@font-face{font-family:"Newsreader";src:url(fonts/newsreader.woff2) format("woff2");font-weight:400 500;font-style:normal;font-display:swap}
@font-face{font-family:"Newsreader";src:url(fonts/newsreader-italic.woff2) format("woff2");font-weight:400;font-style:italic;font-display:swap}
@font-face{font-family:"Plex Mono";src:url(fonts/plex-mono-400.woff2) format("woff2");font-weight:400;font-display:swap}
@font-face{font-family:"VT323";src:url(fonts/vt323.woff2) format("woff2");font-weight:400;font-display:block}

/* the sixteen BGI colours */
:root{
  --black:#000;--blue:#0000aa;--green:#00aa00;--cyan:#00aaaa;--red:#aa0000;--magenta:#aa00aa;--brown:#aa5500;--lightgray:#aaaaaa;
  --darkgray:#555;--lightblue:#5555ff;--lightgreen:#55ff55;--lightcyan:#55ffff;--lightred:#ff5555;--lightmagenta:#ff55ff;--yellow:#ffff55;--white:#fff;
  --paper:#f1ede3;--ink:#161513;--soft:#5d5850;--rule:#d8d1c2;
  --dos:"VT323",ui-monospace,Menlo,monospace;--serif:"Newsreader",Georgia,serif;--mono:"Plex Mono",ui-monospace,Menlo,monospace;
}
*{box-sizing:border-box}
html{background:var(--blue);-webkit-text-size-adjust:100%}
body{margin:0;background:var(--paper);color:var(--ink);font:400 20px/1.62 var(--serif);-webkit-font-smoothing:antialiased}
code{font:400 .8em/1 var(--mono);background:rgba(0,0,170,.07);padding:.1em .3em;border-radius:2px;color:#00007a}
a{color:var(--blue)}
button{font:inherit;color:inherit}

/* ============ the IDE ============ */
.ide{height:100svh;min-height:520px;display:flex;flex-direction:column;background:var(--blue);color:var(--white);font:400 clamp(15px,2.3vw,24px)/1 var(--dos);overflow:hidden;user-select:none}
.ide-menu,.ide-status{display:flex;gap:1.2em;padding:.18em .6em;background:var(--lightgray);color:var(--black);white-space:nowrap;overflow:hidden}
.ide-menu b,.ide-status b{font-weight:400;color:var(--red)}
.ide-menu .sys{color:var(--black)}
.ide-desk{position:relative;flex:1;padding:.5em .6em;background:var(--blue) repeating-conic-gradient(#0a0a9e 0 25%,var(--blue) 0 50%) 0 0/4px 4px}
.ide-win{position:absolute;inset:.5em .6em .5em .6em;border:.28em double var(--white);background:var(--blue);display:flex;flex-direction:column}
.ide-title{position:absolute;top:-.62em;left:0;right:0;display:flex;justify-content:space-between;padding:0 .6em;line-height:1}
.ide-title span{background:var(--blue);padding:0 .3em}
.ide-title .close b{color:var(--lightgreen);font-weight:400}
.ide-title .name{color:var(--white)}
.ide-code{margin:0;flex:1;padding:.7em 1.4em .7em .6em;color:var(--yellow);font:inherit;line-height:1.08;white-space:pre;overflow:hidden}
.ide-code .cur{display:inline-block;width:.55em;height:.95em;vertical-align:-.12em;background:var(--yellow);animation:blink 1s steps(1) infinite}
.ide-scroll{position:absolute;right:-.28em;top:.4em;bottom:1.3em;width:.7em;display:flex;flex-direction:column;align-items:center;background:var(--cyan);color:var(--blue);line-height:1}
.ide-scroll i{flex:1;width:100%;background:repeating-linear-gradient(var(--cyan) 0 2px,#1bb 2px 4px)}
.ide-pos{position:absolute;left:1.2em;bottom:-.6em;line-height:1}
.ide-pos span{background:var(--blue);padding:0 .3em}
@keyframes blink{50%{opacity:0}}
.ide-dialog{position:absolute;left:50%;top:50%;width:min(92%,26em);transform:translate(-50%,-50%) scale(.96);background:var(--lightgray);color:var(--black);border:.28em double var(--white);padding:1.1em 1.2em .9em;box-shadow:1.1em 1em 0 rgba(0,0,0,.72);opacity:0;visibility:hidden;transition:opacity .25s steps(3),transform .25s steps(3)}
.ide-dialog.on{opacity:1;visibility:visible;transform:translate(-50%,-50%)}
.dlg-title{position:absolute;top:-.62em;left:50%;transform:translateX(-50%);background:var(--lightgray);padding:0 .4em;color:var(--white)}
.dlg-body{margin:0;display:grid;gap:.2em}
.dlg-body div{display:grid;grid-template-columns:9em 1fr auto;gap:.4em}
.dlg-body .gap{margin-top:.6em}
.dlg-body dt{margin:0}.dlg-body dd{margin:0;color:var(--black)}
.dlg-ok{margin:1em 0 0;padding:.35em;text-align:center;background:var(--green);color:var(--white)}
.dlg-ok a{color:var(--yellow);text-decoration:none}
.blink{animation:blink 1.2s steps(1) infinite}

/* ============ article ============ */
main{padding:0 22px 40px}
.opener,.chapter,.trick{max-width:680px;margin:0 auto}
.opener{padding:clamp(70px,12vh,130px) 0 40px}
.kicker{margin:0 0 18px;font:400 22px/1 var(--dos);letter-spacing:.08em;text-transform:uppercase;color:var(--blue)}
.kicker::before{content:"■ ";color:var(--red)}
h1{margin:0;font:500 clamp(56px,11vw,112px)/.92 var(--serif);letter-spacing:-.035em}
h1 em{font-style:italic;font-weight:400;color:var(--blue)}
.deck{margin:26px 0 18px;font:400 clamp(22px,2.6vw,28px)/1.36 var(--serif);color:#2b2925}
.byline{margin:0;font:400 21px/1 var(--dos);letter-spacing:.06em;text-transform:uppercase;color:var(--soft)}
.crt{margin:52px -8px 0;padding:18px 18px 0;background:#23211d;border-radius:18px 18px 8px 8px;box-shadow:0 30px 60px -30px rgba(0,0,0,.6),inset 0 0 0 2px #3a3731}
.crt img{display:block;width:100%;height:auto;image-rendering:pixelated;border-radius:8px/10px;box-shadow:0 0 0 1px #000}
.crt figcaption{padding:14px 4px 16px;font:400 15px/1.45 var(--serif);font-style:italic;color:#b9b2a4}
.chapter{padding:70px 0 10px}
.num{margin:0 0 6px}
.num span{display:inline-block;padding:.12em .45em;background:var(--blue);color:var(--yellow);font:400 22px/1 var(--dos)}
h2{margin:0 0 22px;font:500 clamp(36px,5.4vw,52px)/1.04 var(--serif);letter-spacing:-.02em}
.chapter p,.trick p{margin:0 0 18px}
.lead{font-size:1.18em;line-height:1.45}

.turn{font-style:italic;font-size:1.25em;color:var(--blue)}
.palette{display:grid;grid-template-columns:repeat(8,1fr);gap:0;margin:26px 0 8px;border:3px solid var(--ink)}
.palette button{aspect-ratio:1;border:0;padding:0;cursor:pointer;outline-offset:-4px}
.palette button:focus-visible,.palette button[aria-pressed=true]{outline:3px solid var(--yellow);box-shadow:inset 0 0 0 6px var(--ink)}
.palette-name{margin:0 0 22px!important;font:400 22px/1 var(--dos);color:var(--soft);letter-spacing:.06em}
.prims{list-style:none;margin:0 0 22px;padding:0;display:flex;flex-wrap:wrap;gap:8px}
.prims code{display:inline-block;padding:.4em .6em;font-size:15px;background:var(--ink);color:var(--yellow);border-radius:0}

/* the machine */
.machine{margin:34px -8px 10px}
.screen{position:relative;aspect-ratio:4/3;background:#000;border:14px solid #23211d;border-radius:16px;box-shadow:0 30px 60px -30px rgba(0,0,0,.6),inset 0 0 0 2px #3a3731;overflow:hidden}
.screen iframe{position:absolute;left:0;top:0;width:640px;height:480px;border:0;transform-origin:0 0;background:#000}
.boot{position:absolute;inset:0;border:0;background:var(--blue) repeating-conic-gradient(#0a0a9e 0 25%,var(--blue) 0 50%) 0 0/4px 4px;cursor:pointer;display:grid;place-items:center;font:400 clamp(18px,3.4vw,26px)/1 var(--dos);color:var(--black)}
.boot-box{position:relative;display:grid;gap:.5em;min-width:12em;padding:1.2em 1.4em 1em;background:var(--lightgray);border:.22em double var(--white);box-shadow:.8em .7em 0 rgba(0,0,0,.7);text-align:center}
.boot-title{position:absolute;top:-.6em;left:50%;transform:translateX(-50%);background:var(--lightgray);padding:0 .4em;color:var(--white)}
.boot-line{font-size:1.4em}
.boot-key{padding:.3em .6em;background:var(--green);color:var(--white)}.boot-key b{font-weight:400;color:var(--yellow)}
.boot:hover .boot-key{background:#0b0}
.machine-cap{margin:14px 8px 0!important;font:italic 400 16px/1.45 var(--serif);color:var(--soft)}

/* code windows, Turbo C++ style */
.tc{position:relative;margin:26px 0 30px;padding:22px 18px 16px;background:var(--blue);border:5px double var(--white);outline:3px solid var(--blue);box-shadow:12px 12px 0 rgba(0,0,0,.18)}
.tc figcaption{position:absolute;top:-.72em;left:50%;transform:translateX(-50%);padding:0 .5em;background:var(--blue);color:var(--white);font:400 20px/1 var(--dos);white-space:nowrap}
.tc pre{margin:0;color:var(--yellow);font:400 clamp(16px,2.2vw,20px)/1.12 var(--dos);white-space:pre;overflow-x:auto;-webkit-overflow-scrolling:touch}

/* tricks */
.trick{padding:46px 0 6px;border-top:1px solid var(--rule);margin-top:40px}
.q{font:italic 400 clamp(28px,3.8vw,38px)/1.15 var(--serif)!important;color:var(--blue);margin-bottom:20px!important}
.q code{font-style:normal}
.demo{margin:26px 0 8px;padding:18px;background:#000;border:3px solid var(--ink);text-align:center}
.demo canvas{display:block;margin:0 auto;width:100%;max-width:480px;height:auto;image-rendering:pixelated;touch-action:none;cursor:crosshair}
.demo-cap{margin:12px 0 0!important;font:400 21px/1.2 var(--dos);color:var(--lightgray);letter-spacing:.03em}
.demo-cap button,.seg button{margin:2px;padding:.3em .8em;background:var(--lightgray);color:var(--black);border:0;box-shadow:inset -2px -2px 0 var(--darkgray),inset 2px 2px 0 var(--white);cursor:pointer;font:400 20px/1 var(--dos)}
.demo-cap button:active,.seg button[aria-pressed=true]{box-shadow:inset 2px 2px 0 var(--darkgray),inset -2px -2px 0 var(--white);background:#9a9a9a}
.seg button[aria-pressed=true]{background:var(--yellow)}
.demo-cap label{display:inline-flex;align-items:center;gap:8px;margin-left:10px}
.demo-cap input{accent-color:#ffff55}
.readout{color:var(--yellow)!important}

/* DOS directory */
.dos{margin:26px -8px 0;padding:18px 20px;background:#000;color:var(--lightgray);font:400 clamp(18px,2.4vw,22px)/1.1 var(--dos);border:3px solid var(--ink)}
.dos pre{margin:0;font:inherit;white-space:pre}
.dos-list{display:grid;grid-template-columns:repeat(auto-fill,minmax(15.5em,1fr));column-gap:1.5em}
.dos-list button{display:grid;grid-template-columns:5.5em 3.5em 1fr;text-align:left;background:none;border:0;padding:.08em .2em;color:var(--lightgray);cursor:pointer;font:inherit;white-space:pre}
.dos-list button .sz{text-align:right}
.dos-list button.has{color:var(--white)}
.dos-list button.has .n::after{content:"";}
.dos-list button:hover,.dos-list button:focus-visible,.dos-list button[aria-pressed=true]{background:var(--lightgray);color:var(--black);outline:none}
.dos-list button.has:hover .n,.dos-list button.has[aria-pressed=true] .n{color:var(--blue)}
.dos-foot{margin-top:.8em!important}
.dos-foot .cur{display:inline-block;width:.5em;height:.9em;background:var(--lightgray);vertical-align:-.1em;animation:blink 1s steps(1) infinite}
.viewer{position:relative;margin:26px -8px 26px;padding:24px 16px 12px;background:var(--blue);border:5px double var(--white);outline:3px solid var(--blue);box-shadow:12px 12px 0 rgba(0,0,0,.18)}
.viewer-title{position:absolute;top:-.72em;left:0;right:0;display:flex;justify-content:space-between;padding:0 1em;font:400 20px/1 var(--dos);color:var(--white)}
.viewer-title span{background:var(--blue);padding:0 .3em}
.viewer-title button{background:none;border:0;padding:0;color:var(--lightgreen);cursor:pointer;font:inherit}
.viewer-body img{display:block;width:100%;height:auto;image-rendering:pixelated}
.viewer-body pre{margin:0;max-height:26em;overflow:auto;color:var(--yellow);font:400 clamp(16px,2.2vw,20px)/1.12 var(--dos);white-space:pre}
.viewer-note{margin:10px 0 0!important;font:400 19px/1.2 var(--dos);color:var(--lightcyan)}

/* gallery */
.wide{max-width:980px}
.wide>p,.wide>h2,.wide>.num{max-width:680px;margin-left:auto;margin-right:auto}
.gallery{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:26px;margin-top:30px}
.gallery figure{margin:0}
.gallery img{display:block;width:100%;height:auto;image-rendering:pixelated;border:3px solid var(--ink);background:#000}
.gallery figcaption{margin-top:8px;font:italic 400 16px/1.4 var(--serif);color:var(--soft)}
.gallery figcaption b{font:normal 400 19px/1 var(--dos);color:var(--blue);margin-right:6px}

.coda{padding-top:60px}
.coda p{font-size:1.1em}
.end{color:var(--blue)}
.credit{margin-top:40px!important;font:italic 400 15px/1.5 var(--serif)!important;color:var(--soft)}
.home{font:400 21px/1 var(--dos)!important;margin-top:24px!important}
.home a{text-decoration:none}

@media (max-width:640px){
  body{font-size:18.5px}
  .ide-menu span:nth-child(n+7){display:none}
  .ide-status span:nth-child(n+5){display:none}
  .dlg-body div{grid-template-columns:7.5em 1fr auto}
  .gallery{grid-template-columns:1fr}
  .dos-list{grid-template-columns:1fr}
  .crt{padding:10px 10px 0;border-radius:12px 12px 6px 6px}
  .screen{border-width:8px}
}
@media (prefers-reduced-motion:reduce){.ide-code .cur,.blink,.dos-foot .cur{animation:none}}
.ide{cursor:pointer}