/* ROS 2 Web Lab ------------------------------------------------------------ */
:root {
  --bg: #f5f6f8;
  --panel: #ffffff;
  --panel-2: #f9fafc;
  --text: #1c2333;
  --muted: #5d677a;
  --border: #e1e5ec;
  --border-strong: #cdd3de;
  --accent: #2563eb;
  --accent-soft: #e8efff;
  --accent-text: #1d4ed8;
  --teal: #0f9d94;
  --ok: #15803d;
  --ok-soft: #e6f6ec;
  --warn: #b45309;
  --warn-soft: #fff4e0;
  --err: #c62828;
  --err-soft: #fdecec;
  --code-bg: #f2f4f8;
  --code-text: #1c2333;
  --term-bg: #0e1320;
  --term-fg: #d5ddeb;
  --term-muted: #7f8ba3;
  --shadow: 0 1px 2px rgba(16, 24, 40, .06), 0 4px 16px rgba(16, 24, 40, .06);
  --radius: 10px;
  --font: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  --mono: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --topbar-h: 52px;
  --sidebar-w: 268px;
  --lab-w: min(48vw, 860px);
  --view-h: 52%;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0c1018;
    --panel: #121925;
    --panel-2: #0f1520;
    --text: #e4e9f1;
    --muted: #8f9bb0;
    --border: #222c3c;
    --border-strong: #2f3b4f;
    --accent: #5b9cff;
    --accent-soft: #15223a;
    --accent-text: #8cb8ff;
    --teal: #2dd4bf;
    --ok: #4ade80;
    --ok-soft: #10261a;
    --warn: #fbbf24;
    --warn-soft: #2a2110;
    --err: #f87171;
    --err-soft: #2c1414;
    --code-bg: #0d131d;
    --code-text: #dfe6f1;
    --term-bg: #0a0e17;
    --shadow: 0 1px 2px rgba(0, 0, 0, .4), 0 6px 20px rgba(0, 0, 0, .35);
    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --bg: #0c1018;
  --panel: #121925;
  --panel-2: #0f1520;
  --text: #e4e9f1;
  --muted: #8f9bb0;
  --border: #222c3c;
  --border-strong: #2f3b4f;
  --accent: #5b9cff;
  --accent-soft: #15223a;
  --accent-text: #8cb8ff;
  --teal: #2dd4bf;
  --ok: #4ade80;
  --ok-soft: #10261a;
  --warn: #fbbf24;
  --warn-soft: #2a2110;
  --err: #f87171;
  --err-soft: #2c1414;
  --code-bg: #0d131d;
  --code-text: #dfe6f1;
  --term-bg: #0a0e17;
  --shadow: 0 1px 2px rgba(0, 0, 0, .4), 0 6px 20px rgba(0, 0, 0, .35);
  color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 15px/1.6 var(--font);
  -webkit-font-smoothing: antialiased;
  overflow: hidden;
}
body.dragging { user-select: none; cursor: col-resize; }
button, input, select { font: inherit; color: inherit; }
button { cursor: pointer; }
a { color: var(--accent-text); }
code, kbd, pre { font-family: var(--mono); }
code { font-size: .86em; background: var(--code-bg); border: 1px solid var(--border); border-radius: 5px; padding: .08em .35em; }
kbd { font-size: .8em; border: 1px solid var(--border-strong); border-bottom-width: 2px; border-radius: 5px; padding: .05em .4em; background: var(--panel); }
.muted { color: var(--muted); }
.small { font-size: .86em; }
.spacer { flex: 1; }
[hidden] { display: none !important; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.skip { position: absolute; left: -999px; top: 4px; z-index: 100; background: var(--panel); padding: 6px 10px; border-radius: 6px; }
.skip:focus { left: 8px; }

/* ----------------------------------------------------------------- top bar */
.topbar {
  height: var(--topbar-h);
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 0 14px;
  background: var(--panel);
  border-bottom: 1px solid var(--border);
  position: relative;
  z-index: 20;
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; color: var(--text); text-decoration: none; letter-spacing: -.01em; white-space: nowrap; }
.brand svg { width: 28px; height: 28px; }
.brand svg circle { fill: #fff; }
.brand .logo-bg { fill: var(--accent); }
.brand .logo-accent { fill: #99f6e4; }
.progress { display: flex; align-items: center; gap: 10px; color: var(--muted); font-size: 13px; }
#progress-bar { width: 120px; height: 6px; border-radius: 99px; background: var(--border); overflow: hidden; }
#progress-bar span { display: block; height: 100%; width: 0; background: linear-gradient(90deg, var(--accent), var(--teal)); transition: width .4s; }
#sim-status { display: flex; align-items: center; gap: 8px; font-size: 13px; color: var(--muted); white-space: nowrap; }
#sim-status .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--muted); }
#sim-status[data-kind="ok"] .dot { background: var(--ok); box-shadow: 0 0 0 3px var(--ok-soft); }
#sim-status[data-kind="loading"] .dot { background: var(--accent); animation: blink 1s infinite; }
#sim-status[data-kind="warn"] .dot { background: var(--warn); }
#sim-status[data-kind="error"] .dot { background: var(--err); }
@keyframes blink { 50% { opacity: .3; } }

.icon-btn {
  display: inline-grid; place-items: center;
  width: 34px; height: 34px; padding: 0;
  border: 1px solid transparent; border-radius: 8px;
  background: transparent; color: var(--muted);
}
.icon-btn:hover { background: var(--panel-2); border-color: var(--border); color: var(--text); }
.icon-btn svg { width: 18px; height: 18px; fill: currentColor; stroke: currentColor; stroke-width: 0; }
.nav-toggle svg { fill: none; stroke-width: 2; stroke-linecap: round; }
.icon-btn.sm { width: 26px; height: 26px; font-size: 16px; }
.nav-toggle { display: none; }

.menu { position: relative; }
.menu summary { list-style: none; }
.menu summary::-webkit-details-marker { display: none; }
.menu-pop {
  position: absolute; right: 0; top: 40px; min-width: 230px;
  background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: 6px; display: grid;
}
.menu-pop button, .menu-pop a {
  text-align: left; border: 0; background: none; padding: 8px 10px; border-radius: 6px;
  font-size: 14px; color: var(--text); text-decoration: none;
}
.menu-pop button:hover, .menu-pop a:hover { background: var(--panel-2); }
.menu-note { font-size: 12.5px; color: var(--muted); padding: 6px 10px 2px; }
.drive-chip {
  display: flex; align-items: center; gap: 6px; border: 1px solid var(--border); background: var(--panel-2);
  border-radius: 99px; padding: 3px 10px 3px 8px; font-size: 12.5px; color: var(--muted); white-space: nowrap;
}
.drive-chip svg { width: 15px; height: 15px; fill: none; stroke: currentColor; stroke-width: 1.8; }
.drive-chip[data-kind="ok"] svg { stroke: var(--ok); }
.drive-chip[data-kind="busy"] svg { stroke: var(--accent); animation: blink 1s infinite; }
.drive-chip[data-kind="error"] { color: var(--warn); border-color: var(--warn); }
.menu-pop hr { border: 0; border-top: 1px solid var(--border); margin: 4px 2px; width: auto; }

.mobile-switch { display: none; }

/* ------------------------------------------------------------------ layout */
.layout {
  height: calc(100vh - var(--topbar-h));
  height: calc(100dvh - var(--topbar-h));
  display: grid;
  grid-template-columns: var(--sidebar-w) minmax(0, 1fr) 6px var(--lab-w);
}

#sidebar {
  background: var(--panel);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  padding: 14px 10px 20px;
}
#lesson-nav section { margin-bottom: 14px; }
#lesson-nav h3 {
  margin: 8px 10px 6px; font-size: 11.5px; letter-spacing: .06em; text-transform: uppercase;
  color: var(--muted); font-weight: 600;
}
#lesson-nav ol { list-style: none; margin: 0; padding: 0; }
#lesson-nav a {
  display: flex; align-items: flex-start; gap: 10px;
  padding: 6px 10px; border-radius: 7px;
  color: var(--text); text-decoration: none; font-size: 14px; line-height: 1.35;
}
#lesson-nav a:hover { background: var(--panel-2); }
#lesson-nav a.current { background: var(--accent-soft); color: var(--accent-text); font-weight: 600; }
#lesson-nav .check {
  flex: none; width: 16px; height: 16px; margin-top: 1px; border-radius: 50%;
  border: 1.5px solid var(--border-strong);
}
#lesson-nav a.done .check { background: var(--ok); border-color: var(--ok); position: relative; }
#lesson-nav a.done .check::after {
  content: ''; position: absolute; left: 4.5px; top: 1.5px; width: 4px; height: 8px;
  border: solid #fff; border-width: 0 2px 2px 0; transform: rotate(45deg);
}
.sidebar-foot { font-size: 12.5px; color: var(--muted); padding: 0 10px; }
.nav-scrim { display: none; }

/* ------------------------------------------------------------------ lesson */
#lesson {
  overflow-y: auto;
  padding: 34px clamp(18px, 4vw, 56px) 80px;
  outline: none;
}
#lesson > * { max-width: 760px; margin-left: auto; margin-right: auto; }
.lesson-head .crumb { font-size: 13px; color: var(--muted); font-weight: 500; }
.lesson-head h1 { font-size: clamp(26px, 3vw, 34px); line-height: 1.2; letter-spacing: -.02em; margin: 6px 0 10px; }
.lesson-head .intro { font-size: 17px; color: var(--muted); margin: 0 0 18px; }
.goals {
  background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 12px 18px; margin-bottom: 26px;
}
.goals b { font-size: 13px; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); }
.goals ul { margin: 6px 0 0; padding-left: 20px; }
.lesson-body h2 { font-size: 21px; letter-spacing: -.01em; margin: 34px 0 8px; }
.lesson-body h3 { font-size: 17px; margin: 24px 0 6px; }
.lesson-body p, .lesson-body li { max-width: 72ch; }
.lesson-body ul, .lesson-body ol { padding-left: 22px; }
.lesson-body li { margin: 4px 0; }
.steps li { margin: 6px 0; }

.cmd-block {
  display: flex; align-items: center; gap: 10px;
  margin: 10px 0; padding: 9px 10px 9px 14px;
  background: var(--term-bg); color: var(--term-fg);
  border-radius: 9px; border: 1px solid #1b2436;
}
.cmd-block code {
  flex: 1; min-width: 0; background: none; border: 0; padding: 0; color: inherit;
  font-size: 13.5px; white-space: pre-wrap; word-break: break-word;
}
.cmd-block .ps { color: #5eead4; user-select: none; }
.cmd-actions { display: flex; gap: 6px; flex: none; }
.cmd-actions button {
  border: 1px solid #2a3550; background: #182035; color: var(--term-fg);
  border-radius: 6px; padding: 3px 10px; font-size: 12.5px; font-weight: 500;
}
.cmd-actions .btn-run { background: #1f4fd1; border-color: #2c5fe6; color: #fff; }
.cmd-actions .btn-run:hover { background: #2a5ff0; }
.cmd-actions button:hover { filter: brightness(1.15); }

.code-block {
  margin: 14px 0; border: 1px solid var(--border); border-radius: var(--radius);
  background: var(--code-bg); overflow: hidden;
}
.code-block figcaption {
  display: flex; align-items: center; gap: 8px; padding: 6px 8px 6px 14px;
  border-bottom: 1px solid var(--border); background: var(--panel); font-size: 12.5px;
}
.code-file { font-family: var(--mono); color: var(--muted); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.code-block figcaption button {
  border: 1px solid var(--border); background: var(--panel-2); border-radius: 6px;
  padding: 2px 10px; font-size: 12.5px; font-weight: 500; white-space: nowrap;
}
.code-block figcaption .btn-open { background: var(--accent); border-color: var(--accent); color: #fff; }
.code-block pre { margin: 0; padding: 14px 16px; overflow-x: auto; font-size: 13px; line-height: 1.55; max-height: 520px; color: var(--code-text); }
.code-block pre code { background: none; border: 0; padding: 0; font-size: inherit; }
.hl-kw { color: #7c3aed; font-weight: 500; }
.hl-str { color: #0f7b4a; }
.hl-com { color: #8a94a6; font-style: italic; }
.hl-num { color: #c2410c; }
.hl-fn { color: #1d4ed8; }
.hl-tag { color: #1d4ed8; }
.hl-key { color: #7c3aed; }
:root[data-theme="dark"] .hl-kw { color: #c4a5ff; }
:root[data-theme="dark"] .hl-str { color: #86efac; }
:root[data-theme="dark"] .hl-num { color: #fdba74; }
:root[data-theme="dark"] .hl-fn, :root[data-theme="dark"] .hl-tag { color: #93c5fd; }
:root[data-theme="dark"] .hl-key { color: #c4a5ff; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .hl-kw { color: #c4a5ff; }
  :root:not([data-theme="light"]) .hl-str { color: #86efac; }
  :root:not([data-theme="light"]) .hl-num { color: #fdba74; }
  :root:not([data-theme="light"]) .hl-fn, :root:not([data-theme="light"]) .hl-tag { color: #93c5fd; }
  :root:not([data-theme="light"]) .hl-key { color: #c4a5ff; }
}

.callout {
  margin: 16px 0; padding: 12px 16px; border-radius: var(--radius);
  border: 1px solid var(--border); border-left-width: 4px; background: var(--panel);
}
.callout-h { font-size: 12px; font-weight: 700; letter-spacing: .06em; text-transform: uppercase; margin-bottom: 4px; }
.callout p:first-of-type { margin-top: 0; }
.callout p:last-child { margin-bottom: 0; }
.callout pre { background: var(--code-bg); border: 1px solid var(--border); border-radius: 8px; padding: 10px 12px; overflow-x: auto; font-size: 12.5px; }
.callout pre code { background: none; border: 0; padding: 0; }
.callout.local { border-left-color: var(--teal); }
.callout.local .callout-h { color: var(--teal); }
.callout.local .callout-h::before { content: '⌂ '; }
.callout.sim { border-left-color: var(--accent); }
.callout.sim .callout-h { color: var(--accent-text); }
.callout.tip { border-left-color: var(--ok); }
.callout.tip .callout-h { color: var(--ok); }
.callout.warn { border-left-color: var(--warn); background: var(--warn-soft); }
.callout.warn .callout-h { color: var(--warn); }

.table-wrap { overflow-x: auto; margin: 14px 0; border: 1px solid var(--border); border-radius: var(--radius); background: var(--panel); }
table { border-collapse: collapse; width: 100%; font-size: 14px; }
th, td { text-align: left; padding: 8px 12px; border-bottom: 1px solid var(--border); vertical-align: top; }
th { font-size: 12.5px; text-transform: uppercase; letter-spacing: .04em; color: var(--muted); background: var(--panel-2); }
tr:last-child td { border-bottom: 0; }

details.reveal { margin: 14px 0; border: 1px dashed var(--border-strong); border-radius: var(--radius); padding: 8px 14px; }
details.reveal summary { cursor: pointer; font-weight: 600; color: var(--accent-text); }

.tasks, .quiz {
  margin-top: 36px; padding: 18px 20px; border-radius: var(--radius);
  background: var(--panel); border: 1px solid var(--border); box-shadow: var(--shadow);
}
.tasks h2, .quiz h2 { margin: 0 0 4px; font-size: 18px; }
.tasks .muted { margin: 0 0 10px; font-size: 13.5px; }
.tasks ul { list-style: none; margin: 0; padding: 0; }
.tasks li { display: flex; gap: 12px; align-items: flex-start; padding: 8px 0; border-top: 1px solid var(--border); }
.tasks li:first-child { border-top: 0; }
.tasks .box {
  flex: none; width: 20px; height: 20px; border-radius: 6px; margin-top: 2px;
  border: 2px solid var(--border-strong); transition: all .25s; position: relative;
}
.tasks li.ok .box { background: var(--ok); border-color: var(--ok); }
.tasks li.ok .box::after {
  content: ''; position: absolute; left: 5px; top: 1px; width: 5px; height: 10px;
  border: solid #fff; border-width: 0 2.5px 2.5px 0; transform: rotate(45deg);
}
.tasks li.ok > span:last-child { color: var(--muted); }
.tasks li.just .box { animation: pop .5s; }
@keyframes pop { 40% { transform: scale(1.35); } }

.quiz .q { padding: 12px 0; border-top: 1px solid var(--border); }
.quiz .q:first-of-type { border-top: 0; }
.q-text { margin: 0 0 8px; font-weight: 500; }
.opts { display: grid; gap: 6px; }
.opt {
  text-align: left; padding: 8px 12px; border-radius: 8px;
  border: 1px solid var(--border); background: var(--panel-2); font-size: 14px;
}
.opt:hover { border-color: var(--accent); }
.opt.right { border-color: var(--ok); background: var(--ok-soft); }
.opt.wrong { border-color: var(--err); background: var(--err-soft); }
.q-explain { margin: 8px 0 0; font-size: 14px; color: var(--muted); }

.lesson-complete {
  margin-top: 22px; padding: 12px 16px; border-radius: var(--radius);
  background: var(--ok-soft); color: var(--ok); font-weight: 600; display: flex; gap: 10px; align-items: center;
}
.mark-row { margin-top: 26px; }
.btn-mark { border: 1px solid var(--border-strong); background: var(--panel); padding: 8px 16px; border-radius: 8px; font-weight: 500; }
.btn-mark:hover { border-color: var(--accent); }

.pager { display: flex; justify-content: space-between; gap: 12px; margin-top: 40px; }
.pager a {
  flex: 1; max-width: 48%; padding: 12px 16px; border-radius: var(--radius);
  border: 1px solid var(--border); background: var(--panel); text-decoration: none;
  color: var(--text); font-weight: 500; font-size: 14px;
}
.pager a:hover { border-color: var(--accent); color: var(--accent-text); }
.pager .next { text-align: right; margin-left: auto; }

/* ------------------------------------------------------------------- demos */
.demo {
  margin: 18px 0; border: 1px solid var(--border); border-radius: var(--radius);
  background: var(--panel); padding: 10px 12px 12px; box-shadow: var(--shadow);
}
.demo svg { width: 100%; height: auto; display: block; }
.demo-controls { display: flex; flex-wrap: wrap; gap: 8px 14px; align-items: center; font-size: 13.5px; margin-top: 6px; }
.demo-controls button {
  border: 1px solid var(--border-strong); background: var(--panel-2); border-radius: 7px; padding: 4px 12px; font-size: 13px; font-weight: 500;
}
.demo-controls button:first-child { background: var(--accent); border-color: var(--accent); color: #fff; }
.demo-controls .num { width: 64px; padding: 3px 6px; border: 1px solid var(--border-strong); border-radius: 6px; background: var(--panel); }
.demo-log { font-family: var(--mono); font-size: 12px; color: var(--muted); margin-top: 8px; min-height: 1.5em; }
.demo-log div:first-child { color: var(--text); }
.d-node ellipse { fill: var(--accent-soft); stroke: var(--accent); stroke-width: 1.6; }
.d-node text, .d-topic text { font: 500 13px var(--font); fill: var(--text); }
.d-topic rect { fill: var(--panel-2); stroke: var(--border-strong); stroke-width: 1.4; }
.d-svc rect { stroke-dasharray: 5 3; }
.d-cb rect { fill: var(--ok-soft); stroke: var(--ok); }
.d-edge { stroke: var(--muted); stroke-width: 1.5; fill: none; }
.d-service { stroke-dasharray: 6 4; }
.d-arrowhead { fill: var(--muted); }
.d-label { font: 12px var(--font); fill: var(--muted); }
.d-msg circle { fill: var(--teal); }
.d-msg text { font: 600 11px var(--mono); fill: var(--teal); }
.d-req circle { fill: var(--accent); }
.d-req text { fill: var(--accent-text); }
.d-resp circle { fill: var(--ok); }
.d-resp text { fill: var(--ok); }
.d-cancel circle { fill: var(--err); }
.d-cancel text { fill: var(--err); }
.d-off { opacity: .35; }
.pulse ellipse, .pulse rect { animation: dpulse .6s; }
@keyframes dpulse { 40% { stroke-width: 4; } }
.qos-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.qos-grid fieldset { border: 1px solid var(--border); border-radius: 8px; padding: 8px 12px 12px; display: grid; gap: 6px; }
.qos-grid legend { font-weight: 600; font-size: 13.5px; padding: 0 4px; }
.qos-grid label { display: flex; justify-content: space-between; gap: 8px; font-size: 13.5px; align-items: center; }
.qos-grid select { border: 1px solid var(--border-strong); border-radius: 6px; background: var(--panel); padding: 2px 6px; font-size: 13px; }
.qos-result { margin-top: 10px; padding: 10px 12px; border-radius: 8px; font-size: 14px; }
.qos-result.ok { background: var(--ok-soft); }
.qos-result.bad { background: var(--err-soft); }
.overlay-stack { display: grid; gap: 6px; }
.overlay-stack .layer { border-radius: 8px; padding: 10px 14px; display: flex; flex-wrap: wrap; gap: 4px 12px; align-items: baseline; font-size: 14px; }
.overlay-stack .layer span { color: var(--muted); font-size: 13px; }
.l-overlay { background: var(--accent-soft); border: 1px solid var(--accent); }
.l-underlay { background: var(--panel-2); border: 1px solid var(--border-strong); }

/* --------------------------------------------------------------------- lab */
.splitter-v { cursor: col-resize; background: var(--border); position: relative; }
.splitter-v:hover, .splitter-h:hover { background: var(--accent); }
.splitter-h { height: 6px; cursor: row-resize; background: var(--border); flex: none; }
#lab { display: flex; flex-direction: column; min-width: 0; background: var(--panel); position: relative; }
.views { height: var(--view-h); min-height: 120px; display: flex; flex-direction: column; min-width: 0; }
.tabbar {
  display: flex; align-items: center; gap: 2px; padding: 0 6px; height: 38px; flex: none;
  border-bottom: 1px solid var(--border); background: var(--panel-2); overflow-x: auto;
}
.view-tab, .tab {
  border: 0; background: none; height: 38px; padding: 0 14px; font-size: 13.5px; font-weight: 500;
  color: var(--muted); border-bottom: 2px solid transparent; white-space: nowrap;
}
.view-tab.active { color: var(--text); border-bottom-color: var(--accent); }
.view { flex: 1; min-height: 0; position: relative; }

/* turtlesim */
.view[data-view="turtlesim"] { background: var(--panel-2); overflow: auto; }
.tsim-empty { height: 100%; display: grid; place-content: center; text-align: center; color: var(--muted); padding: 20px; }
.tsim-empty svg { width: 64px; margin: 0 auto 6px; fill: var(--border-strong); }
.tsim-empty p { margin: 4px 0; }
.tsim-grid { display: grid; gap: 12px; padding: 12px; height: 100%; align-content: start; justify-content: center; }
.tsim-grid { grid-template-columns: repeat(var(--tsim-cols, 1), var(--tsim-size, 420px)); }
.tsim-window {
  background: var(--panel); border: 1px solid var(--border-strong); border-radius: 9px; overflow: hidden;
  box-shadow: var(--shadow); width: var(--tsim-size, 420px);
}
.tsim-title {
  display: flex; align-items: center; gap: 10px; height: 28px; padding: 0 10px;
  background: #2b2f3a; color: #e8ebf2; font-size: 12.5px; font-weight: 500;
}
.tsim-dots { display: flex; gap: 5px; }
.tsim-dots i { width: 10px; height: 10px; border-radius: 50%; background: #ef5f57; }
.tsim-dots i:nth-child(2) { background: #f6be2f; }
.tsim-dots i:nth-child(3) { background: #2dc840; }
.tsim-window canvas { display: block; width: 100%; height: auto; aspect-ratio: 1; }
.tsim-readout { font: 11.5px var(--mono); color: var(--muted); padding: 5px 10px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; border-top: 1px solid var(--border); }

/* graph */
.view[data-view="graph"] { display: flex; flex-direction: column; }
.graph-opts { display: flex; flex-wrap: wrap; gap: 4px 16px; align-items: center; padding: 6px 12px; font-size: 12.5px; border-bottom: 1px solid var(--border); }
.graph-opts .muted { font-family: var(--mono); }
.graph-opts label { display: flex; gap: 5px; align-items: center; }
.graph-scroll { flex: 1; overflow: auto; position: relative; min-height: 0; display: flex; }
.graph-svg { display: block; margin: auto; flex: none; max-width: none; }
.graph-empty { position: absolute; inset: 0; display: grid; place-content: center; text-align: center; color: var(--muted); }
.graph-empty p { margin: 2px; }
.v { cursor: pointer; }
.v-node ellipse { fill: var(--accent-soft); stroke: var(--accent); stroke-width: 1.6; }
.v-topic rect { fill: var(--panel); stroke: var(--border-strong); stroke-width: 1.4; }
.v-topic.flow rect { stroke: var(--teal); stroke-width: 2; }
.v text { font: 500 12.5px var(--mono); fill: var(--text); pointer-events: none; }
.v:hover ellipse, .v:hover rect, .v:focus-visible ellipse, .v:focus-visible rect { stroke-width: 3; }
.edge { stroke: var(--muted); stroke-width: 1.5; fill: none; }
.edge.flow { stroke: var(--teal); stroke-width: 2; stroke-dasharray: 7 5; animation: flow .7s linear infinite; }
.edge-service { stroke-dasharray: 5 4; stroke: var(--accent); opacity: .7; }
.edge-action { stroke-dasharray: 2 4; stroke: var(--warn); }
.arrowhead { fill: var(--muted); }
@keyframes flow { to { stroke-dashoffset: -12; } }
@media (prefers-reduced-motion: reduce) { .edge.flow { animation: none; } }
.graph-info {
  position: absolute; right: 10px; bottom: 10px; width: min(340px, calc(100% - 20px));
  background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: 10px 14px; font-size: 13px;
}
.graph-info h4 { margin: 0 24px 6px 0; font-size: 14px; }
.graph-info p { margin: 4px 0; }
.graph-info .row { display: flex; gap: 6px; margin-top: 8px; flex-wrap: wrap; }
.graph-info .row button { border: 1px solid var(--border-strong); background: var(--panel-2); border-radius: 6px; padding: 3px 10px; font-size: 12.5px; }
.graph-info .close { position: absolute; right: 8px; top: 6px; border: 0; background: none; font-size: 18px; color: var(--muted); }

/* editor */
.ed { display: flex; height: 100%; min-height: 0; }
.ed-side { width: 210px; flex: none; border-right: 1px solid var(--border); display: flex; flex-direction: column; background: var(--panel-2); }
.ed-side-head { display: flex; align-items: center; gap: 2px; padding: 4px 6px 4px 12px; font-size: 11.5px; font-weight: 600; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); border-bottom: 1px solid var(--border); }
.ed-side-head span { flex: 1; }
.files { overflow: auto; flex: 1; padding: 4px 0; }
.files ul { list-style: none; margin: 0; padding: 0; }
.file-row {
  width: 100%; text-align: left; border: 0; background: none; display: flex; gap: 4px; align-items: center;
  padding: 2px 8px; font: 12.5px var(--mono); color: var(--text); white-space: nowrap;
}
.file-row:hover { background: var(--border); }
.file-row.active { background: var(--accent-soft); color: var(--accent-text); }
.file-row .ic { width: 12px; flex: none; color: var(--muted); font-size: 11px; }
.file-row.dir .nm { font-weight: 600; }
.ed-main { flex: 1; min-width: 0; display: flex; flex-direction: column; position: relative; }
.ed-tabs { display: flex; overflow-x: auto; background: var(--panel-2); border-bottom: 1px solid var(--border); min-height: 34px; flex: none; }
.ed-tab { display: flex; align-items: center; border-right: 1px solid var(--border); font: 12.5px var(--mono); }
.ed-tab.active { background: var(--panel); box-shadow: inset 0 -2px var(--accent); }
.ed-tab button { border: 0; background: none; padding: 6px 4px 6px 12px; white-space: nowrap; }
.ed-tab .ed-tab-close { padding: 6px 10px 6px 4px; color: var(--muted); }
.ed-bar { display: flex; align-items: center; gap: 8px; padding: 4px 8px; border-bottom: 1px solid var(--border); font-size: 12.5px; flex: none; }
.ed-path { font-family: var(--mono); color: var(--muted); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.ed-bar button { border: 1px solid var(--border-strong); background: var(--panel); border-radius: 6px; padding: 2px 10px; font-size: 12.5px; font-weight: 500; white-space: nowrap; }
.ed-bar button kbd { font-size: 10px; margin-left: 4px; }
.ed-bar button.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.ed-cm { flex: 1; min-height: 0; position: relative; }
.ed-cm .CodeMirror { position: absolute; inset: 0; height: auto; font: 13px/1.55 var(--mono); background: var(--panel); color: var(--text); }
.ed-empty { position: absolute; inset: 0; display: grid; place-content: center; padding: 24px; text-align: center; color: var(--text); font-size: 14px; max-width: 460px; margin: auto; }
.CodeMirror-gutters { background: var(--panel-2); border-right: 1px solid var(--border); }
.CodeMirror-linenumber { color: var(--muted); }
.CodeMirror-cursor { border-left-color: var(--text); }
.CodeMirror-activeline-background { background: var(--accent-soft); }
.CodeMirror-selected, .CodeMirror-focused .CodeMirror-selected { background: rgba(91, 156, 255, .25); }
.cm-s-default .cm-keyword { color: #7c3aed; }
.cm-s-default .cm-def { color: #1d4ed8; }
.cm-s-default .cm-string { color: #0f7b4a; }
.cm-s-default .cm-comment { color: #8a94a6; }
.cm-s-default .cm-number { color: #c2410c; }
.cm-s-default .cm-builtin, .cm-s-default .cm-variable-2 { color: #0e7490; }
.cm-s-default .cm-tag { color: #1d4ed8; }
.cm-s-default .cm-attribute { color: #7c3aed; }
:root[data-theme="dark"] .cm-s-default .cm-keyword { color: #c4a5ff; }
:root[data-theme="dark"] .cm-s-default .cm-def, :root[data-theme="dark"] .cm-s-default .cm-tag { color: #93c5fd; }
:root[data-theme="dark"] .cm-s-default .cm-string { color: #86efac; }
:root[data-theme="dark"] .cm-s-default .cm-number { color: #fdba74; }
:root[data-theme="dark"] .cm-s-default .cm-builtin, :root[data-theme="dark"] .cm-s-default .cm-variable-2 { color: #67e8f9; }
:root[data-theme="dark"] .cm-s-default .cm-variable, :root[data-theme="dark"] .cm-s-default .cm-property { color: var(--text); }
:root[data-theme="dark"] .cm-s-default .cm-attribute { color: #c4a5ff; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .cm-s-default .cm-keyword { color: #c4a5ff; }
  :root:not([data-theme="light"]) .cm-s-default .cm-def, :root:not([data-theme="light"]) .cm-s-default .cm-tag { color: #93c5fd; }
  :root:not([data-theme="light"]) .cm-s-default .cm-string { color: #86efac; }
  :root:not([data-theme="light"]) .cm-s-default .cm-number { color: #fdba74; }
  :root:not([data-theme="light"]) .cm-s-default .cm-builtin, :root:not([data-theme="light"]) .cm-s-default .cm-variable-2 { color: #67e8f9; }
  :root:not([data-theme="light"]) .cm-s-default .cm-variable, :root:not([data-theme="light"]) .cm-s-default .cm-property { color: var(--text); }
  :root:not([data-theme="light"]) .cm-s-default .cm-attribute { color: #c4a5ff; }
}

/* terminals */
.terms { flex: 1; min-height: 90px; display: flex; flex-direction: column; background: var(--term-bg); }
.terms .tabbar { background: #121a2b; border-bottom-color: #1e2840; }
.term-tab { display: flex; align-items: center; border-radius: 6px 6px 0 0; }
.term-tab .tab-name {
  border: 0; background: none; color: var(--term-muted); font-size: 12.5px; font-weight: 500;
  padding: 7px 4px 7px 12px; display: flex; align-items: center; gap: 7px;
}
.term-tab .tab-dot { width: 7px; height: 7px; border-radius: 50%; background: transparent; }
.term-tab.activity .tab-dot { background: #5eead4; }
.term-tab .tab-x { border: 0; background: none; color: var(--term-muted); padding: 4px 10px 4px 2px; font-size: 15px; }
.term-tab.active { background: var(--term-bg); }
.term-tab.active .tab-name { color: #e7ecf5; }
#term-add { color: var(--term-muted); }
#term-add:hover { background: #1a2338; border-color: #26324d; color: #fff; }
#term-body { flex: 1; min-height: 0; position: relative; }
.term {
  position: absolute; inset: 0; display: flex; flex-direction: column;
  color: var(--term-fg); font: 13px/1.45 var(--mono); cursor: text;
}
.term-out { flex: 1; overflow-y: auto; padding: 8px 12px 12px; white-space: pre-wrap; word-break: break-word; }
.tl { min-height: 1.45em; }
.term-input { position: absolute; left: -9999px; top: 0; width: 1px; height: 1px; opacity: 0; }
.cursor { background: transparent; outline: 1px solid #93c5fd; }
.term.focused .cursor { background: #93c5fd; color: var(--term-bg); outline: 0; animation: cblink 1.1s step-end infinite; }
@keyframes cblink { 50% { background: transparent; color: inherit; } }
.term-status {
  flex: none; display: flex; align-items: center; gap: 8px; padding: 4px 10px;
  background: #121a2b; border-top: 1px solid #1e2840; font-size: 12px; color: var(--term-muted);
}
.term-status .dot { width: 7px; height: 7px; border-radius: 50%; background: #5eead4; animation: blink 1.2s infinite; flex: none; }
.term-status .txt { flex: 1; overflow: hidden; white-space: nowrap; text-overflow: ellipsis; }
.term-status button { border: 1px solid #2a3550; background: #182035; color: var(--term-fg); border-radius: 5px; padding: 1px 8px; font-size: 11.5px; }
.term-keys {
  flex: none; display: flex; flex-wrap: wrap; gap: 6px; align-items: center; padding: 6px 10px;
  background: #102028; border-top: 1px solid #1d3a44; font-size: 12px; color: #9fe9de;
}
.term-keys-label { flex: 1; min-width: 150px; }
.term-keys button { width: 34px; height: 30px; border-radius: 6px; border: 1px solid #2a4d58; background: #16303a; color: #e2fbf7; font-size: 15px; }
.term-keys button:active { background: #23505d; }
/* ANSI colours */
.c30, .c90 { color: #7f8ba3; } .c31, .c91 { color: #f87171; } .c32, .c92 { color: #4ade80; }
.c33, .c93 { color: #facc15; } .c34, .c94 { color: #60a5fa; } .c35, .c95 { color: #e879f9; }
.c36, .c96 { color: #22d3ee; } .c37, .c97 { color: #f1f5f9; } .b { font-weight: 700; }

/* boot overlay */
#boot { position: absolute; inset: 0; display: grid; place-items: center; background: color-mix(in srgb, var(--panel) 88%, transparent); z-index: 5; backdrop-filter: blur(2px); }
.boot-card { text-align: center; max-width: 340px; padding: 24px; }
.boot-msg { font-weight: 500; margin-bottom: 12px; }
.boot-bar { height: 8px; border-radius: 99px; background: var(--border); overflow: hidden; }
.boot-bar span { display: block; height: 100%; width: 0; background: linear-gradient(90deg, var(--accent), var(--teal)); transition: width .2s; }
.boot-detail { margin: 6px 0 10px; font-variant-numeric: tabular-nums; }
.boot-steps { list-style: none; padding: 0; margin: 0 auto 14px; text-align: left; display: inline-grid; gap: 3px; color: var(--muted); }
.boot-steps li::before { content: '○'; display: inline-block; width: 1.4em; color: var(--border-strong); }
.boot-steps li.active { color: var(--text); font-weight: 500; }
.boot-steps li.active::before { content: '◐'; color: var(--accent); }
.boot-steps li.done::before { content: '✓'; color: var(--ok); }
.spinner { width: 36px; height: 36px; margin: 0 auto 10px; border: 3px solid var(--border); border-top-color: var(--accent); border-radius: 50%; animation: spin .8s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }

#toast {
  position: fixed; left: 50%; bottom: 24px; transform: translate(-50%, 10px); opacity: 0;
  background: #1c2333; color: #fff; padding: 9px 16px; border-radius: 8px; font-size: 14px;
  box-shadow: var(--shadow); transition: all .2s; z-index: 50; pointer-events: none;
}
#toast.show { opacity: 1; transform: translate(-50%, 0); }

/* -------------------------------------------------------------- responsive */
@media (max-width: 1180px) {
  :root { --sidebar-w: 0px; }
  .layout { grid-template-columns: minmax(0, 1fr) 6px var(--lab-w); }
  .nav-toggle { display: inline-grid; }
  #sidebar {
    position: fixed; left: 0; top: var(--topbar-h); bottom: 0; width: 290px; z-index: 30;
    transform: translateX(-100%); transition: transform .2s; box-shadow: var(--shadow);
  }
  body.nav-open #sidebar { transform: none; }
  body.nav-open .nav-scrim { display: block; position: fixed; inset: var(--topbar-h) 0 0 0; background: rgba(0, 0, 0, .3); z-index: 25; }
}

@media (max-width: 900px) {
  body { font-size: 15px; }
  .progress, #sim-status .txt, .drive-chip .txt { display: none; }
  .mobile-switch {
    display: flex; height: 40px; background: var(--panel); border-bottom: 1px solid var(--border);
  }
  .mobile-switch button { flex: 1; border: 0; background: none; font-weight: 600; color: var(--muted); border-bottom: 2px solid transparent; }
  .mobile-switch button.active { color: var(--text); border-bottom-color: var(--accent); }
  .layout { grid-template-columns: minmax(0, 1fr); height: calc(100vh - var(--topbar-h) - 40px); height: calc(100dvh - var(--topbar-h) - 40px); }
  .splitter-v { display: none; }
  body[data-mobile="lesson"] #lab { display: none; }
  body[data-mobile="lab"] #lesson { display: none; }
  #lesson { padding: 22px 16px 60px; }
  .ed-side { width: 150px; }
  .qos-grid { grid-template-columns: 1fr; }
  .cmd-block { flex-direction: column; align-items: stretch; }
  .cmd-actions { justify-content: flex-end; }
}