); background: var(--card); border: 1px dashed var(--line); border-radius: 12px; padding: 10px 14px; }

.timer { width: 64px; height: 64px; }
.timer circle { fill: none; stroke-width: 6; }
.timer .bg { stroke: var(--line); }
.timer .fg { stroke: var(--good); stroke-linecap: round; transform: rotate(-90deg); transform-origin: 50% 50%; }

textarea.type {
  width: 100%; min-height: 96px; border-radius: 14px; border: 2px solid var(--line); background: var(--card); padding: 12px 14px;
  font-size: 18px; resize: vertical;
}
textarea.type:focus { border-color: var(--blue); outline: none; }

.chips { display: flex; flex-wrap: wrap; gap: 8px; min-height: 52px; padding: 10px; border-radius: 14px; }
.chips.answer { background: var(--card); border: 2px dashed var(--line); }
.chip { border: 1px solid var(--line); background: var(--card); border-radius: 10px; padding: 8px 12px; font-size: 17px; font-weight: 500; box-shadow: 0 2px 0 var(--line); }
.chip.used { visibility: hidden; }
.chips.answer .chip { background: var(--blue-soft); border-color: transparent; box-shadow: none; }

.options { display: grid; gap: 10px; }
.opt { text-align: left; background: var(--card); border: 2px solid var(--line); border-radius: 14px; padding: 12px 16px; font-size: 16px; line-height: 1.45; }
.opt.right { border-color: var(--good); background: var(--good-soft); }
.opt.wrong { border-color: var(--bad); background: var(--bad-soft); }

/* flashcard: swap faces instead of a 3D flip, which some phone browsers render with the wrong face showing */
.flip { cursor: pointer; }
.face {
  min-height: 240px; border-radius: 22px; padding: 22px;
  display: grid; align-content: center; gap: 10px; text-align: center; background: var(--card); border: 2px solid var(--line); box-shadow: var(--shadow);
}
.face.back { display: none; border-color: var(--blue); }
.flip.on .face:not(.back) { display: none; }
.flip.on .face.back { display: grid; animation: cardIn .35s ease-out; }
@keyframes cardIn { from { opacity: 0; transform: scale(.96); } to { opacity: 1; transform: none; } }
.face .tap { font-size: 13px; color: var(--ink-2); }

.list-part { margin: 22px 0 10px; font-size: 13px; font-weight: 700; letter-spacing: .12em; text-transform: uppercase; color: var(--ink-2); }
.play-mini { border: 0; background: var(--bg); color: var(--c, var(--ink)); width: 32px; height: 32px; border-radius: 50%; display: inline-grid; place-items: center; }
.play-mini svg { width: 16px; height: 16px; }

.end { text-align: center; display: grid; gap: 12px; justify-items: center; padding: 20px 0; }
.end .big { font-size: 56px; font-weight: 800; line-height: 1; font-variant-numeric: tabular-nums; }
.end p { margin: 0; color: var(--ink-2); max-width: 42ch; }
.empty { text-align: center; color: var(--ink-2); padding: 30px 0; }

@media (max-width: 480px) {
  .bar-in { gap: 10px; }
  .brand span { display: none; }
  .stats { grid-template-columns: 1fr 1fr; }
}
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}