@charset "UTF-8";
:root {
  --ink: #1f2a44; --ink-2: #3b4766; --muted: #6b7489; --line: #e3e0d8;
  --paper: #faf8f3; --card: #ffffff; --seal: #b8322a; --seal-soft: #f7e6e3;
  --green: #2f7d4f; --green-soft: #e3f2e8; --gray-soft: #eeede9; --gold: #c59a3c;
  --radius: 12px; --shadow: 0 1px 2px rgba(31,42,68,.06), 0 4px 16px rgba(31,42,68,.05);
  --zh: "Noto Serif SC", "Songti SC", "SimSun", serif;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; font: 15px/1.55 "Be Vietnam Pro", system-ui, sans-serif; color: var(--ink); background: var(--paper); }
a { color: var(--seal); text-decoration: none; }
h1 { font-size: 1.5rem; margin: .2rem 0; } h2 { font-size: 1.2rem; margin: 1.4rem 0 .6rem; } h3 { font-size: 1.05rem; margin: 0 0 .6rem; }
code, pre, textarea.code { font-family: ui-monospace, Menlo, Consolas, monospace; font-size: 13px; }
.muted { color: var(--muted); } .small, small { font-size: .85rem; }

/* Thanh trên */
#topbar { position: sticky; top: 0; z-index: 20; display: flex; align-items: center; gap: 1rem; padding: .6rem 1rem;
  background: var(--ink); color: #fff; flex-wrap: wrap; }
.brand { display: flex; align-items: center; gap: .5rem; color: #fff; font-weight: 700; }
.seal { display: inline-grid; place-items: center; width: 30px; height: 30px; border-radius: 7px; background: var(--seal); color: #fff; font-family: var(--zh); }
.seal.big { width: 64px; height: 64px; font-size: 36px; border-radius: 14px; margin: 0 auto 1rem; }
#nav { display: flex; gap: .2rem; flex: 1; overflow-x: auto; }
#nav a { color: #cfd5e4; padding: .4rem .75rem; border-radius: 8px; white-space: nowrap; }
#nav a.active, #nav a:hover { background: rgba(255,255,255,.12); color: #fff; }
.who { display: flex; align-items: center; gap: .5rem; font-size: .9rem; }
.who .btn { color: #fff; border-color: rgba(255,255,255,.3); }

main { max-width: 1100px; margin: 0 auto; padding: 1rem 1rem 6rem; }
.loading { padding: 3rem; text-align: center; color: var(--muted); }
.page-head { margin: .5rem 0 1rem; }
.back { display: inline-block; margin-bottom: .3rem; font-size: .9rem; }

/* Khung, nút */
.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 1rem; box-shadow: var(--shadow); margin-bottom: 1rem; }
.card.narrow { max-width: 480px; }
.btn { display: inline-flex; align-items: center; gap: .3rem; padding: .55rem 1rem; border-radius: 9px; border: 1px solid var(--line);
  background: #fff; color: var(--ink); font: inherit; font-weight: 500; cursor: pointer; white-space: nowrap; }
.btn:hover { border-color: var(--ink-2); }
.btn.primary { background: var(--seal); border-color: var(--seal); color: #fff; }
.btn.primary:hover { filter: brightness(1.08); }
.btn.danger { color: var(--seal); border-color: #e7b9b4; }
.btn.ghost { background: transparent; }
.btn.sm { padding: .3rem .65rem; font-size: .85rem; }
.btn.block { width: 100%; justify-content: center; padding: .75rem; }
.btn:disabled { opacity: .6; cursor: wait; }
.icon-btn { border: 0; background: none; cursor: pointer; font-size: 1rem; padding: 0 .2rem; vertical-align: middle; }
.row { display: flex; gap: .5rem; align-items: center; margin: .5rem 0; }
.row.between { justify-content: space-between; flex-wrap: wrap; } .row.end { justify-content: flex-end; } .row.center { justify-content: center; flex-wrap: wrap; }
.row.wrap { flex-wrap: wrap; } .nowrap { flex-wrap: nowrap; }
.badge { display: inline-block; font-size: .75rem; font-weight: 600; padding: .1rem .5rem; border-radius: 99px; vertical-align: middle; }
.badge.green { background: var(--green-soft); color: var(--green); } .badge.red { background: var(--seal-soft); color: var(--seal); } .badge.gray { background: var(--gray-soft); color: var(--muted); }
.hsk { display: inline-block; font-size: .75rem; font-weight: 700; color: #fff; background: var(--ink); padding: .1rem .45rem; border-radius: 6px; vertical-align: middle; }
.alert { background: var(--seal-soft); color: var(--seal); border-radius: 8px; padding: .6rem .8rem; margin: .5rem 0; }
.ok-box { background: var(--green-soft); color: var(--green); border-radius: 8px; padding: .6rem .8rem; margin-top: .5rem; }
.warns { background: #fff7e6; border: 1px solid #f1d9a3; border-radius: 8px; padding: .6rem .8rem; margin-top: .5rem; max-height: 300px; overflow: auto; }
.warns ul { margin: .3rem 0 0; padding-left: 1.2rem; }

/* Form */
.field { display: block; margin-bottom: .8rem; }
.field > span { display: block; font-weight: 600; font-size: .88rem; margin-bottom: .25rem; }
input, select, textarea { width: 100%; font: inherit; color: inherit; padding: .55rem .7rem; border: 1px solid var(--line); border-radius: 8px; background: #fff; }
input[type=checkbox], input[type=radio] { width: auto; }
input:focus, select:focus, textarea:focus { outline: 2px solid #c9d2ea; border-color: var(--ink-2); }
textarea.code { line-height: 1.6; white-space: pre-wrap; }
.field small { color: var(--muted); }
.checks { display: grid; gap: .35rem; margin: .4rem 0; max-height: 320px; overflow: auto; }
.checks label { display: flex; gap: .45rem; align-items: center; }
.switch { display: inline-flex; gap: .35rem; align-items: center; font-size: .88rem; cursor: pointer; }
.grid-form { display: grid; grid-template-columns: 120px 1fr; gap: 0 1rem; }
.grid-form .full { grid-column: 1 / -1; }
.help summary { cursor: pointer; color: var(--ink-2); font-weight: 600; margin-bottom: .4rem; }
.help pre { background: var(--paper); padding: .7rem; border-radius: 8px; white-space: pre-wrap; }

dialog { border: 0; border-radius: 14px; padding: 1.2rem; width: min(560px, 94vw); box-shadow: 0 20px 60px rgba(0,0,0,.25); }
dialog::backdrop { background: rgba(20,26,40,.45); }
dialog textarea { white-space: pre-wrap; }

/* Đăng nhập */
.login { min-height: 80vh; display: grid; place-items: center; }
.login-card { width: min(380px, 100%); background: #fff; border: 1px solid var(--line); border-radius: 18px; padding: 2rem 1.5rem; text-align: center; box-shadow: var(--shadow); }
.login-card form { text-align: left; margin-top: 1rem; }

/* Bảng */
.tbl { width: 100%; border-collapse: collapse; font-size: .9rem; }
.tbl th { text-align: left; font-weight: 600; color: var(--muted); font-size: .8rem; text-transform: uppercase; letter-spacing: .02em; border-bottom: 1px solid var(--line); padding: .5rem; }
.tbl td { padding: .55rem .5rem; border-bottom: 1px solid #f0eee8; vertical-align: middle; }
.tbl.hover tr[data-href] { cursor: pointer; } .tbl.hover tr[data-href]:hover td { background: var(--paper); }
.scroll-x { overflow-x: auto; }
.zh-cell { font-family: var(--zh); font-size: 1.05rem; }
ul.plain { padding-left: 1.1rem; margin: .3rem 0; }

/* Lưới bài */
.lesson-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: .8rem; }
.lesson-card { display: block; color: inherit; margin: 0; transition: transform .1s, border-color .1s; }
.lesson-card:hover { transform: translateY(-2px); border-color: var(--seal); }
.lesson-card.locked { opacity: .55; pointer-events: none; }
.lesson-card.done { border-left: 4px solid var(--green); }
.lesson-no { font-size: .78rem; font-weight: 700; color: var(--seal); text-transform: uppercase; letter-spacing: .04em; }
.lesson-title { font-family: var(--zh); font-size: 1.15rem; margin: .2rem 0 .5rem; }
.bar { height: 6px; background: var(--gray-soft); border-radius: 99px; overflow: hidden; margin: .4rem 0; }
.bar i { display: block; height: 100%; background: linear-gradient(90deg, var(--seal), var(--gold)); border-radius: 99px; }
.continue { display: flex; justify-content: space-between; align-items: center; gap: 1rem; color: inherit; border-left: 4px solid var(--seal); }
.continue > div { flex: 1; }
.stats { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: .8rem; }
.stat { display: flex; flex-direction: column; } .stat b { font-size: 1.8rem; }
.stats.mini { grid-template-columns: repeat(2, 1fr); } .stats.mini div { display: flex; flex-direction: column; } .stats.mini b { font-size: 1.2rem; }
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
details.acc { border-top: 1px solid var(--line); padding: .5rem 0; }
details.acc summary { cursor: pointer; font-weight: 600; }

/* Tabs */
.tabs { display: flex; gap: .3rem; overflow-x: auto; border-bottom: 1px solid var(--line); margin-bottom: 1rem; position: sticky; top: 52px; background: var(--paper); z-index: 5; padding-top: .3rem; }
.card .tabs { position: static; background: none; }
.tabs a { padding: .5rem .8rem; color: var(--muted); border-bottom: 2px solid transparent; white-space: nowrap; font-weight: 500; }
.tabs a.active { color: var(--seal); border-color: var(--seal); }

/* Nội dung tiếng Trung */
.zh-block { margin: .35rem 0; }
.zh-block .zh { font-family: var(--zh); font-size: 1.15rem; }
.zh-block .py { color: var(--ink-2); font-size: .92rem; }
.zh-block .vi { color: var(--muted); font-size: .92rem; }
.zh-block.big .zh { font-size: 1.4rem; }
/* Ẩn pinyin / tiếng Việt: làm mờ, bấm vào để xem (bài kiểm tra giữ nguyên câu hỏi tiếng Việt) */
.view-toggles { display: flex; flex-wrap: wrap; gap: .4rem .9rem; align-items: center; margin: -.4rem 0 .9rem; }
.toggle { display: inline-flex; align-items: center; gap: .4rem; padding: .3rem .75rem; border: 1px solid var(--line); border-radius: 99px; background: #fff; font-size: .88rem; cursor: pointer; }
.toggle:has(input:checked) { border-color: var(--seal); background: var(--seal-soft); color: var(--seal); }
.hide-py .py:not(.peek),
.hide-vi .zh-block .vi:not(.peek),
.hide-vi .vocab-head .meaning:not(.peek) { filter: blur(5px); opacity: .7; cursor: pointer; user-select: none; transition: filter .15s; }
.hide-vi .quiz .zh-block .vi, .hide-vi .quiz .fb .vi,
.hide-py .quiz .fb .py, .hide-py .flash .py, .hide-vi .flash .vi { filter: none; opacity: 1; cursor: auto; user-select: auto; }
@media (prefers-reduced-motion: reduce) { .hide-py .py, .hide-vi .vi { transition: none; } }
.vocab-head { display: grid; grid-template-columns: 32px auto 1fr; gap: .8rem; align-items: center; }
.num { display: inline-grid; place-items: center; min-width: 26px; height: 26px; border-radius: 50%; background: var(--seal-soft); color: var(--seal); font-weight: 700; font-size: .8rem; }
.hanzi { font-family: var(--zh); font-size: 1.8rem; line-height: 1.2; }
.hanzi.xl, .meaning.xl { font-size: 2.6rem; }
.py { color: var(--ink-2); }
.meaning { font-weight: 600; }
.vocab .sub { border-top: 1px dashed var(--line); margin-top: .6rem; padding-top: .5rem; }
.tag { display: inline-block; font-size: .75rem; font-weight: 700; color: var(--gold); text-transform: uppercase; letter-spacing: .03em; }
.colls { display: grid; grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); gap: 0 1rem; }
.grammar .pattern { background: var(--ink); color: #fff; border-radius: 8px; padding: .6rem .8rem; font-family: var(--zh); font-size: 1.1rem; margin-bottom: .6rem; }
.grammar .pattern .py { color: #cfd5e4; font-family: "Be Vietnam Pro", sans-serif; font-size: .85rem; }
.dialogue .line { display: grid; grid-template-columns: 30px 1fr; gap: .5rem; align-items: start; }
.dialogue .who { font-weight: 700; color: var(--seal); padding-top: .35rem; }
.file-row { display: flex; justify-content: space-between; align-items: center; gap: .5rem; padding: .5rem 0; border-bottom: 1px solid #f0eee8; flex-wrap: wrap; }
.rec-out { font-size: .9rem; margin-top: .3rem; }

/* Flashcard */
.flash-wrap { max-width: 520px; margin: 0 auto; }
.flash { position: relative; height: 260px; perspective: 1000px; cursor: pointer; }
.flash > div { position: absolute; inset: 0; display: flex; flex-direction: column; align-items: center; justify-content: center; text-align: center; padding: 1rem;
  background: #fff; border: 1px solid var(--line); border-radius: 18px; box-shadow: var(--shadow); backface-visibility: hidden; transition: transform .45s; }
.flash .back { transform: rotateY(180deg); background: var(--paper); }
.flash.flipped .front { transform: rotateY(180deg); } .flash.flipped .back { transform: rotateY(360deg); }

/* Bài kiểm tra */
.q-title { font-weight: 600; margin-bottom: .3rem; display: flex; gap: .5rem; align-items: center; }
.opts { display: grid; gap: .45rem; margin-top: .5rem; }
.opt { display: flex; gap: .6rem; align-items: center; padding: .6rem .8rem; border: 1px solid var(--line); border-radius: 10px; cursor: pointer; }
.opt:has(input:checked) { border-color: var(--ink-2); background: #f3f5fa; }
.opt span { display: block; } .opt .zh { font-family: var(--zh); font-size: 1.1rem; } .opt .py, .opt .vi { font-size: .85rem; color: var(--muted); }
.opt > span + span { margin-left: .2rem; }
.q.right { border-left: 4px solid var(--green); } .q.wrong { border-left: 4px solid var(--seal); }
.q .opt.correct { border-color: var(--green); background: var(--green-soft); }
.q .fb { margin-top: .5rem; font-weight: 600; }
.q.right .fb { color: var(--green); } .q.wrong .fb { color: var(--seal); }
.q .fb .zh-block { font-weight: 400; color: var(--ink); }
input.answer { font-family: var(--zh); font-size: 1.15rem; margin-top: .4rem; }
.sticky-bottom { position: sticky; bottom: 0; background: linear-gradient(transparent, var(--paper) 30%); padding: 1rem 0; }
.score { font-size: 1.1rem; }

.action-bar { position: sticky; bottom: 0; display: flex; justify-content: flex-end; gap: .5rem; flex-wrap: wrap; padding: .8rem;
  background: rgba(250,248,243,.95); backdrop-filter: blur(6px); border-top: 1px solid var(--line); margin: 0 -1rem; }

#toast { position: fixed; left: 50%; bottom: 1.2rem; transform: translate(-50%, 150%); background: var(--ink); color: #fff; padding: .7rem 1.1rem;
  border-radius: 10px; z-index: 100; transition: transform .25s; max-width: 92vw; box-shadow: 0 8px 30px rgba(0,0,0,.2); }
#toast.show { transform: translate(-50%, 0); } #toast.err { background: var(--seal); } #toast.ok { background: var(--green); }

@media (max-width: 720px) {
  body { font-size: 15px; }
  #topbar { padding: .5rem .75rem; gap: .4rem; }
  #nav { order: 3; flex-basis: 100%; }
  .who #whoName { display: none; }
  main { padding: .75rem .75rem 6rem; }
  .grid2 { grid-template-columns: 1fr; }
  .grid-form { grid-template-columns: 1fr; }
  .tabs { top: 92px; }
  .vocab-head { grid-template-columns: 28px 1fr; } .vocab-head .meaning { grid-column: 2; }
  .hanzi.xl, .meaning.xl { font-size: 2rem; }
  .continue { flex-direction: column; align-items: stretch; }
  .tbl { font-size: .85rem; }
}

.demo-box { margin-top: 1rem; padding: .8rem; border: 1px dashed var(--gold); border-radius: 10px; background: #fffaf0; text-align: left; display: grid; gap: .4rem; font-size: .88rem; }
.demo-box .btn { justify-content: center; }

[hidden] { display: none !important; }
#toast:not(.show) { opacity: 0; pointer-events: none; }

/* Bài viết */
.badge.gold { background: #fbf1dc; color: #8a6414; }
.writing h3 { margin: 0; }
.writing .passage { background: var(--paper); border-radius: 10px; padding: .6rem .9rem; margin: .4rem 0 .8rem; }
.writing .passage-vi p { margin: .3rem 0; }
.answer-box { min-height: 9rem; line-height: 1.7; }
.answer-box.zh-input { font-family: var(--zh); font-size: 1.1rem; }
.word-chips { display: flex; flex-wrap: wrap; gap: .5rem; margin: .5rem 0 .8rem; }
.chip { display: inline-flex; flex-direction: column; align-items: center; padding: .4rem .8rem; border: 1px solid var(--line); border-radius: 10px; background: #fff; min-width: 4.5rem; }
.chip .zh { font-family: var(--zh); font-size: 1.25rem; }
.chip .py { font-size: .82rem; color: var(--ink-2); }
.chip .vi-text { font-size: .78rem; color: var(--muted); }
.chip.used { border-color: var(--green); background: var(--green-soft); }
.chip.used::after { content: "✓ đã dùng"; font-size: .7rem; color: var(--green); }
.grade { text-align: right; }
.score-big { font-size: 1.3rem; color: var(--green); margin-left: .3rem; }
.feedback { text-align: left; background: var(--green-soft); border-radius: 8px; padding: .5rem .7rem; margin-top: .4rem; font-size: .92rem; }
/* Chấm bài (giáo viên) */
.grade-card .meta { display: flex; flex-wrap: wrap; gap: .3rem .8rem; align-items: center; }
.grade-card .student-answer { white-space: pre-wrap; background: var(--paper); border-radius: 10px; padding: .7rem .9rem; font-size: 1.05rem; line-height: 1.8; }
.grade-card .student-answer.zh-text { font-family: var(--zh); font-size: 1.15rem; }
.grade-card details.ref summary { cursor: pointer; color: var(--ink-2); font-weight: 600; margin: .5rem 0; }
.grade-form { display: grid; grid-template-columns: 8rem 1fr; gap: .6rem; align-items: start; margin-top: .6rem; }
@media (max-width: 720px) { .grade-form { grid-template-columns: 1fr; } }
.nav-count { display: inline-grid; place-items: center; min-width: 1.2rem; height: 1.2rem; padding: 0 .3rem; border-radius: 99px; background: var(--seal); color: #fff; font-size: .72rem; margin-left: .25rem; }