:root {
  --paper: #F5F7FA;
  --surface: #FFFFFF;
  --ink: #1B2433;
  --muted: #5A6478;
  --line: #D6DCE5;
  --accent: #0B7A5E;
  --marker: #FFE27A;
  --font: "Be Vietnam Pro", "Segoe UI", system-ui, -apple-system, Roboto, sans-serif;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --paper: #11151C;
    --surface: #182029;
    --ink: #E6EAF0;
    --muted: #9AA4B4;
    --line: #2B3441;
    --accent: #43C59E;
    --marker: rgba(255, 214, 90, .32);
    color-scheme: dark;
  }
}
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font: 400 17px/1.6 var(--font);
  padding: env(safe-area-inset-top, 0) 0 env(safe-area-inset-bottom, 0);
}
a { color: var(--accent); text-underline-offset: 3px; }
a:focus-visible, input:focus-visible, select:focus-visible, summary:focus-visible, button:focus-visible {
  outline: 3px solid var(--accent); outline-offset: 2px;
}
.wrap { max-width: 44rem; margin: 0 auto; padding: 0 1.25rem; }

/* Đầu trang */
.top { border-bottom: 1px solid var(--line); }
.top .wrap { display: flex; flex-wrap: wrap; gap: .25rem 1.25rem; align-items: baseline; padding-top: 1rem; padding-bottom: 1rem; }
.brand { font-weight: 700; font-size: 1.15rem; color: var(--ink); text-decoration: none; letter-spacing: -.01em; }
.brand::before { content: ""; display: inline-block; width: .7em; height: .7em; margin-right: 1.4em; border-radius: 50%; background: var(--accent); box-shadow: .9em 0 0 var(--marker); vertical-align: .02em; }
.top nav { display: flex; flex-wrap: wrap; gap: .25rem 1rem; font-size: .95rem; }
.top nav a { color: var(--muted); text-decoration: none; }
.top nav a:hover, .top nav a[aria-current] { color: var(--ink); }

/* Tiêu đề */
main { padding: 2.25rem 0 3rem; }
h1 { font-size: clamp(1.75rem, 5vw, 2.4rem); line-height: 1.15; letter-spacing: -.02em; margin: 0 0 .6rem; font-weight: 700; }
h2 { font-size: 1.35rem; line-height: 1.3; margin: 2.5rem 0 .6rem; letter-spacing: -.01em; }
h3 { font-size: 1.1rem; margin: 1.75rem 0 .4rem; }
.lede { color: var(--muted); margin: 0 0 1.75rem; max-width: 36rem; }
p, li { max-width: 40rem; }

/* Công cụ */
.tool { background: var(--surface); border: 1px solid var(--line); border-radius: 14px; padding: 1.25rem; }
.seg { display: inline-flex; border: 1px solid var(--line); border-radius: 999px; padding: 3px; margin-bottom: 1.1rem; flex-wrap: wrap; }
.seg label { position: relative; padding: .35rem .9rem; border-radius: 999px; cursor: pointer; font-size: .93rem; color: var(--muted); }
.seg input { position: absolute; opacity: 0; inset: 0; cursor: pointer; }
.seg label:has(input:checked) { background: var(--ink); color: var(--surface); }
.seg label:has(input:focus-visible) { outline: 3px solid var(--accent); outline-offset: 2px; }
.fields { display: grid; grid-template-columns: repeat(auto-fit, minmax(13rem, 1fr)); gap: .9rem 1rem; }
.fields[hidden] { display: none; }
.f { display: flex; flex-direction: column; gap: .3rem; font-size: .88rem; color: var(--muted); }
.f.check { flex-direction: row; align-items: center; gap: .5rem; color: var(--ink); font-size: .95rem; }
input, select {
  font: inherit; font-size: 1.05rem; color: var(--ink); background: var(--paper);
  border: 1px solid var(--line); border-radius: 10px; padding: .6rem .75rem; width: 100%;
  font-variant-numeric: tabular-nums;
}
.f.check input { width: auto; }

/* Kết quả: con số chính được đánh dấu như bút highlight trên phiếu lương */
.result { display: block; margin-top: 1.5rem; padding-top: 1.25rem; border-top: 1px dashed var(--line); }
.hero-label { margin: 0; color: var(--muted); font-size: .95rem; }
.figure { margin: .1rem 0 1rem; font-size: clamp(2rem, 8vw, 3rem); font-weight: 700; letter-spacing: -.03em; line-height: 1.15; font-variant-numeric: tabular-nums; }
.figure span { background: linear-gradient(transparent 58%, var(--marker) 58%, var(--marker) 92%, transparent 92%); padding: 0 .1em; }
.note { color: var(--muted); font-size: .9rem; margin: .5rem 0 0; }
.slip { margin: 0; font-variant-numeric: tabular-nums; }
.slip div { display: flex; align-items: baseline; gap: .5rem; padding: .32rem 0; }
.slip div::before { content: ""; order: 1; flex: 1; min-width: 1rem; border-bottom: 1px dotted var(--line); }
.slip dt { order: 0; color: var(--muted); }
.slip dd { order: 2; margin: 0; text-align: right; white-space: nowrap; }
.slip .sub dt, .slip .sub dd { color: var(--ink); }
.slip .total { border-top: 1px solid var(--ink); margin-top: .35rem; padding-top: .55rem; font-weight: 700; }
.slip .total dt { color: var(--ink); }
.slip .aside { font-size: .9rem; }
details { margin-top: 1rem; }
summary { cursor: pointer; color: var(--accent); }
.scroll { overflow-x: auto; margin-top: .5rem; max-height: 26rem; overflow-y: auto; border: 1px solid var(--line); border-radius: 10px; }
table { border-collapse: collapse; width: 100%; font-size: .88rem; font-variant-numeric: tabular-nums; }
th, td { padding: .4rem .6rem; text-align: right; border-bottom: 1px solid var(--line); white-space: nowrap; }
th { position: sticky; top: 0; background: var(--surface); color: var(--muted); font-weight: 600; }
th:first-child, td:first-child { text-align: left; }

/* Trang chủ */
.tools-list { list-style: none; padding: 0; margin: 0; border-top: 1px solid var(--line); }
.tools-list li { border-bottom: 1px solid var(--line); max-width: none; }
.tools-list a { display: grid; grid-template-columns: 1fr auto; gap: .1rem 1rem; padding: 1rem 0; text-decoration: none; color: var(--ink); }
.tools-list strong { font-size: 1.1rem; }
.tools-list span { color: var(--muted); font-size: .93rem; grid-column: 1; }
.tools-list a::after { content: "Mở"; grid-row: 1 / span 2; grid-column: 2; align-self: center; color: var(--accent); font-size: .93rem; }
.tools-list a:hover strong { color: var(--accent); }
.posts { padding-left: 1.1rem; }
.posts li { margin: .35rem 0; }

/* Bài viết, nhật ký */
.meta { color: var(--muted); font-size: .9rem; margin: 0 0 1.5rem; }
.prose { line-height: 1.7; }
.prose table { margin: 1rem 0; }
.callout { border-left: 3px solid var(--accent); padding: .5rem 0 .5rem 1rem; color: var(--muted); font-size: .93rem; margin: 2rem 0 0; }
.log { list-style: none; padding: 0; border-left: 2px solid var(--line); margin-left: .3rem; }
.log li { position: relative; padding: 0 0 1.25rem 1.25rem; }
.log li::before { content: ""; position: absolute; left: -6px; top: .55em; width: 10px; height: 10px; border-radius: 50%; background: var(--accent); }
.log time { display: block; color: var(--muted); font-size: .88rem; font-variant-numeric: tabular-nums; }
.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(9rem, 1fr)); gap: 1px; background: var(--line); border: 1px solid var(--line); border-radius: 12px; overflow: hidden; margin: 1.25rem 0 2rem; }
.stats div { background: var(--surface); padding: .9rem 1rem; }
.stats b { display: block; font-size: 1.35rem; font-variant-numeric: tabular-nums; }
.stats span { color: var(--muted); font-size: .85rem; }
.sources { font-size: .88rem; color: var(--muted); }

.foot { border-top: 1px solid var(--line); color: var(--muted); font-size: .88rem; }
.foot .wrap { padding-top: 1.25rem; padding-bottom: 2rem; }
.foot p { margin: .3rem 0; }

@media (prefers-reduced-motion: reduce) { * { scroll-behavior: auto !important; } }