/* Muninn, a page about a small language.
 *
 * The page is paper with ink on it, one blue for anything the reader is meant
 * to act on, and one red for anything that failed. There is no second accent
 * and no colour that does not mean something: the tensor grid, the selected
 * example, the current instruction, and a diagnostic are the only coloured
 * things on the page, and each is a thing that happened.
 */

:root {
  --paper: #f6f7f9;
  --panel: #ffffff;
  --panel-2: #eef1f5;
  --ink: #0d1116;
  --ink-2: #2a3138;
  --muted: #525a63;
  --subtle: #5d666e;
  --rule: #d7dce2;
  --rule-soft: #e6eaef;
  --blue: #1b4f8f;
  --blue-deep: #12386b;
  --blue-wash: #e7eef8;
  --red: #9f1d26;
  --red-wash: #fbeceb;
  --tok-num: #0e5a63;
  --tok-str: #3d5a7a;
  --tok-lit: #12386b;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --mono: ui-monospace, "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

code,
kbd,
pre,
.mono {
  font-family: var(--mono);
}

h1,
h2,
h3 {
  line-height: 1.25;
  letter-spacing: -0.01em;
}

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

.skip {
  position: absolute;
  left: -9999px;
}

.skip:focus {
  left: 1rem;
  top: 1rem;
  background: var(--panel);
  padding: 0.5rem 0.75rem;
  z-index: 10;
}

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

/* Masthead */

.masthead {
  max-width: 1240px;
  margin: 0 auto;
  padding: 3.5rem 1.5rem 2rem;
}

.masthead h1 {
  margin: 0;
  font-size: 2.6rem;
  font-weight: 620;
  letter-spacing: -0.03em;
}

.masthead-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.repo-link {
  display: inline-block;
  padding: 0.5rem 0.8rem;
  border-radius: 0;
  background: var(--ink);
  color: #fff;
  font-size: 0.8rem;
  font-weight: 650;
  letter-spacing: 0.01em;
  line-height: 1;
  text-decoration: none;
  white-space: nowrap;
}

.repo-link:hover {
  background: #000;
}

.tagline {
  margin: 0.5rem 0 0;
  max-width: 44rem;
  font-size: 1.15rem;
  color: var(--muted);
}

.provenance {
  margin: 1rem 0 0;
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--subtle);
}

.provenance.failed {
  color: var(--red);
}

main {
  max-width: 1420px;
  margin: 0 auto;
  padding: 0 1.5rem 4rem;
}

/* Workbench */

.workbench {
  display: grid;
  grid-template-columns: 13rem minmax(0, 1fr) 24rem;
  gap: 1.25rem;
  align-items: start;
}

/* Every column starts with a card, so the three columns line up on one top
   edge. The middle column is the card itself rather than containing one: a
   toolbar sitting above its own card pushed that card below its neighbours,
   which is what made the editor look lower than the two panels beside it. */
.panel,
.examples,
.editor-column {
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: 2px;
}

.panel {
  padding: 1rem 1.1rem 1.1rem;
  /* A grid item will not shrink below its content's min-content width unless
     told to. Without this a wide tensor makes the Result panel itself wide,
     and the page gains a horizontal scrollbar instead of the tensor. */
  min-width: 0;
}

.panel h2,
.examples h2 {
  margin: 0 0 0.6rem;
  font-size: 0.8rem;
  font-weight: 650;
  letter-spacing: 0;
  text-transform: none;
  color: var(--muted);
}

.panel-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.75rem;
}

.panel-head h2 {
  margin-bottom: 0.6rem;
}

/* Example list */

.examples {
  padding: 1rem 0.9rem 0.9rem;
  position: sticky;
  top: 1rem;
}

.examples ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.15rem;
}

.examples button {
  width: 100%;
  text-align: left;
  border: 0;
  background: none;
  font: inherit;
  font-size: 0.9rem;
  color: var(--ink-2);
  padding: 0.4rem 0.5rem;
  border-radius: 2px;
  cursor: pointer;
}

.examples button:hover {
  background: var(--blue-wash);
}

.examples button[aria-current="true"] {
  background: var(--blue-wash);
  color: var(--blue-deep);
  font-weight: 600;
}

.examples-note {
  margin: 0.8rem 0 0;
  padding-top: 0.7rem;
  border-top: 1px solid var(--rule-soft);
  font-size: 0.8rem;
  color: var(--subtle);
}

/* Editor */

.editor-column {
  display: grid;
  min-width: 0;
  overflow: hidden;
}

/* The toolbar is the card's header and the hint row is its footer, so the
   Run button sits on the card's top edge, level with the panels beside it. */
.bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.6rem 0.9rem;
  border-bottom: 1px solid var(--rule-soft);
}

.bar-foot {
  padding: 0.55rem 0.9rem;
  border-top: 1px solid var(--rule-soft);
  font-size: 0.8rem;
  color: var(--subtle);
}

.bar-title {
  font-family: var(--mono);
  font-size: 0.82rem;
  color: var(--ink-2);
}

.bar-actions {
  display: flex;
  gap: 0.4rem;
}

button {
  font: inherit;
  font-size: 0.85rem;
  padding: 0.35rem 0.8rem;
  border: 1px solid var(--rule);
  border-radius: 2px;
  background: var(--panel);
  color: var(--ink-2);
  cursor: pointer;
}

button:hover:not(:disabled) {
  border-color: var(--blue);
  color: var(--blue);
}

button:disabled {
  opacity: 0.45;
  cursor: default;
}

button.primary {
  background: var(--blue);
  border-color: var(--blue);
  color: #fff;
  font-weight: 600;
}

button.primary:hover:not(:disabled) {
  background: var(--blue-deep);
  color: #fff;
}

.live {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  cursor: pointer;
}

.hint kbd {
  border: 1px solid var(--rule);
  border-bottom-width: 2px;
  border-radius: 2px;
  padding: 0 0.25rem;
  font-size: 0.72rem;
  background: var(--panel);
}

.editor {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  /* Both columns scroll within one viewport. An auto-sized row lets the
     gutter grow to the entire program, so its scrollTop stays at zero. */
  grid-template-rows: minmax(0, 1fr);
  height: clamp(26rem, 58vh, 42rem);
  overflow: hidden;
}

.gutter,
#source,
.highlight,
.highlight .line {
  font-family: var(--mono);
  font-size: 13.5px;
  line-height: 1.65;
  tab-size: 4;
}

.gutter {
  padding: 0.9rem 0.6rem 0.9rem 0.75rem;
  text-align: right;
  color: var(--subtle);
  background: var(--panel-2);
  border-right: 1px solid var(--rule-soft);
  overflow: hidden;
  user-select: none;
  min-width: 2.4rem;
}

.gutter .marked {
  color: var(--blue);
  font-weight: 600;
}

.code {
  position: relative;
  min-height: 0;
}

/* Nothing here may restate the font. The rule above is the single source of
   the family, size, and leading, because `font: inherit` on a textarea resets
   to the body's 16px sans and the caret then sits between words instead of
   on them. */
.highlight,
#source {
  margin: 0;
  padding: 0.9rem 1rem;
  border: 0;
  tab-size: 4;
}

.highlight {
  position: absolute;
  inset: 0;
  overflow: hidden;
  pointer-events: none;
  color: var(--ink);
}

/* One block per source line, so the line under the caret can be washed across
   the whole editor. A single text run could only be washed behind the words,
   which reads as a selection rather than as a line. */
.highlight .line {
  white-space: pre;
  overflow-wrap: normal;
  word-break: normal;
}

/* Use natural text line boxes, including on blank rows. Safari rounds those
   differently from a fractional min-height, which made the code drift below
   the native caret and line numbers, especially when zoomed out. */
.highlight .line:empty::before {
  content: "\200b";
}

/* Full-bleed wash: pull the line out by the editor's own padding and give
   the padding back inside, so the wash reaches both edges without a shadow
   or a clip path that would cut the text. */
.highlight .line.current {
  margin: 0 -1rem;
  padding: 0 1rem;
  background: var(--blue-wash);
  box-shadow: -1rem 0 0 var(--blue-wash), 1rem 0 0 var(--blue-wash);
}

#source {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  resize: none;
  background: transparent;
  color: transparent;
  caret-color: var(--blue);
  overflow: auto;
}

#source::selection {
  background: var(--blue-wash);
}

.highlight .kw {
  color: var(--blue);
  font-weight: 600;
}

.highlight .ty {
  color: var(--blue-deep);
  font-style: italic;
}

.highlight .num {
  color: var(--tok-num);
}

.highlight .str {
  color: var(--tok-str);
}

.highlight .lit {
  color: var(--tok-lit);
}

/* Result */

.result-column {
  display: grid;
  /* One column that may be narrower than its content, so the panels clamp to
     the 24rem track instead of growing to fit a wide tensor. */
  grid-template-columns: minmax(0, 1fr);
  gap: 1rem;
  min-width: 0;
}

.diagnostics {
  list-style: none;
  margin: 0 0 0.6rem;
  padding: 0;
  display: grid;
  gap: 0.35rem;
}

.diagnostics:empty {
  display: none;
}

.diagnostics li {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.5rem;
  align-items: baseline;
  padding: 0.45rem 0.6rem;
  background: var(--red-wash);
  border-left: 3px solid var(--red);
  border-radius: 0 2px 2px 0;
  font-size: 0.85rem;
}

.diagnostics .where {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--red);
  cursor: pointer;
  background: none;
  border: 0;
  padding: 0;
  text-decoration: underline;
  text-underline-offset: 2px;
}

.diagnostics .phase {
  color: var(--subtle);
}

.output {
  margin: 0;
  padding: 0;
  font-size: 13px;
  line-height: 1.6;
  white-space: pre-wrap;
  word-break: break-word;
  color: var(--ink);
  min-height: 3rem;
}

.output:empty::after {
  content: "Nothing printed yet.";
  color: var(--subtle);
  font-family: var(--sans);
  font-size: 0.85rem;
}

/* A program that never ran has no output, which is not the same as a program
   that ran and printed nothing. */
.output.unreached:empty::after {
  content: "The program never ran, so it printed nothing.";
}

.value {
  margin: 0.7rem 0 0;
  padding-top: 0.6rem;
  border-top: 1px solid var(--rule-soft);
  font-family: var(--mono);
  font-size: 0.85rem;
  color: var(--muted);
}

.value b {
  color: var(--ink);
  font-weight: 600;
}

/* A note under the output, for context that is not the output itself. The
   error variant is a fault, so it is the one place outside diagnostics that
   borrows the fault colour. */
#output-note {
  margin: 0.5rem 0 0;
  font-size: 0.8rem;
  color: var(--muted);
}

#output-note.error {
  color: var(--red);
}

/* The last run no longer matches the text in the editor. That is information,
   not a fault, so it does not borrow the fault colour: crimson here means
   something failed, and nothing has. */
#stale {
  margin: 0.5rem 0 0;
  font-size: 0.8rem;
  color: var(--blue-deep);
}

/* Tensor grid */

/* A wide tensor scrolls inside its own box rather than pushing the page. The
   Result column is 24rem and one cell is 3.6rem, so a tensor of more than a
   handful of columns would otherwise escape the panel and give the whole page
   a horizontal scrollbar. */
.tensor-wrap {
  display: inline-block;
  vertical-align: top;
  max-width: 100%;
  margin: 0.2rem 0 0.6rem;
}

.tensor-shape {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--blue-deep);
  background: var(--blue-wash);
  border: 1px solid var(--rule);
  border-bottom: 0;
  border-radius: 2px 2px 0 0;
  padding: 0.1rem 0.4rem;
  display: inline-block;
}

.tensor {
  display: inline-grid;
  gap: 1px;
  padding: 1px;
  background: var(--rule);
  border: 1px solid var(--rule);
  border-radius: 0 0 2px 2px;
  vertical-align: top;
  max-width: 100%;
  overflow-x: auto;
}

.tensor span {
  background: var(--panel);
  padding: 0.15rem 0.5rem;
  font-family: var(--mono);
  font-size: 12px;
  text-align: right;
  min-width: 3.6rem;
}

/* Execution */

.next {
  margin: 0 0 0.8rem;
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--ink-2);
  min-height: 1.4rem;
}

.next b {
  color: var(--blue);
  font-weight: 600;
}

.next .quiet {
  color: var(--subtle);
}

.transport {
  display: flex;
  gap: 0.4rem;
}

.transport button {
  padding: 0.25rem 0.6rem;
  font-size: 0.78rem;
}

.inspector-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 0.9rem;
  margin-bottom: 0.9rem;
}

.inspector-cell h3,
.listing-wrap h3 {
  margin: 0 0 0.35rem;
  font-size: 0.8rem;
  font-weight: 650;
  letter-spacing: 0;
  text-transform: none;
  color: var(--muted);
}

.slots {
  list-style: none;
  margin: 0;
  padding: 0;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--ink-2);
  display: grid;
  gap: 0.1rem;
  max-height: 8.5rem;
  overflow: auto;
}

.slots li {
  padding: 0.15rem 0.35rem;
  border-radius: 2px;
  background: var(--panel-2);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.slots li:empty::after {
  content: "empty";
  color: var(--subtle);
}

.slots .fn {
  color: var(--blue);
  font-weight: 600;
}

.listing {
  list-style: none;
  margin: 0;
  padding: 0;
  font-family: var(--mono);
  font-size: 12px;
  max-height: 15rem;
  overflow: auto;
  border-top: 1px solid var(--rule-soft);
}

.listing li {
  display: grid;
  grid-template-columns: 2.6rem 1fr;
  gap: 0.5rem;
  padding: 0.1rem 0.35rem;
  color: var(--ink-2);
  white-space: nowrap;
}

.listing .ip {
  color: var(--subtle);
  text-align: right;
}

.listing .op {
  color: var(--ink-2);
}

.listing .arg {
  color: var(--subtle);
}

.listing li.current {
  background: var(--blue-wash);
  color: var(--blue-deep);
}

.listing li.current .op,
.listing li.current .ip {
  color: var(--blue-deep);
  font-weight: 600;
}

.listing li.past {
  color: var(--subtle);
}

/* Notes and reference */

.notes {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(17rem, 1fr));
  gap: 2rem;
  margin-top: 3.5rem;
  padding-top: 2rem;
  border-top: 1px solid var(--rule);
}

.note h2,
.reference h2 {
  margin: 0 0 0.6rem;
  font-size: 1.05rem;
}

.note p {
  margin: 0 0 0.8rem;
  font-size: 0.92rem;
  color: var(--muted);
}

.note code,
.reference code {
  font-size: 0.85em;
  background: var(--panel);
  border: 1px solid var(--rule-soft);
  border-radius: 2px;
  padding: 0.05em 0.3em;
}

.reference {
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--rule);
}

.reference-note {
  margin: 0 0 1rem;
  font-size: 0.9rem;
  color: var(--muted);
  max-width: 40rem;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
}

th,
td {
  text-align: left;
  padding: 0.4rem 0.75rem;
  border-bottom: 1px solid var(--rule-soft);
}

th {
  font-size: 0.8rem;
  letter-spacing: 0;
  text-transform: none;
  color: var(--muted);
  font-weight: 650;
}

td:first-child {
  font-family: var(--mono);
  color: var(--ink);
}

td:nth-child(2) {
  font-family: var(--mono);
  color: var(--muted);
}

td:last-child {
  color: var(--subtle);
}

td .yes {
  color: var(--blue);
}

/* A builtin that traps here is a failure state, so it keeps the fault colour.
   The cell's own words ("traps here") carry the meaning; the colour only
   reinforces it. */
td .no {
  color: var(--red);
}

footer {
  border-top: 1px solid var(--rule);
  padding: 1.5rem;
  text-align: center;
  font-size: 0.82rem;
  color: var(--subtle);
}

footer p {
  max-width: 40rem;
  margin: 0 auto;
}

/* Narrow */

@media (max-width: 1080px) {
  .workbench {
    grid-template-columns: minmax(0, 1fr) 24rem;
  }

  .examples {
    grid-column: 1 / -1;
    position: static;
  }

  /* A picker that hides half its choices behind a horizontal scroll reads as
     truncated rather than scrollable, and there are only seven. Wrapping
     shows all of them at every narrow width. */
  .examples ul {
    grid-auto-flow: row;
    grid-template-columns: repeat(auto-fit, minmax(9rem, 1fr));
    gap: 0.15rem 0.6rem;
  }
}

@media (max-width: 780px) {
  .workbench {
    grid-template-columns: minmax(0, 1fr);
  }

  .editor {
    height: max(26rem, 40vh);
  }
}

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