:root {
  --bg: #f4f6fb;
  --card: #ffffff;
  --ink: #1b2233;
  --muted: #5d6679;
  --line: #e2e6ef;
  --primary: #2563eb;
  --primary-ink: #ffffff;
  --primary-soft: #e6eeff;
  --good: #15803d;
  --good-soft: #e3f6ea;
  --bad: #c2410c;
  --bad-soft: #fdecdf;
  --warn-soft: #fff6db;
  --shadow: 0 1px 2px rgba(20, 30, 60, .06), 0 4px 14px rgba(20, 30, 60, .06);
  --c-vocab: #2563eb;
  --c-pron: #9333ea;
  --c-grammar: #0d9488;
  --c-reading: #ca8a04;
  --c-listening: #db2777;
  --c-speaking: #ea580c;
  --c-writing: #4f46e5;
  --c-test: #b91c1c;
  --c-ipa: #7c3aed;
  --radius: 14px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #11151f; --card: #1a2030; --ink: #e8ecf5; --muted: #9aa3b8; --line: #2b3347;
    --primary: #6b9bff; --primary-ink: #0d1220; --primary-soft: #1f2b48;
    --good: #4ade80; --good-soft: #15301f; --bad: #fb923c; --bad-soft: #3a2316; --warn-soft: #362d12;
    --shadow: 0 1px 2px rgba(0,0,0,.3);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #11151f; --card: #1a2030; --ink: #e8ecf5; --muted: #9aa3b8; --line: #2b3347;
  --primary: #6b9bff; --primary-ink: #0d1220; --primary-soft: #1f2b48;
  --good: #4ade80; --good-soft: #15301f; --bad: #fb923c; --bad-soft: #3a2316; --warn-soft: #362d12;
  --shadow: 0 1px 2px rgba(0,0,0,.3);
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font-family: "Be Vietnam Pro", system-ui, -apple-system, "Segoe UI", Roboto, Arial, sans-serif;
  font-size: 16px; line-height: 1.55;
}
button, input, textarea, select { font: inherit; color: inherit; }
a { color: var(--primary); }
.ipa, .ipa-big { font-family: "Charis SIL", "Doulos SIL", "Lucida Sans Unicode", "Segoe UI", "Noto Sans", Arial, sans-serif; }

/* Thanh trên cùng */
.topbar {
  position: sticky; top: 0; z-index: 10; background: var(--card); border-bottom: 1px solid var(--line);
}
.topbar-in { max-width: 920px; margin: 0 auto; padding: 10px 16px; display: flex; align-items: center; gap: 12px; }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--ink); font-weight: 700; }
.brand-mark { width: 34px; height: 34px; border-radius: 10px; background: var(--primary); color: var(--primary-ink); display: grid; place-items: center; font-weight: 800; font-size: 15px; letter-spacing: -.5px; }
.topbar .spacer { flex: 1; }
.user-chip { font-size: 14px; color: var(--muted); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; max-width: 40vw; }

main { max-width: 920px; margin: 0 auto; padding: 20px 16px 80px; }

/* Nút */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  border: 1px solid var(--line); background: var(--card); border-radius: 10px;
  padding: 10px 16px; cursor: pointer; font-weight: 600; text-decoration: none; color: var(--ink);
  min-height: 44px;
}
.btn:hover { border-color: var(--primary); }
.btn.primary { background: var(--primary); border-color: var(--primary); color: var(--primary-ink); }
.btn.small { min-height: 36px; padding: 6px 12px; font-size: 14px; }
.btn.ghost { background: transparent; border-color: transparent; }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn svg { width: 18px; height: 18px; flex: none; }
.row { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.row.end { justify-content: flex-end; }

.say {
  display: inline-grid; place-items: center; width: 36px; height: 36px; border-radius: 50%;
  border: 1px solid var(--line); background: var(--primary-soft); color: var(--primary); cursor: pointer; flex: none; padding: 0;
}
.say svg { width: 18px; height: 18px; }
.say.lg { width: 56px; height: 56px; }
.say.lg svg { width: 26px; height: 26px; }

/* Thẻ */
.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px; box-shadow: var(--shadow); }
.card + .card { margin-top: 14px; }
h1 { font-size: 26px; line-height: 1.25; margin: 0 0 6px; }
h2 { font-size: 20px; margin: 0 0 10px; }
h3 { font-size: 17px; margin: 0 0 8px; }
.muted { color: var(--muted); }
.small { font-size: 14px; }
.back { display: inline-flex; align-items: center; gap: 6px; color: var(--muted); text-decoration: none; font-size: 15px; margin-bottom: 12px; }
.back svg { width: 18px; height: 18px; }

.grid { display: grid; gap: 14px; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); }
.tile {
  display: flex; flex-direction: column; gap: 6px; text-decoration: none; color: var(--ink);
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px;
  box-shadow: var(--shadow); position: relative; border-top: 4px solid var(--tc, var(--primary));
}
.tile:hover { border-color: var(--tc, var(--primary)); }
.tile .t-title { font-weight: 700; font-size: 17px; }
.tile .t-desc { color: var(--muted); font-size: 14px; flex: 1; }
.tile .t-foot { display: flex; align-items: center; gap: 8px; font-size: 13px; color: var(--muted); }
.tile.locked { opacity: .55; pointer-events: none; }
.tile .t-foot svg { width: 16px; height: 16px; }
.tile .icon { width: 38px; height: 38px; border-radius: 10px; display: grid; place-items: center; background: color-mix(in srgb, var(--tc, var(--primary)) 14%, transparent); color: var(--tc, var(--primary)); }
.tile .icon svg { width: 22px; height: 22px; }

.bar { height: 8px; background: var(--line); border-radius: 99px; overflow: hidden; flex: 1; }
.bar > i { display: block; height: 100%; background: var(--good); border-radius: 99px; }
.badge { display: inline-block; font-size: 12px; font-weight: 700; padding: 2px 8px; border-radius: 99px; background: var(--primary-soft); color: var(--primary); }
.badge.good { background: var(--good-soft); color: var(--good); }

/* Đăng nhập */
.auth-wrap { max-width: 420px; margin: 24px auto; }
.tabs { display: flex; gap: 6px; background: var(--bg); padding: 4px; border-radius: 12px; margin-bottom: 16px; }
.tabs button { flex: 1; border: 0; background: transparent; padding: 10px; border-radius: 9px; cursor: pointer; font-weight: 600; color: var(--muted); }
.tabs button.on { background: var(--card); color: var(--ink); box-shadow: var(--shadow); }
label.f { display: block; margin-bottom: 12px; font-weight: 600; font-size: 14px; }
label.f input, label.f select, textarea {
  display: block; width: 100%; margin-top: 6px; padding: 11px 12px; border: 1px solid var(--line); border-radius: 10px;
  background: var(--bg); font-size: 16px; font-weight: 400;
}
input:focus, select:focus, textarea:focus { outline: 2px solid var(--primary); outline-offset: 1px; }
.err { color: var(--bad); font-size: 14px; min-height: 20px; margin: 4px 0 10px; }
.note { background: var(--warn-soft); border-radius: 10px; padding: 10px 12px; font-size: 14px; margin-top: 14px; }

/* Thẻ từ vựng */
.flash { text-align: center; padding: 26px 18px; min-height: 260px; display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 10px; cursor: pointer; user-select: none; }
.flash .word { font-size: 34px; font-weight: 800; }
.flash .ipa { font-size: 22px; color: var(--muted); }
.flash .mean { font-size: 22px; font-weight: 700; color: var(--primary); }
.flash .ex { font-size: 16px; }
.dots { display: flex; gap: 4px; justify-content: center; flex-wrap: wrap; margin: 12px 0; }
.dots i { width: 8px; height: 8px; border-radius: 50%; background: var(--line); }
.dots i.on { background: var(--primary); }
.dots i.known { background: var(--good); }

.seg { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 16px; }
.seg a, .seg button { border: 1px solid var(--line); background: var(--card); padding: 8px 14px; border-radius: 99px; text-decoration: none; color: var(--ink); font-weight: 600; font-size: 14px; cursor: pointer; }
.seg .on { background: var(--ink); color: var(--card); border-color: var(--ink); }

/* Câu hỏi */
.qhead { display: flex; align-items: center; gap: 10px; margin-bottom: 14px; font-size: 14px; color: var(--muted); }
.qtext { font-size: 19px; font-weight: 600; margin-bottom: 14px; }
.qtext u, .opt u { text-decoration-thickness: 2px; text-underline-offset: 3px; }
.opts { display: grid; gap: 10px; }
.opts.two { grid-template-columns: 1fr 1fr; }
.opt {
  text-align: left; border: 2px solid var(--line); background: var(--card); border-radius: 12px; padding: 12px 14px;
  cursor: pointer; font-size: 17px; min-height: 50px;
}
.opt:hover:not(:disabled) { border-color: var(--primary); }
.opt.right { border-color: var(--good); background: var(--good-soft); }
.opt.wrong { border-color: var(--bad); background: var(--bad-soft); }
.opt.picked { border-color: var(--primary); background: var(--primary-soft); }
.opt:disabled { cursor: default; }
.fb { margin-top: 14px; padding: 12px 14px; border-radius: 12px; font-size: 15px; }
.fb.ok { background: var(--good-soft); }
.fb.no { background: var(--bad-soft); }
.fb b { display: block; margin-bottom: 2px; }
.qinput { width: 100%; padding: 12px; border: 2px solid var(--line); border-radius: 12px; font-size: 18px; background: var(--bg); }

.chips { display: flex; flex-wrap: wrap; gap: 8px; min-height: 52px; padding: 8px; border-radius: 12px; }
.chips.answer { border: 2px dashed var(--line); margin-bottom: 12px; }
.chip { border: 1px solid var(--line); background: var(--card); border-radius: 10px; padding: 8px 12px; font-size: 17px; cursor: pointer; box-shadow: var(--shadow); }
.chip.used { visibility: hidden; }

.score-big { font-size: 54px; font-weight: 800; line-height: 1; }
.review { margin-top: 16px; display: grid; gap: 8px; }
.review .ri { padding: 10px 12px; border-radius: 10px; font-size: 15px; border-left: 4px solid var(--good); background: var(--bg); }
.review .ri.no { border-left-color: var(--bad); }

/* Ngữ pháp */
.rule { border-left: 4px solid var(--c-grammar); padding: 4px 0 4px 14px; margin: 14px 0; }
table.t { border-collapse: collapse; width: 100%; font-size: 15px; margin: 8px 0; }
table.t th, table.t td { border: 1px solid var(--line); padding: 8px 10px; text-align: left; vertical-align: top; }
table.t th { background: var(--bg); }
.tablewrap { overflow-x: auto; }

/* Đọc, nghe */
.passage { font-size: 17px; line-height: 1.75; }
.passage p { margin: 0 0 12px; }
.dlg { display: grid; gap: 8px; }
.dlg .ln { display: flex; gap: 10px; align-items: flex-start; padding: 8px 10px; border-radius: 10px; }
.dlg .ln.on { background: var(--primary-soft); }
.dlg .who { font-weight: 700; min-width: 54px; }
.hidden { display: none !important; }

/* Nói */
.sp-item { display: flex; gap: 12px; align-items: flex-start; padding: 14px 0; border-bottom: 1px solid var(--line); }
.sp-item:last-child { border-bottom: 0; }
.sp-text { flex: 1; min-width: 0; }
.sp-en { font-size: 18px; font-weight: 600; }
.sp-res { margin-top: 6px; font-size: 15px; }
.w-ok { color: var(--good); font-weight: 700; }
.w-no { color: var(--bad); text-decoration: line-through; }
.w-wait { color: var(--muted); }
.mic.rec { background: var(--bad); border-color: var(--bad); color: #fff; }

/* IPA */
.ipa-group h3 { margin-top: 18px; }
.ipa-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(92px, 1fr)); gap: 8px; }
.ipa-cell {
  border: 1px solid var(--line); background: var(--card); border-radius: 12px; padding: 10px 6px; text-align: center; cursor: pointer;
  border-bottom: 3px solid var(--gc, var(--c-ipa));
}
.ipa-cell:hover, .ipa-cell.on { background: var(--primary-soft); }
.ipa-cell .ipa-big { font-size: 26px; font-weight: 600; display: block; }
.ipa-cell .ex { font-size: 13px; color: var(--muted); }
.ipa-cell .done { font-size: 11px; color: var(--good); font-weight: 700; }
.ipa-detail { margin-top: 14px; }
.ex-list { display: grid; gap: 8px; margin-top: 10px; }
.ex-row { display: flex; align-items: center; gap: 10px; padding: 8px 10px; background: var(--bg); border-radius: 10px; }
.ex-row .w { font-weight: 700; min-width: 90px; }

/* Trang chủ: ô số liệu */
.stats { display: grid; gap: 12px; grid-template-columns: repeat(3, 1fr); margin-top: 14px; }
.stats .card + .card { margin-top: 0; }
.stat { padding: 14px; display: flex; flex-direction: column; gap: 6px; }
.stat-num { font-size: 26px; font-weight: 800; line-height: 1.1; }
.stat .bar { flex: none; }
.icon, .icon-lg { width: 32px; height: 32px; border-radius: 9px; display: inline-grid; place-items: center; flex: none;
  background: color-mix(in srgb, var(--tc, var(--primary)) 14%, transparent); color: var(--tc, var(--primary)); }
.icon svg { width: 18px; height: 18px; }
.icon-lg { width: 40px; height: 40px; border-radius: 10px; }
.icon-lg svg { width: 22px; height: 22px; }

.sp-break { display: flex; flex-wrap: wrap; gap: 6px; margin: 4px 0; }
.sp-break span { background: var(--bg); border-radius: 99px; padding: 2px 10px; font-size: 13px; }

/* Đề thi */
.exam-bar { position: sticky; top: 57px; z-index: 5; display: flex; align-items: center; gap: 12px; justify-content: space-between;
  background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 8px 12px; box-shadow: var(--shadow); }
.exam-bar b { font-size: 20px; font-variant-numeric: tabular-nums; }
.ex-sec h3 { color: var(--c-test); }
.ex-q { padding: 12px 0; border-top: 1px solid var(--line); }
.ex-qt { margin-bottom: 8px; font-size: 17px; }
.ex-passage { background: var(--bg); border-radius: 12px; padding: 12px 14px; margin: 10px 0; font-size: 16px; }
.notice { border: 2px solid var(--ink); border-radius: 8px; padding: 10px 14px; margin: 8px 0; text-align: center; background: var(--card); font-size: 16px; }
.ex-passage .notice { text-align: left; }
details summary { cursor: pointer; color: var(--primary); margin: 6px 0; }
.links-card a { font-weight: 600; }

/* Chép chính tả */
.dict-box { margin-top: 12px; padding: 10px 12px; border-radius: 12px; background: var(--warn-soft); }
.dict-line { font-size: 19px; margin-top: 6px; line-height: 1.8; word-spacing: 4px; }
.dict-line .blank { font-family: ui-monospace, Consolas, monospace; color: var(--bad); letter-spacing: 2px; }

/* Mặt sau thẻ từ */
.wd { display: grid; gap: 8px; justify-items: center; width: 100%; }
.wd-ex { background: var(--bg); border-radius: 12px; padding: 10px 12px; width: 100%; max-width: 520px; }
.wd-ant { display: flex; flex-wrap: wrap; gap: 8px; justify-content: center; align-items: center; }
.ant { display: inline-flex; align-items: center; gap: 4px; background: var(--bg); border-radius: 99px; padding: 2px 10px 2px 2px; }
.ant .say { width: 28px; height: 28px; }
.vocab-table td { min-width: 90px; }
.vocab-table td:nth-child(5) { min-width: 240px; }

/* Âm tiết và trọng âm */
.syl { font-size: 20px; letter-spacing: .5px; }
.syl .str { color: var(--c-speaking); font-size: 1.15em; }
.syl .dot { color: var(--muted); padding: 0 1px; }

/* Công thức ngữ pháp tô màu */
.formula { background: var(--bg); border-radius: 12px; padding: 12px 14px; margin: 10px 0; display: grid; gap: 6px; font-size: 16px; }
.formula .tag { display: inline-block; min-width: 30px; font-weight: 800; color: var(--muted); }
.formula .ex-line { margin-top: 4px; font-size: 17px; font-weight: 600; }
.fS { color: #2563eb; font-weight: 700; }
.fV { color: #c2410c; font-weight: 700; }
.fX { color: #7c3aed; font-weight: 700; }
.fO { color: #0f766e; font-weight: 600; }
:root[data-theme="dark"] .fS { color: #7aa2ff; } :root[data-theme="dark"] .fV { color: #fb923c; } :root[data-theme="dark"] .fX { color: #c4b5fd; } :root[data-theme="dark"] .fO { color: #5eead4; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .fS { color: #7aa2ff; } :root:not([data-theme="light"]) .fV { color: #fb923c; } :root:not([data-theme="light"]) .fX { color: #c4b5fd; } :root:not([data-theme="light"]) .fO { color: #5eead4; } }

/* Biểu đồ cột thời gian học */
.week { display: grid; grid-template-columns: repeat(7, 1fr); gap: 8px; align-items: end; height: 150px; margin-top: 10px; }
.week .col { display: flex; flex-direction: column; align-items: center; gap: 4px; height: 100%; justify-content: flex-end; font-size: 12px; color: var(--muted); }
.week .col i { display: block; width: 100%; max-width: 34px; background: var(--primary); border-radius: 6px 6px 2px 2px; min-height: 2px; }
.week .col i.met { background: var(--good); }
.week .col b { color: var(--ink); font-size: 12px; }
.badges { display: grid; gap: 10px; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); }
.badge-card { border: 1px solid var(--line); border-radius: 12px; padding: 12px; text-align: center; background: var(--card); }
.badge-card .icon-lg { margin: 0 auto 6px; }
.badge-card.off { opacity: .45; filter: grayscale(1); }
.badge-card b { display: block; font-size: 14px; }
.badge-card span { font-size: 12px; color: var(--muted); }
table.t.data td, table.t.data th { white-space: nowrap; }
table.t.data a { font-weight: 600; }

@media print {
  .topbar, .back, .no-print, .btn { display: none !important; }
  body { background: #fff; }
  .card { box-shadow: none; break-inside: avoid; }
}

/* Thông báo nhỏ */
.toast { position: fixed; left: 50%; bottom: 24px; transform: translateX(-50%); background: var(--ink); color: var(--card); padding: 10px 16px; border-radius: 10px; font-size: 15px; z-index: 50; max-width: calc(100% - 32px); }

@media (max-width: 560px) {
  .hide-sm, .brand > span:last-child { display: none; }
  .stats { gap: 8px; }
  .stat { padding: 10px; gap: 4px; }
  .stat .row { flex-direction: column; align-items: flex-start; gap: 4px; }
  .stat .row .small { font-size: 12px; line-height: 1.3; }
  .stat-num { font-size: 18px; }
  .stat-num .small { font-size: 12px; }
  .stat > .small.muted { display: none; }
  h1 { font-size: 22px; }
  .opts.two { grid-template-columns: 1fr; }
  .flash .word { font-size: 28px; }
  .card { padding: 14px; }
}