/* Light: a Chinese school exercise book. Dark: the classroom blackboard. */
:root {
  --paper: #d9e8d3;
  --sheet: #e8f1e3;
  --ink: #16261f;
  --muted: #435448;
  --grid: #c23b2e;
  --grid-soft: #c23b2e80;
  --on-grid: #ffffff;
  --on-grid-soft: #ffffff66;
  --red-text: #9c281d;
  --line: #16261f2e;
  --zh: "LXGW WenKai", "Kaiti SC", "STKaiti", "KaiTi", serif;
  --ui: "Be Vietnam Pro", "LXGW WenKai", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  --text-caption: .8125rem;
  --text-small: .875rem;
  --text-control: .9375rem;
  --text-body: 1rem;
  --text-title: 1.125rem;
  --text-section: 1.25rem;
  --ease-out: cubic-bezier(0.23, 1, 0.32, 1);
  --gutter: max(16px, env(safe-area-inset-left), env(safe-area-inset-right));
  --target: 40px;
  color-scheme: light;
}
@media (pointer: coarse) { :root { --target: 44px; } }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #16332a;
    --sheet: #1e4035;
    --ink: #eef3e8;
    --muted: #b4cabd;
    --grid: #e88a7d;
    --grid-soft: #e88a7d80;
    --on-grid: #16261f;
    --on-grid-soft: #16261f55;
    --red-text: #f4aca1;
    --line: #eef3e82e;
    color-scheme: dark;
  }
}
*, *::before, *::after { box-sizing: border-box; }
html {
  -webkit-text-size-adjust: 100%;
  -webkit-tap-highlight-color: transparent;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  font-synthesis: none;
}
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font: 400 var(--text-body)/1.55 var(--ui);
  overflow-wrap: break-word;
}
a { color: inherit; }
img { display: block; max-width: 100%; }
h1, h2, h3, p { margin: 0; }
h1, h2, h3 { text-wrap: balance; }
button, a, input, [role="button"] { touch-action: manipulation; }
button { user-select: none; -webkit-user-select: none; }
:focus-visible { outline: 2px solid var(--ink); outline-offset: 2px; }
main:focus { outline: none; }
::selection { background: #c23b2e33; }
.zh { font-family: var(--zh); }
.skip { position: absolute; left: -999px; }
.skip:focus { left: 16px; top: 8px; background: var(--sheet); padding: 8px 12px; z-index: 1; }

/* 田字格: solid box, dashed red guides through the centre. */
.cell {
  position: relative; display: grid; place-items: center;
  border: 1.5px solid var(--grid); background: var(--sheet);
  aspect-ratio: 1;
}
.cell::before, .cell::after { content: ""; position: absolute; pointer-events: none; }
.cell::before { left: 50%; top: 0; bottom: 0; border-left: 1px dashed var(--grid-soft); }
.cell::after { top: 50%; left: 0; right: 0; border-top: 1px dashed var(--grid-soft); }
.cell > .zh { position: relative; z-index: 1; line-height: 1; }
.cell-sm { width: 36px; font-size: 26px; flex: none; }

/* Header */
.top {
  display: flex; flex-wrap: wrap; align-items: center; gap: 4px 20px;
  max-width: 1320px; margin: 0 auto;
  padding: max(12px, env(safe-area-inset-top)) var(--gutter) 12px;
}
.brand { display: inline-flex; align-items: center; gap: 10px; min-height: var(--target); text-decoration: none; font-weight: 700; font-size: var(--text-title); margin-right: auto; }
.top nav { display: flex; flex-wrap: wrap; gap: 0 18px; }
.top nav a {
  display: inline-flex; align-items: center; justify-content: center; min-height: var(--target); min-width: var(--target);
  text-decoration: none; white-space: nowrap; color: var(--muted); box-shadow: inset 0 -2px 0 transparent;
  transition: color 120ms ease-out;
}
.top nav a[aria-current="page"] { color: var(--ink); box-shadow: inset 0 -2px 0 var(--grid); }
.langs { display: inline-flex; border: 1px solid var(--line); }
.lang {
  appearance: none; border: 0; background: none; font: inherit; font-size: var(--text-small); font-weight: 600; color: var(--muted);
  min-width: var(--target); min-height: var(--target); padding: 0 8px; cursor: pointer;
  transition: color 120ms ease-out, background-color 120ms ease-out;
}
.lang[aria-pressed="true"] { background: var(--ink); color: var(--paper); }

main { max-width: 1320px; margin: 0 auto; padding: 8px var(--gutter) max(64px, env(safe-area-inset-bottom)); min-height: 60svh; }
.status { padding: 48px 16px; color: var(--muted); }

/* Level picker: the one loud thing on the page. */
.intro { max-width: 34em; font-size: clamp(1.25rem, 2.6vw, 1.625rem); line-height: 1.3; font-weight: 600; padding: 12px 0 20px; text-wrap: pretty; }
.levels { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); align-items: start; max-width: 760px; margin-bottom: 8px; }
.level {
  appearance: none; font: inherit; color: inherit; background: none; border: 0; padding: 0;
  text-align: start; cursor: pointer; display: block; min-width: 0;
}
.level + .level .cell { border-inline-start-width: 0; }
.level .cell {
  font-size: clamp(3rem, 11vw, 6.25rem);
  transition: background-color 120ms ease-out, color 120ms ease-out, transform 120ms var(--ease-out);
}
.level:active .cell { transform: scale(0.96); }
.level[aria-pressed="true"] .cell { background: var(--grid); color: var(--on-grid); }
.level[aria-pressed="true"] .cell::before, .level[aria-pressed="true"] .cell::after { border-color: var(--on-grid-soft); }
.level-name { display: block; font-weight: 600; margin-top: 8px; line-height: 1.25; font-size: var(--text-control); padding-inline-end: 4px; }
.level-hsk { display: block; color: var(--muted); font-size: var(--text-small); }

/* Filters */
.filters { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 16px; margin: 20px 0 8px; }
.chips { display: flex; flex-wrap: wrap; gap: 6px; }
.chip {
  appearance: none; font: inherit; font-size: var(--text-control); color: var(--ink); background: none; cursor: pointer;
  border: 1px solid var(--line); padding: 0 12px; min-height: var(--target);
  display: inline-flex; align-items: center; text-decoration: none; white-space: nowrap;
  transition: background-color 120ms ease-out, color 120ms ease-out, border-color 120ms ease-out, transform 120ms var(--ease-out);
}
.chip:active { transform: scale(0.96); }
.chip[aria-pressed="true"], .chip[aria-current="page"] { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.search {
  font: inherit; font-size: 16px; color: var(--ink); background: var(--sheet); border: 1px solid var(--line); border-radius: 0;
  padding: 0 12px; min-height: var(--target); flex: 1 1 220px; max-width: 340px; margin-inline-start: auto; appearance: none;
}
.search::placeholder { color: var(--muted); opacity: 1; }
.result-note { color: var(--muted); font-size: var(--text-small); margin-bottom: 12px; min-height: 1.55em; font-variant-numeric: tabular-nums; }

/* Video grid */
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(min(100%, 280px), 1fr)); gap: 28px 20px; }
.card { min-width: 0; }
.card > a { text-decoration: none; display: block; }
.thumb { position: relative; aspect-ratio: 16 / 9; overflow: hidden; background: var(--sheet); }
.thumb img { width: 100%; height: 100%; object-fit: cover; }
.dur { position: absolute; inset-inline-end: 6px; bottom: 6px; background: #000000cc; color: #fff; font-size: var(--text-caption); line-height: 1.4; padding: 1px 5px; font-variant-numeric: tabular-nums; pointer-events: none; }
.card-title {
  font-weight: 600; line-height: 1.35; margin-top: 8px; font-size: var(--text-body); overflow-wrap: anywhere; text-wrap: pretty;
  display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden;
}
.meta { color: var(--muted); font-size: var(--text-small); margin-top: 3px; display: flex; flex-wrap: wrap; gap: 0 10px; font-variant-numeric: tabular-nums; }
.meta a { text-decoration: none; }
.lvl { color: var(--red-text); }
.sentinel { height: 1px; }

/* Watch */
.watch { display: grid; grid-template-columns: minmax(0, 1fr) 360px; gap: 28px; align-items: start; }
.player { position: relative; aspect-ratio: 16 / 9; background: #000; }
.player iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }
.watch h1 { font-size: clamp(var(--text-title), 2.2vw, 1.375rem); line-height: 1.3; margin-top: 14px; overflow-wrap: anywhere; }
.actions { display: flex; flex-wrap: wrap; gap: 6px; margin: 12px 0 20px; }
.evidence { border-top: 1px solid var(--line); padding-top: 14px; max-width: 65ch; }
.evidence h2 { font-size: var(--text-body); }
.evidence p { margin-top: 4px; text-wrap: pretty; }
.quote { margin: 12px 0 0; padding-inline-start: 12px; border-inline-start: 2px solid var(--grid); max-width: 65ch; }
.quote a { display: block; color: var(--muted); font-size: var(--text-small); margin-top: 2px; text-underline-offset: 3px; }
.next h2 { font-size: var(--text-body); margin-bottom: 12px; }
.next-item { display: grid; grid-template-columns: 148px minmax(0, 1fr); gap: 10px; text-decoration: none; margin-bottom: 12px; }
.next-item .card-title { margin-top: 0; font-size: var(--text-control); }

/* Channels */
.page-title { font-size: clamp(1.5rem, 3vw, 2rem); line-height: 1.2; padding: 12px 0 6px; }
.page-lead { color: var(--muted); max-width: 65ch; margin-bottom: 20px; text-wrap: pretty; }
.page-lead a { text-underline-offset: 3px; text-decoration-thickness: from-font; }
.rank { list-style: none; margin: 0; padding: 0; max-width: 56rem; }
.rank li { display: grid; grid-template-columns: 2.5rem minmax(0, 1fr); gap: 4px 8px; padding: 14px 0; border-top: 1px solid var(--line); }
.rank .pos { font-variant-numeric: tabular-nums; color: var(--muted); font-size: var(--text-title); }
.rank h2 { font-size: var(--text-title); line-height: 1.3; }
.rank h2 a { text-decoration: none; }
.rank p { color: var(--muted); font-size: var(--text-control); max-width: 65ch; }
.tabs { display: flex; flex-wrap: wrap; gap: 6px; margin: 8px 0 20px; }

/* Long-form reading */
.prose { max-width: 65ch; }
.prose h2 { font-size: var(--text-section); margin: 32px 0 8px; line-height: 1.25; }
.prose p, .prose ul, .prose ol { margin: 0 0 12px; }
.prose ul, .prose ol { padding-inline-start: 1.25rem; }
.prose li { margin-bottom: 6px; }
.prose li::marker { color: var(--muted); }
.prose a { text-underline-offset: 3px; text-decoration-thickness: from-font; }

/* Empty states keep the feed's footprint so filters don't make the page jump. */
.empty { padding: 32px 0; max-width: 34rem; min-height: 280px; }
.empty p + p { color: var(--muted); margin-top: 4px; }
.empty .chip { margin-top: 14px; }

/* Hover only where hovering exists, so a tap can't leave a state stuck on. */
@media (hover: hover) and (pointer: fine) {
  .top nav a:hover { color: var(--ink); }
  .lang[aria-pressed="false"]:hover { color: var(--ink); }
  .level[aria-pressed="false"]:hover .cell { background: var(--paper); }
  .chip:not([aria-pressed="true"]):not([aria-current="page"]):hover { border-color: var(--ink); }
  .card:hover .card-title, .next-item:hover .card-title, .rank h2 a:hover {
    text-decoration: underline; text-decoration-color: var(--grid); text-decoration-thickness: from-font; text-underline-offset: 3px;
  }
  .meta a:hover { text-decoration: underline; text-underline-offset: 3px; }
}

@media (max-width: 1000px) {
  .watch { grid-template-columns: minmax(0, 1fr); }
}
@media (max-width: 640px) {
  .top nav { order: 3; width: 100%; flex-wrap: nowrap; justify-content: space-between; gap: 0 8px; font-size: var(--text-control); }
  .search { max-width: none; margin-inline-start: 0; flex-basis: 100%; }
  .level-name { font-size: var(--text-caption); }
  .level-hsk { font-size: var(--text-caption); }
}
/* Long names wrap on small phones. Reserve both lines so the HSK labels stay in a row. */
@media (max-width: 430px) {
  .level-name { min-height: 2.5em; }
}
/* Grow small inline links to a finger-sized target without moving the layout. */
@media (pointer: coarse) {
  .meta a, .quote a { position: relative; }
  .meta a::before, .quote a::before { content: ""; position: absolute; inset: -9px 0; }
}
@media (prefers-reduced-motion: reduce) {
  .level .cell, .chip { transition: background-color 120ms ease-out, color 120ms ease-out, border-color 120ms ease-out; }
  .level:active .cell, .chip:active { transform: none; }
}