/* AI cho Backend Developer (.NET) – shared styles */
:root {
  --bg: #f7f8fa;
  --surface: #ffffff;
  --surface-2: #f1f3f6;
  --text: #111827;
  --muted: #5b6472;
  --border: #e3e6eb;
  --accent: #2b78e4;
  --accent-soft: #e8f1fd;
  --on-accent: #ffffff;
  --ok: #15803d;
  --ok-soft: #e3f6e9;
  --bad: #b93f0c;
  --bad-soft: #fdeee5;
  --warn: #8a5a00;
  --warn-soft: #fdf6dc;
  /* focus labels = roadmap.sh legend colours */
  --f-core: #7c3aed;
  --f-be: #6b8e23;
  --f-ext: #9ca3af;
  --code-bg: #1f2428;
  --code-text: #e6edf3;
  --radius: 10px;
  --shadow: 0 1px 2px rgba(0, 0, 0, .05), 0 4px 14px rgba(0, 0, 0, .05);
  --font: "Segoe UI", system-ui, -apple-system, Roboto, "Helvetica Neue", Arial, sans-serif;
  --hand: "Balsamiq Sans", "Segoe UI", system-ui, sans-serif;
  --mono: "Cascadia Code", Consolas, "SF Mono", Menlo, monospace;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f1216; --surface: #171b21; --surface-2: #20262e; --text: #e8ebf0; --muted: #9aa4b2; --border: #2b323c;
    --accent: #60a5fa; --accent-soft: #15253b; --on-accent: #0b1220;
    --ok: #4ade80; --ok-soft: #14301f; --bad: #ff9a5c; --bad-soft: #3b2216; --warn: #f5cf5a; --warn-soft: #332b10;
    --f-core: #a78bfa; --f-be: #a3c45a; --f-ext: #8b93a1; --code-bg: #0d1014; --shadow: none; color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0f1216; --surface: #171b21; --surface-2: #20262e; --text: #e8ebf0; --muted: #9aa4b2; --border: #2b323c;
  --accent: #60a5fa; --accent-soft: #15253b; --on-accent: #0b1220;
  --ok: #4ade80; --ok-soft: #14301f; --bad: #ff9a5c; --bad-soft: #3b2216; --warn: #f5cf5a; --warn-soft: #332b10;
  --f-core: #a78bfa; --f-be: #a3c45a; --f-ext: #8b93a1; --code-bg: #0d1014; --shadow: none; color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--text); font: 16px/1.6 var(--font); }
a { color: var(--accent); }
code { font-family: var(--mono); font-size: .86em; background: var(--surface-2); padding: 1px 5px; border-radius: 4px; overflow-wrap: anywhere; }
h1 { font-size: 2.4rem; line-height: 1.15; margin: .1em 0 .3em; letter-spacing: -.02em; }
h2 { font-size: 1.35rem; line-height: 1.3; margin: 0 0 .5em; }
h3 { font-size: 1.08rem; line-height: 1.35; margin: 0 0 .5em; }
.muted { color: var(--muted); }
.small { font-size: .875rem; }
.kicker { font-size: .74rem; text-transform: uppercase; letter-spacing: .07em; color: var(--muted); font-weight: 700; }
button:focus-visible, a:focus-visible, input:focus-visible, textarea:focus-visible, select:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

/* ---------- top bar ---------- */
.topbar { position: sticky; top: 0; z-index: 20; background: #111827; color: #f9fafb; }
.topbar-inner { max-width: 1200px; margin: 0 auto; padding: 10px 20px; display: flex; align-items: center; gap: 14px; flex-wrap: wrap; }
.brand { font-weight: 800; text-decoration: none; color: #fff; margin-right: auto; display: inline-flex; align-items: center; gap: 8px; }
.brand .logo { width: 26px; height: 26px; border-radius: 6px; background: #fff; color: #111827; display: inline-grid; place-items: center; font-size: 15px; }
.nav { display: flex; gap: 2px; flex-wrap: wrap; align-items: center; }
.nav a, .nav button { font: inherit; font-size: .9rem; text-decoration: none; color: #d1d5db; background: transparent; border: 0; padding: 6px 10px; border-radius: 7px; cursor: pointer; }
.nav a:hover, .nav button:hover { color: #fff; background: #1f2937; }
.nav a.active { color: #fff; background: #374151; }

.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

/* ---------- buttons, pills ---------- */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 6px; border: 1px solid var(--accent); background: var(--accent); color: var(--on-accent); border-radius: 8px; padding: 8px 14px; font: inherit; font-weight: 600; cursor: pointer; text-decoration: none; line-height: 1.25; }
.btn:hover { filter: brightness(1.07); }
.btn-ghost { background: transparent; color: var(--accent); }
.btn-ghost:hover { background: var(--accent-soft); filter: none; }
.btn-dark { background: #111827; border-color: #111827; color: #fff; }
.btn-sm { padding: 5px 10px; font-size: .85rem; }
.btn-row { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; margin-top: 10px; }
.icon-btn { width: 34px; height: 34px; border-radius: 8px; border: 1px solid var(--border); background: var(--surface); cursor: pointer; font-size: 15px; display: inline-grid; place-items: center; color: var(--text); flex-shrink: 0; }
.icon-btn:hover { border-color: var(--accent); }
.pill { display: inline-block; font-size: .74rem; padding: 2px 9px; border-radius: 999px; background: var(--surface-2); color: var(--muted); font-weight: 700; white-space: nowrap; }
.pill.ok { background: var(--ok-soft); color: var(--ok); }
.pill.warn { background: var(--warn-soft); color: var(--warn); }
.pill.info { background: var(--accent-soft); color: var(--accent); }
.chips { display: flex; gap: 6px; flex-wrap: wrap; }
.chip { border: 1px solid var(--border); background: var(--surface); border-radius: 999px; padding: 4px 12px; font: inherit; font-size: .85rem; cursor: pointer; color: var(--text); }
.chip.active { background: var(--text); color: var(--bg); border-color: var(--text); }

/* focus label chips */
.focus { display: inline-flex; align-items: center; gap: 5px; font-size: .74rem; font-weight: 700; padding: 1px 8px 1px 6px; border-radius: 999px; border: 1px solid var(--border); color: var(--muted); white-space: nowrap; }
.focus::before { content: "✓"; display: inline-grid; place-items: center; width: 14px; height: 14px; border-radius: 50%; color: #fff; font-size: 9px; background: var(--f-ext); }
.focus.core::before { background: var(--f-core); }
.focus.be::before { background: var(--f-be); }
.focus.opt { border-style: dashed; }
.focus.opt::before { content: "?"; background: var(--warn); }

/* ---------- cards ---------- */
.card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px 20px; box-shadow: var(--shadow); margin: 0 0 16px; }
.block-head { display: flex; align-items: center; gap: 8px; margin-bottom: 8px; flex-wrap: wrap; }
.block-head h2, .block-head h3 { margin: 0 auto 0 0; }
.prose p { margin: .35em 0 .8em; }
.prose ul, .prose ol { padding-left: 1.3em; margin: .3em 0 .8em; }
.prose li { margin: .25em 0; }
.prose > :last-child { margin-bottom: 0; }
.callout { border-radius: 10px; padding: 12px 16px; background: var(--warn-soft); border: 1px solid color-mix(in srgb, var(--warn) 25%, transparent); margin: 0 0 18px; }
.callout.info { background: var(--accent-soft); border-color: color-mix(in srgb, var(--accent) 25%, transparent); }
.callout.ok { background: var(--ok-soft); border-color: color-mix(in srgb, var(--ok) 25%, transparent); }
.callout h3, .callout h4 { margin: 0 0 .3em; }

/* ---------- tables ---------- */
.tbl-wrap { overflow-x: auto; margin: 4px 0; }
table.tbl { width: 100%; border-collapse: collapse; font-size: .92rem; }
.tbl th, .tbl td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border); vertical-align: top; }
.tbl th { font-size: .74rem; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); }
.tbl tr:last-child td { border-bottom: 0; }

/* ---------- code ---------- */
.code-block { margin: 0 0 20px; border-radius: 10px; overflow: hidden; background: var(--code-bg); border: 1px solid #30363d; }
.code-head { display: flex; align-items: center; gap: 10px; padding: 6px 8px 6px 14px; background: #262c33; color: #c9d1d9; font-size: .8rem; }
.code-head .lang { font-family: var(--mono); color: #8b949e; }
.code-head .code-title { font-weight: 600; color: #e6edf3; }
.code-head .copy { font: inherit; font-size: .78rem; color: #c9d1d9; background: transparent; border: 1px solid #3d444d; border-radius: 6px; padding: 2px 9px; cursor: pointer; margin-left: auto; }
.code-head .copy:hover { border-color: #8b949e; color: #fff; }
.code-block pre { margin: 0; padding: 14px 16px; overflow-x: auto; font: .82rem/1.6 var(--mono); color: var(--code-text); tab-size: 4; }
.code-block pre code { background: none; padding: 0; font-size: inherit; color: inherit; overflow-wrap: normal; }
.code-note { padding: 8px 14px 10px; font-size: .86rem; color: #c9d1d9; border-top: 1px solid #30363d; }
.code-note code { background: #30363d; color: #e6edf3; }
.code-note a { color: #79c0ff; }

/* ---------- quiz ---------- */
.qs { counter-reset: q; }
.q { padding: 12px 0; border-bottom: 1px solid var(--border); counter-increment: q; }
.q:last-child { border-bottom: 0; padding-bottom: 2px; }
.q-text { line-height: 1.6; font-weight: 500; }
.q-text::before { content: counter(q) ". "; font-weight: 700; color: var(--muted); }
.opts { display: grid; grid-template-columns: 1fr; gap: 6px; margin-top: 8px; }
.opt { text-align: left; border: 1px solid var(--border); background: var(--surface); border-radius: 8px; padding: 7px 12px; font: inherit; font-size: .94rem; cursor: pointer; color: var(--text); line-height: 1.4; }
.opt:hover:not(:disabled) { border-color: var(--accent); background: var(--accent-soft); }
.opt:disabled { cursor: default; }
.opt.is-correct { border-color: var(--ok); background: var(--ok-soft); color: var(--ok); font-weight: 600; }
.opt.is-wrong { border-color: var(--bad); background: var(--bad-soft); color: var(--bad); text-decoration: line-through; }
.fb { margin-top: 8px; font-size: .92rem; border-radius: 8px; }
.fb:empty { display: none; }
.fb.ok, .fb.bad { padding: 8px 12px; }
.fb.ok { background: var(--ok-soft); color: var(--ok); }
.fb.bad { background: var(--bad-soft); color: var(--bad); }
.fb .explain { color: var(--text); margin-top: 4px; }

/* ---------- forms & checklists ---------- */
textarea, input.text, select { width: 100%; font: inherit; border: 1px solid var(--border); border-radius: 8px; padding: 8px 12px; background: var(--surface); color: var(--text); }
textarea { resize: vertical; line-height: 1.5; }
label.field { display: block; margin: 0; font-weight: 600; font-size: .86rem; }
label.field > input, label.field > textarea, label.field > select { margin-top: 4px; font-weight: 400; }
.check { display: flex; gap: 10px; align-items: flex-start; padding: 6px 0; cursor: pointer; }
.check input { margin-top: 4px; width: 18px; height: 18px; accent-color: var(--ok); flex-shrink: 0; cursor: pointer; }
.check.done > .label { color: var(--muted); text-decoration: line-through; }
.check .label { flex: 1; }

/* ---------- progress ---------- */
.progress { height: 8px; background: var(--surface-2); border-radius: 999px; overflow: hidden; display: flex; }
.progress > i { display: block; height: 100%; background: var(--ok); transition: width .3s; }
.progress > i.doing { background: #f59e0b; }
.progress > i.skip { background: var(--f-ext); }

/* ---------- dialog & toast ---------- */
dialog { border: 1px solid var(--border); border-radius: 14px; background: var(--surface); color: var(--text); padding: 0; max-width: 520px; width: calc(100% - 32px); }
dialog::backdrop { background: rgba(0, 0, 0, .45); }
.dlg-body { padding: 20px; max-height: 80vh; overflow-y: auto; }
.toast { position: fixed; bottom: 20px; left: 50%; transform: translateX(-50%); background: #111827; color: #fff; padding: 8px 18px; border-radius: 999px; font-size: .9rem; z-index: 80; box-shadow: 0 4px 16px rgba(0, 0, 0, .25); }

/* ---------- secondary pages ---------- */
.page-head { padding: 34px 0 18px; }
.page-head p { max-width: 70ch; }
.mt-ch { display: flex; align-items: center; gap: 8px; margin-bottom: 6px; }
.mt-tbl td:nth-child(3) { font-family: var(--mono); font-size: .86rem; white-space: nowrap; }
.term { padding: 12px 0; border-bottom: 1px solid var(--border); }
.term:last-child { border-bottom: 0; }
.term-head { display: flex; flex-wrap: wrap; gap: 4px 10px; align-items: baseline; }
.term-head b { font-size: 1.02rem; }
.term-head .alias { color: var(--muted); font-size: .9rem; }
.term-head a { margin-left: auto; font-size: .85rem; }
.term .net { font-size: .88rem; color: var(--muted); margin-top: 2px; }
.term .net::before { content: ".NET ≈ "; font-family: var(--mono); font-size: .75rem; color: var(--accent); }

@media (max-width: 640px) {
  body { font-size: 15px; }
  h1 { font-size: 1.8rem; }
  .card { padding: 14px; }
  .topbar-inner { padding: 8px 14px; }
  .container { padding: 0 14px; }
}