/* Styling for the eForth-on-MUXLEQ tutorial. Adapted from the Easy Forth book
   by Nick Morgan, with the layout redone for a single static page. */

:root {
  --bg: #ffffff;
  --fg: #24292e;
  --muted: #6a737d;
  --rule: #e1e4e8;
  --accent: #0366d6;
  --code-bg: #f6f8fa;
  --editor-bg: #fbfcfd;
  --stack-bg: #eef2f6;
  --fresh-bg: #dcf5e3;
  --fresh-edge: #46a758;
  --sel-bg: #dceafd;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d1117;
    --fg: #c9d1d9;
    --muted: #8b949e;
    --rule: #21262d;
    --accent: #58a6ff;
    --code-bg: #161b22;
    --editor-bg: #10151c;
    --stack-bg: #161b22;
    --fresh-bg: #14301f;
    --fresh-edge: #3fb950;
    --sel-bg: #12253d;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  padding: 0 20px 80px;
  background: var(--bg);
  color: var(--fg);
  font: 16px/1.6 -apple-system, "Segoe UI", Helvetica, Arial, sans-serif;
}

.wrapper { max-width: 780px; margin: 0 auto; }

header {
  border-bottom: 1px solid var(--rule);
  margin-bottom: 32px;
  padding: 40px 0 24px;
}

header h1 { font-size: 30px; margin: 0 0 8px; }
header p { color: var(--muted); margin: 4px 0; }

h2 {
  font-size: 24px;
  margin: 48px 0 16px;
  padding-top: 12px;
  border-top: 1px solid var(--rule);
}

h3 { font-size: 18px; margin: 28px 0 12px; }

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

code, pre, .editor, .stack, .transcript-preview {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

code {
  background: var(--code-bg);
  border-radius: 4px;
  font-size: 88%;
  padding: 2px 5px;
}

pre {
  background: var(--code-bg);
  border-radius: 6px;
  font-size: 14px;
  overflow-x: auto;
  padding: 12px 14px;
}

pre code { background: none; padding: 0; }

table { border-collapse: collapse; width: 100%; }
th, td {
  border-bottom: 1px solid var(--rule);
  padding: 6px 10px;
  text-align: left;
  vertical-align: top;
}
td code { white-space: nowrap; }

blockquote {
  border-left: 3px solid var(--rule);
  color: var(--muted);
  margin: 20px 0;
  padding: 0 0 0 16px;
}

.toc {
  background: var(--code-bg);
  border-radius: 6px;
  margin-bottom: 32px;
  padding: 16px 20px;
}
.toc ol { margin: 0; padding-left: 20px; }
.toc li { margin: 2px 0; }

/* -- the interactive editor -------------------------------------------- */

.editor {
  background: var(--editor-bg);
  border: 1px solid var(--rule);
  border-radius: 6px;
  font-size: 14px;
  margin: 20px 0 28px;
  padding: 8px;
  position: relative;
}

/* -- the stack viewer -------------------------------------------------- */

.stack-viewer {
  background: var(--stack-bg);
  border-radius: 4px;
  margin-bottom: 6px;
  padding: 14px 8px 5px;
}

.stack-row {
  align-items: center;
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  min-height: 26px;
}

/* Cells run bottom of the stack to top, left to right, which is the order the
   ( n1 n2 -- sum ) notation reads in. */
.stack-cell {
  background: var(--bg);
  border: 1px solid var(--rule);
  border-radius: 3px;
  color: var(--fg);
  cursor: pointer;
  font: inherit;
  padding: 1px 9px;
  position: relative;
  transition: background-color 0.45s ease, border-color 0.45s ease;
}

.stack-cell:hover { border-color: var(--accent); }

/* The top is the one beginners misread, so it is labeled, not just implied. */
.stack-cell.top {
  border-color: var(--accent);
  box-shadow: inset 0 -2px 0 var(--accent);
}

.stack-cell.top::after {
  color: var(--accent);
  content: "top";
  font-size: 9px;
  left: 0;
  letter-spacing: 0.04em;
  position: absolute;
  right: 0;
  text-align: center;
  top: -11px;
}

/* Whatever the last line pushed, so a change is visible without re-reading. */
.stack-cell.fresh {
  animation: stack-land 0.5s ease;
  background: var(--fresh-bg);
  border-color: var(--fresh-edge);
}

@keyframes stack-land {
  from { transform: translateY(-5px); opacity: 0.25; }
  to { transform: none; opacity: 1; }
}

.stack-cell.selected { background: var(--sel-bg); border-color: var(--accent); }

.stack-empty, .stack-more, .stack-note {
  color: var(--muted);
  font-size: 12px;
}

.stack-note { margin-left: auto; padding-left: 10px; white-space: nowrap; }

.stack-detail {
  border-top: 1px dashed var(--rule);
  color: var(--muted);
  display: flex;
  flex-wrap: wrap;
  font-size: 12px;
  gap: 4px 16px;
  margin-top: 5px;
  padding-top: 5px;
}

.stack-bits { color: var(--accent); letter-spacing: 0.02em; }

.editor-tools {
  align-items: center;
  display: flex;
  gap: 12px;
  justify-content: flex-end;
  margin-top: 6px;
}

.step-toggle {
  color: var(--muted);
  cursor: pointer;
  font-size: 12px;
  user-select: none;
}

.step-toggle input { margin-right: 2px; vertical-align: -1px; }

.editor-body { display: flex; gap: 8px; }

.transcript {
  flex: 1;
  height: 260px;
  min-width: 0;
  overflow-y: auto;
}

.editor.small .transcript { height: 120px; }

.lines p { margin: 0; white-space: pre-wrap; word-break: break-word; }
.code { color: var(--fg); }
.output { color: var(--muted); }

.canvas {
  background: #12141c;
  border-radius: 4px;
  flex: none;
  height: 240px;
  image-rendering: pixelated;
  width: 240px;
}

.editor .input {
  background: none;
  border: 0;
  border-top: 1px solid var(--rule);
  color: var(--fg);
  font: inherit;
  margin-top: 4px;
  outline: 0;
  padding: 4px 0 0;
  resize: none;
  width: 100%;
}

/* While a program is running the caret would be misleading: keystrokes are
   going to the program, not into a line being edited. */
.editor .input.busy { color: transparent; text-shadow: none; caret-color: transparent; }
.editor .input.busy::placeholder { color: var(--muted); }

.editor .reset {
  background: none;
  border: 1px solid var(--rule);
  border-radius: 4px;
  color: var(--muted);
  cursor: pointer;
  font: inherit;
  font-size: 12px;
  padding: 1px 8px;
}
.editor .reset:hover { color: var(--fg); }

/* A non-interactive illustration of what an editor should look like. */
.transcript-preview {
  background: var(--code-bg);
  border-radius: 6px;
  font-size: 14px;
  margin: 16px 0;
  padding: 10px 14px;
  white-space: pre-wrap;
}

.stack {
  background: var(--stack-bg);
  border-radius: 4px;
  font-size: 14px;
  margin: 14px 0 18px;
  padding: 14px 8px 5px;
}

/* -- a stack effect drawn as before and after -------------------------- */

.effect { margin: 18px 0 22px; }

.effect figcaption {
  color: var(--muted);
  font-size: 13px;
  margin-top: 8px;
}

.effect-row { display: flex; gap: 12px; }

.effect-side { flex: 1 1 0; min-width: 0; }

.effect-label {
  color: var(--muted);
  font-size: 11px;
  letter-spacing: 0.05em;
  margin-bottom: 4px;
  text-transform: uppercase;
}

/* The pictures are the live viewer's own boxes; only the framing differs. */
.effect-row .stack { margin: 0; }

/* Each picture would otherwise repeat "depth N". In a pair the comparison is
   the point, not the count. */
.effect-row .stack-note { display: none; }

.effect-arrow {
  align-self: center;
  color: var(--accent);
  flex: none;
  padding-top: 16px;
  text-align: center;
}

.effect-arrow::after { content: "\2192"; display: block; }

@media (max-width: 640px) {
  .editor-body { flex-direction: column; }
  .canvas { width: 100%; height: auto; aspect-ratio: 1; }
  /* Stacked vertically, an arrow pointing right would point at nothing. */
  .effect-row { flex-direction: column; }
  .effect-arrow { align-self: flex-start; padding-top: 0; }
  .effect-arrow::after { content: "\2193"; }
}