:root {
  color-scheme: light dark;
  --bg: #f5f5f4; --fg: #18181b; --muted: #5f5f67; --card: #fff; --line: #e2e2e5; --line-strong: #c4c4ca; --field: #8d8d95;
  --hover: rgba(0, 0, 0, .05); --accent: #18181b; --on-accent: #fff; --ok: #1d7a37; --bad: #c42b22;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #111113; --fg: #ececee; --muted: #a0a0a8; --card: #1a1a1d; --line: #2c2c31; --line-strong: #46464d; --field: #6a6a72;
    --hover: rgba(255, 255, 255, .06); --accent: #ececee; --on-accent: #111113; --ok: #62d083; --bad: #ff7b72;
  }
}
* { box-sizing: border-box; }
body { margin: 0; padding: 0 16px 56px; background: var(--bg); color: var(--fg); accent-color: var(--accent);
       font: 15px/1.6 -apple-system, system-ui, sans-serif; -webkit-font-smoothing: antialiased; }
main { max-width: 760px; margin: 0 auto; }
[hidden] { display: none !important; }  /* buttons set display, which would beat the hidden attribute */

nav { max-width: 760px; margin: 0 auto; display: flex; flex-wrap: wrap; gap: 4px 18px; align-items: baseline;
      padding: 20px 0 32px; }
nav .brand { font-weight: 700; font-size: 17px; letter-spacing: -.01em; margin-right: auto; color: var(--fg); }
nav a { color: var(--muted); text-decoration: none; transition: color .15s; }
nav a:hover, nav a[aria-current] { color: var(--fg); }
nav a[aria-current] { font-weight: 600; }
@media (max-width: 420px) { nav { gap: 4px 14px; } }

h1 { font-size: 26px; line-height: 1.25; letter-spacing: -.02em; margin: 0 0 8px; }
h2 { font-size: 18px; letter-spacing: -.01em; margin: 0 0 6px; }
h3 { letter-spacing: -.01em; }
p.sub, .muted { color: var(--muted); }
p.sub { margin: 0 0 24px; }
section { margin-bottom: 40px; }
a { color: inherit; text-decoration: underline; text-decoration-color: var(--line-strong);
    text-underline-offset: 2px; transition: text-decoration-color .15s; }
a:hover { text-decoration-color: currentColor; }
:focus-visible { outline: 2px solid var(--fg); outline-offset: 2px; }

.card { background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 18px; }
.grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
@media (max-width: 640px) { .grid { grid-template-columns: 1fr; } }

button, .button { font: inherit; font-weight: 600; min-height: 40px; padding: 9px 18px; border-radius: 8px;
         border: 1px solid transparent; background: var(--accent); color: var(--on-accent); cursor: pointer;
         display: inline-block; text-decoration: none; transition: opacity .15s, background-color .15s, transform .1s; }
button:hover:not(:disabled) { opacity: .85; }
button:active:not(:disabled) { transform: translateY(1px); }
button:disabled { opacity: .35; cursor: not-allowed; }
button.secondary { background: transparent; color: var(--fg); border-color: var(--line-strong); }
button.secondary:hover:not(:disabled) { opacity: 1; background: var(--hover); }

label { display: block; margin: 12px 0 4px; font-weight: 600; font-size: 13px; }
label .hint { font-weight: 400; color: var(--muted); }
input[type=text], input[type=password], input[type=number], textarea {
  font: inherit; padding: 8px 10px; border: 1px solid var(--field); border-radius: 8px; width: 100%;
  background: var(--bg); color: var(--fg); transition: border-color .15s, box-shadow .15s; }
input::placeholder, textarea::placeholder { color: var(--muted); opacity: .7; }
input:focus, textarea:focus { outline: none; border-color: var(--fg); box-shadow: 0 0 0 3px var(--hover); }
input:disabled, textarea:disabled { opacity: .5; cursor: not-allowed; }
textarea { font: 11px/1.4 ui-monospace, Menlo, monospace; resize: vertical; }
.check { display: flex; gap: 8px; align-items: center; font-weight: 500; }
.check input { margin: 0; }

code, pre { font: 13px/1.5 ui-monospace, Menlo, monospace; }
pre { background: var(--card); border: 1px solid var(--line); border-radius: 8px; padding: 10px 12px; overflow-x: auto; }
.note { color: var(--muted); font-size: 13px; }
.status { color: var(--muted); font-size: 13px; min-height: 1.4em; margin: 8px 0 0; font-variant-numeric: tabular-nums; }
.ok { color: var(--ok); }
.bad { color: var(--bad); }
.unsupported { border: 1px solid var(--line); border-radius: 8px; padding: 10px 12px; }
ol { padding-left: 20px; }
li + li { margin-top: 2px; }

/* Segmented choice (radio buttons styled as one bar), on Tools and Notes */
.seg { display: flex; border: 1px solid var(--line-strong); border-radius: 8px; overflow: hidden; }
.seg label { margin: 0; flex: 1; font-weight: 500; text-align: center; }
.seg label + label { border-left: 1px solid var(--line-strong); }
.seg input { position: absolute; opacity: 0; }
.seg span { display: block; padding: 7px 4px; cursor: pointer; transition: background-color .15s, color .15s; }
.seg input:not(:checked) + span:hover { background: var(--hover); }
.seg input:checked + span { background: var(--accent); color: var(--on-accent); }
.seg input:focus-visible + span { outline: 2px solid var(--fg); outline-offset: -2px; }
.seg input:disabled + span { cursor: not-allowed; opacity: .5; }

/* Footer on every page */
.foot { max-width: 760px; margin: 48px auto 0; padding-top: 16px; border-top: 1px solid var(--line); display: flex;
  flex-wrap: wrap; gap: 6px 18px; font-size: 13px; }
.foot a { color: var(--muted); text-decoration: none; transition: color .15s; }
.foot a:hover { color: var(--fg); }

@media (prefers-reduced-motion: reduce) { * { transition: none !important; } }