:root {
  --bg: #0f172a;
  --bg-soft: #1e293b;
  --bg-card: #1e293b;
  --bg-elevated: #273449;
  --border: #334155;
  --text: #e2e8f0;
  --text-dim: #94a3b8;
  --accent: #3b82f6;
  --accent-2: #8b5cf6;
  --green: #10b981;
  --amber: #f59e0b;
  --radius: 14px;
  --shadow: 0 8px 30px rgba(0,0,0,.25);
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  background: linear-gradient(160deg, #0f172a 0%, #131c31 100%);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
}

/* ---------- Header ---------- */
.app-header {
  position: sticky; top: 0; z-index: 20;
  background: rgba(15,23,42,.85);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  max-width: 1200px; margin: 0 auto; padding: 14px 22px;
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
}
.brand { display: flex; align-items: center; gap: 14px; }
.logo { font-size: 34px; }
.app-header h1 { font-size: 20px; font-weight: 700; }
.subtitle { font-size: 13px; color: var(--text-dim); }
.streak-box {
  display: flex; flex-direction: column; align-items: center;
  background: var(--bg-elevated); border: 1px solid var(--border);
  padding: 8px 16px; border-radius: 12px; min-width: 90px;
}
.streak-num { font-size: 26px; font-weight: 800; color: var(--green); line-height: 1; }
.streak-label { font-size: 11px; color: var(--text-dim); }
.tabs { max-width: 1200px; margin: 0 auto; padding: 0 22px 10px; display: flex; gap: 8px; }
.tab {
  background: var(--bg-elevated); border: 1px solid var(--border); color: var(--text-dim);
  padding: 8px 16px; border-radius: 10px 10px 0 0; cursor: pointer; font-size: 14px; font-weight: 600;
}
.tab:hover { color: var(--text); }
.tab.active { background: var(--accent); color: #fff; border-color: var(--accent); }
.tab .ti { margin-right: 5px; }
.tab .tl { }
.progress-bar { height: 4px; background: var(--bg-soft); }
.progress-fill {
  height: 100%; width: 0%;
  background: linear-gradient(90deg, var(--accent), var(--green));
  transition: width .4s ease;
}

/* ---------- Layout ---------- */
.layout {
  max-width: 1200px; margin: 0 auto; padding: 22px;
  display: grid; grid-template-columns: 280px 1fr; gap: 22px;
  align-items: start;
}

/* ---------- Sidebar ---------- */
.sidebar {
  position: sticky; top: 84px;
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 16px; box-shadow: var(--shadow);
}
.sidebar-head { display: flex; align-items: center; justify-content: space-between; margin-bottom: 12px; }
.sidebar-head h2 { font-size: 15px; }
.reset-btn {
  background: transparent; border: 1px solid var(--border); color: var(--text-dim);
  font-size: 11px; padding: 4px 9px; border-radius: 8px; cursor: pointer;
}
.reset-btn:hover { color: #fca5a5; border-color: #fca5a5; }

.week-group { margin-bottom: 14px; }
.week-title {
  font-size: 11px; font-weight: 700; text-transform: uppercase;
  letter-spacing: .04em; color: var(--text-dim); margin-bottom: 8px;
  display: flex; align-items: center; gap: 6px;
}
.week-dot { width: 8px; height: 8px; border-radius: 50%; }
.day-grid { display: grid; grid-template-columns: repeat(7, 1fr); gap: 6px; }
.day-cell {
  aspect-ratio: 1; border-radius: 9px; border: 1px solid var(--border);
  background: var(--bg-elevated); color: var(--text-dim);
  font-size: 13px; font-weight: 600; cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  position: relative; transition: transform .12s, border-color .12s;
}
.day-cell:hover { transform: translateY(-2px); border-color: var(--accent); color: var(--text); }
.day-cell.active { border-color: var(--accent); background: var(--accent); color: #fff; }
.day-cell.done { background: var(--green); color: #fff; border-color: var(--green); }
.day-cell.done.active { box-shadow: 0 0 0 2px var(--accent); }
.day-cell .check { position: absolute; top: -4px; right: -4px; font-size: 11px; }

/* ---------- Content ---------- */
.content {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 26px; box-shadow: var(--shadow);
  min-height: 70vh;
}
.lesson-top { display: flex; align-items: flex-start; justify-content: space-between; gap: 16px; flex-wrap: wrap; }
.badge {
  display: inline-block; font-size: 12px; font-weight: 700;
  padding: 4px 12px; border-radius: 999px; color: #fff; margin-bottom: 8px;
}
.lesson-title { font-size: 26px; font-weight: 800; margin-bottom: 4px; }
.lesson-topic { color: var(--text-dim); font-size: 14px; font-style: italic; }
.nav-buttons { display: flex; gap: 8px; }
.nav-buttons button {
  background: var(--bg-elevated); border: 1px solid var(--border); color: var(--text);
  padding: 8px 14px; border-radius: 10px; cursor: pointer; font-size: 14px;
}
.nav-buttons button:hover:not(:disabled) { border-color: var(--accent); }
.nav-buttons button:disabled { opacity: .4; cursor: not-allowed; }

.intro {
  margin: 18px 0; padding: 14px 16px; border-left: 3px solid var(--accent);
  background: rgba(59,130,246,.08); border-radius: 8px; font-size: 15px;
}

/* video */
.video-zone { margin: 20px 0; }
.video-wrap {
  position: relative; width: 100%; aspect-ratio: 16/9;
  border-radius: 12px; overflow: hidden; background: #000; border: 1px solid var(--border);
}
.video-wrap iframe { width: 100%; height: 100%; border: 0; }
.yt-facade {
  position: absolute; inset: 0; width: 100%; height: 100%;
  border: 0; cursor: pointer; padding: 0;
  background-size: cover; background-position: center; background-color: #000;
  display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 14px;
}
.yt-facade::after { content: ""; position: absolute; inset: 0; background: rgba(0,0,0,.28); transition: background .2s; }
.yt-facade:hover::after { background: rgba(0,0,0,.12); }
.yt-play {
  position: relative; z-index: 1; width: 74px; height: 74px; border-radius: 50%;
  background: #ff0000; color: #fff; font-size: 30px; line-height: 74px; text-align: center;
  padding-left: 4px; box-shadow: 0 6px 20px rgba(0,0,0,.4);
}
.yt-facade:hover .yt-play { background: #cc0000; transform: scale(1.06); }
.yt-hint { position: relative; z-index: 1; color: #fff; font-size: 13px; font-weight: 600; text-shadow: 0 1px 4px rgba(0,0,0,.8); }
.video-placeholder {
  width: 100%; aspect-ratio: 16/9; border-radius: 12px;
  border: 2px dashed var(--border); background: var(--bg-elevated);
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 14px; text-align: center; padding: 24px;
}
.video-placeholder .vp-icon { font-size: 46px; }
.video-placeholder p { color: var(--text-dim); max-width: 420px; }
.source-row { display: flex; align-items: center; gap: 10px; margin-top: 12px; flex-wrap: wrap; }
.source-label { font-size: 13px; color: var(--text-dim); font-weight: 600; }
.source-select {
  background: var(--bg); border: 1px solid var(--border); color: var(--text);
  padding: 8px 12px; border-radius: 10px; font-size: 13px; cursor: pointer;
}
.source-select:disabled { opacity: .5; cursor: not-allowed; }
.source-desc { font-size: 12px; color: var(--text-dim); font-style: italic; }
.playlist-link { font-size: 12px; color: var(--accent); text-decoration: none; }
.playlist-link:hover { text-decoration: underline; }
.video-actions { display: flex; gap: 10px; margin-top: 12px; flex-wrap: wrap; align-items: center; }
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 10px 18px; border-radius: 10px; cursor: pointer; font-size: 14px;
  font-weight: 600; border: 1px solid transparent; text-decoration: none;
}
.btn-yt { background: #ff0000; color: #fff; }
.btn-yt:hover { background: #cc0000; }
.btn-ghost { background: var(--bg-elevated); color: var(--text); border-color: var(--border); }
.btn-ghost:hover { border-color: var(--accent); }
.id-input {
  flex: 1; min-width: 200px; background: var(--bg); border: 1px solid var(--border);
  color: var(--text); padding: 9px 12px; border-radius: 10px; font-size: 13px;
}

/* sections */
.section { margin-top: 26px; }
.section h3 {
  font-size: 16px; margin-bottom: 12px; display: flex; align-items: center; gap: 8px;
  padding-bottom: 8px; border-bottom: 1px solid var(--border);
}
.section h3 .ico { font-size: 18px; }

.vocab-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.vocab-item {
  background: var(--bg-elevated); border: 1px solid var(--border);
  border-radius: 10px; padding: 10px 14px;
  display: flex; align-items: center; justify-content: space-between; gap: 10px;
}
.vocab-en { font-weight: 600; }
.vocab-vi { color: var(--text-dim); font-size: 13px; text-align: right; }
.speak-btn {
  background: transparent; border: none; cursor: pointer; font-size: 16px;
  color: var(--accent); padding: 2px 4px; flex-shrink: 0;
}
.speak-btn:hover { color: var(--accent-2); }

.phrase-list { list-style: none; display: flex; flex-direction: column; gap: 8px; }
.phrase-item {
  display: flex; align-items: center; gap: 12px;
  background: var(--bg-elevated); border: 1px solid var(--border);
  border-radius: 10px; padding: 10px 14px;
}
.phrase-en { font-weight: 600; }
.phrase-vi { color: var(--text-dim); font-size: 13px; }
.phrase-text { flex: 1; }

.q-list { display: flex; flex-direction: column; gap: 10px; }
.q-item { background: var(--bg-elevated); border: 1px solid var(--border); border-radius: 10px; padding: 12px 14px; }
.q-text { font-weight: 600; margin-bottom: 6px; }
.q-toggle { background: transparent; border: 1px dashed var(--border); color: var(--text-dim);
  font-size: 12px; padding: 4px 10px; border-radius: 8px; cursor: pointer; }
.q-answer { margin-top: 8px; color: var(--green); font-size: 14px; display: none; }
.q-answer.show { display: block; }

/* ---------- Bài tập luyện nghe ---------- */
.ex-score {
  margin-left: auto; font-size: 13px; font-weight: 700; color: var(--green);
  background: rgba(16,185,129,.12); padding: 3px 12px; border-radius: 999px;
}
.ex-hint { font-size: 13px; color: var(--text-dim); margin-bottom: 14px; }
.ex-list { display: flex; flex-direction: column; gap: 12px; }
.ex-card { background: var(--bg-elevated); border: 1px solid var(--border); border-radius: 12px; padding: 14px 16px; }
.ex-head { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; }
.ex-num {
  width: 24px; height: 24px; border-radius: 50%; background: var(--accent); color: #fff;
  font-size: 13px; font-weight: 700; display: flex; align-items: center; justify-content: center; flex-shrink: 0;
}
.ex-say {
  font-size: 13px !important; font-weight: 600; color: var(--accent);
  border: 1px solid var(--border) !important; border-radius: 8px; padding: 4px 10px !important;
  background: var(--bg) !important;
}
.ex-say:hover { border-color: var(--accent) !important; }
.ex-type { font-size: 13px; color: var(--text-dim); }
.ex-sentence { font-size: 16px; margin-bottom: 10px; letter-spacing: .2px; }
.ex-sentence .blank { color: var(--amber); font-weight: 700; letter-spacing: 2px; }
.ex-row { display: flex; gap: 8px; flex-wrap: wrap; }
.ex-input {
  flex: 1; min-width: 160px; background: var(--bg); border: 1px solid var(--border);
  color: var(--text); padding: 9px 12px; border-radius: 9px; font-size: 14px;
}
.ex-input:focus { outline: none; border-color: var(--accent); }
.ex-input-sm { flex: 0 1 220px; }
.ex-input:disabled { opacity: .7; }
.ex-options { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.ex-opt {
  text-align: left; background: var(--bg); border: 1px solid var(--border); color: var(--text);
  padding: 10px 14px; border-radius: 9px; cursor: pointer; font-size: 14px; transition: border-color .12s;
}
.ex-opt:hover:not(:disabled) { border-color: var(--accent); }
.ex-opt:disabled { cursor: default; }
.ex-opt.correct { background: rgba(16,185,129,.18); border-color: var(--green); color: #6ee7b7; font-weight: 600; }
.ex-opt.wrong { background: rgba(239,68,68,.16); border-color: #ef4444; color: #fca5a5; }
.ex-fb { margin-top: 10px; font-size: 14px; padding: 8px 12px; border-radius: 8px; }
.ex-fb.ok { background: rgba(16,185,129,.12); color: #6ee7b7; }
.ex-fb.no { background: rgba(239,68,68,.12); color: #fca5a5; }
.ex-actions { margin-top: 14px; }

.tip-box {
  margin-top: 26px; padding: 14px 16px; border-radius: 10px;
  background: rgba(245,158,11,.1); border: 1px solid rgba(245,158,11,.3);
  font-size: 14px; display: flex; gap: 10px;
}
.tip-box .ico { font-size: 18px; }

.complete-zone { margin-top: 28px; text-align: center; }
.complete-btn {
  padding: 14px 30px; border-radius: 12px; border: none; cursor: pointer;
  font-size: 16px; font-weight: 700; background: var(--green); color: #fff;
  transition: transform .12s;
}
.complete-btn:hover { transform: translateY(-2px); }
.complete-btn.done { background: var(--bg-elevated); color: var(--green); border: 1px solid var(--green); }

/* ---------- Học qua truyện ---------- */
.story-nav { display: flex; flex-direction: column; gap: 8px; }
.story-link {
  display: flex; align-items: center; gap: 10px; text-align: left;
  background: var(--bg-elevated); border: 1px solid var(--border); color: var(--text);
  padding: 10px 12px; border-radius: 10px; cursor: pointer; position: relative;
}
.story-link:hover { border-color: var(--accent); }
.story-link.active { border-color: var(--accent); background: rgba(59,130,246,.12); }
.story-link.read { border-color: var(--green); }
.story-emoji { font-size: 22px; flex-shrink: 0; }
.story-link-text { display: flex; flex-direction: column; line-height: 1.3; }
.story-link-text b { font-size: 14px; }
.story-link-text small { font-size: 12px; color: var(--text-dim); }
.story-check { color: var(--green); font-weight: 700; margin-left: auto; }

.story-intro h2 { font-size: 24px; margin-bottom: 6px; }
.story-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 16px; }
.story-card {
  text-align: left; background: var(--bg-elevated); border: 1px solid var(--border);
  border-radius: 12px; padding: 16px; cursor: pointer; transition: transform .12s, border-color .12s;
}
.story-card:hover { transform: translateY(-3px); border-color: var(--accent); }
.story-card-emoji { font-size: 34px; }
.story-card-title { font-size: 17px; font-weight: 700; margin-top: 6px; }
.story-card-en { font-size: 13px; color: var(--text-dim); font-style: italic; margin-bottom: 6px; }
.story-card-sum { font-size: 13px; color: var(--text-dim); }

.reader-controls {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  margin: 18px 0; padding: 12px 14px; background: var(--bg-elevated);
  border: 1px solid var(--border); border-radius: 12px;
}
.rate-ctl { font-size: 13px; color: var(--text-dim); display: flex; align-items: center; gap: 6px; }

.reader { display: flex; flex-direction: column; gap: 4px; }
.sentence {
  padding: 8px 12px; border-radius: 8px; cursor: pointer; border: 1px solid transparent;
  transition: background .15s;
}
.sentence:hover { background: var(--bg-elevated); }
.sentence-en { font-size: 17px; line-height: 1.7; }
.sentence-vi { display: none; font-size: 14px; color: var(--text-dim); font-style: italic; }
.reader.show-vi .sentence-vi { display: block; margin-top: 2px; }
.sentence.reading {
  background: rgba(245,158,11,.16); border-color: rgba(245,158,11,.5);
}
.sentence.reading .sentence-en { color: #fcd34d; font-weight: 600; }

/* ---------- Từ vựng & Thành ngữ ---------- */
.cat-nav { display: flex; flex-direction: column; gap: 6px; }
.cat-link {
  text-align: left; background: var(--bg-elevated); border: 1px solid var(--border); color: var(--text);
  padding: 9px 12px; border-radius: 9px; cursor: pointer; font-size: 13px;
}
.cat-link small { color: var(--text-dim); }
.cat-link:hover { border-color: var(--accent-2); }
.cat-link.active { background: rgba(139,92,246,.18); border-color: var(--accent-2); }
.side-info { font-size: 14px; display: flex; flex-direction: column; gap: 8px; }
.side-info b { color: var(--accent-2); }

.vocab-item.learned { border-color: var(--green); background: rgba(16,185,129,.08); }
.learn-btn {
  background: transparent; border: 1px solid var(--border); color: var(--text-dim);
  width: 26px; height: 26px; border-radius: 50%; cursor: pointer; font-size: 14px; flex-shrink: 0;
  display: inline-flex; align-items: center; justify-content: center;
}
.learn-btn:hover { border-color: var(--green); color: var(--green); }
.learn-btn.on { background: var(--green); border-color: var(--green); color: #fff; }

.idiom-list { display: flex; flex-direction: column; gap: 10px; }
.idiom-card { background: var(--bg-elevated); border: 1px solid var(--border); border-radius: 12px; padding: 14px 16px; }
.idiom-card.learned { border-color: var(--green); }
.idiom-head { display: flex; align-items: center; gap: 10px; }
.idiom-en { font-size: 17px; font-weight: 700; color: var(--amber); }
.idiom-head .learn-btn { margin-left: auto; }
.idiom-vi { margin-top: 4px; font-size: 15px; }
.idiom-ex { margin-top: 6px; font-size: 14px; color: var(--text-dim); font-style: italic; }
.speak-btn.mini { font-size: 13px; }

/* Ảnh minh hoạ (emoji nền + ảnh thật Wikipedia đè lên khi có) */
.thumb { position: relative; width: 100%; overflow: hidden; flex-shrink: 0; }
.thumb.emoji { display: flex; align-items: center; justify-content: center; font-size: 42px;
  background: linear-gradient(135deg, var(--bg-elevated), var(--bg)); }
.thumb.has-photo { font-size: 0; background: #000; }
.thumb img { width: 100%; height: 100%; object-fit: cover; display: block; }

.pexels-bar {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  margin: 12px 0; padding: 10px 12px; background: var(--bg-elevated);
  border: 1px solid var(--border); border-radius: 10px; font-size: 13px;
}
.pexels-bar .src-tag { color: var(--text-dim); }
.pexels-bar .src-tag b { color: var(--accent-2); }
.pexels-bar .ex-input { flex: 1; min-width: 200px; }

.vi-body { display: flex; align-items: center; justify-content: space-between; gap: 10px; flex: 1; }
.vocab-item.has-img {
  flex-direction: column; align-items: stretch; padding: 0; gap: 0;
  overflow: hidden; border-radius: 12px;
}
.vocab-item.has-img .thumb { height: 160px; }
.vocab-item.has-img .thumb.emoji { font-size: 56px; }
.vocab-item.has-img .vi-body { flex-direction: column; align-items: flex-start; gap: 6px; padding: 12px 14px; }
.vocab-item.has-img .vocab-en { font-size: 16px; }

.idiom-card { display: flex; gap: 0; padding: 0; overflow: hidden; align-items: stretch; }
.idiom-card .thumb { width: 190px; min-height: 140px; }
.idiom-card .thumb.emoji { font-size: 52px; }
.idiom-body { flex: 1; padding: 16px 18px; }
@media (max-width: 640px) {
  .idiom-card { flex-direction: column; }
  .idiom-card .thumb { width: 100%; height: 180px; }
}

/* ---------- Nghe & chép chính tả ---------- */
.dict-progress { height: 6px; background: var(--bg-elevated); border-radius: 999px; overflow: hidden; margin: 8px 0 18px; }
.dict-progress-fill { height: 100%; background: linear-gradient(90deg, var(--accent), var(--green)); transition: width .3s; }
.dict-card { background: var(--bg-elevated); border: 1px solid var(--border); border-radius: 14px; padding: 22px; }
.dict-controls { display: flex; gap: 10px; margin-bottom: 14px; flex-wrap: wrap; }
.dict-input {
  width: 100%; background: var(--bg); border: 1px solid var(--border); color: var(--text);
  padding: 14px 16px; border-radius: 12px; font-size: 17px; line-height: 1.6; resize: vertical;
  font-family: inherit;
}
.dict-input:focus { outline: none; border-color: var(--accent); }
.dict-input:disabled { opacity: .8; }
.dict-nav { display: flex; gap: 10px; margin-top: 14px; flex-wrap: wrap; }
.dict-feedback { margin-top: 16px; padding: 14px 16px; border-radius: 12px; font-weight: 700; }
.dict-feedback.ok { background: rgba(16,185,129,.14); color: #6ee7b7; }
.dict-feedback.no { background: rgba(239,68,68,.14); color: #fca5a5; }
.dict-answer { margin-top: 8px; font-size: 18px; font-weight: 700; color: var(--text); }
.dict-vi { margin-top: 4px; font-size: 14px; font-weight: 400; color: var(--text-dim); font-style: italic; }
.dict-summary { text-align: center; padding: 40px 20px; background: var(--bg-elevated); border: 1px solid var(--border); border-radius: 14px; }
.dict-score-big { font-size: 56px; font-weight: 800; color: var(--green); }
.dict-summary p { margin: 10px 0 20px; color: var(--text-dim); }
.dict-speaker { font-size: 13px; font-weight: 700; color: var(--accent); margin-bottom: 10px; }

/* ---------- Nghe nâng cao: hội thoại ---------- */
.dlg-list { display: flex; flex-direction: column; gap: 10px; margin-bottom: 18px; }
.dlg-line { display: flex; gap: 12px; padding: 10px 12px; border-radius: 10px; cursor: pointer;
  background: var(--bg-elevated); border: 1px solid var(--border); transition: border-color .12s; }
.dlg-line:hover { border-color: var(--accent); }
.dlg-sp { flex-shrink: 0; min-width: 86px; font-size: 12px; font-weight: 700; color: var(--accent);
  text-transform: uppercase; letter-spacing: .03em; padding-top: 3px; }
.dlg-en { font-size: 16px; line-height: 1.6; }
.dlg-vi { display: none; font-size: 13px; color: var(--text-dim); font-style: italic; margin-top: 2px; }
.dlg-list.show-vi .dlg-vi { display: block; }
.adv-actions { display: flex; gap: 10px; flex-wrap: wrap; }
.voice-bar { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; margin: 0 0 14px;
  padding: 10px 12px; background: var(--bg-elevated); border: 1px solid var(--border); border-radius: 10px; font-size: 13px; }
.voice-bar .src-tag { color: var(--text-dim); }
.voice-bar .source-select { max-width: 230px; }

.timed-bar { display: flex; align-items: center; gap: 12px; margin-bottom: 12px; flex-wrap: wrap; }
.timed-clock { font-size: 22px; font-weight: 800; color: var(--amber); }
.timed-compare { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 18px; }
.timed-block { background: var(--bg-elevated); border: 1px solid var(--border); border-radius: 12px; padding: 14px 16px; }
.timed-block b { display: block; margin-bottom: 8px; color: var(--text-dim); font-size: 13px; }
.timed-block div { font-size: 15px; line-height: 1.6; }
@media (max-width: 640px) {
  .timed-compare { grid-template-columns: 1fr; }
  .dlg-sp { min-width: 64px; }
}

/* ---------- Điền từ (cloze) ---------- */
.cloze-list { display: flex; flex-direction: column; gap: 10px; margin-bottom: 16px; }
.cloze-line { display: flex; align-items: baseline; gap: 10px; background: var(--bg-elevated);
  border: 1px solid var(--border); border-radius: 10px; padding: 10px 14px; }
.cloze-line .speak-btn { align-self: center; }
.cloze-text { font-size: 16px; line-height: 2; }
.cloze-in { background: var(--bg); border: none; border-bottom: 2px solid var(--accent); color: var(--text);
  font-size: 15px; padding: 2px 6px; margin: 0 2px; border-radius: 4px 4px 0 0; font-family: inherit; }
.cloze-in:focus { outline: none; background: rgba(59,130,246,.12); }
.cloze-res { font-weight: 700; padding: 1px 6px; border-radius: 5px; margin: 0 2px; }
.cloze-res.ok { background: rgba(16,185,129,.2); color: #6ee7b7; }
.cloze-res.no { background: rgba(239,68,68,.2); color: #fca5a5; }

/* ---------- Flashcard ---------- */
.flash-card { background: var(--bg-elevated); border: 1px solid var(--border); border-radius: 16px;
  padding: 40px 24px; text-align: center; margin-bottom: 18px; }
.flash-front { font-size: 30px; font-weight: 800; display: flex; align-items: center; justify-content: center; gap: 10px; flex-wrap: wrap; }
.flash-front .speak-btn { font-size: 22px; }
.flash-back { display: none; margin-top: 20px; padding-top: 20px; border-top: 1px solid var(--border); }
.flash-back.show { display: block; }
.flash-vi { font-size: 22px; color: var(--green); font-weight: 700; }
.flash-ex { margin-top: 10px; font-size: 15px; color: var(--text-dim); font-style: italic; }
.flash-actions { display: flex; gap: 12px; justify-content: center; }
.flash-actions .btn { padding: 14px 30px; font-size: 16px; font-weight: 700; }
.flash-no { background: rgba(239,68,68,.16); color: #fca5a5; border: 1px solid #ef4444; }
.flash-yes { background: rgba(16,185,129,.16); color: #6ee7b7; border: 1px solid var(--green); }

/* ---------- Nghe song ngữ ---------- */
.bl-nav { display: flex; flex-direction: column; gap: 6px; }
.bl-track { display: flex; align-items: center; gap: 8px; text-align: left; background: var(--bg-elevated);
  border: 1px solid var(--border); color: var(--text); padding: 9px 11px; border-radius: 9px; cursor: pointer; font-size: 13px; }
.bl-track:hover { border-color: var(--accent-2); }
.bl-track.active { background: rgba(139,92,246,.18); border-color: var(--accent-2); }
.bl-track-ico { flex-shrink: 0; }
.bl-track-name { line-height: 1.3; }
.bl-player { background: var(--bg-elevated); border: 1px solid var(--border); border-radius: 14px; padding: 18px; }
.bl-player audio { margin-bottom: 14px; }
.bl-frame { width: 100%; margin-bottom: 14px; border-radius: 10px; overflow: hidden; background: #000; }
.bl-frame iframe { width: 100%; height: 80px; border: 0; display: block; }
.bl-controls { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; margin-bottom: 12px; }
.bl-check { display: flex; align-items: center; gap: 6px; font-size: 13px; color: var(--text-dim); }
.bl-timer-disp { font-size: 15px; font-weight: 700; color: var(--amber); }
.bl-add { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 14px; padding-top: 14px; border-top: 1px solid var(--border); }
.bl-add .ex-input { flex: 1; min-width: 140px; }

.app-footer { text-align: center; color: var(--text-dim); font-size: 13px; padding: 24px; }

/* responsive */
@media (max-width: 860px) {
  .layout { grid-template-columns: 1fr; }
  .sidebar { position: static; }
  .vocab-grid { grid-template-columns: 1fr; }
  .ex-options { grid-template-columns: 1fr; }
  .story-grid { grid-template-columns: 1fr; }
  .header-inner { flex-direction: column; align-items: flex-start; }
}

/* ============================================================
   GIAO DIỆN ĐIỆN THOẠI — kiểu app (thanh điều hướng dưới đáy)
   ============================================================ */
@media (max-width: 768px) {
  /* Bỏ backdrop-filter để .tabs fixed bám đáy MÀN HÌNH (không bám đáy header) */
  .app-header { backdrop-filter: none; -webkit-backdrop-filter: none; background: rgba(15,23,42,.97); }
  /* Header gọn */
  .header-inner { padding: 10px 14px; }
  .app-header h1 { font-size: 16px; }
  .subtitle { display: none; }
  .logo { font-size: 26px; }
  .streak-box { padding: 5px 11px; min-width: 62px; }
  .streak-num { font-size: 20px; }

  /* Tabs -> thanh điều hướng cố định dưới đáy */
  .tabs {
    position: fixed; left: 0; right: 0; bottom: 0; z-index: 60;
    max-width: none; margin: 0; padding: 3px 2px calc(3px + env(safe-area-inset-bottom, 0px));
    gap: 0; display: flex; overflow-x: auto;
    background: rgba(15, 23, 42, .97); backdrop-filter: blur(12px);
    border-top: 1px solid var(--border);
    -webkit-overflow-scrolling: touch; scrollbar-width: none;
  }
  .tabs::-webkit-scrollbar { display: none; }
  .tab {
    flex: 1 0 13.4%; min-width: 48px; border: none; border-radius: 0;
    background: transparent; color: var(--text-dim);
    display: flex; flex-direction: column; align-items: center; gap: 2px; padding: 6px 2px;
  }
  .tab .ti { margin: 0; font-size: 21px; line-height: 1; }
  .tab .tl { font-size: 9.5px; white-space: nowrap; font-weight: 600; }
  .tab.active { background: transparent; color: var(--accent); }

  /* Bố cục 1 cột, full màn hình */
  .layout { grid-template-columns: 1fr; gap: 12px; padding: 12px; }
  .sidebar { position: static; padding: 13px; }
  .content { padding: 16px 14px; }
  body { padding-bottom: 64px; }          /* chừa chỗ cho thanh dưới */
  .app-footer { padding: 20px 16px 84px; }

  /* Nút / chạm to hơn */
  .lesson-title { font-size: 21px; }
  .lesson-top { gap: 10px; }
  .nav-buttons button, .btn { min-height: 40px; }
  .day-cell { font-size: 15px; border-radius: 11px; }
  .complete-btn { width: 100%; }
  .vocab-grid, .ex-options, .story-grid, .timed-compare { grid-template-columns: 1fr; }
  .flash-front { font-size: 26px; }
  .flash-actions .btn { flex: 1; }
}

/* ============================================================
   HIỆU ỨNG KIỂU APP (tap feedback, chuyển màn, nảy icon)
   ============================================================ */
* { -webkit-tap-highlight-color: transparent; }

/* Nhấn là lún nhẹ (touch feedback) */
.btn, .tab, .day-cell, .cat-link, .story-link, .bl-track, .story-card,
.vocab-item, .idiom-card, .ex-opt, .flash-card, .sentence, .dlg-line,
.speak-btn, .learn-btn, .complete-btn, .nav-buttons button, .q-toggle {
  transition: transform .12s ease, border-color .12s, background .15s, box-shadow .15s;
}
.btn:active, .tab:active, .day-cell:active, .cat-link:active, .story-link:active,
.bl-track:active, .story-card:active, .vocab-item:active, .idiom-card:active,
.ex-opt:active, .flash-card:active, .sentence:active, .dlg-line:active,
.speak-btn:active, .learn-btn:active, .complete-btn:active,
.nav-buttons button:active, .q-toggle:active {
  transform: scale(.95);
}

/* Chuyển màn: nội dung trượt + hiện dần */
.content.page-in { animation: pageIn .3s cubic-bezier(.4,0,.2,1); }
@keyframes pageIn { from { opacity: 0; transform: translateY(14px); } to { opacity: 1; transform: none; } }

/* Lật thẻ Flashcard mượt */
.flash-back.show { animation: fadeUp .28s ease; }
@keyframes fadeUp { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: none; } }

/* Thẻ ngày/bài xuất hiện có đà nhẹ */
@keyframes popIn { from { opacity: 0; transform: scale(.9); } to { opacity: 1; transform: none; } }

@media (max-width: 768px) {
  /* Icon tab nảy khi được chọn + gạch chỉ báo phía trên */
  .tab.active .ti { animation: navPop .35s ease; }
  @keyframes navPop { 0% { transform: scale(1); } 45% { transform: scale(1.35); } 100% { transform: scale(1); } }
  .tab.active { position: relative; }
  .tab.active::before {
    content: ""; position: absolute; top: 0; left: 50%; transform: translateX(-50%);
    width: 22px; height: 3px; border-radius: 0 0 3px 3px; background: var(--accent);
  }
  /* Cuộn có quán tính */
  body, .content { -webkit-overflow-scrolling: touch; }
  /* Thẻ trong lưới ngày nảy nhẹ khi mở */
  .day-cell { animation: popIn .25s ease backwards; }
  .story-card, .bl-track, .cat-link { animation: popIn .22s ease backwards; }
}

/* ---------- Vuốt chuyển màn (trượt ngang) ---------- */
.content.slide-left { animation: slideL .26s cubic-bezier(.4,0,.2,1); }
.content.slide-right { animation: slideR .26s cubic-bezier(.4,0,.2,1); }
@keyframes slideL { from { opacity: 0; transform: translateX(46px); } to { opacity: 1; transform: none; } }
@keyframes slideR { from { opacity: 0; transform: translateX(-46px); } to { opacity: 1; transform: none; } }

/* ---------- Ripple khi chạm nút ---------- */
.btn, .tab { position: relative; overflow: hidden; }
.ripple {
  position: absolute; border-radius: 50%; pointer-events: none;
  background: rgba(255, 255, 255, .35); transform: scale(0);
  animation: ripple .55s ease-out;
}
@keyframes ripple { to { transform: scale(2.4); opacity: 0; } }