/* The terminal's palette and proportions, in a document that also has to work on a phone. */

:root {
  color-scheme: light dark;

  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --sans: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --line: 1.45rem;

  --bg: #fbfbfd;
  --surface: #ffffff;
  --sunken: #f2f3f7;
  --ink: #12161c;
  --muted: #5c6674;
  --edge: #dfe3ea;
  --accent: #2563a8;
  --accent-ink: #ffffff;

  --black: #2b3038;
  --red: #b4242c;
  --green: #1f7a3d;
  --yellow: #8a6200;
  --blue: #2554a8;
  --magenta: #8f2f8f;
  --cyan: #12707d;
  --gray: #6b7482;
  --darkGray: #8b93a1;
  --lightRed: #cf3b45;
  --lightGreen: #2b9350;
  --lightYellow: #9c7300;
  --lightBlue: #2f6fbf;
  --lightMagenta: #a3459f;
  --lightCyan: #16808e;
  --white: #12161c;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0b0f14;
    --surface: #121821;
    --sunken: #0e131a;
    --ink: #e6ebf2;
    --muted: #93a0b1;
    --edge: #222c39;
    --accent: #5aa2f0;
    --accent-ink: #06111f;

    --black: #0b0f14;
    --red: #ff6b6b;
    --green: #56d68a;
    --yellow: #e3c05c;
    --blue: #6b9bf0;
    --magenta: #d98fdc;
    --cyan: #5fd2de;
    --gray: #9aa6b4;
    --darkGray: #6c7a8a;
    --lightRed: #ff8a8a;
    --lightGreen: #7ce3a6;
    --lightYellow: #f2d47a;
    --lightBlue: #8dbcff;
    --lightMagenta: #eaa8ec;
    --lightCyan: #86e6f0;
    --white: #ffffff;
  }
}

* {
  box-sizing: border-box;
}

/* Framed: the app is not drawn at all, only the refusal. */
#framed {
  display: none;
  padding: 2rem max(1rem, env(safe-area-inset-left));
  font-family: var(--sans);
}

#framed h1 {
  font-size: 1.1rem;
  margin: 0 0 0.5rem;
}

#framed p {
  color: var(--muted);
  line-height: 1.6;
  margin: 0;
}

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

:root[data-framed] #framed {
  display: block;
}

:root[data-framed] body > :not(#framed) {
  display: none !important;
}

html,
body {
  height: 100%;
}

/*
 * A phone's toolbars slide away and its keyboard slides in; `100%` measures the viewport they are
 * not in, which puts the footer and the tabs under one of them. `dvh` measures what is on screen.
 */
@supports (height: 100dvh) {
  html,
  body {
    height: 100dvh;
  }
}

body {
  margin: 0;
  display: grid;
  grid-template-rows: auto minmax(0, 1fr) auto auto;
  grid-template-columns: minmax(0, 1fr);
  font-family: var(--sans);
  font-size: 15px;
  background: var(--bg);
  color: var(--ink);
  -webkit-text-size-adjust: 100%;
}

/* ---------------------------------------------------------------- chrome */

.chrome {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem max(0.75rem, env(safe-area-inset-left));
  background: var(--surface);
  border-bottom: 1px solid var(--edge);
}

footer.chrome {
  border-bottom: 0;
  border-top: 1px solid var(--edge);
}

.wordmark {
  font-family: var(--mono);
  font-weight: 700;
  color: var(--accent);
  letter-spacing: 0.02em;
}

.grow {
  flex: 1;
}

.pill {
  font: 600 0.72rem/1 var(--mono);
  padding: 0.35rem 0.55rem;
  border-radius: 999px;
  border: 1px solid var(--edge);
  background: var(--sunken);
  color: var(--muted);
  cursor: pointer;
  min-width: 0;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* The half of the pill a narrow header drops; the footer says the same thing in full. */
.pill-note {
  color: inherit;
}

.pill.live {
  border-color: var(--green);
  color: var(--green);
}

button {
  font-family: inherit;
  font-size: 0.85rem;
  border-radius: 8px;
  border: 1px solid var(--edge);
  background: var(--surface);
  color: var(--ink);
  padding: 0.45rem 0.7rem;
  cursor: pointer;
}

button:hover {
  border-color: var(--accent);
}

button.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-ink);
  font-weight: 600;
}

button.ghost {
  background: transparent;
}

button.drop {
  color: var(--muted);
  border-color: transparent;
  padding: 0.3rem 0.5rem;
}

.status {
  flex: 1;
  min-width: 0;
  font-size: 0.8rem;
  color: var(--muted);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* ---------------------------------------------------------------- panels */

main {
  min-height: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
}

.panel {
  min-height: 0;
  display: none;
  flex-direction: column;
  gap: 0.6rem;
  padding: 0.75rem max(0.75rem, env(safe-area-inset-left)) 0.75rem
    max(0.75rem, env(safe-area-inset-right));
  overflow: auto;
}

body[data-tab="page"] [data-panel="page"],
body[data-tab="build"] [data-panel="build"],
body[data-tab="learn"] [data-panel="learn"],
body[data-tab="preview"] [data-panel="preview"] {
  display: flex;
}

.panel-head {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.hint {
  font-size: 0.75rem;
  color: var(--muted);
  margin: 0;
}

.legend {
  font-size: 0.72rem;
  color: var(--muted);
  margin: 0;
  line-height: 1.6;
}

.legend code,
.panel-head code {
  font-family: var(--mono);
  background: var(--sunken);
  border-radius: 4px;
  padding: 0.05rem 0.25rem;
}

/* ---------------------------------------------------------------- the page editor */

.editor {
  flex: 1;
  min-height: 12rem;
  position: relative;
  display: flex;
  background: var(--surface);
  border: 1px solid var(--edge);
  border-radius: 10px;
  overflow: hidden;
}

.gutter {
  width: 5.2rem;
  flex: none;
  padding: 0.6rem 0.35rem 0.6rem 0.6rem;
  background: var(--sunken);
  border-right: 1px solid var(--edge);
  overflow: hidden;
  font: 0.78rem / var(--line) var(--mono);
  user-select: none;
}

.gutter-row {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  height: var(--line);
  white-space: nowrap;
}

/*
 * The page, laid out again at the textarea's own width, so the gutter can ask how tall each line
 * became once it wrapped. Never painted, never in the tab order, never read aloud.
 */
.mirror {
  position: absolute;
  top: 0;
  left: 0;
  visibility: hidden;
  pointer-events: none;
  z-index: -1;
  white-space: pre-wrap;
  overflow-wrap: break-word;
  word-break: normal;
}

.flag {
  width: 0.6rem;
}

#page {
  flex: 1;
  min-width: 0;
  border: 0;
  resize: none;
  padding: 0.6rem 0.75rem;
  background: transparent;
  color: var(--ink);
  font: 0.86rem / var(--line) var(--mono);
  white-space: pre;
  overflow: auto;
  tab-size: 2;
}

#page:focus {
  outline: none;
}

.problems {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

.problem {
  display: flex;
  gap: 0.5rem;
  text-align: left;
  font-size: 0.78rem;
  border-color: var(--red);
  color: var(--ink);
  background: transparent;
}

.problem-line {
  font-family: var(--mono);
  color: var(--red);
  flex: none;
}

/* ---------------------------------------------------------------- the build form */

.cards {
  display: flex;
  flex-direction: column;
  gap: 0.7rem;
}

.card {
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
  padding: 0.7rem;
  background: var(--surface);
  border: 1px solid var(--edge);
  border-radius: 10px;
}

.card header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.card .pill {
  cursor: default;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  font-size: 0.72rem;
  color: var(--muted);
  min-width: 0;
}

.field.inline {
  flex-direction: row;
  align-items: center;
  gap: 0.4rem;
  min-width: 0;
}

/*
 * A select is as wide as its widest option — here, a preset's whole description. The cap is a
 * length rather than a percentage: a percentage counts as no cap at all while the row is working
 * out how wide it wants to be, and the hint beside it gets pushed onto a line of its own.
 */
.field.inline select {
  width: auto;
  max-width: 20rem;
}

.field input,
.field select,
.field textarea {
  font: 0.86rem / 1.5 var(--mono);
  padding: 0.4rem 0.5rem;
  border-radius: 8px;
  border: 1px solid var(--edge);
  background: var(--sunken);
  color: var(--ink);
  min-width: 0;
  width: 100%;
}

.field input:focus,
.field textarea:focus,
.field select:focus {
  outline: 2px solid var(--accent);
  outline-offset: -1px;
}

/* Narrow: the two halves of an option stack, with one remove button beside both. */
.pair {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 0.4rem;
  align-items: end;
}

.pair .field {
  grid-column: 1;
}

.pair .drop {
  grid-column: 2;
  grid-row: 1 / span 2;
  align-self: center;
}

@media (min-width: 560px) {
  .pair {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr) auto;
  }

  .pair .field:nth-of-type(2) {
    grid-column: 2;
  }

  .pair .drop {
    grid-row: 1;
    align-self: end;
  }
}

.row {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  align-items: center;
}

.check {
  display: flex;
  gap: 0.5rem;
  font-size: 0.75rem;
  color: var(--muted);
  align-items: flex-start;
}

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

/* ---------------------------------------------------------------- preview */

.segmented {
  display: flex;
  max-width: 100%;
  border: 1px solid var(--edge);
  border-radius: 8px;
  overflow-x: auto;
  overflow-y: hidden;
  scrollbar-width: none;
}

.segmented::-webkit-scrollbar {
  display: none;
}

.segmented button {
  border: 0;
  border-radius: 0;
  font-size: 0.78rem;
  background: transparent;
  white-space: nowrap;
  flex: none;
}

.segmented button.on {
  background: var(--accent);
  color: var(--accent-ink);
}

.preview {
  flex: 1;
  min-height: 0;
  overflow: auto;
  background: var(--surface);
  border: 1px solid var(--edge);
  border-radius: 10px;
  padding: 0.7rem;
}

.preview pre,
.raw {
  margin: 0;
  font: 0.8rem / 1.5 var(--mono);
  white-space: pre;
  overflow-x: auto;
}

.answer {
  margin-bottom: 0.6rem;
}

.line {
  font: 0.8rem / 1.5 var(--mono);
  white-space: pre;
}

.raw-body summary {
  font-size: 0.78rem;
  color: var(--muted);
  cursor: pointer;
  margin-top: 0.6rem;
}

/* ---------------------------------------------------------------- lessons */

.lesson h2 {
  font-size: 1.05rem;
  margin: 0.2rem 0;
}

.lesson p {
  line-height: 1.55;
  margin: 0.4rem 0;
  max-width: 62ch;
}

.lesson .count {
  font: 0.72rem var(--mono);
  color: var(--muted);
}

.try {
  font: 0.8rem / 1.5 var(--mono);
  background: var(--sunken);
  border: 1px solid var(--edge);
  border-radius: 8px;
  padding: 0.5rem;
  white-space: pre-wrap;
  overflow-x: auto;
}

/* ---------------------------------------------------------------- tabs */

.tabs {
  display: flex;
  border-top: 1px solid var(--edge);
  background: var(--surface);
  padding-bottom: env(safe-area-inset-bottom);
}

.tabs button {
  flex: 1;
  border: 0;
  border-radius: 0;
  padding: 0.7rem 0.2rem;
  color: var(--muted);
  background: transparent;
}

.tabs button.on {
  color: var(--accent);
  box-shadow: inset 0 -2px 0 var(--accent);
  font-weight: 600;
}

/* ---------------------------------------------------------------- dialog */

dialog {
  width: min(34rem, calc(100vw - 2rem));
  max-height: calc(100% - 2rem);
  overflow: auto;
  overscroll-behavior: contain;
  border: 1px solid var(--edge);
  border-radius: 12px;
  background: var(--surface);
  color: var(--ink);
  padding: 1rem;
}

dialog::backdrop {
  background: rgb(0 0 0 / 55%);
}

dialog h2 {
  margin: 0 0 0.4rem;
  font-size: 1rem;
}

dialog p {
  font-size: 0.8rem;
  color: var(--muted);
  line-height: 1.5;
  margin: 0.4rem 0;
}

dialog .field,
dialog .check {
  margin: 0.6rem 0;
}

dialog form {
  display: contents;
}

/* ---------------------------------------------------------------- phones */

/*
 * A phone is not a narrow terminal. Nobody reads a rubric by dragging it sideways, so the page
 * wraps here and the gutter grows with it — `drawGutter` measures each wrapped line. And anything
 * you can type into is at least 16px, because iOS zooms the whole page in on a smaller one and
 * never zooms back out.
 */
@media (max-width: 700px) {
  .panel {
    padding: 0.6rem max(0.6rem, env(safe-area-inset-left)) 0.6rem
      max(0.6rem, env(safe-area-inset-right));
  }

  .chrome {
    padding: 0.4rem max(0.6rem, env(safe-area-inset-left)) 0.4rem
      max(0.6rem, env(safe-area-inset-right));
  }

  .chrome button {
    min-height: 2.25rem;
  }

  .gutter {
    width: 4rem;
    padding: 0.6rem 0.3rem 0.6rem 0.45rem;
    font-size: 0.68rem;
  }

  #page {
    padding: 0.6rem 0.5rem;
    font-size: 16px;
    white-space: pre-wrap;
    overflow-wrap: break-word;
    overflow-x: hidden;
  }

  .field input,
  .field select,
  .field textarea {
    font-size: 16px;
  }

  .field.inline {
    flex: 1;
  }

  .field.inline select {
    flex: 1;
    max-width: none;
  }

  /* The spacer that holds the hint to the right has nothing to spare here. */
  .panel-head .grow {
    flex: none;
  }

  .editor {
    min-height: 9rem;
  }

  /* `rows` counts lines of text; the border box would then hide the last one under the padding. */
  #state {
    min-height: calc(6em + 0.8rem + 2px);
  }

  dialog {
    width: min(34rem, calc(100vw - 1rem));
    max-height: calc(100% - 1rem);
    padding: 0.85rem;
  }

  /* Save stays on the screen however long the explanations above it are. */
  dialog .row {
    position: sticky;
    bottom: -0.85rem;
    margin: 0 -0.85rem -0.85rem;
    padding: 0.6rem 0.85rem 0.85rem;
    background: var(--surface);
    border-top: 1px solid var(--edge);
  }
}

/* Under this, the header has room for the mode but not for the note beside it. */
@media (max-width: 340px) {
  .pill-note {
    display: none;
  }
}

/* ---------------------------------------------------------------- wide screens */

@media (min-width: 900px) {
  main {
    grid-template-columns: minmax(0, 1fr) minmax(22rem, 38%);
  }

  .tabs button[data-tab="preview"] {
    display: none;
  }

  .tabs button {
    flex: 0 0 auto;
    padding: 0.55rem 1.2rem;
  }

  body[data-tab="preview"] [data-panel="page"] {
    display: flex;
  }

  [data-panel="preview"] {
    display: flex !important;
    border-left: 1px solid var(--edge);
  }
}

/* ---------------------------------------------------------------- the terminal palette */

.bold {
  font-weight: 700;
}

.reverse {
  background: var(--ink);
  color: var(--bg);
}

.c-black {
  color: var(--black);
}
.c-red {
  color: var(--red);
}
.c-green {
  color: var(--green);
}
.c-yellow {
  color: var(--yellow);
}
.c-blue {
  color: var(--blue);
}
.c-magenta {
  color: var(--magenta);
}
.c-cyan {
  color: var(--cyan);
}
.c-gray {
  color: var(--gray);
}
.c-darkGray {
  color: var(--darkGray);
}
.c-lightRed {
  color: var(--lightRed);
}
.c-lightGreen {
  color: var(--lightGreen);
}
.c-lightYellow {
  color: var(--lightYellow);
}
.c-lightBlue {
  color: var(--lightBlue);
}
.c-lightMagenta {
  color: var(--lightMagenta);
}
.c-lightCyan {
  color: var(--lightCyan);
}
.c-white {
  color: var(--white);
}