/* Programming+: a lab notebook for algorithms. Tokens first; light and dark; IBM Plex in two voices. */
:root {
    --paper: #f7f8fa;
    --paper-2: #ffffff;
    --paper-3: #eef0f4;
    --ink: #16191f;
    --ink-2: #5c6370;
    --ink-3: #8a919c;
    --line: #dde1e8;
    --line-2: #c9cfd8;
    --accent: #2f5bea;
    --accent-ink: #ffffff;
    --accent-bg: #e7edfd;
    --marker: #f6c453;
    --marker-bg: #fff3cf;
    --last-bg: #e3ecfb;
    --ok: #1f9d63;
    --ok-bg: #e2f5ea;
    --warn: #b5700d;
    --warn-bg: #fdf0d6;
    --err: #d64545;
    --err-bg: #fbe3e3;
    --mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
    --sans: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
    --r: 6px;
    --r-lg: 10px;
    --shadow: 0 10px 30px rgba(22, 25, 31, .10);
    --tok-keyword: #1d46c7;
    --tok-builtin: #7a3fc4;
    --tok-string: #a8580d;
    --tok-number: #0f7b6c;
    --tok-comment: #8a919c;
    --tok-label: #b4247a;
    color-scheme: light;
}
:root[data-theme="dark"] {
    --paper: #141821; --paper-2: #1b2029; --paper-3: #232935; --ink: #e9ecf1; --ink-2: #a7afbc; --ink-3: #7c8594; --line: #2c333f; --line-2: #3b4452;
    --accent: #8db0ff; --accent-ink: #0f1626; --accent-bg: #1f2b4a; --marker: #f0c05a; --marker-bg: #4a3c12; --last-bg: #1f3350;
    --ok: #5fd39a; --ok-bg: #16331f; --warn: #f0b860; --warn-bg: #3a2c12; --err: #ff8585; --err-bg: #3f1b1b;
    --shadow: 0 10px 30px rgba(0, 0, 0, .45);
    --tok-keyword: #8db0ff; --tok-builtin: #c9a7ff; --tok-string: #f2b56b; --tok-number: #5fd3c6; --tok-comment: #7c8594; --tok-label: #f49ac2;
    color-scheme: dark;
}
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]):not([data-theme="dark"]) {
        --paper: #141821; --paper-2: #1b2029; --paper-3: #232935; --ink: #e9ecf1; --ink-2: #a7afbc; --ink-3: #7c8594; --line: #2c333f; --line-2: #3b4452;
        --accent: #8db0ff; --accent-ink: #0f1626; --accent-bg: #1f2b4a; --marker: #f0c05a; --marker-bg: #4a3c12; --last-bg: #1f3350;
        --ok: #5fd39a; --ok-bg: #16331f; --warn: #f0b860; --warn-bg: #3a2c12; --err: #ff8585; --err-bg: #3f1b1b;
        --shadow: 0 10px 30px rgba(0, 0, 0, .45);
        --tok-keyword: #8db0ff; --tok-builtin: #c9a7ff; --tok-string: #f2b56b; --tok-number: #5fd3c6; --tok-comment: #7c8594; --tok-label: #f49ac2;
        color-scheme: dark;
    }
}

/* legacy aliases used by older rules */
:root { --bg: var(--paper); --bg-2: var(--paper-2); --bg-3: var(--paper-3); --fg: var(--ink); --fg-2: var(--ink-2); --note: var(--ink-3); --current: var(--marker-bg); --last: var(--last-bg); --radius: var(--r-lg); }

* { box-sizing: border-box; }
html, body { height: 100%; }
body { margin: 0; background: var(--paper); color: var(--ink); font: 14px/1.5 var(--sans); -webkit-font-smoothing: antialiased; }
body.is-embed { background: var(--paper-2); }
#app { height: 100%; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3, h4 { margin: 0 0 .4em; font-weight: 600; line-height: 1.2; letter-spacing: -.01em; }
h4 { font-size: 13px; color: var(--ink-2); font-weight: 600; margin: 14px 0 6px; letter-spacing: 0; }
code, .mono { font-family: var(--mono); font-size: 12.5px; }
.muted { color: var(--ink-2); }
.small { font-size: 12px; }
.hint { font-size: 12.5px; color: var(--ink-2); background: var(--paper-3); border-left: 3px solid var(--accent); padding: 6px 10px; border-radius: 4px; margin: 0 0 10px; }
.math { font-family: "STIX Two Math", "Cambria Math", var(--mono); font-size: 13px; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { transition: none !important; animation: none !important; } }

/* ---------- controls ---------- */
.btn { font: inherit; font-size: 13px; padding: 5px 11px; border: 1px solid var(--line-2); border-radius: var(--r); background: var(--paper-2); color: var(--ink); cursor: pointer; transition: border-color .12s, background .12s; }
.btn:hover { border-color: var(--ink-3); }
.btn-primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); font-weight: 600; }
.btn-primary:hover { filter: brightness(1.06); }
.btn-quiet { background: transparent; border-color: transparent; color: var(--ink-2); }
.btn-quiet:hover { background: var(--paper-3); border-color: transparent; }
.btn-small { padding: 2px 8px; font-size: 12px; }
.btn-option { margin: 4px 6px 0 0; background: var(--accent-bg); border-color: transparent; }
.btn.on { background: var(--accent-bg); border-color: var(--accent); color: var(--accent); }
.linkish { background: none; border: 0; padding: 0; color: var(--accent); cursor: pointer; font: inherit; text-decoration: underline dotted; }
.select, .input { font: inherit; font-size: 13px; padding: 5px 8px; border: 1px solid var(--line-2); border-radius: var(--r); background: var(--paper-2); color: var(--ink); }
.input { min-width: 240px; }
.tool-label { display: inline-flex; align-items: center; gap: 6px; color: var(--ink-2); font-size: 12.5px; }
.badge { display: inline-block; font-size: 11.5px; padding: 1px 8px; border-radius: 10px; font-weight: 600; margin-right: 6px; line-height: 1.6; }
.badge-proved { background: var(--ok-bg); color: var(--ok); }
.badge-broken { background: var(--err-bg); color: var(--err); }
.badge-open { background: var(--warn-bg); color: var(--warn); }
.badge-gen { background: var(--paper-3); color: var(--ink-2); }
.chip { display: inline-block; font-size: 11.5px; padding: 1px 8px; border-radius: 10px; background: var(--paper-3); color: var(--ink-2); margin-right: 4px; line-height: 1.6; }
.chip-saved { background: var(--ok-bg); color: var(--ok); }
.chip-level-intro { background: var(--ok-bg); color: var(--ok); }
.chip-level-advanced { background: var(--warn-bg); color: var(--warn); }
.chip-tag { background: transparent; border: 1px solid var(--line); }
kbd { font-family: var(--mono); font-size: 11px; padding: 1px 6px; border: 1px solid var(--line-2); border-bottom-width: 2px; border-radius: 4px; background: var(--paper-2); color: var(--ink); }

/* ---------- top bar ---------- */
.toolbar { display: flex; align-items: center; gap: 10px; padding: 8px 14px; border-bottom: 1px solid var(--line); background: var(--paper-2); flex-wrap: wrap; }
.brand { display: inline-flex; align-items: center; gap: 8px; font-weight: 700; font-size: 15px; color: var(--ink); margin-right: 6px; white-space: nowrap; letter-spacing: -.01em; }
.brand:hover { text-decoration: none; }
.brand-mark { min-width: 22px; height: 22px; padding: 0 4px; border-radius: 6px; background: var(--ink); color: var(--marker); display: inline-grid; place-items: center; font-family: var(--mono); font-size: 11px; font-weight: 700; }
.spacer { flex: 1; }
.icon-btn { width: 32px; height: 32px; padding: 0; display: inline-grid; place-items: center; font-size: 15px; }

/* ---------- home ---------- */
.home { max-width: 1120px; margin: 0 auto; padding: 0 24px 64px; }
.home-nav { display: flex; align-items: center; gap: 16px; padding: 18px 0 8px; }
.home-nav a { color: var(--ink-2); font-size: 13.5px; }
.hero { display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr); gap: 40px; align-items: center; padding: 36px 0 44px; border-bottom: 1px solid var(--line); }
.hero h1 { font-size: 44px; line-height: 1.08; letter-spacing: -.025em; margin: 0 0 16px; max-width: 14ch; }
.hero .lede { font-size: 17px; color: var(--ink-2); margin: 0 0 22px; max-width: 48ch; line-height: 1.5; }
.hero-actions { display: flex; gap: 10px; flex-wrap: wrap; }
.hero-actions .btn { padding: 9px 16px; font-size: 14px; }
.demo { border: 1px solid var(--line); border-radius: var(--r-lg); background: var(--paper-2); overflow: hidden; box-shadow: var(--shadow); }
.demo-head { display: flex; align-items: center; gap: 8px; padding: 8px 12px; border-bottom: 1px solid var(--line); font-size: 12.5px; color: var(--ink-2); }
.demo-head b { color: var(--ink); font-weight: 600; }
.demo-code { margin: 0; padding: 12px 14px; font-family: var(--mono); font-size: 12.5px; line-height: 1.7; white-space: pre; overflow-x: auto; }
.demo-line { display: block; padding: 0 6px; margin: 0 -6px; border-radius: 3px; }
.demo-line.cur { background: var(--marker-bg); box-shadow: inset 3px 0 var(--marker); }
.demo-foot { display: grid; grid-template-columns: 1fr auto; gap: 10px; align-items: center; padding: 10px 12px; border-top: 1px solid var(--line); background: var(--paper); }
.demo-vars { display: flex; gap: 14px; font-family: var(--mono); font-size: 12.5px; flex-wrap: wrap; }
.demo-vars b { font-weight: 600; }
.demo-vars .v-new { background: var(--last-bg); border-radius: 3px; padding: 0 4px; }
.demo-ctl { display: flex; gap: 4px; }
.ruler { display: inline-flex; gap: 2px; font-family: var(--mono); }
.ruler-cell { display: inline-flex; flex-direction: column; align-items: center; min-width: 20px; line-height: 1.1; border-radius: 3px; padding: 2px 1px; }
.ruler-cell b { font-weight: 600; font-size: 13px; }
.ruler-cell i { font-style: normal; font-size: 9.5px; color: var(--ink-3); }
.ruler-cell.read { background: var(--marker-bg); box-shadow: inset 0 -2px var(--marker); }
.ruler-cell.wrote { background: var(--last-bg); }
.how { padding: 36px 0 8px; }
.how h2, .home-h2, .reference h2 { font-size: 24px; letter-spacing: -.02em; margin-bottom: 6px; }
.how > p, .home-sub { color: var(--ink-2); max-width: 64ch; margin: 0 0 18px; }
.ways { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 10px; }
.way { border: 1px solid var(--line); border-radius: var(--r-lg); background: var(--paper-2); padding: 12px 12px 10px; min-width: 0; }
.way h3 { font-size: 14px; margin: 0 0 2px; }
.way p { margin: 0 0 8px; font-size: 12.5px; color: var(--ink-2); min-height: 3.6em; }
.way pre { margin: 0; font-family: var(--mono); font-size: 11px; line-height: 1.5; white-space: pre; overflow: hidden; color: var(--ink); border-top: 1px solid var(--line); padding-top: 8px; }
.problems-head { display: flex; align-items: baseline; gap: 16px; flex-wrap: wrap; margin: 40px 0 12px; }
.filters { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 14px; }
.filter { font: inherit; font-size: 12.5px; padding: 3px 10px; border-radius: 12px; border: 1px solid var(--line-2); background: var(--paper-2); color: var(--ink-2); cursor: pointer; }
.filter.on { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.search { min-width: 220px; }
.home-group { font-size: 13px; color: var(--ink-2); margin: 20px 0 8px; font-weight: 600; }
.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 12px; }
.card { display: block; color: inherit; background: var(--paper-2); border: 1px solid var(--line); border-radius: var(--r-lg); padding: 14px 16px 12px; transition: border-color .12s; }
.card:hover { border-color: var(--accent); text-decoration: none; }
.card h3 { font-size: 15px; margin-bottom: 4px; }
.card p { margin: 0 0 10px; color: var(--ink-2); font-size: 13px; }
.card-meta, .card-foot { display: flex; flex-wrap: wrap; gap: 2px; }
.card-meta { margin-bottom: 6px; }
.home-foot { margin-top: 40px; color: var(--ink-2); font-size: 12.5px; border-top: 1px solid var(--line); padding-top: 14px; }

/* ---------- shell ---------- */
.shell { display: flex; flex-direction: column; height: 100%; }
.workspace { --split: 56%; flex: 1; min-height: 0; display: grid; grid-template-columns: minmax(240px, var(--split)) 6px minmax(300px, 1fr); }
.panes, .views { min-height: 0; display: flex; flex-direction: column; min-width: 0; }
.tabs { display: flex; gap: 2px; padding: 6px 10px 0; border-bottom: 1px solid var(--line); background: var(--paper); overflow-x: auto; align-items: flex-end; }
.tab { font: inherit; font-size: 13px; padding: 6px 12px; border: 1px solid transparent; border-bottom: 0; border-radius: var(--r) var(--r) 0 0; background: transparent; color: var(--ink-2); cursor: pointer; white-space: nowrap; }
.tab:hover { color: var(--ink); }
.tab.active { background: var(--paper-2); border-color: var(--line); color: var(--ink); font-weight: 600; margin-bottom: -1px; }
.tab-badge { display: inline-block; min-width: 16px; padding: 0 5px; margin-left: 6px; border-radius: 8px; font-size: 11px; font-weight: 600; }
.tab-badge.err { background: var(--err-bg); color: var(--err); }
.tab-badge.warn { background: var(--warn-bg); color: var(--warn); }
.tabs .spacer { flex: 1; }
.tab-toggle { margin-left: auto; font-size: 14px; padding: 4px 10px; }
.pane-split { --companion: 60%; flex: 1; min-height: 0; display: grid; grid-template-columns: minmax(0, 1fr); }
.pane-split.has-companion { grid-template-columns: minmax(0, var(--companion)) 6px minmax(0, 1fr); }
.pane-host { min-height: 0; display: flex; }
.pane-host .ed { flex: 1; }
.companion { min-height: 0; min-width: 0; display: flex; flex-direction: column; background: var(--paper); }
.companion-title { font-size: 12px; color: var(--ink-2); padding: 6px 10px; border-bottom: 1px solid var(--line); display: flex; justify-content: space-between; align-items: center; }
.companion .ed { flex: 1; font-size: 12px; }
.pane-head { display: flex; align-items: center; gap: 10px; padding: 6px 12px; border-bottom: 1px solid var(--line); background: var(--paper); font-size: 12px; flex-wrap: wrap; }
.pane-note { color: var(--ink-2); flex: 1; min-width: 160px; }
.setup-label { flex: 1; align-items: flex-start; }
.setup-label .setup-ta { flex: 1; margin: 0; }
.setup-ta { width: 100%; font-size: 12.5px; border: 1px solid var(--line-2); border-radius: var(--r); padding: 6px 8px; background: var(--paper-2); color: var(--ink); font-family: var(--mono); }
.tool-label.check { gap: 4px; cursor: pointer; }
.view-host { flex: 1; min-height: 0; overflow: auto; background: var(--paper-2); }
.view { padding: 12px 14px 24px; }
.splitter { background: var(--line); cursor: col-resize; position: relative; touch-action: none; }
.splitter::after { content: ''; position: absolute; inset: 0 -4px; }
.splitter:hover, .splitter.dragging, .splitter:focus-visible { background: var(--accent); outline: none; }
body.resizing { cursor: col-resize; user-select: none; }
body.resizing iframe, body.resizing textarea { pointer-events: none; }
.workspace.views-collapsed { grid-template-columns: minmax(0, 1fr) 6px 44px !important; }
.workspace.views-collapsed .views { overflow: hidden; }
.workspace.views-collapsed .view-tabs { flex-direction: column; align-items: stretch; padding: 6px 4px; height: 100%; border-bottom: 0; }
.workspace.views-collapsed .view-tabs .tab { writing-mode: vertical-rl; transform: rotate(180deg); border-radius: 0 6px 6px 0; padding: 10px 4px; font-size: 12px; }
.workspace.views-collapsed .view-tabs .tab-toggle { writing-mode: horizontal-tb; transform: none; margin: 0 0 6px; order: -1; }
.workspace.views-collapsed .view-tabs .spacer { display: none; }
.workspace.views-collapsed .view-host { display: none; }

/* ---------- editor ---------- */
.ed { position: relative; display: grid; grid-template-columns: auto 1fr; min-height: 160px; background: var(--paper-2); font-family: var(--mono); font-size: 13px; line-height: 20px; overflow: hidden; }
.ed-gutter { overflow: hidden; background: var(--paper); border-right: 1px solid var(--line); user-select: none; will-change: transform; padding-top: 8px; }
.ed-gline { display: grid; grid-template-columns: 14px auto 36px 14px; align-items: center; gap: 4px; height: 20px; padding: 0 6px; color: var(--ink-3); font-size: 11.5px; cursor: pointer; }
.ed-gline:hover .ed-num { color: var(--ink); }
.ed-num { text-align: right; }
.ed-hits { text-align: right; color: var(--ink-3); font-size: 10.5px; }
.ed-mark { cursor: pointer; font-size: 9px; }
.ed-gline-error .ed-mark { color: var(--err); }
.ed-gline-warning .ed-mark { color: var(--warn); }
.ed-gline-note .ed-mark { color: var(--ink-3); }
.ed-arrow { color: var(--accent); font-size: 10px; }
.ed-gcurrent { background: var(--marker-bg); }
.ed-gbreak .ed-num { color: var(--err); font-weight: 700; }
.ed-gbreak .ed-num::before { content: '●'; font-size: 8px; margin-right: 3px; vertical-align: middle; }
.ed-body { position: relative; overflow: hidden; }
.ed-pre, .ed-ta { margin: 0; padding: 8px 12px; font: inherit; line-height: inherit; white-space: pre; tab-size: 4; }
.ed-pre { position: absolute; inset: 0; pointer-events: none; will-change: transform; min-width: 100%; width: max-content; }
.ed-ta { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; outline: none; resize: none; background: transparent; color: transparent; caret-color: var(--ink); overflow: auto; }
.ed-ta::placeholder { color: var(--ink-3); opacity: .8; }
.ed-ta::selection { background: rgba(47, 91, 234, .22); }
.ed-ro .ed-ta { cursor: default; }
.ed-derived .ed-pre { opacity: .85; }
.ed-line { min-height: 20px; }
.ed-line-error { box-shadow: inset 0 -2px var(--err); }
.ed-line-warning { box-shadow: inset 0 -1px var(--warn); }
.ed-current { background: var(--marker-bg); box-shadow: inset 3px 0 var(--marker); }
.ed-last { background: var(--last-bg); }
.ed-linked { outline: 2px solid var(--accent); outline-offset: -2px; }
.ed-msg { font-style: italic; font-size: 11.5px; opacity: .9; }
.ed-msg-error { color: var(--err); }
.ed-msg-warning { color: var(--warn); }
.ed-msg-note { color: var(--ink-3); }
.tok-keyword { color: var(--tok-keyword); font-weight: 600; }
.tok-builtin { color: var(--tok-builtin); }
.tok-string { color: var(--tok-string); }
.tok-number { color: var(--tok-number); }
.tok-comment { color: var(--tok-comment); font-style: italic; }
.tok-label { color: var(--tok-label); font-weight: 600; }
.tok-op { color: var(--ink-2); }

/* ---------- step through ---------- */
.stepper { display: flex; align-items: center; gap: 6px; flex-wrap: wrap; margin-bottom: 6px; }
.stepper .btn { min-width: 34px; }
.stepper-slider { flex: 1; min-width: 120px; accent-color: var(--accent); }
.stepper-count { font-size: 12.5px; color: var(--ink-2); white-space: nowrap; font-variant-numeric: tabular-nums; }
.stepper-row2 { display: flex; align-items: center; gap: 6px; flex-wrap: wrap; margin-bottom: 8px; font-size: 12.5px; color: var(--ink-2); }
.speed { width: 90px; accent-color: var(--accent); }
.trace-status { font-size: 12.5px; color: var(--ink-2); min-height: 1.2em; margin-bottom: 6px; }
.trace-next { background: var(--marker-bg); border-left: 3px solid var(--marker); padding: 6px 10px; border-radius: 4px; margin-bottom: 10px; font-size: 13px; }
.trace-next .mono { font-size: 12.5px; }
.predict { background: var(--paper-3); border: 1px solid var(--line); border-radius: var(--r); padding: 8px 10px; margin-bottom: 10px; font-size: 13px; }
.predict-row { display: flex; gap: 6px; align-items: center; flex-wrap: wrap; margin-top: 6px; }
.predict-score { font-size: 12px; color: var(--ink-2); margin-left: auto; }
.predict-right { color: var(--ok); font-weight: 600; }
.predict-wrong { color: var(--err); font-weight: 600; }
.trace-output { background: var(--paper); border: 1px solid var(--line); border-radius: var(--r); padding: 8px 10px; margin: 10px 0 0; font-size: 12.5px; white-space: pre-wrap; font-family: var(--mono); }
.trace-cols { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
@media (max-width: 1100px) { .trace-cols { grid-template-columns: 1fr; } }
.trace-col { min-width: 0; }
.trace-empty { padding: 12px 0; }
.tbl { border-collapse: collapse; width: 100%; font-size: 12.5px; }
.tbl caption { text-align: left; font-weight: 600; font-size: 12px; color: var(--ink-2); padding: 4px 0; }
.tbl th { text-align: left; font-weight: 600; font-size: 11.5px; color: var(--ink-2); padding: 3px 6px; border-bottom: 1px solid var(--line); }
.tbl td { padding: 3px 6px; border-bottom: 1px solid var(--line); vertical-align: top; }
.trace-tbl tr { cursor: pointer; }
.trace-tbl tr:hover td { background: var(--paper-3); }
.row-last td { background: var(--last-bg); }
.row-next td { background: var(--marker-bg); }
.just-wrote td, .just-wrote { background: var(--last-bg); }
.about-to-read td { box-shadow: inset 3px 0 var(--marker); }
.vars-tbl { margin-bottom: 10px; }
.var-hist { color: var(--ink-3); font-size: 11.5px; }
.var-hist .linkish { color: var(--ink-2); }
.var-ruler { padding: 2px 6px 6px; }
.flags { display: flex; gap: 6px; }
.flag { font-family: var(--mono); font-size: 12px; padding: 2px 8px; border: 1px solid var(--line); border-radius: 4px; color: var(--ink-2); }
.flag.on { background: var(--accent-bg); color: var(--accent); border-color: transparent; font-weight: 600; }
.flag.just-wrote { outline: 2px solid var(--accent); }
.mem-region { margin-bottom: 8px; }
.mem-label { font-size: 11.5px; color: var(--ink-2); margin-bottom: 2px; font-family: var(--mono); }
.mem-cells { display: flex; flex-wrap: wrap; gap: 2px; }
.mem-cell { display: inline-flex; flex-direction: column; align-items: center; width: 26px; border: 1px solid var(--line); border-radius: 3px; font-family: var(--mono); line-height: 1.1; padding: 2px 0; }
.mem-cell b { font-weight: 600; font-size: 12px; }
.mem-cell i { font-style: normal; font-size: 9.5px; color: var(--ink-2); }
.mem-cell.touched { background: var(--marker-bg); border-color: var(--marker); }
.explain ul { margin: 4px 0 0; padding-left: 18px; }

/* ---------- other views ---------- */
.problems, .obligations, .failures, .facts { list-style: none; margin: 0; padding: 0; }
.problem { display: grid; grid-template-columns: 14px auto 1fr auto auto; gap: 8px; align-items: start; padding: 7px 0; border-bottom: 1px solid var(--line); font-size: 13px; }
.problem-sev { font-size: 10px; padding-top: 3px; }
.problem-error .problem-sev { color: var(--err); }
.problem-warning .problem-sev { color: var(--warn); }
.problem-note .problem-sev { color: var(--ink-3); }
.problem-guide { font-size: 12px; white-space: nowrap; }
.problem-question { grid-column: 3 / -1; background: var(--paper); border: 1px solid var(--line); border-radius: var(--r); padding: 6px 10px; }
.problem-q { font-size: 12.5px; color: var(--ink-2); }
.proof-counts { margin-bottom: 10px; }
.proof-unit { margin-bottom: 10px; border: 1px solid var(--line); border-radius: var(--r); padding: 6px 10px; }
.proof-unit summary { cursor: pointer; font-size: 13px; }
.obligation { display: grid; grid-template-columns: auto auto 1fr; gap: 8px; align-items: baseline; padding: 6px 0; border-top: 1px solid var(--line); font-size: 13px; }
.ob-detail { grid-column: 1 / -1; font-size: 12.5px; }
.ob-detail summary { color: var(--ink-2); cursor: pointer; font-size: 12px; }
.facts li { padding: 1px 0 1px 12px; }
.goal { padding: 2px 0 2px 12px; font-weight: 600; }
.tests-unit { margin-bottom: 14px; }
.failures li { padding: 3px 0; font-size: 13px; }
.perf-tbl { max-width: 520px; }
.perf-tbl td:first-child { color: var(--ink-2); }
.bounds { padding-left: 18px; }
.compile-out { border-bottom: 1px solid var(--line); background: var(--paper); padding: 8px 12px; max-height: 45%; overflow: auto; font-size: 12.5px; }
.compile-head { display: flex; gap: 10px; align-items: center; margin-bottom: 6px; }
.compile-err { color: var(--err); white-space: pre-wrap; margin: 0 0 6px; font-size: 12px; }
.compile-std { white-space: pre-wrap; margin: 0 0 6px; font-size: 12px; }
.compile-asm { margin: 0; font-family: var(--mono); font-size: 12px; line-height: 1.4; white-space: pre; }

/* ---------- dialogs, tooltip ---------- */
.share { border: 1px solid var(--line); border-radius: var(--r-lg); padding: 18px 20px; width: min(720px, 92vw); background: var(--paper-2); color: var(--ink); box-shadow: var(--shadow); }
.share::backdrop { background: rgba(10, 12, 18, .4); }
.share h3 { font-size: 17px; }
.share-row { display: grid; grid-template-columns: 110px 1fr auto; gap: 8px; align-items: center; margin: 8px 0; }
.share-row label { font-size: 12.5px; color: var(--ink-2); }
.share-actions { text-align: right; margin-top: 10px; display: flex; gap: 8px; justify-content: flex-end; }
.compiler-row { grid-template-columns: 90px 1fr 1fr; }
.compiler-head { margin-bottom: 0; }
.keys { display: grid; grid-template-columns: auto 1fr; gap: 6px 14px; font-size: 13px; align-items: center; }
.tip { position: fixed; z-index: 50; background: var(--paper-2); color: var(--ink); border: 1px solid var(--line); border-radius: var(--r); padding: 8px 10px; box-shadow: var(--shadow); font-size: 12.5px; line-height: 1.4; pointer-events: none; }
.tip-title { display: flex; justify-content: space-between; gap: 12px; margin-bottom: 3px; }
.tip-title code { font-weight: 600; font-size: 12.5px; }
.tip-where { color: var(--ink-2); font-size: 11px; }

/* ---------- reference ---------- */
.reference { margin: 36px 0 24px; }
.ref-nav { display: flex; gap: 14px; flex-wrap: wrap; margin: 6px 0 14px; font-size: 13.5px; }
.ref-lang { border: 1px solid var(--line); border-radius: var(--r-lg); background: var(--paper-2); margin-bottom: 10px; }
.ref-lang > summary { list-style: none; cursor: pointer; padding: 12px 16px; display: flex; gap: 12px; align-items: baseline; flex-wrap: wrap; }
.ref-lang > summary::-webkit-details-marker { display: none; }
.ref-lang > summary::before { content: '▸'; color: var(--ink-3); font-size: 12px; }
.ref-lang[open] > summary::before { content: '▾'; }
.ref-lang > summary h3 { margin: 0; font-size: 16px; }
.ref-body { padding: 0 16px 16px; }
.ref-toc { display: flex; gap: 12px; flex-wrap: wrap; font-size: 12.5px; margin-bottom: 8px; }
.ref-section { margin-top: 18px; }
.ref-section h4 { font-size: 14px; color: var(--ink); }
.ref-table { border-collapse: collapse; width: 100%; font-size: 13px; }
.ref-table th { text-align: left; font-size: 11.5px; color: var(--ink-2); font-weight: 600; padding: 4px 8px; border-bottom: 1px solid var(--line); }
.ref-table td { padding: 6px 8px; border-bottom: 1px solid var(--line); vertical-align: top; }
.ref-term { white-space: nowrap; max-width: 320px; }
.ref-term code { white-space: pre-wrap; font-size: 12.5px; }
.ref-meaning { min-width: 220px; }
.ref-extra { min-width: 200px; }
.ref-code { margin: 0; font-family: var(--mono); font-size: 12px; line-height: 1.4; white-space: pre; background: var(--paper); border: 1px solid var(--line); border-radius: 5px; padding: 6px 8px; overflow-x: auto; max-width: 520px; }

/* ---------- embed ---------- */
.embed { display: flex; flex-direction: column; height: 100%; min-height: 100vh; font-size: 13px; }
.embed-title { display: flex; justify-content: space-between; align-items: center; padding: 6px 12px; border-bottom: 1px solid var(--line); font-size: 12.5px; }
.embed-open { font-size: 12px; }
.embed-pane-label { font-size: 12px; color: var(--ink-2); padding: 6px 12px 0; }
.embed .ed { min-height: 120px; max-height: 45vh; border-bottom: 1px solid var(--line); }
.embed-row { display: flex; gap: 6px; align-items: center; padding: 6px 12px; border-bottom: 1px solid var(--line); }
.embed-call { flex: 1; }
.embed-panel { flex: 1; overflow: auto; }
.embed .trace-cols { grid-template-columns: 1fr; }
.embed-foot { display: none; }

@media (max-width: 900px) {
    .workspace { grid-template-columns: 1fr !important; grid-template-rows: minmax(0, 1fr) 6px minmax(0, 1fr); }
    .workspace > .splitter { cursor: row-resize; }
    .workspace.views-collapsed { grid-template-rows: minmax(0, 1fr) 6px 40px; }
    .workspace.views-collapsed .view-tabs { flex-direction: row; height: auto; }
    .workspace.views-collapsed .view-tabs .tab { writing-mode: horizontal-tb; transform: none; }
    .companion { display: none !important; }
    .pane-split.has-companion { grid-template-columns: minmax(0, 1fr); }
    .input { min-width: 140px; }
    .hero { grid-template-columns: 1fr; gap: 24px; }
    .hero h1 { font-size: 34px; }
    .ways { grid-template-columns: 1fr 1fr; }
    .ref-table, .ref-table thead, .ref-table tbody, .ref-table tr, .ref-table td { display: block; }
    .ref-table th { display: none; }
    .ref-term { white-space: normal; }
}
@media (max-width: 560px) { .ways { grid-template-columns: 1fr; } .home { padding: 0 16px 48px; } }
.way pre { max-height: 150px; -webkit-mask-image: linear-gradient(#000 70%, transparent); mask-image: linear-gradient(#000 70%, transparent); }

/* ------------------------------------------------------------------ */
/* Home: pitch sections                                               */
/* ------------------------------------------------------------------ */
.home-nav a.on { color: var(--ink); font-weight: 600; }
.lede-2 { color: var(--ink-2); max-width: 72ch; margin: 0 0 20px; font-size: 15px; line-height: 1.55; }
.hub { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.35fr) minmax(0, 1fr); gap: 12px; align-items: stretch; }
.hub-col { display: grid; gap: 12px; align-content: stretch; }
.hub .way { display: flex; flex-direction: column; }
.hub .way p { min-height: 0; flex: 0 0 auto; }
.hub .way pre { flex: 1; }
.hub-center { border: 1px solid var(--ink); border-radius: var(--r-lg); background: var(--paper-2); padding: 16px 16px 12px; min-width: 0; box-shadow: var(--shadow); position: relative; }
.hub-center::before { content: ""; position: absolute; inset: -1px; border-radius: inherit; pointer-events: none; box-shadow: 0 0 0 3px var(--marker-bg); }
.hub-center h3 { font-size: 20px; margin: 0 0 4px; letter-spacing: -.01em; }
.hub-center > p { margin: 0 0 10px; font-size: 13px; color: var(--ink-2); }
.hub-center pre { margin: 0; font-family: var(--mono); font-size: 12px; line-height: 1.6; white-space: pre; overflow-x: auto; border-top: 1px solid var(--line); padding-top: 10px; }
.flavors, .agents, .learn-teaser, .depsec, .lessons { padding: 36px 0 8px; }
.flavors h2, .agents h2, .learn-teaser h2, .depsec h2, .lessons h2, .learn-hero h1 { font-size: 24px; letter-spacing: -.02em; margin: 0 0 6px; }
.flavor-tabs { display: flex; gap: 4px; flex-wrap: wrap; margin: 0 0 10px; }
.pane-tab { font: inherit; font-size: 13px; padding: 6px 12px; border: 1px solid var(--line); border-radius: 999px; background: var(--paper-2); color: var(--ink-2); cursor: pointer; }
.pane-tab:hover { color: var(--ink); border-color: var(--line-2); }
.pane-tab.on { background: var(--ink); color: var(--paper); border-color: var(--ink); font-weight: 600; }
.flavor-code { margin: 0 0 8px; padding: 14px 16px; font-family: var(--mono); font-size: 12.5px; line-height: 1.6; white-space: pre; overflow-x: auto; border: 1px solid var(--line); border-radius: var(--r-lg); background: var(--paper-2); max-height: 420px; overflow-y: auto; }
.agent-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 24px; }
.agent-col h3 { font-size: 15px; margin: 0 0 6px; }
.agent-col p { margin: 0; color: var(--ink-2); font-size: 13.5px; }
.learn-teaser { display: grid; grid-template-columns: minmax(0, 1.1fr) minmax(0, 1fr); gap: 32px; align-items: center; border-top: 1px solid var(--line); }
.learn-teaser-map { display: block; border: 1px solid var(--line); border-radius: var(--r-lg); background: var(--paper-2); padding: 12px; }
.learn-teaser-map svg { width: 100%; height: auto; display: block; }
.learn-teaser-map:hover { border-color: var(--line-2); }

/* ------------------------------------------------------------------ */
/* Learn                                                              */
/* ------------------------------------------------------------------ */
.learn-hero { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr); gap: 36px; align-items: start; padding: 32px 0 36px; border-bottom: 1px solid var(--line); }
.learn-hero h1 { font-size: 36px; line-height: 1.1; letter-spacing: -.025em; margin: 0 0 14px; max-width: 18ch; }
.learn-hero .lede { font-size: 16px; color: var(--ink-2); margin: 0 0 18px; max-width: 54ch; line-height: 1.5; }
.flavor-pick { border: 1px solid var(--line); border-radius: var(--r-lg); background: var(--paper-2); padding: 16px; }
.flavor-pick h3 { margin: 0 0 4px; font-size: 15px; }
.flavor-pick .filters { margin: 10px 0 0; }
.depmap-wrap { border: 1px solid var(--line); border-radius: var(--r-lg); background: var(--paper-2); overflow: hidden; }
.depmap-scroll { overflow-x: auto; padding: 8px; }
.depmap { display: block; font-family: var(--sans); }
.depmap-edge { fill: none; stroke: var(--line-2); stroke-width: 1.4; }
.depmap-edge.edge-done { stroke: var(--ok); opacity: .7; }
.depmap-edge.edge-dim { opacity: .18; }
.depmap-edge.edge-focus { stroke: var(--accent); stroke-width: 2; }
.depmap-node rect { fill: var(--paper-3); stroke: var(--line-2); stroke-width: 1; transition: transform .12s; }
.depmap-node.node-available rect { fill: var(--accent-bg); stroke: var(--accent); }
.depmap-node.node-done rect { fill: var(--ok-bg); stroke: var(--ok); }
.depmap-node.node-current rect { stroke: var(--ink); stroke-width: 2; }
.depmap-node.node-dim { opacity: .35; }
.depmap-node:hover rect { stroke: var(--ink); }
.depmap-node:focus-visible rect { stroke: var(--accent); stroke-width: 2.5; }
.depmap-title { font-size: 12px; fill: var(--ink); }
.depmap-mark { font-size: 12px; fill: var(--ink-2); font-weight: 700; }
.node-done .depmap-mark { fill: var(--ok); }
.node-available .depmap-mark { fill: var(--accent); }
.depmap-mini rect.node-locked { fill: var(--paper-3); stroke: var(--line-2); }
.depmap-mini rect.node-available { fill: var(--accent-bg); stroke: var(--accent); }
.depmap-mini rect.node-done { fill: var(--ok-bg); stroke: var(--ok); }
.depmap-legend { display: flex; gap: 16px; flex-wrap: wrap; align-items: center; padding: 8px 12px; border-top: 1px solid var(--line); font-size: 12.5px; color: var(--ink-2); }
.lg { padding: 2px 8px; border-radius: 999px; border: 1px solid var(--line-2); background: var(--paper-3); }
.lg-done { background: var(--ok-bg); border-color: var(--ok); color: var(--ok); }
.lg-available { background: var(--accent-bg); border-color: var(--accent); color: var(--accent); }
.lesson-cards .card { position: relative; }
.card-top { display: flex; align-items: flex-start; justify-content: space-between; gap: 8px; }
.card-top h3 { margin: 0; }
.chip-status { white-space: nowrap; }
.chip-done { background: var(--ok-bg); color: var(--ok); border-color: transparent; }
.chip-available { background: var(--accent-bg); color: var(--accent); border-color: transparent; }
.chip-locked { background: var(--paper-3); color: var(--ink-3); }
.lesson-card.lesson-locked { opacity: .78; }
.lesson-card.lesson-locked:hover { opacity: 1; }
.lesson-card .card-foot { display: block; margin-top: 8px; }

/* a lesson */
.lesson { max-width: 880px; }
.crumbs { color: var(--ink-3); margin: 8px 0 18px; }
.crumbs a { color: var(--ink-2); }
.lesson-head h1 { font-size: 34px; line-height: 1.1; letter-spacing: -.025em; margin: 0 0 10px; }
.lesson-head .lede { font-size: 17px; color: var(--ink-2); margin: 0 0 12px; line-height: 1.5; }
.lesson-head .chip-status { margin-top: 10px; }
.lesson-sec { padding: 28px 0 4px; border-top: 1px solid var(--line); margin-top: 24px; }
.lesson-sec h2 { font-size: 20px; letter-spacing: -.015em; margin: 0 0 10px; }
.lesson-sec h3.sub { font-size: 15px; margin: 18px 0 8px; }
.lesson-prose p { max-width: 70ch; font-size: 15px; line-height: 1.6; margin: 0 0 14px; }
.lesson-prose ul { max-width: 70ch; margin: 0 0 14px; padding-left: 20px; }
.lesson-prose li { margin: 4px 0; font-size: 14.5px; line-height: 1.55; }
.lesson-prose code, .check code, .lesson-sec p code { font-family: var(--mono); font-size: .92em; background: var(--paper-3); padding: 1px 5px; border-radius: 4px; }
.req-list { list-style: none; padding: 0; margin: 0 0 12px; display: grid; gap: 6px; }
.req-list li { padding: 8px 12px; border: 1px solid var(--line); border-radius: var(--r); background: var(--paper-2); font-size: 13.5px; }
.req-list .req-mark { display: inline-block; width: 18px; font-weight: 700; }
.req-ok .req-mark { color: var(--ok); }
.req-missing .req-mark { color: var(--ink-3); }
.req-missing { border-left: 3px solid var(--marker); }
.lesson-link { font-weight: 500; }
.callout { border: 1px solid var(--marker); background: var(--marker-bg); border-radius: var(--r); padding: 10px 14px; font-size: 13.5px; margin: 8px 0; }
.lesson .demo { margin: 12px 0; }
.demo-out { margin: 0; padding: 6px 10px; font-family: var(--mono); font-size: 12.5px; white-space: pre-wrap; border: 1px solid var(--line); border-radius: var(--r); background: var(--paper-2); max-height: 140px; overflow: auto; grid-column: 1 / -1; }
.demo-stop { color: var(--err); }
.demo-frame { color: var(--accent); font-weight: 600; }
.lesson .demo-foot { grid-template-columns: 1fr auto; }
.lesson .demo-foot .demo-out { order: 3; }
.targets { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.targets .way pre { max-height: 300px; mask-image: none; -webkit-mask-image: none; overflow-x: auto; }
.check { padding: 12px 14px; border: 1px solid var(--line); border-radius: var(--r-lg); background: var(--paper-2); margin: 0 0 10px; }
.check-q { margin: 0 0 8px; font-weight: 500; }
.check-opts { display: flex; gap: 8px; flex-wrap: wrap; }
.check-opt.right { background: var(--ok-bg); border-color: var(--ok); color: var(--ok); font-weight: 600; }
.check-opt.wrong { background: var(--err-bg); border-color: var(--err); color: var(--err); }
.check-fb { margin: 8px 0 0; color: var(--ink-2); min-height: 1em; }
.flavor-body { border: 1px solid var(--line); border-radius: var(--r-lg); background: var(--paper-2); padding: 16px; }
.flavor-hook { font-size: 15px; color: var(--ink-2); margin: 0 0 10px; font-style: italic; }
.flavor-actions { display: flex; gap: 8px; flex-wrap: wrap; margin: 12px 0 0; }
.solution { margin-top: 14px; padding-top: 12px; border-top: 1px dashed var(--line-2); }
.solution h4 { margin: 0 0 6px; font-size: 13.5px; }
.ref-code.starter { border-left: 3px solid var(--accent); }
.ref-prints { display: block; margin-top: 4px; }
.lesson-finish { background: var(--paper-2); border: 1px solid var(--line); border-radius: var(--r-lg); padding: 20px 22px; margin-top: 28px; }
.lesson-finish h2 { margin-top: 0; }
.input-lines { resize: none; min-height: 30px; line-height: 1.4; padding: 5px 8px; }
@media (max-width: 900px) {
    .hub { grid-template-columns: 1fr; }
    .hub-center { order: -1; }
    .agent-grid { grid-template-columns: 1fr; }
    .learn-teaser, .learn-hero { grid-template-columns: 1fr; }
    .targets { grid-template-columns: 1fr; }
}
.demo-vars > span { display: inline-flex; align-items: center; gap: 6px; }
.demo-vars .ruler { display: inline-flex; }
.demo-foot { display: flex; flex-direction: column; gap: 8px; align-items: stretch; }
.demo-ctl { display: flex; gap: 4px; flex-wrap: wrap; align-items: center; }
.demo-ctl .btn { white-space: nowrap; }
.demo-ctl a.btn { margin-left: auto; }
.lesson .demo-foot .demo-out { order: 0; }
.depmap-scroll { overflow: auto; }
.depmap { width: 100%; height: auto; }
.depmap-title { font-size: 11.5px; }
.depmap-mark { font-size: 11px; }
.depmap-edge { stroke-width: 1.2; }
.toolbar .input-lines { min-width: 120px; width: 180px; }
.toolbar:has(.input-lines) .input { min-width: 170px; }
@media (max-width: 560px) {
    .home-nav { flex-wrap: wrap; gap: 10px 12px; }
    .home-nav .brand { flex-basis: 100%; }
    .home-nav .spacer { display: none; }
    .learn-hero h1 { font-size: 30px; }
    .lesson-head h1 { font-size: 28px; }
    .flavor-actions .btn { flex: 1 1 auto; text-align: center; }
}