/* The lab kit (templates/labkit/*): shared look of the labs. */
.lk { --ink: rgb(var(--c-ink)); --muted: rgb(var(--c-slate-500)); --line: rgb(var(--c-line)); --card: rgb(var(--c-card)); --paper: rgb(var(--c-paper));
  --teal: rgb(var(--c-accent-2)); --teal-tint: rgb(var(--c-accent-2-tint)); --brand: rgb(var(--c-accent-1)); --soft: rgb(var(--c-ink) / .05); color: var(--ink); }
.lk [hidden] { display: none !important; }
.lk code { font-family: "JetBrains Mono", ui-monospace, monospace; font-size: .9em; padding: 1px 5px; border-radius: 5px; background: rgb(var(--c-ink) / .07); }
.lk h2 { margin: 0; }
.lk-small { margin: 4px 0 8px; font-size: 13px; color: var(--muted); }

.lk-top { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: flex-end; gap: 12px; }
.lk-top-right { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }
.lk-lead { margin: 4px 0 0; max-width: 820px; color: var(--muted); }
.lk-score { padding: 4px 12px; border-radius: 999px; background: #fef3c7; color: #92400e; font-weight: 700; font-size: 14px; }
.lk-status { padding: 4px 12px; border-radius: 999px; font-size: 13px; max-width: 440px; background: #e0f2fe; color: #075985; }
.lk-status[data-kind="busy"]::before { content: ""; display: inline-block; width: 10px; height: 10px; margin-right: 6px; border-radius: 50%;
  border: 2px solid currentColor; border-right-color: transparent; animation: lk-spin .8s linear infinite; vertical-align: -1px; }
.lk-status[data-kind="ok"] { background: #dcfce7; color: #166534; }
.lk-status[data-kind="bad"] { background: #fee2e2; color: #991b1b; }
@keyframes lk-spin { to { transform: rotate(360deg); } }
body:not(.lk-running) .lk .lk-stop { display: none; }
.lk-note { margin-top: 10px; padding: 8px 12px; border-radius: 10px; background: var(--teal-tint); font-size: 14px; }

/* the free demo */
.lk-demo { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 10px; margin-top: 14px; padding: 12px 16px;
  border-radius: 14px; border: 1px solid #86efac; background: #f0fdf4; color: #14532d; font-size: 14px; }
.lk-demo-btns { display: flex; gap: 6px; }
.lk-lockcard { display: flex; flex-direction: column; align-items: flex-start; gap: 8px; margin: 10px 0; padding: 16px; border-radius: 16px;
  border: 2px dashed #f59e0b; background: #fffbeb; color: #78350f; font-size: 14px; }
.lk-lockcard b { font-size: 16px; }
.lk-locked-panel { position: relative; }
.lk-locked-panel > [inert] { opacity: .35; filter: grayscale(.6); pointer-events: none; user-select: none; }
.lk-tab-lock { font-size: 11px; }

/* tabs and panels */
.lk-tabs { display: flex; gap: 6px; margin: 18px 0 14px; overflow-x: auto; border-bottom: 1px solid var(--line); scrollbar-width: none; }
.lk-tab { flex: none; padding: 9px 14px; border: 0; border-bottom: 3px solid transparent; background: none; color: var(--muted); font-weight: 600; font-size: 14px; cursor: pointer; }
.lk-tab:hover { color: var(--ink); }
.lk-tab[aria-selected="true"] { color: var(--ink); border-bottom-color: var(--teal); }
.lk-lead2 { margin: 0 0 10px; color: var(--muted); }

/* buttons, chips, controls */
.lk-btn { display: inline-flex; align-items: center; gap: 4px; padding: 7px 13px; border-radius: 10px; border: 1px solid var(--line); background: var(--card);
  color: var(--ink); font-weight: 600; font-size: 14px; cursor: pointer; text-decoration: none; transition: transform .1s, border-color .15s; }
.lk-btn:hover { border-color: var(--teal); }
.lk-btn:active { transform: translateY(1px); }
.lk-btn:disabled { opacity: .5; cursor: not-allowed; }
.lk-btn.is-primary { background: var(--teal); border-color: var(--teal); color: #fff; }
.lk-btn.is-quiet { background: none; }
.lk-btn.is-on { background: var(--teal-tint); border-color: var(--teal); }
.lk-chips { display: flex; flex-wrap: wrap; gap: 6px; margin: 8px 0 12px; }
.lk-chip { padding: 5px 11px; border-radius: 999px; border: 1px solid var(--line); background: var(--card); color: var(--ink); font-size: 13px; cursor: pointer; }
.lk-chip:hover, .lk-chip.is-on { border-color: var(--teal); background: var(--teal-tint); }
.lk-ctl { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 16px; padding: 12px; border-radius: 14px; border: 1px solid var(--line); background: var(--card); font-size: 14px; }
.lk-ctl label { display: inline-flex; align-items: center; gap: 6px; flex-wrap: wrap; }
.lk select, .lk input:not([type="checkbox"]):not([type="radio"]):not([type="range"]):not([type="color"]):not([type="file"]), .lk textarea {
  padding: 5px 8px; border-radius: 8px; border: 1px solid var(--line); background: var(--paper); color: var(--ink); font-size: 14px; }
.lk input[type="range"] { accent-color: var(--teal); }
.lk-card { padding: 14px; border-radius: 16px; border: 1px solid var(--line); background: var(--card); }
.lk-card h3 { margin: 0 0 6px; font-weight: 700; font-size: 16px; }
.lk-grid2 { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 16px; align-items: start; }
.lk-grid-side { display: grid; grid-template-columns: minmax(0, 7fr) minmax(0, 5fr); gap: 16px; align-items: start; }
.lk-stack { display: flex; flex-direction: column; gap: 12px; min-width: 0; }
.lk-canvas { width: 100%; height: auto; border-radius: 14px; background: #0f172a; display: block; }
.lk-stat { display: flex; flex-wrap: wrap; gap: 8px; font-size: 13px; }
.lk-stat span { padding: 3px 10px; border-radius: 999px; background: var(--soft); }
.lk-stat b { font-variant-numeric: tabular-nums; }

/* lesson player */
.lk-learn { display: grid; grid-template-columns: 260px minmax(0, 1fr); gap: 20px; align-items: start; }
.lk-list { position: sticky; top: 76px; max-height: calc(100vh - 96px); overflow-y: auto; padding-right: 4px; }
.lk-track { margin-bottom: 14px; }
.lk-track h3 { margin: 0 0 6px; font-weight: 700; font-size: 15px; }
.lk-track h3 small { font-weight: 500; color: var(--muted); }
.lk-item { display: flex; width: 100%; align-items: center; gap: 8px; padding: 6px 8px; border: 1px solid transparent; border-radius: 10px; background: none;
  color: var(--ink); text-align: left; font-size: 14px; cursor: pointer; }
.lk-item:hover { background: var(--soft); }
.lk-item.is-on { border-color: var(--teal); background: var(--teal-tint); }
.lk-num { flex: none; display: grid; place-items: center; width: 22px; height: 22px; border-radius: 50%; background: rgb(var(--c-ink) / .08); font-size: 12px; font-weight: 700; }
.lk-item.is-done .lk-num { background: #fcd34d; color: #78350f; }
.lk-name { flex: 1; }
.lk-stars { flex: none; color: #f59e0b; font-size: 12px; letter-spacing: 1px; }
.lk-crumb { margin: 0; font-size: 13px; color: var(--muted); }
.lk-title { font-size: 1.5rem; }
.lk-explain { margin: 8px 0 12px; line-height: 1.6; max-width: 820px; }
.lk-explain p { margin: 0 0 8px; }
.lk-explain ul, .lk-explain ol { margin: 0 0 8px; padding-left: 20px; }
.lk-explain ul { list-style: disc; } .lk-explain ol { list-style: decimal; }
.lk-explain pre { margin: 6px 0 10px; padding: 10px 12px; border-radius: 10px; background: #0f172a; color: #e2e8f0; overflow-x: auto; font-size: 13px; }
.lk-explain pre code { background: none; padding: 0; }
.lk-task { margin: 0 0 12px; padding: 10px 14px; border-radius: 12px; background: #fef3c7; color: #78350f; }
.lk-code { border: 1px solid var(--line); border-radius: 14px; background: var(--paper); overflow: hidden; }
.lk-editor { min-height: 140px; max-height: 440px; overflow: auto; }
.lk-editor.is-tall { min-height: 280px; max-height: 560px; }
.lk-editor .cm-editor { color: var(--ink); }
.lk-editor .cm-activeLine, .lk-editor .cm-activeLineGutter { background: rgb(var(--c-ink) / .04); }
.lk-bar { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; padding: 8px; border-top: 1px solid var(--line); background: var(--card); }
.lk-keys { margin-left: auto; font-size: 12px; color: var(--muted); }
.lk-hint { margin: 10px 0 0; padding: 8px 12px; border-radius: 10px; background: #e0f2fe; color: #075985; }
.lk-feedback { position: relative; display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-top: 10px; padding: 10px 14px; border-radius: 12px; }
.lk-feedback.is-ok { background: #dcfce7; color: #14532d; animation: lk-pop .35s ease-out; }
.lk-feedback.is-bad { background: #fee2e2; color: #7f1d1d; }
@keyframes lk-pop { from { transform: scale(.96); opacity: .4; } }
.lk-burst { position: absolute; left: 24px; top: 50%; pointer-events: none; }
.lk-burst i { position: absolute; width: 8px; height: 8px; border-radius: 2px; background: hsl(var(--h) 90% 55%); animation: lk-fly .85s ease-out forwards; transform: rotate(var(--a)); }
@keyframes lk-fly { to { transform: rotate(var(--a)) translateY(-60px) scale(.3); opacity: 0; } }

/* output */
.lk-out { margin-top: 12px; min-width: 0; }
.lk-out:empty { display: none; }
.lk-out > * + * { margin-top: 8px; }
.lk-empty { margin: 0; color: var(--muted); font-size: 14px; }
.lk-text, .lk-value, .lk-gen { margin: 0; padding: 10px 12px; border-radius: 10px; background: var(--soft); font: 13px/1.5 "JetBrains Mono", ui-monospace, monospace;
  white-space: pre-wrap; overflow-x: auto; overflow-wrap: anywhere; }
.lk-gen { background: #0f172a; color: #e2e8f0; }
.lk-error { display: flex; flex-direction: column; gap: 4px; padding: 10px 12px; border-radius: 10px; background: #fee2e2; color: #7f1d1d; font-size: 14px; }
.lk-error b { font-family: "JetBrains Mono", ui-monospace, monospace; font-weight: 600; font-size: 13px; white-space: pre-wrap; }
.lk-table { overflow-x: auto; max-width: 100%; }
#main .lk-table table { width: auto; border-collapse: collapse; font-size: 13px; }
#main .lk-table th { position: static; padding: 5px 10px; background: var(--teal-tint); color: var(--ink); font-size: 13px; text-transform: none; letter-spacing: 0; text-align: left; }
.lk-table td { padding: 4px 10px; border-bottom: 1px solid var(--line); white-space: nowrap; }
.lk-table tr:hover td { background: var(--soft); }

@media (max-width: 900px) {
  .lk-learn, .lk-grid2, .lk-grid-side { grid-template-columns: minmax(0, 1fr); }
  .lk-list { position: static; max-height: none; display: grid; grid-template-columns: repeat(auto-fill, minmax(230px, 1fr)); gap: 0 14px; }
}
@media (max-width: 520px) { .lk-keys { display: none; } }

/* homework: the tutor's picker and the student's pins */
.lk-assign { margin-bottom: 12px; }
.lk-assign.is-on { display: grid; gap: 8px; padding: 10px; border: 1px dashed var(--teal); border-radius: 12px; background: var(--teal-tint); font-size: 13px; }
.lk-assign p { margin: 0; }
.lk-assign input { width: 100%; padding: 5px 8px; border: 1px solid var(--line); border-radius: 8px; background: var(--card); color: var(--ink); font-size: 13px; }
.lk-assign label input { width: auto; margin-left: 4px; }
.lk-assign-btns { display: flex; gap: 6px; }
.lk-item.is-picked { border-color: var(--teal); background: var(--teal-tint); }
.lk-pin { font-size: 12px; }

/* lessons with several exercises, a quick check and common mistakes */
.lk-steps { display: flex; flex-wrap: wrap; gap: 8px; margin: 4px 0 10px; }
.lk-step { display: flex; flex-direction: column; align-items: flex-start; padding: 7px 14px; border: 1px solid var(--line); border-radius: 12px; background: var(--card); color: var(--ink); cursor: pointer; font-weight: 600; font-size: 14px; }
.lk-step small { font-weight: 500; font-size: 11px; color: var(--muted); }
.lk-step.is-on { border-color: var(--teal); box-shadow: 0 0 0 2px var(--teal-tint); }
.lk-step.is-done small { color: #b45309; }
.lk-dots { letter-spacing: 1px; color: #d97706; font-size: 11px; }
.lk-quiz { display: grid; gap: 10px; margin: 0 0 12px; max-width: 820px; }
.lk-q { padding: 10px 14px; border-radius: 12px; border: 1px solid var(--line); background: var(--card); }
.lk-q p { margin: 0 0 8px; }
.lk-q-opts { display: flex; flex-wrap: wrap; gap: 6px; }
.lk-q-opt { padding: 5px 12px; border: 1px solid var(--line); border-radius: 999px; background: var(--paper); color: var(--ink); cursor: pointer; font-size: 14px; }
.lk-q-opt:hover:not(:disabled) { border-color: var(--teal); }
.lk-q-opt.is-right { border-color: #16a34a; background: #dcfce7; color: #14532d; }
.lk-q-opt.is-wrong { border-color: #dc2626; background: #fee2e2; color: #7f1d1d; text-decoration: line-through; }
.lk-q-why { margin: 8px 0 0 !important; font-size: 14px; }
.lk-mistakes { margin: 0 0 14px; padding: 10px 14px; max-width: 820px; border-radius: 12px; background: #fff1f2; color: #881337; font-size: 14px; }
.lk-mistakes ul { margin: 4px 0 0; padding-left: 20px; list-style: disc; }
.lk-try { display: flex; gap: 6px; margin: -4px 0 10px; }
.lk-try-out { margin: -4px 0 12px; padding: 8px 12px; border-radius: 10px; background: var(--soft); font: 13px/1.5 ui-monospace, monospace; white-space: pre-wrap; max-width: 820px; }