/* SPDX-License-Identifier: AGPL-3.0-only */
/* The fonts: see fonts/README.md. */
@font-face { font-family: "Forum"; font-style: normal; font-weight: 400; font-display: swap; src: url(fonts/forum-400-cyrillic.woff2) format("woff2"); unicode-range: U+0301, U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116; }
@font-face { font-family: "Forum"; font-style: normal; font-weight: 400; font-display: swap; src: url(fonts/forum-400-latin-ext.woff2) format("woff2"); unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C4, U+2113, U+2C60-2C7F, U+A720-A7FF; }
@font-face { font-family: "Forum"; font-style: normal; font-weight: 400; font-display: swap; src: url(fonts/forum-400-latin.woff2) format("woff2"); unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD; }
@font-face { font-family: "IBM Plex Mono"; font-style: normal; font-weight: 400; font-display: swap; src: url(fonts/ibm-plex-mono-400-cyrillic.woff2) format("woff2"); unicode-range: U+0301, U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116; }
@font-face { font-family: "IBM Plex Mono"; font-style: normal; font-weight: 400; font-display: swap; src: url(fonts/ibm-plex-mono-400-latin-ext.woff2) format("woff2"); unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C4, U+2113, U+2C60-2C7F, U+A720-A7FF; }
@font-face { font-family: "IBM Plex Mono"; font-style: normal; font-weight: 400; font-display: swap; src: url(fonts/ibm-plex-mono-400-latin.woff2) format("woff2"); unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD; }
@font-face { font-family: "IBM Plex Mono"; font-style: normal; font-weight: 500; font-display: swap; src: url(fonts/ibm-plex-mono-500-cyrillic.woff2) format("woff2"); unicode-range: U+0301, U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116; }
@font-face { font-family: "IBM Plex Mono"; font-style: normal; font-weight: 500; font-display: swap; src: url(fonts/ibm-plex-mono-500-latin-ext.woff2) format("woff2"); unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C4, U+2113, U+2C60-2C7F, U+A720-A7FF; }
@font-face { font-family: "IBM Plex Mono"; font-style: normal; font-weight: 500; font-display: swap; src: url(fonts/ibm-plex-mono-500-latin.woff2) format("woff2"); unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD; }
@font-face { font-family: "Jost"; font-style: normal; font-weight: 400; font-display: swap; src: url(fonts/jost-400-cyrillic.woff2) format("woff2"); unicode-range: U+0301, U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116; }
@font-face { font-family: "Jost"; font-style: normal; font-weight: 400; font-display: swap; src: url(fonts/jost-400-latin-ext.woff2) format("woff2"); unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C4, U+2113, U+2C60-2C7F, U+A720-A7FF; }
@font-face { font-family: "Jost"; font-style: normal; font-weight: 400; font-display: swap; src: url(fonts/jost-400-latin.woff2) format("woff2"); unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD; }
@font-face { font-family: "Jost"; font-style: normal; font-weight: 500; font-display: swap; src: url(fonts/jost-400-cyrillic.woff2) format("woff2"); unicode-range: U+0301, U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116; }
@font-face { font-family: "Jost"; font-style: normal; font-weight: 500; font-display: swap; src: url(fonts/jost-400-latin-ext.woff2) format("woff2"); unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C4, U+2113, U+2C60-2C7F, U+A720-A7FF; }
@font-face { font-family: "Jost"; font-style: normal; font-weight: 500; font-display: swap; src: url(fonts/jost-400-latin.woff2) format("woff2"); unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD; }
@font-face { font-family: "Jost"; font-style: normal; font-weight: 600; font-display: swap; src: url(fonts/jost-400-cyrillic.woff2) format("woff2"); unicode-range: U+0301, U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116; }
@font-face { font-family: "Jost"; font-style: normal; font-weight: 600; font-display: swap; src: url(fonts/jost-400-latin-ext.woff2) format("woff2"); unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C4, U+2113, U+2C60-2C7F, U+A720-A7FF; }
@font-face { font-family: "Jost"; font-style: normal; font-weight: 600; font-display: swap; src: url(fonts/jost-400-latin.woff2) format("woff2"); unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD; }
@font-face { font-family: "Caveat"; font-style: normal; font-weight: 600; font-display: swap; src: url(fonts/caveat-600-cyrillic.woff2) format("woff2"); unicode-range: U+0301, U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116; }
@font-face { font-family: "Caveat"; font-style: normal; font-weight: 600; font-display: swap; src: url(fonts/caveat-600-latin-ext.woff2) format("woff2"); unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C4, U+2113, U+2C60-2C7F, U+A720-A7FF; }
@font-face { font-family: "Caveat"; font-style: normal; font-weight: 600; font-display: swap; src: url(fonts/caveat-600-latin.woff2) format("woff2"); unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD; }

/* Art deco: gold lines and glass panes on wool felt, like the cloth of a
   billiard table; the pictures and the tables are chalk on school boards
   in polished wooden frames. Every colour is a token, and the components
   take them from the tokens. The dark theme is the default; the light one
   follows the system, or the reader's choice in the header (site.js sets
   data-theme on <html>). */

:root {
  --f-display: "Forum", "Didot", Georgia, serif;
  --f-body: "Jost", "Futura", system-ui, -apple-system, "Segoe UI", Roboto, "Noto Sans", "Noto Sans Arabic", "Noto Sans Hebrew", "Noto Sans Devanagari", "PingFang SC", "Microsoft YaHei", sans-serif;
  --f-mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --f-hand: "Caveat", "Segoe Print", "Bradley Hand", cursive;
  --bg: #0B1A20;
  --felt: url(felt.jpg);
  --glow: rgba(60, 110, 120, .16);
  --vignette: rgba(0, 0, 0, .45);
  --raised: rgba(241, 234, 216, .045);
  --menu: #0C1E25;
  --text: #F1EAD8;
  --dim: #A8B9B9;
  --accent: #D8B46A;
  --on-accent: #1A1206;
  --line: rgba(216, 180, 106, .32);
  --grid: rgba(216, 180, 106, .07);
  --code: #0F252D;
  --shadow: 0 18px 40px -20px rgba(0, 0, 0, .8);
  --gold: linear-gradient(180deg, #F6DC9C, #D2A552 55%, #B4863A);
  --gold-text: linear-gradient(180deg, #F6DC9C, #C99A45 60%, #F1D48A);
  /* The board: black slate, a faint grid, and chalk in white and yellow,
     in a frame of old walnut. */
  --wood-h: url(wood-h.jpg);
  --wood-v: url(wood-v.jpg);
  --frame-shadow: 0 28px 46px -22px rgba(0, 0, 0, .95), 0 4px 10px rgba(0, 0, 0, .55);
  --slate: #141514;
  --slate-grid: rgba(255, 255, 255, .045);
  --slate-shadow: inset 0 3px 6px rgba(0, 0, 0, .8), inset 0 0 0 1px rgba(0, 0, 0, .7);
  --chalk: #F2F0EA;
  --chalk-words: #ECE9E1;
  --chalk-yellow: #EFD38E;
  --chalk-rule: rgba(242, 240, 234, .45);
  --chalk-strong: rgba(242, 240, 234, .85);
  --chalk-faint: rgba(242, 240, 234, .6);
  color-scheme: dark;
}

/* The light theme: sand-coloured cloth, pale oak frames, and boards of
   light grey slate written on in graphite and red-brown chalk. */
@media (prefers-color-scheme: light) {
  :root:not([data-theme="dark"]) {
    --bg: #DCD3C1;
    --felt: url(felt-light.jpg);
    --glow: rgba(255, 252, 240, .55);
    --vignette: rgba(110, 85, 45, .2);
    --raised: rgba(255, 251, 242, .5);
    --menu: #EFE8DA;
    --text: #2A251E;
    --dim: #574F43;
    --accent: #6E4D10;
    --on-accent: #1A1206;
    --line: rgba(110, 77, 16, .32);
    --grid: rgba(110, 77, 16, .08);
    --code: #ECE4D4;
    --shadow: 0 18px 40px -22px rgba(70, 50, 20, .45);
    --gold-text: linear-gradient(180deg, #A67A26, #7D5814 60%, #9C7022);
    --wood-h: url(oak-h.jpg);
    --wood-v: url(oak-v.jpg);
    --frame-shadow: 0 24px 40px -22px rgba(70, 50, 20, .55), 0 3px 8px rgba(70, 50, 20, .25);
    --slate: #ECE8DF;
    --slate-grid: rgba(60, 52, 40, .07);
    --slate-shadow: inset 0 2px 5px rgba(70, 50, 20, .25), inset 0 0 0 1px rgba(70, 50, 20, .2);
    --chalk: #3A3530;
    --chalk-words: #3A3530;
    --chalk-yellow: #94491A;
    --chalk-rule: rgba(58, 53, 48, .4);
    --chalk-strong: rgba(58, 53, 48, .75);
    --chalk-faint: rgba(58, 53, 48, .5);
    color-scheme: light;
  }
}
:root[data-theme="light"] {
  --bg: #DCD3C1;
  --felt: url(felt-light.jpg);
  --glow: rgba(255, 252, 240, .55);
  --vignette: rgba(110, 85, 45, .2);
  --raised: rgba(255, 251, 242, .5);
  --menu: #EFE8DA;
  --text: #2A251E;
  --dim: #574F43;
  --accent: #6E4D10;
  --on-accent: #1A1206;
  --line: rgba(110, 77, 16, .32);
  --grid: rgba(110, 77, 16, .08);
  --code: #ECE4D4;
  --shadow: 0 18px 40px -22px rgba(70, 50, 20, .45);
  --gold-text: linear-gradient(180deg, #A67A26, #7D5814 60%, #9C7022);
  --wood-h: url(oak-h.jpg);
  --wood-v: url(oak-v.jpg);
  --frame-shadow: 0 24px 40px -22px rgba(70, 50, 20, .55), 0 3px 8px rgba(70, 50, 20, .25);
  --slate: #ECE8DF;
  --slate-grid: rgba(60, 52, 40, .07);
  --slate-shadow: inset 0 2px 5px rgba(70, 50, 20, .25), inset 0 0 0 1px rgba(70, 50, 20, .2);
  --chalk: #3A3530;
  --chalk-words: #3A3530;
  --chalk-yellow: #94491A;
  --chalk-rule: rgba(58, 53, 48, .4);
  --chalk-strong: rgba(58, 53, 48, .75);
  --chalk-faint: rgba(58, 53, 48, .5);
  color-scheme: light;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-padding-top: 80px; }
/* The felt: a tile of wool under a soft light from above that falls off
   towards the edges. */
body {
  margin: 0;
  color: var(--text);
  font: 17px/1.6 var(--f-body);
  overflow-x: clip;
  background-color: var(--bg);
  background-image: radial-gradient(60rem 40rem at 50% 8%, var(--glow), transparent 70%), radial-gradient(120% 90% at 50% 40%, transparent 55%, var(--vignette)), var(--felt);
  background-size: auto, auto, 256px 256px;
}
a { color: var(--accent); text-underline-offset: 3px; }
code, pre { font-family: var(--f-mono); font-size: .88em; }
code { background: var(--code); padding: .1em .4em; border-radius: 5px; direction: ltr; unicode-bidi: isolate; white-space: nowrap; display: inline-block; max-width: 100%; overflow-x: auto; vertical-align: bottom; }
pre { background: var(--code); padding: 12px 14px; border-radius: 8px; overflow-x: auto; direction: ltr; text-align: left; white-space: pre; }
pre code { background: none; padding: 0; white-space: pre; display: block; max-width: none; overflow: visible; } /* keeps the lines of a command */
/* A command is shown whole: a long one wraps on the screen, and is still
   one line when copied. */
.card pre, .card pre code { white-space: pre-wrap; overflow-wrap: anywhere; }
pre { position: relative; }
pre:has(.copy) { padding-inline-end: 84px; }
.copy { position: absolute; top: 8px; inset-inline-end: 8px; min-height: 32px; padding: 4px 10px; font: 500 12px/1 var(--f-mono); letter-spacing: .1em; text-transform: uppercase; color: var(--accent); background: transparent; border: 1px solid var(--line); border-radius: 6px; cursor: pointer; }
.copy:hover { border-color: var(--accent); }
h1, h2, h3 { font-family: var(--f-display); line-height: 1.1; text-wrap: balance; font-weight: 400; text-transform: uppercase; letter-spacing: .05em; }
h1 { font-size: clamp(34px, 4.4vw, 60px); margin: 0 0 20px; letter-spacing: .04em; }
h2 { font-size: clamp(28px, 3.2vw, 38px); margin: 88px 0 18px; text-align: center; color: var(--accent); }
h2::after { content: ""; display: block; width: 120px; height: 7px; margin: 16px auto 0; border-block: 1px solid var(--accent); }
h3 { font-size: 20px; margin: 0 0 8px; }

.wrap { max-width: 1160px; margin: 0 auto; padding-inline: max(20px, env(safe-area-inset-left, 0px)) max(20px, env(safe-area-inset-right, 0px)); }
.dim { color: var(--dim); }
.lead { font-size: clamp(18px, 1.7vw, 20px); color: var(--dim); }
/* No word left alone on the last line of centred text: it is balanced
   across its lines. Text set to the left fills each line as usual. */
/* In the narrow columns of the cards long words break with a hyphen, so
   no line ends far short of the edge. */
.card p, .card li, .steps li { hyphens: auto; -webkit-hyphens: auto; hyphenate-limit-chars: 10 4 4; }
.lead, .intro, .final p, .hero .platforms, .facts span, .steps.boards li { text-wrap: balance; }
[hidden] { display: none !important; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; }
.sprites { position: absolute; width: 0; height: 0; overflow: hidden; }

/* The header. */
.top { position: sticky; top: 0; z-index: 10; background: color-mix(in srgb, var(--bg) 82%, transparent); border-bottom: 1px solid var(--line); -webkit-backdrop-filter: blur(14px); backdrop-filter: blur(14px); }
.bar { display: flex; align-items: center; gap: 14px; min-height: 66px; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--text); text-decoration: none; font: 400 20px/1 var(--f-display); text-transform: uppercase; letter-spacing: .12em; }
.brand img { display: block; }
nav { display: flex; gap: 4px; margin-inline-start: auto; }
nav a { color: var(--dim); text-decoration: none; font-weight: 500; padding: 8px 12px; border-radius: 8px; white-space: nowrap; text-transform: uppercase; letter-spacing: .14em; font-size: 13.5px; }
nav a:hover { color: var(--text); }
nav a[aria-current] { color: var(--accent); }

.langs { position: relative; }
.langs summary {
  display: flex; align-items: center; gap: 8px; min-height: 44px; padding: 4px 12px; cursor: pointer; list-style: none;
  font: 500 14px/1 var(--f-mono); color: var(--text); background: transparent; border: 1px solid var(--line); border-radius: 8px;
}
.langs summary::-webkit-details-marker { display: none; }
.globe { width: 18px; height: 18px; fill: none; stroke: currentColor; stroke-width: 1.6; color: var(--dim); }
.langs ul {
  position: absolute; inset-inline-end: 0; top: calc(100% + 8px); margin: 0; padding: 6px; list-style: none; min-width: 190px; z-index: 20;
  background: var(--menu); border: 1px solid var(--line); border-radius: 10px; box-shadow: var(--shadow);
}
.langs li a { display: block; padding: 10px 12px; border-radius: 6px; color: var(--text); text-decoration: none; }
.langs li a:hover { background: var(--grid); }
.langs li a[aria-current] { color: var(--accent); font-weight: 600; }

/* The theme button: it shows the theme chosen now, and each press moves to
   the next of "as the system", light and dark. site.js shows it. */
.theme { display: grid; place-items: center; width: 44px; height: 44px; padding: 0; color: var(--dim); background: transparent; border: 1px solid var(--line); border-radius: 8px; cursor: pointer; }
.theme[hidden] { display: none; }
.theme:hover { color: var(--text); }
.theme svg { width: 20px; height: 20px; fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; }
.theme .t-auto path { fill: currentColor; }
.theme g { display: none; }
.theme[data-choice="auto"] .t-auto, .theme[data-choice="light"] .t-light, .theme[data-choice="dark"] .t-dark { display: inline; }
/* The icon in the header: the light one on a light page. */
.brand .on-light { display: none; }
:root[data-theme="light"] .brand .on-light { display: block; }
:root[data-theme="light"] .brand .on-dark { display: none; }
@media (prefers-color-scheme: light) {
  :root:not([data-theme="dark"]) .brand .on-light { display: block; }
  :root:not([data-theme="dark"]) .brand .on-dark { display: none; }
}

/* A school board: black slate with a faint grid, in a frame of old,
   well-kept walnut whose four rails meet in mitred corners; a rounded,
   waxed moulding catches the light from the upper left. */
.frame { --f: 26px; position: relative; padding: var(--f); border-radius: 4px; box-shadow: var(--frame-shadow); }
.rail { position: absolute; display: block; background-repeat: repeat; }
.rail::after { content: ""; position: absolute; inset: 0; }
.rail.t, .rail.b { left: 0; right: 0; height: var(--f); background-image: var(--wood-h); background-size: auto 150px; }
.rail.l, .rail.r { top: 0; bottom: 0; width: var(--f); background-image: var(--wood-v); background-size: 150px auto; }
.rail.t { top: 0; clip-path: polygon(0 0, 100% 0, calc(100% - var(--f)) 100%, var(--f) 100%); background-position: -120px -20px; }
.rail.b { bottom: 0; clip-path: polygon(var(--f) 0, calc(100% - var(--f)) 0, 100% 100%, 0 100%); background-position: -640px -70px; }
.rail.l { left: 0; clip-path: polygon(0 0, 100% var(--f), 100% calc(100% - var(--f)), 0 100%); background-position: -40px -300px; }
.rail.r { right: 0; clip-path: polygon(0 var(--f), 100% 0, 100% 100%, 0 calc(100% - var(--f))); background-position: -90px -900px; }
.rail.t::after { background: linear-gradient(180deg, rgba(0, 0, 0, .35), rgba(255, 226, 180, .32) 22%, rgba(255, 226, 180, .1) 45%, rgba(0, 0, 0, .15) 75%, rgba(0, 0, 0, .55)); }
.rail.b::after { background: linear-gradient(180deg, rgba(0, 0, 0, .55), rgba(255, 226, 180, .22) 25%, rgba(255, 226, 180, .06) 50%, rgba(0, 0, 0, .25) 80%, rgba(0, 0, 0, .6)); }
.rail.l::after { background: linear-gradient(90deg, rgba(0, 0, 0, .3), rgba(255, 226, 180, .28) 22%, rgba(255, 226, 180, .08) 45%, rgba(0, 0, 0, .18) 75%, rgba(0, 0, 0, .55)); }
.rail.r::after { background: linear-gradient(90deg, rgba(0, 0, 0, .55), rgba(255, 226, 180, .16) 25%, rgba(0, 0, 0, .05) 50%, rgba(0, 0, 0, .3) 80%, rgba(0, 0, 0, .65)); }
.surface {
  position: relative; background-color: var(--slate);
  background-image: linear-gradient(var(--slate-grid) 1px, transparent 1px), linear-gradient(90deg, var(--slate-grid) 1px, transparent 1px);
  background-size: 28px 28px; background-position: -1px -1px;
  box-shadow: var(--slate-shadow);
}
.surface > svg { display: block; width: 100%; height: auto; }

/* Chalk: solid lines with a hand's wobble (drawn by chalk.js), a soft edge
   and a little dust (the filters in layout.html). */
.chalk { filter: url(#chalk); }
.chalk .w, .chalk .y { fill: none; stroke-width: 3.2; stroke-linecap: round; stroke-linejoin: round; }
.chalk .w { stroke: var(--chalk); }
.chalk .y { stroke: var(--chalk-yellow); }
.words { filter: url(#chalk-words); }
.words text { font: 600 25px var(--f-hand); fill: var(--chalk-words); letter-spacing: .02em; }
.words text.y { fill: var(--chalk-yellow); }
.words text.long { font-size: 20px; }
.words text.longer { font-size: 17px; }

/* A table written in chalk: the words by hand, the rules drawn with a
   chalk line. */
.board-table .surface { padding: 22px 26px 26px; overflow-x: auto; }
.chalk-table { width: 100%; border-collapse: collapse; filter: url(#chalk-words); font: 600 24px/1.25 var(--f-hand); color: var(--chalk-words); }
.chalk-table th, .chalk-table td { padding: 12px 16px; text-align: start; vertical-align: middle; }
.chalk-table thead th { color: var(--chalk-yellow); border-bottom: 2.5px solid var(--chalk-strong); font-weight: 600; }
.chalk-table tbody tr + tr > * { border-top: 2px solid var(--chalk-rule); }
.chalk-table tr > * + * { border-inline-start: 2px solid var(--chalk-rule); }
.chalk-table thead td { border: 0; }
.chalk-table tbody th { font-size: 26px; font-weight: 600; }
.compare td, .compare thead th { text-align: center; }
.chalk-table td.one { text-align: center; } /* a cell of one word */
.compare tr.us th { color: var(--chalk-yellow); }
.mark { display: inline-block; width: 30px; height: 30px; vertical-align: middle; fill: none; stroke-width: 3.4; stroke-linecap: round; stroke-linejoin: round; }
.mark.yes { stroke: var(--chalk-yellow); }
.mark.no { stroke: var(--chalk-faint); }

/* The hero: the title, then the board with the picture. */
.hero { padding: 48px 0 24px; text-align: center; }
.hero h1 { font-size: clamp(36px, 5vw, 64px); }
.hero h1 span { background: var(--gold-text); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero .lead { margin: 0 auto; font-size: clamp(17px, 1.6vw, 20px); line-height: 1.65; }
.hero-board { max-width: 880px; margin: 34px auto 0; }
.platforms { color: var(--dim); font: 500 13px/1.4 var(--f-mono); letter-spacing: .22em; text-transform: uppercase; margin: 26px 0 0; }
.hero .actions { justify-content: center; }

/* Buttons. */
.actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 30px; }
.button {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px; min-height: 50px; padding: 10px 24px;
  text-decoration: none; color: var(--accent); border: 1px solid var(--accent); background: transparent;
  text-transform: uppercase; letter-spacing: .14em; font-weight: 500; font-size: 15px;
}
.button.accent {
  color: var(--on-accent); border: 0; background: var(--gold); padding-inline: 32px;
  clip-path: polygon(12px 0, calc(100% - 12px) 0, 100% 50%, calc(100% - 12px) 100%, 12px 100%, 0 50%);
}
.button.go::after { content: "→"; display: inline-block; }
[dir="rtl"] .button.go::after { content: "←"; }
.button:focus-visible, a:focus-visible, summary:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }

.skip { position: absolute; inset-inline-start: 16px; top: -100px; z-index: 30; }
.skip:focus { top: 8px; background: var(--menu); padding: 10px 14px; border-radius: 8px; }

/* Raised surfaces: glass panes with cut corners and a gold bar. */
.card, .facts div, .note, .steps li {
  background: var(--raised); border: 1px solid var(--line); position: relative;
  -webkit-backdrop-filter: blur(8px); backdrop-filter: blur(8px);
  clip-path: polygon(14px 0, calc(100% - 14px) 0, 100% 14px, 100% 100%, 0 100%, 0 14px);
}
.card::before, .facts div::before {
  content: ""; position: absolute; left: 50%; top: 0; width: 44px; height: 2px; margin-left: -22px; background: var(--accent);
}

.facts { display: grid; gap: 14px; grid-template-columns: repeat(4, 1fr); margin-top: 22px; }
.facts div { padding: 24px 20px 18px; display: grid; justify-items: center; text-align: center; }
.facts .ico { width: 34px; height: 34px; margin-bottom: 8px; fill: none; stroke: var(--accent); stroke-width: 1.7; stroke-linecap: round; stroke-linejoin: round; overflow: visible; }
.facts strong { display: block; font: 400 18px/1.25 var(--f-display); text-transform: uppercase; letter-spacing: .06em; color: var(--accent); }
.facts span { color: var(--dim); font-size: 14.5px; line-height: 1.35; }

.faq details { border-bottom: 1px solid var(--line); }
.faq summary { cursor: pointer; padding: 16px 20px; font-weight: 600; min-height: 44px; list-style: none; display: flex; justify-content: space-between; gap: 16px; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; color: var(--accent); font: 400 24px/1 var(--f-mono); transition: transform .2s; }
.faq details[open] summary::after { transform: rotate(45deg); }
.faq details p { margin: 0; padding: 0 20px 18px; color: var(--dim); }

/* The closing call: a gold-framed pane. */
.final { margin-top: 88px; text-align: center; padding: 12px 36px 40px; border: 1px solid var(--accent); background: var(--raised); outline: 1px solid var(--line); outline-offset: 6px; }
.final h2 { margin-top: 28px; }
.final h2::after { display: none; }
.final .actions { justify-content: center; }

.oops { text-align: center; padding-bottom: 40px; }
.oops .actions { justify-content: center; }
.oops .code { font: 400 96px/1 var(--f-display); color: var(--accent); margin: 32px 0 8px; }

.dock { display: none; }

.cards { display: grid; gap: 16px; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
/* Four cards are four in a row or two by two, and the cards of the
   download page, which hold commands, two by two: never three and one. */
.cards.four { grid-template-columns: repeat(4, 1fr); }
.cards.pairs { grid-template-columns: repeat(2, 1fr); }
/* The computers of the download page: the two with commands across the
   whole width, so each command shows whole, then two small ones side by
   side. */
.cards.computers { grid-template-columns: repeat(2, 1fr); }
.cards.computers > :nth-child(-n + 2) { grid-column: 1 / -1; }
@media (max-width: 960px) { .cards.computers { grid-template-columns: 1fr; } }
@media (max-width: 960px) { .cards.four, .facts { grid-template-columns: repeat(2, 1fr); } }
.cards.two { grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); }
.card { padding: 24px; min-width: 0; }
.card p { margin: 0 0 10px; color: var(--dim); }
.card h3 + p { margin-top: 4px; }
.card ul { padding-inline-start: 20px; margin: 12px 0 0; }
.card li { margin-bottom: 8px; }
.card li::marker { color: var(--accent); }
.badge {
  display: inline-block; font: 500 12px/1 var(--f-mono); letter-spacing: .2em; text-transform: uppercase; color: var(--on-accent);
  background: linear-gradient(180deg, #F6DC9C, #C99A45); padding: 7px 12px; margin: 0 0 12px;
}
.card .badge { margin: 0 0 12px; color: var(--on-accent); }
/* The two groups share their rows, so both boards hang at the same height
   whether or not a card carries a badge. */
.groups { grid-template-columns: 1fr 1fr; }
.groups .card { display: grid; grid-row: span 3; grid-template-rows: subgrid; row-gap: 0; align-content: start; }
.groups .card header { align-self: end; }
.groups .frame { --f: 16px; margin: 16px 0 22px; }
.note { border-inline-start: 3px solid var(--accent); padding: 16px 20px; margin-top: 20px; }

.steps { padding: 0; list-style: none; counter-reset: step; display: grid; gap: 14px; }
.steps li { counter-increment: step; position: relative; padding: 18px 20px 18px 70px; }
[dir="rtl"] .steps li { padding: 18px 70px 18px 20px; }
.steps li::before {
  content: counter(step); position: absolute; inset-inline-start: 18px; top: 13px; width: 40px; height: 40px;
  display: grid; place-items: center; font: 400 18px/1 var(--f-display); color: var(--on-accent);
  background: var(--gold); clip-path: polygon(50% 0, 100% 50%, 50% 100%, 0 50%);
}
/* The steps with a small board each: three in a row, one under another on
   a phone. */
.steps.boards { grid-template-columns: repeat(3, 1fr); gap: 16px; }
.steps.boards li { padding: 18px 20px 20px; text-align: center; }
.steps.boards li::before { position: static; margin: 0 auto 12px; }
[dir="rtl"] .steps.boards li { padding: 18px 20px 20px; }
.steps.boards .frame { --f: 12px; margin: 0 0 14px; }
.steps.boards strong { display: block; margin-bottom: 4px; }
@media (max-width: 860px) { .steps.boards { grid-template-columns: 1fr; } }
/* A mark between yes and no, with what it means in a note under the table. */
.mark.part { stroke: var(--chalk-faint); }
.board-table .sources { margin: 12px 4px 0; font: 15px/1.5 var(--f-body); color: var(--dim); }
.chalk-table sup { font-size: .6em; color: var(--chalk-yellow); }
/* The download page: the reader's own system first, marked. */
.pick { justify-content: center; }
.card.mine { border-color: var(--accent); outline: 1px solid var(--line); outline-offset: 4px; }
.card .mine-badge { display: none; }
.card.mine .mine-badge { display: inline-block; }

/* A page's title, its lead and its closing block are centred with the
   headings, and the text under them spans the width. */
.page { padding-top: 48px; }
.page ul { padding-inline-start: 22px; }
.page > h1, .page > .lead, .page > .lead + .dim { text-align: center; margin-inline: auto; }

.foot { margin-top: 96px; padding: 32px 0 44px; border-top: 1px solid var(--line); color: var(--dim); font-size: 15px; }
.foot a { color: var(--dim); }

@media (max-width: 760px) {
  .frame, .groups .frame { --f: 12px; }
  .groups { grid-template-columns: 1fr; }
  .groups .card { grid-row: auto; grid-template-rows: none; }
  .chalk .w, .chalk .y { stroke-width: 4.2; }
  .board-table .surface { padding: 10px; }
  .chalk-table { font-size: 18px; }
  .chalk-table thead th { font-size: 16px; hyphens: auto; }
  .chalk-table tbody th { font-size: 18px; }
  .chalk-table th, .chalk-table td { padding: 7px 5px; }
  .compare td { padding: 7px 2px; }
  .mark { width: 22px; height: 22px; }
  /* The servers' table is a list on a phone: each server with its three
     answers under it. */
  .servers thead { display: none; }
  .servers tr, .servers th, .servers td { display: block; }
  .servers tbody tr + tr { border-top: 2px solid var(--chalk-rule); }
  .chalk-table.servers tbody tr + tr > *, .chalk-table.servers tr > * + * { border: 0; }
  .servers tbody th { padding-top: 12px; color: var(--chalk-yellow); font-size: 22px; }
  .servers td, .servers td.one { padding: 2px 5px 8px; text-align: start; }
  .servers td::before { content: attr(data-label); display: block; font-size: 15px; color: var(--dim); }
}

/* Phones: one column, the menu in a row of its own that scrolls sideways,
   the languages in a sheet from the bottom, and the download button
   docked at the bottom. */
@media (max-width: 640px) {
  body { font-size: 16px; padding-bottom: 84px; }
  .wrap { padding-inline: max(16px, env(safe-area-inset-left, 0px)) max(16px, env(safe-area-inset-right, 0px)); }
  .bar { flex-wrap: wrap; gap: 8px 10px; min-height: 56px; padding-top: 6px; }
  .brand { font-size: 15px; gap: 8px; letter-spacing: .06em; }
  .brand img { width: 28px; height: 28px; }
  .lname { position: absolute; width: 1px; height: 1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; }
  nav { order: 3; margin: 0 -16px; padding: 0 12px 8px; gap: 2px; overflow-x: auto; scrollbar-width: none; width: calc(100% + 32px); }
  nav::-webkit-scrollbar { display: none; }
  nav a { padding: 6px 10px; font-size: 13px; }
  /* A blurred header would hold the fixed sheet inside itself, so here it
     is opaque instead. */
  .top { -webkit-backdrop-filter: none; backdrop-filter: none; background: var(--bg); }
  .langs { margin-inline-start: auto; }
  .langs summary { min-height: 40px; padding: 4px 10px; }
  .langs ul { position: fixed; inset: auto 12px calc(12px + env(safe-area-inset-bottom)); top: auto; border-radius: 14px; padding: 8px; display: grid; grid-template-columns: 1fr 1fr; gap: 2px; }
  .langs li a { padding: 14px; text-align: center; }
  /* A tap outside the sheet closes it: the dimmed page is the summary. */
  .langs[open] summary::after { content: ""; position: fixed; inset: 0; z-index: 15; background: rgba(0, 0, 0, .4); cursor: default; }
  .dock {
    display: block; position: fixed; inset-inline: 10px; bottom: calc(10px + env(safe-area-inset-bottom)); z-index: 9; margin: 0; padding: 8px;
    background: color-mix(in srgb, var(--bg) 70%, transparent); border: 1px solid var(--line); -webkit-backdrop-filter: blur(16px); backdrop-filter: blur(16px);
  }
  .dock .button { width: 100%; }
  .hero { padding-top: 32px; }
  .hero .actions .accent { display: none; }
  .hero .actions .button { flex: 1; }
  .facts, .cards.four, .cards.pairs, .cards.two { grid-template-columns: 1fr; }
  .facts { grid-template-columns: 1fr 1fr; }
  .facts div { padding: 16px; }
  .card { padding: 20px; }
  h2 { margin-top: 60px; }
  .final { padding: 6px 18px 28px; }
  .steps li { padding: 16px 16px 16px 62px; }
  [dir="rtl"] .steps li { padding: 16px 62px 16px 16px; }
  .steps li::before { inset-inline-start: 14px; }
}

/* Motion: short, and none for those who ask for less. */
@media (prefers-reduced-motion: no-preference) {
  .hero .wrap > * { animation: rise .7s cubic-bezier(.2, .7, .2, 1) both; }
  .hero .lead { animation-delay: .08s; }
  .hero-board { animation-delay: .16s; }
  .hero .platforms { animation-delay: .24s; }
  .hero .actions { animation-delay: .3s; }
  .card, .facts div, .steps li { transition: transform .3s cubic-bezier(.2, .7, .2, 1); }
  .card:hover, .facts div:hover, .steps li:hover { transform: translateY(-3px); }
  .button { transition: filter .2s, transform .2s; }
  .button:hover { filter: brightness(1.07); transform: translateY(-1px); }
  .button.go::after { transition: transform .2s ease-out; }
  .button.go:hover::after { transform: translateX(4px); }
  [dir="rtl"] .button.go:hover::after { transform: translateX(-4px); }
  /* The hero's chalk is drawn in: the devices, then the key, then the
     line that joins them, then the words. */
  .hero-board .chalk path { stroke-dasharray: 1; animation: draw 1.4s cubic-bezier(.4, .1, .3, 1) .3s both; }
  .hero-board .chalk .y { animation-delay: .9s; }
  .hero-board .chalk .link { animation-delay: 1.6s; animation-duration: .8s; }
  .hero-board .words { animation: chalk-in .6s ease-out 2.1s both; }
  @supports (animation-timeline: view()) {
    .reveal { animation: rise linear both; animation-timeline: view(); animation-range: entry 0% entry 35%; }
  }
}
@keyframes draw { from { stroke-dashoffset: 1; } to { stroke-dashoffset: 0; } }
@keyframes chalk-in { from { opacity: 0; } to { opacity: 1; } }
@keyframes rise { from { opacity: 0; transform: translateY(16px); } to { opacity: 1; transform: none; } }

.soon { min-height: 100vh; display: flex; flex-direction: column; justify-content: center; align-items: center; text-align: center; padding-block: 40px; }
.soon img { display: block; }
.soon h1 { margin-top: 20px; }
.soon p { margin: 6px 0; }

/* Paper: the text in black on white, the boards kept, nothing to press. */
@media print {
  :root { --bg: #FFF; --felt: none; --glow: transparent; --vignette: transparent; --raised: transparent; --text: #000; --dim: #333; --accent: #6B4A10; --line: #999; --code: #F2F2F2; }
  body { background: #FFF; padding: 0; }
  .top, .skip, .dock, .theme, .actions, .foot { display: none; }
  .card, .facts div, .note, .steps li { -webkit-backdrop-filter: none; backdrop-filter: none; break-inside: avoid; }
  .frame { box-shadow: none; break-inside: avoid; print-color-adjust: exact; -webkit-print-color-adjust: exact; }
  .reveal, .hero .wrap > * { animation: none; }
  h2 { margin-top: 36px; }
  a[href^="http"]::after { content: " (" attr(href) ")"; font-size: .8em; color: var(--dim); word-break: break-all; }
}