/* ==========================================================================
   WebSerial Simulaties — Drukknop Codelab stijl
   ========================================================================== */

:root {
  --bg: oklch(99% .003 270);
  --bg-sub: oklch(97.5% .004 270);
  --surface: #ffffff;
  --surface-2: oklch(98% .003 270);
  --surface-3: oklch(95.5% .005 270);
  --border: oklch(92% .006 270);
  --border-strong: oklch(86% .008 270);
  --fg: oklch(20% .012 270);
  --fg-muted: oklch(45% .012 270);
  --fg-faint: oklch(62% .01 270);
  --accent: oklch(55% .16 265);
  --accent-soft: color-mix(in oklch, var(--accent) 12%, var(--surface));
  --danger: oklch(55% .18 25);
  --danger-soft: color-mix(in oklch, var(--danger) 10%, var(--surface));
  --assignment: oklch(58% .16 145);
  --assignment-soft: color-mix(in oklch, var(--assignment) 11%, var(--surface));
  --product: oklch(68% .14 75);
  --product-soft: color-mix(in oklch, var(--product) 12%, var(--surface));
  --knowledge: oklch(60% .14 235);
  --side: oklch(60% .14 305);
  --shadow-sm: 0 1px 0 oklch(0% 0 0 / .04), 0 1px 2px oklch(0% 0 0 / .04);
  --shadow-md: 0 1px 0 oklch(0% 0 0 / .04), 0 4px 12px -2px oklch(0% 0 0 / .08), 0 2px 4px -1px oklch(0% 0 0 / .04);
  --radius-sm: 6px;
  --radius: 8px;
  --radius-lg: 12px;
  --radius-pill: 999px;
  --font-body: Inter, system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-code: "Geist Mono", ui-monospace, "SFMono-Regular", "JetBrains Mono", monospace;
  --mono: var(--font-code);

  --scope-screen: oklch(19% .018 265);
  --scope-well: oklch(25% .022 265);
  --scope-rule: oklch(33% .025 265);
  --scope-ink: oklch(96% .006 265);
  --scope-muted: oklch(72% .015 265);
  --scope-ctrl-fill: oklch(28% .05 305);
  --scope-ctrl-border: oklch(58% .14 305);
  --scope-ctrl-ink: oklch(85% .08 305);
  --scope-byte-dec: oklch(78% .14 150);
  --scope-warn: oklch(80% .14 75);
  --scope-err: oklch(72% .16 25);
}

/* CodeMirror-skin, afgestemd op de drukknop-tokens */
.CodeMirror {
  height: auto;
  min-height: 190px;
  font-family: var(--mono);
  font-size: 12.5px;
  line-height: 1.6;
  background: var(--surface);
  color: var(--fg);
}
.CodeMirror-gutters { background: var(--surface-2); border-right: 1px solid var(--border); }
.CodeMirror-linenumber { color: var(--fg-faint); font-size: 11px; }
.CodeMirror-cursor { border-left: 1.6px solid var(--accent); }
.CodeMirror-activeline-background { background: var(--surface-2); }
.CodeMirror-selected { background: color-mix(in oklch, var(--accent) 16%, transparent) !important; }
.CodeMirror-matchingbracket { color: var(--accent) !important; font-weight: 700; text-decoration: none !important; }
.cm-s-default .cm-keyword    { color: oklch(50% .18 300); }
.cm-s-default .cm-def        { color: oklch(48% .15 250); }
.cm-s-default .cm-variable   { color: var(--fg); }
.cm-s-default .cm-variable-2 { color: oklch(46% .13 250); }
.cm-s-default .cm-property   { color: oklch(44% .12 210); }
.cm-s-default .cm-number     { color: oklch(50% .16 45); }
.cm-s-default .cm-string     { color: oklch(46% .14 150); }
.cm-s-default .cm-comment    { color: var(--fg-faint); font-style: italic; }
.cm-s-default .cm-operator   { color: var(--fg-muted); }
.cm-s-default .cm-atom       { color: oklch(50% .16 45); }

* {
  box-sizing: border-box;
}

html,
body,
#app {
  height: 100%;
}

body {
  margin: 0;
  font-family: var(--font-body);
  font-size: 14px;
  line-height: 1.5;
  color: var(--fg);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
}

.muted {
  color: var(--fg-muted);
}

.text-danger {
  color: var(--danger);
}

.text-ok {
  color: color-mix(in oklch, var(--assignment) 65%, var(--fg));
}

[hidden] {
  display: none !important;
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* --------------------------------------------------------------- shell & topbar */

.app-shell {
  display: flex;
  flex-direction: column;
  height: 100%;
  background: var(--bg-sub);
}

.topbar {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 20px;
  background: color-mix(in oklch, var(--surface) 88%, transparent);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
  z-index: 20;
}

.topbar .brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13.5px;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--fg);
  text-decoration: none;
}

.brand-mark {
  width: 20px;
  height: 20px;
  border-radius: 5px;
  background: var(--accent);
  color: #ffffff;
  display: grid;
  place-items: center;
  font-size: 0;
  flex-shrink: 0;
}

.brand-mark::after {
  content: "";
  width: 10px;
  height: 10px;
  border-radius: 50%;
  border: 1.6px solid #ffffff;
  box-shadow: inset 0 0 0 1.6px var(--accent);
  background: #ffffff;
  background-clip: content-box;
  padding: 1.4px;
}

.brand-sub {
  font-size: 12px;
  font-weight: 500;
  color: var(--fg-muted);
  padding-left: 8px;
  border-left: 1px solid var(--border);
}

.topbar-spacer {
  flex: 1;
}

.topbar-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.pill-action {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 12px;
  border: 1px solid var(--border);
  border-radius: 99px;
  background: var(--surface);
  box-shadow: var(--shadow-sm);
  font-size: 12.5px;
  font-weight: 500;
  color: var(--fg);
  text-decoration: none;
  cursor: pointer;
  white-space: nowrap;
}

.pill-action:hover {
  border-color: var(--border-strong);
  background: var(--bg-sub);
}

.pill-action.accent {
  background: var(--accent);
  border-color: var(--accent);
  color: #ffffff;
}

.pill-action.accent:hover {
  background: color-mix(in oklch, var(--accent) 86%, black);
}

.open-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  flex-shrink: 0;
  padding: 5px 12px;
  border: 1px solid var(--border);
  border-radius: 99px;
  background: var(--surface);
  box-shadow: var(--shadow-sm);
  font-size: 12.5px;
  font-weight: 500;
  color: var(--fg);
  text-decoration: none;
  white-space: nowrap;
}

.open-btn:hover {
  border-color: var(--border-strong);
  background: var(--bg-sub);
}

.open-btn svg {
  width: 12px;
  height: 12px;
  fill: currentColor;
  opacity: 0.7;
  display: block;
}

/* --------------------------------------------------------------- simulation switcher bar */

.cardbar-wrap {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
  z-index: 15;
}

.cardbar {
  display: grid;
  grid-template-columns: repeat(6, minmax(128px, 1fr));
  gap: 8px;
  padding: 8px 20px;
  overflow-x: auto;
  max-width: 1040px;
  margin: 0 auto;
  scrollbar-width: thin;
}

.nav-card {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 7px 11px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  border-left: 3px solid var(--border-strong);
  background: var(--surface);
  color: var(--fg);
  text-decoration: none;
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  min-width: 0;
}

.nav-card:hover {
  border-color: var(--border-strong);
  background: var(--surface-2);
}

.nav-card.active {
  background: var(--accent-soft);
  border-color: color-mix(in oklch, var(--accent) 40%, var(--border));
  border-left: 3px solid var(--accent);
}

.nav-card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 4px;
}

.nav-card-step {
  font-size: 10.5px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--fg-faint);
}

.nav-card.active .nav-card-step {
  color: var(--accent);
}

.nav-card-check {
  width: 15px;
  height: 15px;
  border-radius: 99px;
  font-size: 10px;
  display: inline-grid;
  place-items: center;
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: transparent;
  font-weight: 700;
}

.nav-card.done .nav-card-check {
  background: var(--assignment);
  border-color: var(--assignment);
  color: #ffffff;
}

.nav-card-title {
  font-size: 12.5px;
  font-weight: 600;
  line-height: 1.25;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* --------------------------------------------------------------- main scroller & head */

.scroller {
  flex: 1;
  min-height: 0;
  overflow-y: auto;
}

.article {
  max-width: 980px;
  margin: 0 auto;
  padding: 20px 24px 64px;
}

.article-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 14px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}

.article-head-row {
  display: flex;
  align-items: center;
  gap: 9px;
  flex-wrap: wrap;
}

.article-head h1 {
  font-size: 1.35rem;
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.015em;
  margin: 0;
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.kind-badge {
  display: inline-block;
  padding: 2px 9px;
  border-radius: 99px;
  font-size: 10.5px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  background: color-mix(in oklch, var(--knowledge) 12%, var(--surface));
  color: color-mix(in oklch, var(--knowledge) 62%, var(--fg));
  border: 1px solid color-mix(in oklch, var(--knowledge) 30%, var(--border));
}

/* --------------------------------------------------------------- (i) button & .more block */

button.info {
  display: inline-grid;
  place-items: center;
  width: 19px;
  height: 19px;
  padding: 0;
  margin-left: 4px;
  border-radius: 50%;
  border: 1px solid color-mix(in oklch, var(--accent) 35%, var(--border));
  background: var(--accent-soft);
  color: var(--accent);
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 700;
  line-height: 1;
  cursor: pointer;
  vertical-align: middle;
  flex-shrink: 0;
}

button.info:hover,
button.info[aria-expanded="true"] {
  background: var(--accent);
  color: #ffffff;
  border-color: var(--accent);
}

.more {
  margin: 8px 0 12px;
  padding: 10px 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: 0 var(--radius) var(--radius) 0;
  box-shadow: var(--shadow-sm);
  font-size: 13px;
  line-height: 1.55;
  color: var(--fg);
}

.more[hidden] {
  display: none !important;
}

.more p {
  margin: 4px 0;
}

.more p:first-child {
  margin-top: 0;
}

.more p:last-child {
  margin-bottom: 0;
}

.more code {
  font-family: var(--mono);
  font-size: 12px;
  background: var(--surface-2);
  padding: 1px 5px;
  border-radius: 4px;
  border: 1px solid var(--border);
}

/* --------------------------------------------------------------- prose & tables */

.prose {
  font-size: 14px;
  line-height: 1.65;
  color: var(--fg);
}

.prose > :first-child {
  margin-top: 0 !important;
}

.prose h2 {
  font-size: 1.15rem;
  font-weight: 700;
  margin: 16px 0 8px;
}

.prose p {
  margin: 8px 0;
}

.prose a:not([class]) {
  color: var(--accent);
  text-decoration: none;
}

.prose a:not([class]):hover {
  text-decoration: underline;
}

.prose code {
  background: var(--surface-2);
  padding: 2px 6px;
  border-radius: 4px;
  font-family: var(--mono);
  font-size: 0.86em;
  border: 1px solid var(--border);
}

.prose pre {
  margin: 10px 0;
  border-radius: var(--radius);
  overflow: auto;
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 11px 14px;
  font-family: var(--mono);
  font-size: 12.5px;
  line-height: 1.6;
}

.prose pre code {
  background: none;
  padding: 0;
  border: none;
  font-size: inherit;
}

.prose table {
  width: 100%;
  border-collapse: collapse;
  margin: 10px 0;
  font-size: 13px;
}

.prose th,
.prose td {
  border: 1px solid var(--border);
  padding: 7px 10px;
  text-align: left;
  vertical-align: top;
}

.prose th {
  background: var(--surface-2);
  font-weight: 600;
}

.table-scroll {
  overflow-x: auto;
  margin: 10px 0;
}

/* --------------------------------------------------------------- codepair & static codeblocks */

.codepair {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 10px;
  margin: 8px 0;
}

.codepair > .codeblock {
  margin: 0;
  min-width: 0;
}

.codepair > .codeblock pre {
  margin: 0;
}

.codeblock {
  position: relative;
  margin: 10px 0;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  overflow: hidden;
}

.codeblock-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 5px 10px 5px 12px;
  border-bottom: 1px solid var(--border);
  background: var(--surface-2);
  font-size: 11.5px;
  font-weight: 600;
  color: var(--fg-muted);
}

.codeblock-lang {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--fg-faint);
}

.prose .codeblock pre {
  margin: 0;
  border: 0;
  border-radius: 0;
  background: transparent;
}

.codeblock-bad {
  border-color: color-mix(in oklch, var(--danger) 35%, var(--border));
}

.codeblock-bad .codeblock-head {
  background: color-mix(in oklch, var(--danger) 9%, var(--surface));
  border-bottom-color: color-mix(in oklch, var(--danger) 25%, var(--border));
  color: color-mix(in oklch, var(--danger) 62%, var(--fg));
}

.codeblock-good {
  border-color: color-mix(in oklch, var(--assignment) 35%, var(--border));
}

.codeblock-good .codeblock-head {
  background: color-mix(in oklch, var(--assignment) 10%, var(--surface));
  border-bottom-color: color-mix(in oklch, var(--assignment) 25%, var(--border));
  color: color-mix(in oklch, var(--assignment) 62%, var(--fg));
}

.copy-btn {
  position: absolute;
  top: 5px;
  right: 8px;
  padding: 2px 9px;
  border-radius: 99px;
  border: 1px solid var(--border);
  background: var(--surface);
  font: inherit;
  font-size: 11px;
  font-weight: 500;
  color: var(--fg-muted);
  cursor: pointer;
  opacity: 0;
}

.codeblock:hover .copy-btn,
.copy-btn:focus-visible {
  opacity: 1;
}

.copy-btn:hover {
  border-color: var(--border-strong);
  color: var(--fg);
}

/* --------------------------------------------------------------- collapsible admonitions (drukknop style) */

.admonition {
  --adm-color: var(--accent);
  border-left: 4px solid var(--adm-color);
  border-radius: 0 var(--radius) var(--radius) 0;
  background: var(--surface);
  border-top: 1px solid var(--border);
  border-right: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  margin: 10px 0;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.admonition-uitleg,
.admonition-info,
.admonition-note {
  --adm-color: var(--knowledge);
}

.admonition-code,
.admonition-dieper {
  --adm-color: var(--side);
}

.admonition-tip {
  --adm-color: var(--assignment);
}

.admonition-warning {
  --adm-color: var(--product);
}

.admonition-danger {
  --adm-color: var(--danger);
}

.admonition-title {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 7px 14px;
  font-size: 12px;
  font-weight: 700;
  background: color-mix(in oklch, var(--adm-color) 11%, var(--surface));
  color: color-mix(in oklch, var(--adm-color) 65%, var(--fg));
}

.admonition-hint-tag {
  margin-left: auto;
  font-size: 11px;
  font-weight: 600;
  opacity: 0.75;
}

.admonition-icon {
  width: 15px;
  height: 15px;
  flex-shrink: 0;
  fill: currentColor;
}

.admonition-collapsible > summary {
  list-style: none;
  cursor: pointer;
  user-select: none;
}

.admonition-collapsible > summary::-webkit-details-marker {
  display: none;
}

.admonition-collapsible > summary > .admonition-title:hover {
  background: color-mix(in oklch, var(--adm-color) 16%, var(--surface));
}

.admonition-collapsible[open] .admonition-hint-tag {
  display: none;
}

.admonition-body {
  padding: 12px 14px;
  border-top: 1px solid var(--border);
  background: var(--surface);
  font-size: 13.5px;
}

.admonition-body > :first-child {
  margin-top: 0;
}

.admonition-body > :last-child {
  margin-bottom: 0;
}

/* --------------------------------------------------------------- interactive simulation widgets (.sim style) */

.widget {
  margin: 0 0 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}

.widget.widget-hub {
  background: transparent;
  border: none;
  box-shadow: none;
  border-radius: 0;
  overflow: visible;
}

.w-head {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 12px;
  background: var(--surface-2);
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}

.lab-chip,
.sim-badge {
  flex-shrink: 0;
  padding: 2px 8px;
  border-radius: 99px;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  background: color-mix(in oklch, var(--side) 14%, var(--surface));
  color: color-mix(in oklch, var(--side) 62%, var(--fg));
  border: 1px solid color-mix(in oklch, var(--side) 30%, var(--border));
  white-space: nowrap;
}

.sim-badge.is-danger {
  background: color-mix(in oklch, var(--danger) 12%, var(--surface));
  color: var(--danger);
  border-color: color-mix(in oklch, var(--danger) 35%, var(--border));
}

.w-title {
  font-size: 12.5px;
  font-weight: 600;
  color: var(--fg);
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.w-head-right {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 6px;
}

.w-body {
  padding: 14px;
}

.widget-hub > .w-body {
  padding: 0;
}

.w-row {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.w-row-between {
  justify-content: space-between;
}

.w-col {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.w-grow {
  flex: 1;
  min-width: 180px;
}

.w-svg {
  width: 100%;
  height: auto;
  display: block;
  border-radius: var(--radius-sm);
  background: var(--scope-screen);
  margin: 8px 0;
}

.w-note {
  font-size: 12.5px;
  color: var(--fg-muted);
  line-height: 1.5;
}

.w-readout {
  font-family: var(--mono);
  font-size: 12px;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--surface-2);
  color: var(--fg);
}

.w-readout.is-overflow {
  background: color-mix(in oklch, var(--danger) 8%, var(--surface));
  border-color: color-mix(in oklch, var(--danger) 35%, var(--border));
}

.w-readout-row {
  margin-top: 8px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.w-scope-lines {
  min-height: 64px;
  margin-top: 6px;
  background: var(--scope-screen);
  border-color: var(--scope-rule);
  color: var(--scope-ink);
}

.w-scope-line {
  border-bottom: 1px solid var(--scope-rule);
  padding: 2px 0;
}

.w-scope-cr {
  color: var(--scope-ctrl-ink);
  font-weight: 700;
}

.w-scope-lf {
  color: var(--scope-byte-dec);
  font-weight: 700;
}

.w-section-divider {
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
}

.w-slider-well {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 8px 12px;
  margin: 8px 0;
}

.w-label {
  font-size: 12px;
  font-weight: 600;
  color: var(--fg-muted);
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.w-control {
  display: flex;
  flex-direction: column;
  gap: 4px;
  font-size: 12px;
  color: var(--fg-muted);
}

.w-control > span {
  display: flex;
  justify-content: space-between;
  gap: 8px;
  align-items: center;
}

.w-control > span b {
  color: var(--fg);
  font-family: var(--mono);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.w-control input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
  cursor: pointer;
}

.w-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  align-items: center;
  margin: 4px 0;
}

.w-chip {
  padding: 4px 11px;
  border-radius: 99px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--fg);
  font: inherit;
  font-size: 12px;
  font-weight: 500;
  cursor: pointer;
  white-space: nowrap;
}

.w-chip:hover {
  border-color: var(--border-strong);
  background: var(--bg-sub);
}

.w-chip[aria-pressed="true"],
.w-chip.active {
  background: var(--accent);
  border-color: var(--accent);
  color: #ffffff;
}

.w-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 13px;
  border-radius: 99px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--fg);
  font: inherit;
  font-size: 12px;
  font-weight: 500;
  cursor: pointer;
  white-space: nowrap;
}

.w-btn:hover {
  border-color: var(--border-strong);
  background: var(--bg-sub);
}

.w-btn.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #ffffff;
}

.w-btn.primary:hover {
  background: color-mix(in oklch, var(--accent) 86%, black);
}

.w-btn.danger {
  background: color-mix(in oklch, var(--danger) 10%, var(--surface));
  border-color: color-mix(in oklch, var(--danger) 35%, var(--border));
  color: var(--danger);
}

.w-btn.ok {
  background: color-mix(in oklch, var(--assignment) 10%, var(--surface));
  border-color: color-mix(in oklch, var(--assignment) 35%, var(--border));
  color: color-mix(in oklch, var(--assignment) 62%, var(--fg));
}

/* --------------------------------------------------------------- challenge bar (.opdracht style) */

.w-challenge {
  display: flex;
  align-items: center;
  gap: 9px;
  padding: 8px 14px;
  background: color-mix(in oklch, var(--assignment) 6%, var(--surface));
  border-top: 1px solid color-mix(in oklch, var(--assignment) 22%, var(--border));
  font-size: 12.5px;
}

.w-challenge .badge {
  font-size: 10.5px;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 2px 8px;
  border-radius: 99px;
  background: color-mix(in oklch, var(--assignment) 14%, var(--surface));
  color: color-mix(in oklch, var(--assignment) 65%, var(--fg));
  border: 1px solid color-mix(in oklch, var(--assignment) 30%, var(--border));
  flex-shrink: 0;
}

.w-challenge .text {
  flex: 1;
  color: var(--fg);
}

.w-challenge.solved {
  background: color-mix(in oklch, var(--assignment) 12%, var(--surface));
}

.w-challenge.solved .badge {
  background: var(--assignment);
  border-color: var(--assignment);
  color: #ffffff;
}

.w-feedback {
  font-weight: 600;
  margin-left: 6px;
}

.w-feedback.ok {
  color: color-mix(in oklch, var(--assignment) 65%, var(--fg));
}

.w-feedback.nok {
  color: var(--danger);
}

/* --------------------------------------------------------------- bit switchboard & byte packets */

.bit-row {
  display: grid;
  grid-template-columns: repeat(8, minmax(0, 1fr));
  gap: 8px;
  margin: 8px 0;
}

.bit-cell {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 8px 4px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: var(--surface-2);
  cursor: pointer;
  user-select: none;
}

.bit-cell:hover {
  border-color: var(--border-strong);
}

.bit-cell.on {
  background: var(--accent-soft);
  border-color: var(--accent);
}

.bit-led {
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: oklch(88% .006 270);
  border: 1px solid var(--border-strong);
}

.bit-cell.on .bit-led {
  background: var(--assignment);
  border-color: var(--assignment);
  box-shadow: 0 0 6px color-mix(in oklch, var(--assignment) 60%, transparent);
}

.bit-digit {
  font-family: var(--mono);
  font-size: 16px;
  font-weight: 700;
  line-height: 1;
  color: var(--fg-muted);
  font-variant-numeric: tabular-nums;
}

.bit-cell.on .bit-digit {
  color: var(--accent);
}

.bit-weight {
  font-family: var(--mono);
  font-size: 10.5px;
  color: var(--fg-faint);
  font-variant-numeric: tabular-nums;
}

.bit-cell.on .bit-weight {
  color: var(--fg);
  font-weight: 700;
}

.byte-stream {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  align-items: center;
  padding: 10px 12px;
  margin: 6px 0;
  border-radius: var(--radius-sm);
  background: var(--scope-screen);
  color: var(--scope-ink);
  min-height: 54px;
}

.byte-stream-between {
  justify-content: space-between;
}

.byte-packet {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  padding: 4px 8px;
  border-radius: var(--radius-sm);
  background: var(--scope-well);
  border: 1px solid var(--scope-rule);
  font-family: var(--mono);
  min-width: 50px;
  font-variant-numeric: tabular-nums;
}

.byte-packet.ctrl {
  background: var(--scope-ctrl-fill);
  border-color: var(--scope-ctrl-border);
}

.byte-char {
  font-size: 13px;
  font-weight: 700;
  color: var(--scope-ink);
}

.byte-dec {
  font-size: 10.5px;
  color: var(--scope-byte-dec);
}

.byte-bin {
  font-size: 9.5px;
  color: var(--scope-muted);
}

.wire-json-line {
  font-family: var(--mono);
  font-size: 13.5px;
  font-weight: 700;
  color: var(--scope-byte-dec);
}

.wire-status-ok {
  font-size: 11.5px;
  color: var(--scope-ink);
}

.wire-status-err {
  font-size: 11.5px;
  color: var(--scope-err);
}

/* --------------------------------------------------------------- panes & stats inside widgets */

.compare-panes {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 10px;
  margin: 6px 0;
}

.compare-card {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  padding: 10px 12px;
}

.compare-card.bad {
  border-color: color-mix(in oklch, var(--danger) 35%, var(--border));
  background: color-mix(in oklch, var(--danger) 6%, var(--surface));
}

.compare-card.good {
  border-color: color-mix(in oklch, var(--assignment) 35%, var(--border));
  background: color-mix(in oklch, var(--assignment) 7%, var(--surface));
}

.compare-card h4 {
  margin: 0;
  font-size: 12.5px;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
}

.stat-strip {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 8px;
  margin-top: 8px;
}

.stat-box {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  padding: 7px 10px;
}

.stat-box .lbl {
  font-size: 10.5px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--fg-faint);
  display: flex;
  justify-content: space-between;
  gap: 4px;
}

.stat-box .val {
  font-family: var(--mono);
  font-size: 15px;
  font-weight: 700;
  margin-top: 2px;
  font-variant-numeric: tabular-nums;
}

.stat-box.danger {
  border-color: color-mix(in oklch, var(--danger) 40%, var(--border));
  background: color-mix(in oklch, var(--danger) 7%, var(--surface));
}

.stat-box.danger .val {
  color: var(--danger);
}

.stat-box.ok {
  border-color: color-mix(in oklch, var(--assignment) 40%, var(--border));
  background: color-mix(in oklch, var(--assignment) 7%, var(--surface));
}

.stat-box.ok .val {
  color: color-mix(in oklch, var(--assignment) 65%, var(--fg));
}

/* --------------------------------------------------------------- overview hub cards & troubleshooting cards (.overview-card style) */

.hub-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin: 8px 0 16px;
}

.hub-card {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 12px 14px;
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
  text-decoration: none;
  color: var(--fg);
  cursor: pointer;
}

.hub-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--border-strong);
  border-left-color: var(--accent);
}

.hub-thumb {
  width: 100%;
  height: 92px;
  border-radius: var(--radius-sm);
  background: var(--scope-screen);
  display: block;
}

.hub-card-num {
  font-size: 10.5px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent);
}

.hub-card h3 {
  margin: 0;
  font-size: 15px;
  font-weight: 600;
  line-height: 1.25;
}

.symptom-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin: 8px 0 16px;
}

.symptom-btn {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 13px 15px;
  border: 1px solid var(--border);
  border-left: 4px solid var(--danger);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
  text-align: left;
  cursor: pointer;
  text-decoration: none;
  color: var(--fg);
}

.symptom-btn:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--border-strong);
  border-left-color: var(--danger);
}

.symptom-quote {
  font-weight: 700;
  font-size: 13.5px;
  color: var(--fg);
}

.symptom-go {
  font-size: 12px;
  font-weight: 600;
  color: var(--accent);
  margin-top: auto;
  padding-top: 4px;
}

/* --------------------------------------------------------------- runnable p5.webserial lab */

.lab {
  margin: 10px 0;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}

.lab-head {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 10px 7px 12px;
  background: var(--surface-2);
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}

.lab-title {
  font-size: 11.5px;
  font-weight: 600;
  color: var(--fg-muted);
}

.lab-actions {
  margin-left: auto;
  display: flex;
  gap: 5px;
}

.lab-btn {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 4px 10px;
  border: 1px solid var(--border);
  border-radius: 99px;
  background: var(--surface);
  font: inherit;
  font-size: 11.5px;
  font-weight: 500;
  color: var(--fg);
  cursor: pointer;
  white-space: nowrap;
}

.lab-btn:hover {
  border-color: var(--border-strong);
  background: var(--bg-sub);
}

.lab-btn.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #ffffff;
}

.lab-btn.primary:hover {
  background: color-mix(in oklch, var(--accent) 86%, black);
}

.lab-split {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr);
  min-height: 220px;
}

.lab-code {
  border-right: 1px solid var(--border);
  min-width: 0;
  overflow: hidden;
}

.lab-preview-pane {
  display: flex;
  flex-direction: column;
  background: var(--bg-sub);
  min-width: 0;
}

.lab-stage {
  flex: 1;
  display: grid;
  place-items: center;
  padding: 12px;
  min-height: 152px;
  background-image:
    linear-gradient(45deg, oklch(95.5% .004 270) 25%, transparent 25%),
    linear-gradient(-45deg, oklch(95.5% .004 270) 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, oklch(95.5% .004 270) 75%),
    linear-gradient(-45deg, transparent 75%, oklch(95.5% .004 270) 75%);
  background-size: 16px 16px;
  background-position: 0 0, 0 8px, 8px -8px, -8px 0;
}

.lab-stage iframe {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: #ffffff;
  box-shadow: var(--shadow-sm);
  max-width: 100%;
}

.lab-serial-panel {
  border-top: 1px solid var(--border);
  background: var(--surface-2);
  padding: 7px 10px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 11.5px;
}

.lab-serial-row {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.lab-console {
  border-top: 1px solid var(--border);
  background: var(--surface);
  color: var(--fg);
  font-family: var(--mono);
  font-size: 11.5px;
  line-height: 1.5;
  max-height: 90px;
  overflow-y: auto;
  padding: 6px 10px;
  display: none;
}

.lab-console.has-output {
  display: block;
}

.lab-console .row {
  display: flex;
  gap: 7px;
  padding: 1px 0;
}

.lab-console .row .marker {
  color: var(--fg-faint);
  user-select: none;
}

.lab-console .row.error {
  color: var(--danger);
}

.lab-console .row.warn {
  color: color-mix(in oklch, var(--product) 55%, var(--fg));
}

/* --------------------------------------------------------------- bottom step nav */

.stepnav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 10px;
  margin-top: 24px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
}

.stepnav .navcard {
  flex: 1 1 200px;
  max-width: 42%;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
  text-decoration: none;
  color: var(--fg);
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.stepnav .navcard:hover {
  border-color: var(--border-strong);
  box-shadow: var(--shadow-md);
}

.stepnav .navcard .dir {
  font-size: 10.5px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--fg-faint);
  font-weight: 700;
}

.stepnav .navcard .name {
  font-weight: 600;
  font-size: 13.5px;
}

.stepnav .navcard.next {
  margin-left: auto;
  text-align: right;
}

.boot,
.error-box {
  padding: 24px;
  color: var(--fg-muted);
}

.error-box {
  background: color-mix(in oklch, var(--danger) 8%, var(--surface));
  border: 1px solid color-mix(in oklch, var(--danger) 35%, var(--border));
  color: var(--danger);
  border-radius: var(--radius);
  margin: 16px;
}

/* --------------------------------------------------------------- responsive */

@media (max-width: 820px) {
  .hub-grid,
  .symptom-grid,
  .compare-panes,
  .codepair,
  .lab-split,
  .stat-strip {
    grid-template-columns: minmax(0, 1fr);
  }
  .bit-row {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
  .brand-sub,
  .open-btn-label {
    display: none;
  }
  .open-btn {
    padding: 6px 9px;
  }
  .topbar {
    padding: 8px 12px;
  }
  .article {
    padding: 16px 12px 48px;
  }
}

@media (prefers-reduced-motion: reduce) {
  * {
    transition: none !important;
  }
}