/* DialUpSounds — lab instrument, not costume. Tokens per design-spec.md */
@font-face { font-family: "IBM Plex Mono"; font-style: normal; font-weight: 400; font-display: swap; src: url("../fonts/ibm-plex-mono-400.woff2") format("woff2"); }
@font-face { font-family: "IBM Plex Mono"; font-style: normal; font-weight: 600; font-display: swap; src: url("../fonts/ibm-plex-mono-600.woff2") format("woff2"); }
@font-face { font-family: "Newsreader"; font-style: normal; font-weight: 400; font-display: swap; src: url("../fonts/newsreader-400.woff2") format("woff2"); }
@font-face { font-family: "Newsreader"; font-style: italic; font-weight: 400; font-display: swap; src: url("../fonts/newsreader-400-italic.woff2") format("woff2"); }
@font-face { font-family: "Newsreader"; font-style: normal; font-weight: 600; font-display: swap; src: url("../fonts/newsreader-600.woff2") format("woff2"); }

:root {
  --bg: #14161a; --panel: #1d2026; --panel2: #23272e; --rule: #2c3038; --text: #E8E6E1; --muted: #9AA0A6;
  --caller: #7CFFB2; --answer: #FFB347; --line: #8AB4FF; --warn: #FF6B6B; --on-accent: #0c1a12;
  --mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  --serif: "Newsreader", Georgia, "Times New Roman", serif;
  --u: 8px; --radius: 2px; --maxw: 1120px;
  color-scheme: dark;
}
@media (prefers-color-scheme: light) {
  :root:not([data-theme="dark"]) {
    --bg: #F6F3EC; --panel: #ECE7DC; --panel2: #E4DED1; --rule: #D6CFC0; --text: #1F1D1A; --muted: #5E5A52;
    --caller: #0B6A3D; --answer: #9A5600; --line: #2F5DB3; --warn: #B3261E; --on-accent: #ffffff; color-scheme: light;
  }
}
:root[data-theme="light"] {
  --bg: #F6F3EC; --panel: #ECE7DC; --panel2: #E4DED1; --rule: #D6CFC0; --text: #1F1D1A; --muted: #5E5A52;
  --caller: #0B6A3D; --answer: #9A5600; --line: #2F5DB3; --warn: #B3261E; --on-accent: #ffffff; color-scheme: light;
}

*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--text); font: 400 15px/1.45 var(--mono); overflow-x: hidden; }
a { color: var(--caller); text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 2px solid var(--caller); outline-offset: 2px; }
img, svg, canvas { max-width: 100%; }
.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 16px; }
.skip { position: absolute; left: -9999px; }
.skip:focus { left: 16px; top: 8px; background: var(--panel); padding: 8px; z-index: 10; }

/* header / footer */
.site-head { border-bottom: 1px solid var(--rule); }
.site-head .wrap { padding-top: 8px; padding-bottom: 8px; display: flex; align-items: center; justify-content: space-between; gap: 16px; flex-wrap: wrap; min-height: 56px; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--text); text-decoration: none; font-weight: 600; letter-spacing: .02em; }
.brand svg { width: 28px; height: 18px; }
.nav { display: flex; flex-wrap: wrap; gap: 4px 16px; font-size: 13px; }
.nav a { color: var(--muted); text-decoration: none; padding: 13px 0; min-height: 44px; display: inline-block; }
.nav a:hover, .nav a[aria-current="page"] { color: var(--text); }
.site-foot { border-top: 1px solid var(--rule); margin-top: 64px; padding: 24px 0 40px; color: var(--muted); font-size: 13px; }
.site-foot nav { display: flex; flex-wrap: wrap; gap: 4px 20px; margin-bottom: 12px; }
.site-foot nav a { color: var(--text); padding: 12px 0; min-height: 44px; display: inline-block; }
.site-foot p { margin: 6px 0; max-width: 80ch; }

/* type */
h1 { font: 600 1.6rem/1.2 var(--mono); margin: 28px 0 8px; letter-spacing: -.01em; }
h2 { font: 600 1.25rem/1.25 var(--mono); margin: 40px 0 10px; }
h3 { font: 600 1rem/1.3 var(--mono); margin: 28px 0 8px; }
.lede { color: var(--muted); margin: 0 0 20px; max-width: 75ch; }
.prose { font: 400 1.1rem/1.6 var(--serif); max-width: 68ch; }
.prose h2, .prose h3 { font-family: var(--mono); }
.prose p, .prose li { margin: 0 0 1em; }
.prose code, code, kbd { font-family: var(--mono); font-size: .88em; background: var(--panel); padding: 1px 5px; border-radius: var(--radius); }
.prose table, table.data { border-collapse: collapse; font: 400 13px/1.4 var(--mono); width: 100%; margin: 12px 0 20px; }
table.data th, table.data td, .prose th, .prose td { border-bottom: 1px solid var(--rule); padding: 8px 10px 8px 0; text-align: left; vertical-align: top; }
.tablewrap { overflow-x: auto; }
.cite { color: var(--muted); font: 400 12px/1.4 var(--mono); }
.badge { display: inline-block; font-size: 11px; padding: 1px 6px; border: 1px solid var(--rule); border-radius: var(--radius); color: var(--muted); }
.caller { color: var(--caller); } .answer { color: var(--answer); } .linec { color: var(--line); }

/* controls */
.btn { font: 600 14px/1 var(--mono); min-height: 44px; padding: 0 16px; border-radius: var(--radius); border: 1px solid var(--rule); background: var(--panel); color: var(--text); cursor: pointer; display: inline-flex; align-items: center; gap: 8px; text-decoration: none; }
.btn:hover { filter: brightness(1.15); }
.btn:active { transform: translateY(1px); }
.btn[disabled] { opacity: .45; cursor: not-allowed; }
.btn.primary { background: var(--caller); color: var(--on-accent); border-color: var(--caller); }
.btn.big { min-height: 56px; font-size: 17px; padding: 0 28px; }
.btn.hang { background: var(--warn); border-color: var(--warn); color: var(--bg); }
.btn svg { width: 16px; height: 16px; }
label.f { display: grid; gap: 4px; font-size: 12px; color: var(--muted); }
select, input[type="text"], input[type="number"], input[type="tel"] { font: 400 14px var(--mono); min-height: 44px; padding: 0 10px; background: var(--panel2); color: var(--text); border: 1px solid var(--rule); border-radius: var(--radius); width: 100%; }
input[type="range"] { accent-color: var(--caller); width: 100%; min-height: 44px; }
.check { display: inline-flex; align-items: center; gap: 8px; min-height: 44px; font-size: 13px; color: var(--muted); cursor: pointer; }
.check input { width: 18px; height: 18px; accent-color: var(--caller); }

/* tool */
.tool { background: var(--panel); border: 1px solid var(--rule); border-radius: var(--radius); padding: 16px; margin: 16px 0 8px; }
.tool-top { display: grid; grid-template-columns: auto 1fr; gap: 16px; align-items: end; }
.tool-fields { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 12px; }
.chips { display: flex; flex-wrap: wrap; gap: 8px; margin: 14px 0 4px; }
.chip { font: 400 13px/1 var(--mono); min-height: 44px; padding: 0 12px; border: 1px solid var(--rule); border-radius: var(--radius); background: transparent; color: var(--text); cursor: pointer; }
.chip[aria-pressed="true"] { border-color: var(--caller); color: var(--caller); }
.status { display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; font-size: 13px; color: var(--muted); margin: 12px 0 6px; min-height: 20px; }
.status .result { color: var(--text); font-weight: 600; }
.status .result.bad { color: var(--warn); }
.notice { font-size: 12px; color: var(--answer); margin: 6px 0 0; }

.spec-panel { position: relative; background: var(--bg); border: 1px solid var(--rule); border-radius: var(--radius); overflow-x: auto; overflow-y: hidden; -webkit-overflow-scrolling: touch; touch-action: pan-x; }
.spec-inner { position: relative; }
.spec-panel canvas { display: block; max-width: none; }
canvas.spec { cursor: crosshair; }
.spec-empty { position: absolute; inset: 0; display: grid; place-items: center; color: var(--muted); font-size: 13px; pointer-events: none; text-align: center; padding: 16px; }
.tip { position: fixed; z-index: 20; max-width: 340px; background: var(--panel2); border: 1px solid var(--rule); border-radius: var(--radius); padding: 10px 12px; font-size: 12px; line-height: 1.45; pointer-events: none; box-shadow: 0 6px 24px rgba(0,0,0,.35); }
.tip b { display: block; margin-bottom: 4px; }
.tip .cite { margin-top: 6px; }
.legend { display: flex; flex-wrap: wrap; gap: 16px; font-size: 12px; color: var(--muted); margin: 8px 0 0; }
.legend i { display: inline-block; width: 10px; height: 10px; margin-right: 6px; vertical-align: -1px; }

.transport { display: flex; flex-wrap: wrap; gap: 8px 12px; align-items: center; margin: 12px 0 0; }
.transport .speed { display: flex; align-items: center; gap: 8px; font-size: 12px; color: var(--muted); min-width: 220px; }
.transport .speed input { width: 140px; }
.captions { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin: 12px 0 0; }
.cap { border-left: 3px solid var(--rule); padding: 8px 12px; min-height: 76px; background: var(--panel2); }
.cap.c { border-color: var(--caller); } .cap.a { border-color: var(--answer); } .cap.l { border-color: var(--line); }
.cap .who { font-size: 0.8125rem; color: var(--muted); }
.cap .lab { font-weight: 600; margin: 2px 0 4px; }
.cap .exp { font-size: 13px; color: var(--muted); }
.cap .nerd { font-size: 11px; color: var(--muted); word-break: break-all; margin-top: 6px; display: none; }
.show-nerd .cap .nerd { display: block; }
@media (prefers-reduced-motion: no-preference) { .cap .lab, .cap .exp { transition: opacity .15s; } }

.console { margin: 14px 0 0; border: 1px solid var(--rule); border-radius: var(--radius); }
.console summary { cursor: pointer; padding: 12px; font-size: 13px; min-height: 44px; }
.console .log { height: 160px; overflow-y: auto; padding: 8px 12px; font-size: 13px; background: var(--bg); white-space: pre-wrap; border-top: 1px solid var(--rule); }
.console .log .in { color: var(--caller); } .console .log .out { color: var(--text); } .console .log .err { color: var(--warn); }
.console form { display: flex; gap: 8px; padding: 8px; border-top: 1px solid var(--rule); }
.console input { flex: 1; text-transform: uppercase; }

.share-row { display: flex; flex-wrap: wrap; gap: 8px; margin: 12px 0 0; }
.share-row input { flex: 1 1 260px; }

.events { margin: 12px 0 0; font-size: 12px; }
.events summary { cursor: pointer; min-height: 44px; padding: 12px 0; }
.events ol { padding-left: 0; list-style: none; max-height: 280px; overflow: auto; margin: 0; }
.events li { padding: 6px 0; border-bottom: 1px solid var(--rule); display: grid; grid-template-columns: 110px 80px 1fr; gap: 8px; }
.events ol.two li { grid-template-columns: 130px 1fr; }
.events button { all: unset; cursor: pointer; color: var(--text); }
.events button:focus-visible { outline: 2px solid var(--caller); }

.mini { display: inline-flex; gap: 8px; align-items: center; margin: 4px 0 12px; }
.sit-table .mob { display: none; color: var(--muted); font-size: 0.8125rem; }
.grid2 { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 12px; }
.card { background: var(--panel); border: 1px solid var(--rule); border-radius: var(--radius); padding: 14px; }
.card h3 { margin-top: 0; }

/* embed */
body.embed { background: var(--panel); }
body.embed .tool { margin: 0; border: 0; padding: 10px; }
body.embed .credit { font-size: 11px; color: var(--muted); padding: 0 10px 8px; }

@media (max-width: 760px) {
  .sit-table .seg { display: none; }
  .sit-table .mob { display: block; }
  .tool-top { grid-template-columns: 1fr; }
  .tool-fields { grid-template-columns: 1fr 1fr; }
  .captions { grid-template-columns: 1fr; }
  .events li { grid-template-columns: 80px 1fr; }
  .events li .p { display: none; }
  .events ol.two li { grid-template-columns: 1fr; }
  .events ol.two li .p { display: block; }
  h1 { font-size: 1.35rem; }
}
@media (prefers-reduced-motion: reduce) { * { scroll-behavior: auto !important; transition: none !important; } }

/* long-scroll walkthrough (/handshake-explained/) */
.walk-head { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 16px; margin: 20px 0 10px; }
.walk-head .chips { margin: 0; }
.walk-now { font-size: 12px; color: var(--muted); min-height: 18px; }
.walk-legend { margin: 6px 0 24px; }
.spec-mark { position: absolute; top: 0; background: var(--text); opacity: .10; pointer-events: none; transition: left .25s ease, width .25s ease; }
.step { margin: 40px 0 8px; padding-left: 0; transition: box-shadow .2s ease, padding .2s ease; }
.step.now { box-shadow: inset 3px 0 0 var(--caller); padding-left: 14px; }
.step-n { display: inline-block; min-width: 1.6em; color: var(--muted); font-weight: 400; }
.step-figure { margin: 12px 0 20px; }
.step-figure figcaption { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 14px; margin-top: 8px; }
.aside { font: 400 13px/1.5 var(--mono); color: var(--muted); border-left: 2px solid var(--rule); padding: 2px 0 2px 12px; }
.aside b { color: var(--text); font-weight: 600; }
.aside .mini { display: inline-flex; margin-left: 4px; }
@media (prefers-reduced-motion: reduce) { .spec-mark, .step { transition: none; } }
.step-figure .spec-panel { min-height: 260px; }
.walk-overview { min-height: 128px; }