/* Shared by lab/week04/index.html (student worksheet) and guide.html (instructor guide). */
:root{
  --ground:#F2F0EB;
  --card:#FBFAF7;
  --sunk:#E9E6DF;
  --ink:#1C1B18;
  --ink-soft:#5B5952;
  --rule:#D5D1C7;
  --rule-soft:#E4E0D8;
  --acc:#2A5A86;
  --acc-wash:#DEE8F2;
  --ok:#1D7443;
  --ok-wash:#D5EDDC;
  --bad:#AE3B25;
  --bad-wash:#F6E0DA;
  --z-work:#855C00;
  --z-stage:#2F4F96;
  --z-local:#1D7443;
  --z-remote:#6A4596;
  --cls:#2F4F96;
  --qty:#855C00;
  --anc:#A14A34;
  --sel:#C9DAEC;
  --rx:#9C3A62;
  --code-bg:#24272D;
  --code-ink:#F2F0EB;
  --code-soft:#A8ADB6;
  --code-hover:#353941;
  --code-ok:#7FD6A1;
  --code-wash:#E3E6EC;
  --code-edge:#CBD0D9;
  --code-text:#23304A;

  --font-body:"Noto Sans TC","PingFang TC","Microsoft JhengHei",system-ui,sans-serif;
  --font-mono:"Fira Code",ui-monospace,"SFMono-Regular",Menlo,Consolas,monospace;

  --t-small:.875rem;
  --t-body:1rem;
  --t-h3:1.125rem;
  --t-h2:clamp(1.6rem,4.4vw,1.95rem);
  --t-h1:clamp(1.953rem,6vw,2.441rem);

  --s1:4px; --s2:8px; --s3:12px; --s4:16px; --s5:24px; --s6:40px; --s7:64px; --s8:96px;
  --radius:6px;
  --ease-out:cubic-bezier(.16,1,.3,1);
  --z-sticky:100;
  color-scheme:light;
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --ground:#16171A;
    --card:#1F2024;
    --sunk:#121316;
    --ink:#E8E6E1;
    --ink-soft:#A3A09A;
    --rule:#45474D;
    --rule-soft:#2A2B30;
    --acc:#8DB4DA;
    --acc-wash:#1E2A36;
    --ok:#74D29A;
    --ok-wash:#173322;
    --bad:#FF8E72;
    --bad-wash:#3A211B;
    --z-work:#E0B764;
    --z-stage:#98B2EC;
    --z-local:#74D29A;
    --z-remote:#C6A8EC;
    --cls:#98B2EC;
    --qty:#E0B764;
    --anc:#EF9A80;
    --sel:#2C4560;
    --rx:#F09BBE;
    --code-bg:#0B0C0F;
    --code-ink:#ECEAE5;
    --code-soft:#9A9FA8;
    --code-hover:#23262C;
    --code-ok:#74D29A;
    --code-wash:#262B35;
    --code-edge:#3A4150;
    --code-text:#D6DEEE;
    color-scheme:dark;
  }
}
:root[data-theme="dark"]{
  --ground:#16171A;
  --card:#1F2024;
  --sunk:#121316;
  --ink:#E8E6E1;
  --ink-soft:#A3A09A;
  --rule:#45474D;
  --rule-soft:#2A2B30;
  --acc:#8DB4DA;
  --acc-wash:#1E2A36;
  --ok:#74D29A;
  --ok-wash:#173322;
  --bad:#FF8E72;
  --bad-wash:#3A211B;
  --z-work:#E0B764;
  --z-stage:#98B2EC;
  --z-local:#74D29A;
  --z-remote:#C6A8EC;
  --cls:#98B2EC;
  --qty:#E0B764;
  --anc:#EF9A80;
  --sel:#2C4560;
  --rx:#F09BBE;
    --code-bg:#0B0C0F;
  --code-ink:#ECEAE5;
  --code-soft:#9A9FA8;
  --code-hover:#23262C;
  --code-ok:#74D29A;
  --code-wash:#262B35;
  --code-edge:#3A4150;
  --code-text:#D6DEEE;
  color-scheme:dark;
}

*{box-sizing:border-box}
html,body{overflow-x:clip}
html{scroll-padding-top:88px}
body{
  margin:0;background:var(--ground);color:var(--ink);
  font-family:var(--font-body);font-size:var(--t-body);line-height:1.75;
  -webkit-font-smoothing:antialiased;text-underline-offset:.22em;
}
::selection{background:var(--sel);color:var(--ink)}
:focus-visible{outline:2px solid var(--acc);outline-offset:2px;border-radius:3px}
a{color:var(--acc);text-decoration-thickness:1px}
a:hover{text-decoration-thickness:2px}
@media (min-width:64rem){body{font-size:1.0625rem}}
code,kbd,pre,.mono{font-family:var(--font-mono);font-variant-ligatures:none}
p code,li code,td code,dd code,summary code,figcaption code,span code{
  font-size:.9em;font-weight:500;color:var(--code-text);background:var(--code-wash);
  border:1px solid var(--code-edge);border-radius:4px;padding:0 5px;
  overflow-wrap:anywhere;
}
kbd{
  font-size:.85em;border:1px solid var(--rule);border-bottom-width:2px;border-radius:4px;
  padding:0 6px;background:var(--card);
}

.wrap{
  max-width:72rem;margin:0 auto;
  padding-block:var(--s6) var(--s8);padding-inline:clamp(1rem,4vw,1.5rem);
  display:flex;flex-direction:column;gap:var(--s7);
}

/* ── the page is wide for widgets and tables; running text keeps a readable measure ── */
.wrap p,.wrap ol,.wrap ul,.wrap details,.wrap .cmds,.wrap h1,.wrap h2,.wrap h3,.wrap .meta{max-width:56rem}
.wrap .widget p,.wrap .widget ol,.wrap .tablewrap p{max-width:none}

/* ── headings and prose ── */
h1{font-size:var(--t-h1);line-height:1.25;margin:0;font-weight:700;letter-spacing:-.01em;text-wrap:balance}
h2{font-size:var(--t-h2);line-height:1.35;margin:0;font-weight:700;text-wrap:balance}
h3{font-size:var(--t-h3);line-height:1.4;margin:0;font-weight:700}
h4{font-size:var(--t-body);line-height:1.5;margin:0;font-weight:700}
p{margin:0}
.lede{font-size:var(--t-h3);line-height:1.6;color:var(--ink-soft);max-width:30em}
.soft{color:var(--ink-soft)}
.small{font-size:var(--t-small);line-height:1.6}
section{display:flex;flex-direction:column;gap:var(--s5)}
.block{display:flex;flex-direction:column;gap:var(--s3)}
.head{display:flex;flex-direction:column;gap:var(--s1)}
.meta{
  display:flex;flex-wrap:wrap;gap:var(--s1) var(--s4);
  font-size:var(--t-small);color:var(--ink-soft);font-variant-numeric:tabular-nums;
}
.meta b{color:var(--ink);font-weight:700}
ol,ul{margin:0;padding-left:1.4em;display:flex;flex-direction:column;gap:var(--s2)}
li::marker{color:var(--ink-soft);font-variant-numeric:tabular-nums}

/* ── commands ── */
.cmds{display:flex;flex-direction:column;gap:var(--s2)}
.cmd{
  display:grid;grid-template-columns:minmax(0,1fr) auto;align-items:center;gap:var(--s2);
  background:var(--code-bg);border:1px solid var(--code-bg);border-radius:var(--radius);
  padding:var(--s1) var(--s1) var(--s1) var(--s4);min-height:48px;
}
.cmd code{font-size:.95rem;font-weight:500;color:var(--code-ink);white-space:pre-wrap;overflow-wrap:anywhere;min-width:0}
.cmd .why{grid-column:1/-1;font-size:var(--t-small);color:var(--code-soft);padding:0 0 var(--s2);margin-top:calc(-1 * var(--s1))}
.cmd ::selection{background:#4A6A92;color:#fff}
.copy{
  font:inherit;font-size:var(--t-small);color:var(--ink-soft);background:transparent;
  border:1px solid transparent;border-radius:4px;min-height:44px;min-width:64px;padding:0 var(--s3);
  cursor:pointer;transition:color .15s,background-color .15s;
}
.cmd .copy{
  display:inline-flex;align-items:center;gap:6px;align-self:center;min-height:40px;
  color:var(--code-ink);border-color:color-mix(in srgb,var(--code-soft) 55%,transparent);background:color-mix(in srgb,var(--code-ink) 6%,transparent);
}
.cmd .copy::before{
  content:"";width:14px;height:14px;flex:none;background:currentColor;
  -webkit-mask:var(--copy-ico) center/contain no-repeat;mask:var(--copy-ico) center/contain no-repeat;
}
:root{--copy-ico:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='black' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Crect x='9' y='9' width='12' height='12' rx='2'/%3E%3Cpath d='M5 15H4a1 1 0 0 1-1-1V4a1 1 0 0 1 1-1h10a1 1 0 0 1 1 1v1'/%3E%3C/svg%3E")}
@media (hover:hover){.copy:hover{color:var(--acc);background:var(--acc-wash)}.cmd .copy:hover{color:var(--code-ink);background:var(--code-hover)}}
.copy[data-done],.cmd .copy[data-done]{color:var(--code-ok)}
.cmd .copy:focus-visible{outline-color:var(--code-ink)}
pre.out{
  margin:0;background:var(--sunk);border-radius:var(--radius);
  padding:var(--s3) var(--s4);font-size:.86rem;line-height:1.6;
  white-space:pre-wrap;overflow-wrap:anywhere;color:var(--ink);
}

/* ── tables ── */
.tablewrap{overflow-x:auto;border:1px solid var(--rule);border-radius:var(--radius);background:var(--card)}
table{border-collapse:collapse;width:100%;font-size:.95rem}
th,td{text-align:left;vertical-align:top;padding:var(--s3) var(--s4);border-bottom:1px solid var(--rule-soft)}
tr:last-child td{border-bottom:none}
th{font-size:var(--t-small);font-weight:700;color:var(--ink-soft);background:var(--ground);white-space:nowrap}
td code{white-space:nowrap}
td.n{font-variant-numeric:tabular-nums;color:var(--ink-soft);width:1%;white-space:nowrap}

/* ── hints and folded answers ── */
details{border-top:1px solid var(--rule-soft)}
details:last-of-type{border-bottom:1px solid var(--rule-soft)}
summary{
  cursor:pointer;list-style:none;display:flex;align-items:center;gap:var(--s2);
  min-height:44px;padding:var(--s2) 0;color:var(--acc);
}
summary::-webkit-details-marker{display:none}
summary::before{
  content:"";flex:none;width:8px;height:8px;border-right:2px solid currentColor;border-bottom:2px solid currentColor;
  transform:rotate(-45deg);transition:transform .2s var(--ease-out);margin-right:4px;
}
details[open]>summary::before{transform:rotate(45deg)}
details>.body{padding:0 0 var(--s4) 20px;display:flex;flex-direction:column;gap:var(--s3)}

/* ── sidebars: optional notes, always open ── */
.note{
  background:var(--card);border:1px solid var(--rule);border-radius:var(--radius);
  padding:var(--s3) var(--s4) var(--s4);display:flex;flex-direction:column;gap:var(--s2);
  font-size:.95rem;max-width:56rem;
}
.note-h{display:flex;align-items:center;gap:var(--s2);font-size:var(--t-small);line-height:1.4;color:var(--ink-soft);margin-bottom:2px}
.note-h span{font-weight:700;color:var(--acc);letter-spacing:.04em}
.note-h b{color:var(--ink);font-weight:700}
.note ul,.note ol{gap:var(--s1)}
.note .block{gap:var(--s2)}
.note.warn{border-color:color-mix(in srgb,var(--bad) 45%,var(--rule));background:var(--bad-wash)}
.note.warn .note-h span{color:var(--bad)}

/* ── scenarios, diffs and the branch figure ── */
.scen{margin:0;display:flex;flex-direction:column;gap:var(--s3);max-width:56rem}
.scen>div{display:grid;grid-template-columns:8.5em minmax(0,1fr);gap:var(--s3)}
.scen dt{font-weight:700}
.scen dd{margin:0}
@media (max-width:40rem){.scen>div{grid-template-columns:minmax(0,1fr);gap:0}}
figure.fig{margin:0;display:flex;flex-direction:column;gap:var(--s2);max-width:56rem}
figure.fig figcaption{font-size:var(--t-small);line-height:1.6;color:var(--ink-soft)}
pre.diff{
  margin:0;background:var(--card);border:1px solid var(--rule);border-radius:var(--radius);
  padding:var(--s3) 0;font-size:.86rem;line-height:1.7;overflow-x:auto;white-space:pre;
}
pre.diff span{display:block;padding:0 var(--s4)}
pre.diff .dh{color:var(--ink-soft);font-weight:500}
pre.diff .dk{color:var(--z-stage)}
pre.diff .dd{background:var(--bad-wash);color:var(--bad)}
pre.diff .da{background:var(--ok-wash);color:var(--ok)}
pre.diff del{text-decoration:none;background:var(--bad-wash);color:var(--bad)}
pre.diff.explain span[data-x]{cursor:help;transition:box-shadow .12s}
pre.diff.explain span[data-x]:hover,pre.diff.explain span.on{box-shadow:inset 3px 0 0 var(--acc);background-color:color-mix(in srgb,var(--acc) 10%,transparent)}
pre.diff.explain span.dd.on,pre.diff.explain span.dd:hover{background-color:color-mix(in srgb,var(--bad) 22%,var(--card))}
pre.diff.explain span.da.on,pre.diff.explain span.da:hover{background-color:color-mix(in srgb,var(--ok) 22%,var(--card))}
pre.diff.explain span[data-x]:focus-visible{outline:2px solid var(--acc);outline-offset:-2px}
.diff-lbl{margin:var(--s2) 0 0;font-size:var(--t-small);font-weight:700;color:var(--ink-soft)}
.diff-note{margin:0;min-height:3.4em;padding:var(--s3) var(--s4);border-radius:var(--radius);background:var(--acc-wash);color:var(--ink);font-size:.92rem}
pre.diff .ln{display:inline-block;width:2.4em;padding-right:.8em;vertical-align:top;white-space:pre;text-align:right;font-weight:400;color:var(--ink-soft);opacity:.8;user-select:none}
pre.diff .dd .ln,pre.diff .da .ln{color:inherit;opacity:.7}
pre.diff ins{text-decoration:none;background:var(--ok-wash);color:var(--ok)}
.figscroll{overflow-x:auto;background:var(--card);border:1px solid var(--rule);border-radius:var(--radius);padding:var(--s3)}
.branch-svg{display:block;width:100%;min-width:560px;height:auto;font-family:var(--font-mono);font-size:13px}
.branch-svg .l-main{stroke:var(--acc)}
.branch-svg .l-feat{stroke:var(--z-remote)}
.branch-svg .l-agent{stroke:var(--ink-soft)}
.branch-svg .c-main circle{fill:var(--acc)}
.branch-svg .c-feat circle{fill:var(--z-remote)}
.branch-svg .c-agent circle{fill:var(--card);stroke:var(--ink-soft);stroke-width:2.5}
.branch-svg .x-agent{stroke:var(--bad)}
.branch-svg text{fill:var(--ink)}
.branch-svg .t-main{fill:var(--acc);font-weight:500}
.branch-svg .t-feat{fill:var(--z-remote);font-weight:500}
.branch-svg .t-agent,.branch-svg .t-soft{fill:var(--ink-soft);font-family:var(--font-body)}
.branch-svg .tag rect{fill:var(--card);stroke:var(--z-work);stroke-width:1.5}
.branch-svg .tag text{fill:var(--z-work);font-weight:500}
.branch-svg .tag path{stroke:var(--z-work)}

/* ── light/dark toggle ── */
.theme{
  display:inline-grid;place-items:center;width:44px;height:44px;border-radius:var(--radius);
  border:1px solid var(--rule);background:var(--card);color:var(--ink);cursor:pointer;
  transition:border-color .15s,color .15s;
}
@media (hover:hover){.theme:hover{border-color:var(--acc);color:var(--acc)}}
.theme .i-moon{display:none}
.theme[aria-pressed="true"] .i-sun{display:none}
.theme[aria-pressed="true"] .i-moon{display:block}
.guide-top{display:flex;align-items:center;justify-content:space-between;gap:var(--s4)}

/* placeholders the reader replaces */
var{font-style:normal;color:var(--z-work);font-weight:700;border-bottom:1px dashed currentColor}
.cmd var{color:#F2C46B}

.note.has-art{display:grid;grid-template-columns:minmax(0,1fr) auto;column-gap:var(--s5);row-gap:var(--s2);align-content:start}
.note.has-art>*{grid-column:1}
.note.has-art>.note-h{grid-column:1 / -1}
.note.has-art>figure.tux{grid-column:2;grid-row:2 / span 3;align-self:start}
figure.tux{margin:0;width:88px;display:flex;flex-direction:column;align-items:center;gap:4px}
figure.tux img{width:72px;height:auto}
figure.tux figcaption{font-size:.72rem;line-height:1.35;color:var(--ink-soft);text-align:center}
.note .credit{font-size:.72rem;color:var(--ink-soft)}
@media (max-width:40rem){.note.has-art{grid-template-columns:minmax(0,1fr)}.note.has-art>figure.tux{grid-column:1;grid-row:auto;justify-self:center}}

.famtree{grid-column:1 / -1}
.fam-svg{display:block;width:100%;min-width:520px;height:auto;font-family:var(--font-body);font-size:13px}
.fam-svg .grp{fill:color-mix(in srgb,var(--z-local) 6%,transparent);stroke:var(--z-local);stroke-width:1.5;stroke-dasharray:6 5}
.fam-svg .grp-t{fill:var(--z-local);font-family:var(--font-mono);font-weight:700;font-size:15px}
.fam-svg .edges path{stroke:var(--ink-soft)}
.fam-svg .edges .dash{stroke-dasharray:5 5}
.fam-svg .edges .wsl{stroke:var(--acc)}
.fam-svg .n-unix rect{fill:var(--card);stroke:var(--z-local);stroke-width:1.8}
.fam-svg .n-win rect{fill:var(--card);stroke:var(--acc);stroke-width:1.8}
.fam-svg text{fill:var(--ink)}
.fam-svg .b{font-weight:700;font-size:15px}
.fam-svg .y{fill:var(--ink-soft);font-size:11.5px}
.fam-svg .lbl{fill:var(--ink-soft);font-size:11.5px}
.fam-svg .wsl-t{fill:var(--acc);font-weight:700;font-family:var(--font-mono)}

/* commit list figure */
.clog{list-style:none;margin:0;padding:var(--s3) var(--s4);display:flex;flex-direction:column;gap:0;
  background:var(--card);border:1px solid var(--rule);border-radius:var(--radius);max-width:56rem}
.clog li{position:relative;display:grid;grid-template-columns:18px 5.2em minmax(0,1fr) auto;column-gap:var(--s3);align-items:baseline;padding:8px 0}
.clog li::before{content:"";position:absolute;left:8px;top:0;bottom:0;width:2px;background:var(--z-local);opacity:.45}
.clog li:first-child::before{top:50%}
.clog li:last-child::before{bottom:50%}
.clog i{position:relative;z-index:1;align-self:center;width:14px;height:14px;border-radius:50%;background:var(--card);border:2.5px solid var(--z-local);margin-left:2px}
.clog li.head i{background:var(--z-local)}
.clog code{background:none;border:0;padding:0;color:var(--z-work);font-weight:500;font-size:.86rem}
.clog .m{font-weight:700;overflow-wrap:anywhere}
.clog .who{grid-column:3;font-size:var(--t-small);color:var(--ink-soft)}
.clog .ref{grid-column:4;grid-row:1;align-self:baseline;line-height:1.4;font-family:var(--font-mono);font-size:.72rem;font-weight:700;color:var(--card);background:var(--z-local);border-radius:999px;padding:2px 8px;white-space:nowrap}
@media (max-width:40rem){.clog li{grid-template-columns:18px minmax(0,1fr)}.clog code,.clog .m,.clog .who{grid-column:2}.clog .ref{grid-column:2;grid-row:auto;justify-self:start}}

/* repo statistics */
.stats{margin:0;display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:var(--s2);max-width:56rem}
.stats>div{background:var(--card);border:1px solid var(--rule);border-radius:var(--radius);padding:var(--s3) var(--s4);display:flex;flex-direction:column-reverse;gap:2px}
.stats dt{font-size:var(--t-small);color:var(--ink-soft)}
@media (max-width:40rem){.stats{grid-template-columns:repeat(2,minmax(0,1fr))}}
.stats dd{margin:0;font-size:1.35rem;font-weight:700;color:var(--sec,var(--ink));font-variant-numeric:tabular-nums}

/* click-to-enlarge screenshots */
figure.shot img[role="button"]{cursor:zoom-in}
.lightbox{position:fixed;inset:0;z-index:600;background:rgba(10,11,13,.86);display:flex;flex-direction:column;align-items:center;justify-content:center;gap:var(--s3);padding:max(16px,env(safe-area-inset-top,0px)) 16px max(16px,env(safe-area-inset-bottom,0px))}
.lightbox[hidden]{display:none}
.lb-frame{max-width:100%;max-height:calc(100% - 7rem);overflow:auto;display:flex;align-items:center;justify-content:center}
.lb-frame img{display:block;max-width:none;width:auto;height:auto;background:#fff;border-radius:4px;cursor:zoom-out}
@media (max-width:60rem){.lb-frame img{max-width:100%}}
.lb-cap{margin:0;max-width:60rem;color:#E8E6E1;font-size:.9rem;text-align:center}
.lb-x{position:absolute;top:max(12px,env(safe-area-inset-top,0px));right:12px;min-height:44px;padding:0 var(--s4);border-radius:var(--radius);border:1px solid rgba(255,255,255,.35);background:rgba(0,0,0,.4);color:#fff;font:inherit;cursor:pointer}
html.lb-open{overflow:hidden}

/* hands-on markers */
.tag-do,.tag-sim{
  display:inline-flex;align-items:center;gap:4px;vertical-align:.18em;margin-left:var(--s2);
  font-family:var(--font-body);font-size:.72rem;font-weight:700;line-height:1;letter-spacing:.02em;
  padding:4px 8px;border-radius:999px;white-space:nowrap;
}
.tag-do{background:var(--z-work);color:var(--card)}
.tag-sim{background:var(--acc-wash);color:var(--acc);box-shadow:inset 0 0 0 1px color-mix(in srgb,var(--acc) 40%,transparent)}
h2 .tag-do{font-size:.8rem;vertical-align:.3em}
.legend{display:flex;flex-direction:column;gap:6px;color:var(--ink-soft)}
.legend .item{display:flex;align-items:center;gap:var(--s2);flex-wrap:wrap}
.legend .tag-do,.legend .tag-sim{margin-left:0;min-width:6.2em;justify-content:center}

/* icons drawn once in CSS (masks take the text colour) */
.note-h::before,.tag-do::before,.tag-sim::before{content:"";flex:none;background:currentColor;-webkit-mask:var(--ico) center/contain no-repeat;mask:var(--ico) center/contain no-repeat}
.note-h::before{width:16px;height:16px;color:var(--acc);--ico:url("data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2216%22%20height%3D%2216%22%20viewBox%3D%220%200%2016%2016%22%20fill%3D%22none%22%20stroke%3D%22%23000%22%20stroke-width%3D%221.5%22%3E%3Ccircle%20cx%3D%228%22%20cy%3D%228%22%20r%3D%226.5%22/%3E%3Cpath%20d%3D%22M8%207v4.2M8%204.6v.2%22%20stroke-linecap%3D%22round%22/%3E%3C/svg%3E")}
.note.warn .note-h::before{color:var(--bad);--ico:url("data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2216%22%20height%3D%2216%22%20viewBox%3D%220%200%2016%2016%22%20fill%3D%22none%22%20stroke%3D%22%23000%22%20stroke-width%3D%221.5%22%20stroke-linejoin%3D%22round%22%3E%3Cpath%20d%3D%22M8%201.8%2015%2014H1z%22/%3E%3Cpath%20d%3D%22M8%206.2v3.6M8%2011.8v.2%22%20stroke-linecap%3D%22round%22/%3E%3C/svg%3E")}
.tag-do::before,.tag-sim::before{width:14px;height:14px}
.tag-do::before{--ico:url("data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2214%22%20height%3D%2214%22%20viewBox%3D%220%200%2016%2016%22%20fill%3D%22none%22%20stroke%3D%22%23000%22%20stroke-width%3D%221.5%22%20stroke-linecap%3D%22round%22%3E%3Crect%20x%3D%221.5%22%20y%3D%223.5%22%20width%3D%2213%22%20height%3D%229%22%20rx%3D%221.5%22/%3E%3Cpath%20d%3D%22M4%206.5h1M7%206.5h1M10%206.5h2M4%209.5h8%22/%3E%3C/svg%3E")}
.tag-sim::before{--ico:url("data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2214%22%20height%3D%2214%22%20viewBox%3D%220%200%2016%2016%22%20fill%3D%22none%22%20stroke%3D%22%23000%22%20stroke-width%3D%221.5%22%20stroke-linejoin%3D%22round%22%3E%3Cpath%20d%3D%22M4%202.5l8%205.5-3.6.9%202%203.8-1.5.8-2-3.8L4%2012z%22/%3E%3C/svg%3E")}

/* ── OS-specific content ── */
body[data-os="win"] [data-os="mac"],
body[data-os="mac"] [data-os="win"]{display:none}
.os-tag{
  font-size:var(--t-small);font-weight:700;color:var(--ink-soft);
}

/* ── checklists ── */
.check{list-style:none;padding:0;gap:0}
.check li{border-bottom:1px solid var(--rule-soft)}
.check li:first-child{border-top:1px solid var(--rule-soft)}
.check label{display:grid;grid-template-columns:24px minmax(0,1fr);gap:var(--s3);padding:var(--s3) 0;cursor:pointer;align-items:start}
.check input{
  appearance:none;width:20px;height:20px;margin:4px 0 0;border:2px solid var(--rule);border-radius:4px;
  background:var(--card);display:grid;place-content:center;cursor:pointer;
  transition:background-color .15s,border-color .15s;
}
.check input::after{content:"";width:10px;height:6px;border-left:2px solid var(--card);border-bottom:2px solid var(--card);transform:rotate(-45deg) translate(1px,-1px);opacity:0}
.check input:checked{background:var(--ok);border-color:var(--ok)}
.check input:checked::after{opacity:1}
.check input:checked+span{color:var(--ink-soft)}

footer{border-top:1px solid var(--rule);padding-top:var(--s5);font-size:var(--t-small);color:var(--ink-soft);display:flex;flex-direction:column;gap:var(--s2)}

@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{transition-duration:.01ms!important;animation-duration:.01ms!important}
}
@media print{
  .bar,.copy,.sim-input{display:none!important}
  details{border:none}
  details>.body{padding-left:0}
}

/* ── colour per part: shell green, Git purple, regex magenta, exercise amber ── */
.cmd{border-color:var(--code-bg)}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]) .cmd{border-color:var(--rule)}
  :root:not([data-theme="light"]) figure.shot img{filter:brightness(.82) contrast(1.05);border-color:var(--rule)}
}
:root[data-theme="dark"] .cmd{border-color:var(--rule)}
:root[data-theme="dark"] figure.shot img{filter:brightness(.82) contrast(1.05);border-color:var(--rule)}
section>.block+.block{margin-top:var(--s3)}
dfn{font-style:normal;font-weight:700;color:var(--sec,var(--ink))}
.note{background:color-mix(in srgb,var(--acc) 5%,var(--card));border-color:color-mix(in srgb,var(--acc) 28%,var(--rule))}