/* Locator Lab: an inspector on a notebook page. One signal colour for
   matches, green/red only for survive/break. */

:root {
  --paper: #edf0f3;
  --panel: #f8f9fb;
  --ink: #14181d;
  --muted: #5a636e;
  --rule: #cfd5dc;
  --rule-soft: #e1e5ea;
  --hit: #1f6fbf;
  --hit-fill: rgba(111, 168, 220, 0.35);
  --good: #1e7a3c;
  --good-bg: #ddefe2;
  --bad: #b3261e;
  --bad-bg: #f6e0de;
  --warn: #8a5a00;
  --warn-bg: #f3e8cf;
  --code-bg: #e2e6eb;
  --tag: #14181d;
  --tag-fg: #f8f9fb;
  --shadow: 0 1px 0 rgba(20, 24, 29, 0.06);
  --sans: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;
  --gutter: 16px;
  --radius: 6px;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #0f1216;
    --panel: #161a1f;
    --ink: #e3e7ec;
    --muted: #949eaa;
    --rule: #2a3037;
    --rule-soft: #1f242a;
    --hit: #7ab6ec;
    --hit-fill: rgba(111, 168, 220, 0.26);
    --good: #6cc583;
    --good-bg: #16291c;
    --bad: #ff8b80;
    --bad-bg: #361b19;
    --warn: #e5b453;
    --warn-bg: #30260f;
    --code-bg: #1d2228;
    --tag: #e3e7ec;
    --tag-fg: #0f1216;
    --shadow: none;
    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --paper: #0f1216;
  --panel: #161a1f;
  --ink: #e3e7ec;
  --muted: #949eaa;
  --rule: #2a3037;
  --rule-soft: #1f242a;
  --hit: #7ab6ec;
  --hit-fill: rgba(111, 168, 220, 0.26);
  --good: #6cc583;
  --good-bg: #16291c;
  --bad: #ff8b80;
  --bad-bg: #361b19;
  --warn: #e5b453;
  --warn-bg: #30260f;
  --code-bg: #1d2228;
  --tag: #e3e7ec;
  --tag-fg: #0f1216;
  --shadow: none;
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; scroll-padding-top: 72px; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 16px/1.6 var(--sans);
  overflow-x: hidden;
}

a { color: inherit; text-underline-offset: 3px; }
code, pre, textarea, .mono-input { font-family: var(--mono); }
button { font: inherit; color: inherit; }
:focus-visible { outline: 2px solid var(--hit); outline-offset: 2px; }

.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

.skip { position: absolute; left: -9999px; }
.skip:focus { left: var(--gutter); top: 8px; z-index: 10; background: var(--panel); padding: 6px 10px; }

/* ---------- Top bar ---------- */

.top {
  position: sticky; top: env(safe-area-inset-top, 0px); z-index: 5;
  display: flex; align-items: center; gap: 16px;
  padding: 10px var(--gutter);
  background: color-mix(in srgb, var(--paper) 92%, transparent);
  backdrop-filter: saturate(1.2) blur(6px);
  border-bottom: 1px solid var(--rule);
}

.mark {
  display: inline-flex; align-items: center; gap: 8px;
  font: 600 15px/1 var(--mono); text-decoration: none; letter-spacing: -0.01em;
}
.mark-box {
  width: 14px; height: 14px;
  border: 1.5px solid var(--hit); background: var(--hit-fill); border-radius: 2px;
}
.mark-dim { color: var(--muted); font-weight: 400; }

.top-nav { display: none; gap: 18px; margin-left: 12px; font-size: 14px; }
.top-nav a { color: var(--muted); text-decoration: none; }
.top-nav a:hover { color: var(--ink); }

.top-actions { margin-left: auto; display: flex; align-items: center; gap: 8px; }

.seg { display: inline-flex; border: 1px solid var(--rule); border-radius: var(--radius); overflow: hidden; }
.seg button {
  border: 0; background: transparent; padding: 4px 9px; cursor: pointer;
  font: 500 12px/1.4 var(--mono); color: var(--muted);
}
.seg button[aria-pressed="true"] { background: var(--ink); color: var(--paper); }

.icon-toggle {
  display: grid; place-items: center; width: 30px; height: 30px; padding: 0;
  border: 1px solid var(--rule); border-radius: var(--radius); background: transparent; cursor: pointer;
}
.icon-toggle svg { width: 15px; height: 15px; fill: currentColor; }

/* ---------- Intro ---------- */

.intro { max-width: 1240px; margin: 0 auto; padding: 44px var(--gutter) 28px; }
.eyebrow { margin: 0 0 14px; font: 500 12px/1.4 var(--mono); color: var(--muted); text-transform: uppercase; letter-spacing: 0.06em; }
.intro h1 {
  margin: 0; max-width: 17ch;
  font-size: clamp(2rem, 6.4vw, 3.6rem); line-height: 1.04; letter-spacing: -0.03em; font-weight: 700;
}
.lead { max-width: 62ch; margin: 18px 0 0; color: var(--muted); font-size: 1.05rem; }

.how { list-style: none; display: flex; flex-wrap: wrap; gap: 8px 22px; margin: 26px 0 0; padding: 0; font-size: 14px; }
.how li { display: flex; align-items: baseline; gap: 8px; }
.how li span:first-child { font: 500 12px var(--mono); color: var(--hit); }

/* ---------- Layout ---------- */

.page-grid {
  max-width: 1240px; margin: 0 auto; padding: 0 var(--gutter) 40px;
  display: grid; gap: 28px;
  grid-template-columns: minmax(0, 1fr);
}

.block { min-width: 0; padding-top: 28px; border-top: 1px solid var(--ink); }
.block-head { display: flex; align-items: baseline; gap: 12px; }
.block-head h2 { margin: 0; font-size: 1.45rem; letter-spacing: -0.02em; }
.num { font: 500 13px var(--mono); color: var(--hit); }
.block-lead { max-width: 64ch; margin: 8px 0 18px; color: var(--muted); }

@media (min-width: 1000px) {
  .top-nav { display: flex; }
  .page-grid { grid-template-columns: minmax(0, 1fr) minmax(380px, 460px); column-gap: 40px; }
  .block { grid-column: 1; }
  .bench { grid-column: 2; grid-row: 1 / span 4; align-self: start; position: sticky; top: 64px; }
}

/* ---------- Buttons, chips, inputs ---------- */

.button {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 7px 13px; border: 1px solid var(--ink); border-radius: var(--radius);
  background: var(--ink); color: var(--paper); cursor: pointer;
  font: 500 14px/1.3 var(--sans);
}
.button:hover { opacity: 0.88; }
.button-quiet { background: transparent; color: var(--ink); border-color: var(--rule); }
.button-small { padding: 3px 9px; font-size: 12px; }

.chips { display: flex; flex-wrap: wrap; gap: 6px; }
.chip {
  max-width: 100%;
  padding: 4px 9px; border: 1px solid var(--rule); border-radius: 999px;
  background: var(--panel); cursor: pointer; text-align: left;
  font: 12px/1.4 var(--mono); color: var(--ink);
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.chip:hover { border-color: var(--ink); }
.chip[aria-pressed="true"] { background: var(--ink); color: var(--paper); border-color: var(--ink); }

.field-label { display: block; margin-bottom: 6px; font: 500 12px var(--mono); color: var(--muted); text-transform: uppercase; letter-spacing: 0.06em; }

.editor {
  display: flex; gap: 10px; align-items: flex-start;
  padding: 12px 14px; background: var(--panel);
  border: 1px solid var(--rule); border-radius: var(--radius); box-shadow: var(--shadow);
}
.editor:focus-within { border-color: var(--ink); }
.prompt { font: 600 15px/1.55 var(--mono); color: var(--hit); }
.editor textarea {
  flex: 1; min-width: 0; resize: vertical; min-height: 3.2em;
  border: 0; outline: 0; background: transparent; color: var(--ink);
  font-size: 14.5px; line-height: 1.55;
}

.examples { display: flex; align-items: baseline; gap: 8px; margin-top: 10px; font-size: 13px; color: var(--muted); }
.examples .chips { min-width: 0; }
@media (max-width: 640px) {
  .examples { flex-direction: column; gap: 6px; }
  .examples .chips { flex-wrap: nowrap; overflow-x: auto; width: 100%; padding-bottom: 4px; scrollbar-width: thin; }
  .examples .chip { flex: none; max-width: none; }
}

.mono-input {
  flex: 1; min-width: 0; padding: 8px 10px;
  border: 1px solid var(--rule); border-radius: var(--radius); background: var(--panel); color: var(--ink);
  font-size: 13.5px;
}
.mono-input:focus { border-color: var(--ink); outline: 0; }

.row-actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 14px; }

/* ---------- Playground result ---------- */

.result { margin-top: 16px; }
.count-line { display: flex; align-items: baseline; gap: 10px; flex-wrap: wrap; font: 600 15px var(--mono); }
.count-line .pill { font-weight: 500; }
.pill {
  display: inline-block; padding: 1px 8px; border-radius: 999px;
  font: 500 12px/1.6 var(--mono); white-space: nowrap;
}
.pill-good { background: var(--good-bg); color: var(--good); }
.pill-bad { background: var(--bad-bg); color: var(--bad); }
.pill-warn { background: var(--warn-bg); color: var(--warn); }
.pill-muted { background: var(--code-bg); color: var(--muted); }

.error-box, .strict-box {
  margin: 12px 0 0; padding: 10px 12px; border-left: 3px solid var(--bad);
  background: var(--bad-bg); color: var(--ink); border-radius: 0 var(--radius) var(--radius) 0;
  font-size: 14px;
}
.strict-box strong { display: block; margin-bottom: 6px; color: var(--bad); font-size: 13px; }
.strict-box pre, .error-box pre {
  margin: 0; white-space: pre-wrap; word-break: break-word; font-size: 12.5px; line-height: 1.5;
}
.error-box .caret { color: var(--bad); }
.error-box p { margin: 6px 0 0; }

.action-note { margin: 10px 0 0; font-size: 13px; color: var(--muted); }

.notes { list-style: none; margin: 14px 0 0; padding: 0; display: grid; gap: 6px; }
.notes li { display: grid; grid-template-columns: 14px 1fr; gap: 8px; font-size: 14px; line-height: 1.5; }
.notes li::before { content: ""; width: 8px; height: 8px; margin-top: 7px; border-radius: 50%; background: var(--muted); }
.notes .good::before { background: var(--good); }
.notes .ok::before { background: var(--muted); }
.notes .info::before { background: transparent; border: 1.5px solid var(--muted); }
.notes .warn::before { background: var(--warn); }
.notes .bad::before { background: var(--bad); }

/* ---------- Bench (sample app) ---------- */

.bench {
  min-width: 0; padding: 12px; background: var(--panel);
  border: 1px solid var(--rule); border-radius: 10px; box-shadow: var(--shadow);
}
.bench-bar { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.bench-title { font-size: 14px; }
.bench-title span { color: var(--muted); font: 12px var(--mono); }
.refactors { margin-top: 10px; display: grid; gap: 6px; }
.refactors-label { font: 500 11px var(--mono); color: var(--muted); text-transform: uppercase; letter-spacing: 0.06em; }
.refactor-hint { min-height: 1.4em; margin: 8px 0; font-size: 12.5px; color: var(--muted); }

.frame { border: 1px solid var(--rule); border-radius: 8px; overflow: hidden; background: var(--panel); }
.frame-chrome {
  display: flex; align-items: center; gap: 5px; padding: 7px 10px;
  background: var(--code-bg); border-bottom: 1px solid var(--rule);
  font: 11px var(--mono); color: var(--muted);
}
.frame-chrome i { width: 8px; height: 8px; border-radius: 50%; background: var(--rule); }
.frame-chrome span { margin-left: 8px; padding: 1px 8px; border-radius: 4px; background: var(--panel); }
.frame-body { position: relative; }

.overlay { position: absolute; inset: 0; pointer-events: none; }
.hit {
  position: absolute; border: 1.5px solid var(--hit); background: var(--hit-fill); border-radius: 3px;
  animation: hit-in 160ms ease-out;
}
.hit-tag {
  position: absolute; left: -2px; top: -18px; padding: 0 5px;
  background: var(--tag); color: var(--tag-fg); font: 500 10px/16px var(--mono); border-radius: 3px 3px 3px 0;
  white-space: nowrap;
}
.hit.compact .hit-tag { top: auto; bottom: -18px; border-radius: 0 3px 3px 3px; }
@keyframes hit-in { from { opacity: 0; transform: scale(1.04); } }
@media (prefers-reduced-motion: reduce) { .hit { animation: none; } }

.baseline { position: absolute; left: -10000px; top: 0; width: 460px; visibility: visible; }

/* ---------- Break table ---------- */

.br-summary { margin: 0 0 4px; font: 500 14px var(--mono); }
#break-hint { margin: 0 0 12px; min-height: 1.2em; }
.refactors-inline { margin: 0 0 14px; }
@media (min-width: 1000px) { .refactors-inline { display: none; } }
.table-wrap { overflow-x: auto; border: 1px solid var(--rule); border-radius: var(--radius); background: var(--panel); }
.break-table { width: 100%; border-collapse: collapse; font-size: 13px; }
.break-table th {
  text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--rule);
  font: 500 11px var(--mono); color: var(--muted); text-transform: uppercase; letter-spacing: 0.05em; white-space: nowrap;
}
.break-table td { padding: 9px 10px; border-bottom: 1px solid var(--rule-soft); vertical-align: top; }
.break-table tr:last-child td { border-bottom: 0; }
.break-table code { font-size: 12.5px; word-break: break-word; }
.break-table .loc-btn { all: unset; cursor: pointer; }
.break-table .loc-btn:hover code { text-decoration: underline; text-underline-offset: 3px; }
.break-table .loc-btn:focus-visible { outline: 2px solid var(--hit); }
.break-table .n { font-family: var(--mono); color: var(--muted); white-space: nowrap; }
.verdict-hint { font-size: 13px; color: var(--bad); }
.remove {
  border: 0; background: none; cursor: pointer; color: var(--muted); padding: 0 4px; font-size: 16px; line-height: 1;
}
.remove:hover { color: var(--bad); }

@media (max-width: 640px) {
  .break-table thead { display: none; }
  .break-table, .break-table tbody, .break-table tr, .break-table td { display: block; }
  .break-table tr { position: relative; padding: 10px 34px 10px 12px; border-bottom: 1px solid var(--rule-soft); }
  .break-table tr:last-child { border-bottom: 0; }
  .break-table td { padding: 2px 0; border: 0; }
  .break-table td.n { display: inline-block; margin-right: 10px; }
  .break-table td.n::before { content: attr(data-label) " "; }
  .break-table td:last-child { position: absolute; top: 8px; right: 8px; }
}

.add-row { display: flex; gap: 8px; margin-top: 12px; }
.lesson {
  margin: 18px 0 0; padding: 12px 14px; border: 1px dashed var(--rule); border-radius: var(--radius);
  font-size: 14px; color: var(--muted);
}

/* ---------- Ladder ---------- */

.ladder { list-style: none; margin: 0; padding: 0; counter-reset: rung; }
.rung {
  display: grid; grid-template-columns: 34px minmax(0, 1fr); gap: 0 12px;
  padding: 16px 0; border-bottom: 1px solid var(--rule-soft);
}
.rung:first-child { padding-top: 4px; }
.rung-num { font: 600 13px/1.9 var(--mono); color: var(--hit); }
.rung h3 { margin: 0; font: 600 16px/1.6 var(--mono); }
.rung-when { margin: 2px 0 10px; font-size: 14px; color: var(--muted); }
.rung-when b { font-weight: 500; color: var(--ink); }
.ex { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 4px 10px; align-items: start; margin-top: 8px; }
.ex-code {
  display: flex; gap: 8px; align-items: baseline; padding: 7px 10px; border-radius: var(--radius);
  background: var(--code-bg); min-width: 0;
}
.ex-code code { font-size: 12.5px; word-break: break-word; }
.ex-code .pill { flex: none; }
.ex p { grid-column: 1 / -1; margin: 0 0 2px; font-size: 13.5px; color: var(--muted); }

/* ---------- Quiz ---------- */

.quiz {
  padding: 16px; background: var(--panel); border: 1px solid var(--rule); border-radius: 10px; box-shadow: var(--shadow);
}
.quiz-top { display: flex; justify-content: space-between; gap: 8px; font: 500 12px var(--mono); color: var(--muted); }
.quiz-progress { display: flex; gap: 3px; margin-top: 8px; }
.quiz-progress i { flex: 1; height: 3px; background: var(--rule); border-radius: 2px; }
.quiz-progress i.done { background: var(--ink); }
.quiz-progress i.right { background: var(--good); }
.quiz-progress i.wrong { background: var(--bad); }
.quiz h3 { margin: 14px 0 8px; font-size: 1.1rem; }
.target-label { margin-right: 6px; font-size: 14px; font-weight: 500; color: var(--muted); }
.quiz pre {
  margin: 0 0 14px; padding: 10px 12px; background: var(--code-bg); border-radius: var(--radius);
  font-size: 12.5px; line-height: 1.5; white-space: pre-wrap; word-break: break-word;
}
.options { display: grid; gap: 8px; }
.option {
  display: grid; grid-template-columns: 22px minmax(0, 1fr); gap: 8px; align-items: start;
  width: 100%; padding: 10px 12px; text-align: left; cursor: pointer;
  background: transparent; border: 1px solid var(--rule); border-radius: var(--radius);
}
.option:hover:not([disabled]) { border-color: var(--ink); }
.option[disabled] { cursor: default; }
.option .key { font: 600 12px/1.6 var(--mono); color: var(--muted); }
.option code { font-size: 12.5px; line-height: 1.6; word-break: break-word; }
.option .meta { grid-column: 2; display: flex; gap: 6px; flex-wrap: wrap; margin-top: 4px; }
.option.right { border-color: var(--good); background: var(--good-bg); }
.option.wrong { border-color: var(--bad); background: var(--bad-bg); }
.feedback { margin: 14px 0 0; font-size: 14.5px; }
.feedback strong { margin-right: 4px; }
.quiz-actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 14px; }
.score { font: 600 1.6rem/1.2 var(--mono); margin: 8px 0; }

/* ---------- Footer ---------- */

.foot {
  max-width: 1240px; margin: 0 auto; padding: 24px var(--gutter) 48px;
  border-top: 1px solid var(--rule); font-size: 13px; color: var(--muted);
}
.foot p { max-width: 70ch; margin: 0 0 10px; }
.foot-links { display: flex; flex-wrap: wrap; gap: 6px 18px; }