/* VIOS manual: the look of the VIOS display server (lib/vios-vds) in CSS.
 * Smalltalk style: a grey dithered desktop, white windows with black frames,
 * hard shadows and yellow title tabs. Turbo Vision style: blue desktop and
 * windows, double white frames, a grey menu bar with red mnemonics.
 * Colours are the server's RGB222 palettes (0, 85, 170, 255 per channel). */

@font-face {
  font-family: "Agon8";
  src: url("fonts/agon8.woff") format("woff");
  font-display: swap;
}

:root {
  --px: 2px;                                  /* one display pixel */
  --desk-a: #555555;
  --desk-b: #aaaaaa;
  --win: #ffffff;
  --ink: #000000;
  --frame: #000000;
  --shadow: #000000;
  --tab: #ffffaa;
  --tab-ink: #000000;
  --sel: #000000;
  --sel-ink: #ffffff;
  --muted: #555555;
  --link: #0000aa;
  --code-bg: #ffffff;
  --code-ink: #000000;
  --inline-bg: #e6e6e6;
  --bar: #ffffff;
  --bar-ink: #000000;
  --mn: inherit;
  --rule: #000000;
  --pixel: "Agon8", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --text: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color-scheme: light;
}

:root[data-style="turbo"] {
  --desk-a: #000055;
  --desk-b: #0055aa;
  --win: #0000aa;
  --ink: #ffffff;
  --frame: #ffffff;
  --shadow: #000000;
  --tab: #0000aa;
  --tab-ink: #ffffff;
  --sel: #00aa00;
  --sel-ink: #ffffff;
  --muted: #aaaaaa;
  --link: #55ffff;
  --code-bg: #000055;
  --code-ink: #ffff55;
  --inline-bg: #000055;
  --bar: #aaaaaa;
  --bar-ink: #000000;
  --mn: #ff0000;
  --rule: #aaaaaa;
  color-scheme: dark;
}

* { box-sizing: border-box; }

html {
  background-color: var(--desk-a);
  background-image: conic-gradient(var(--desk-b) 25%, var(--desk-a) 0 50%, var(--desk-b) 0 75%, var(--desk-a) 0);
  background-size: calc(var(--px) * 2) calc(var(--px) * 2);
  scroll-padding-top: 48px;
}

body {
  margin: 0;
  font: 16px/1.6 var(--text);
  color: var(--ink);
  -webkit-text-size-adjust: 100%;
}

/* ---------------------------------------------------------------- menu bar */

/* The menu bar scrolls sideways when it is wider than the screen: a thin
 * scroll bar and a fade at the clipped edge show that more items follow. */
.menubar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 6px 16px;
  background: var(--bar);
  color: var(--bar-ink);
  border-bottom: var(--px) solid var(--ink);
  font: 16px/16px var(--pixel);
  overflow-x: auto;
  overscroll-behavior-x: contain;
  -webkit-overflow-scrolling: touch;
  white-space: nowrap;
  scrollbar-width: thin;
  scrollbar-color: var(--bar-ink) var(--bar);
}
:root[data-style="turbo"] .menubar { border-bottom-color: #000000; }
.menubar::-webkit-scrollbar { height: 4px; }
.menubar::-webkit-scrollbar-thumb { background: var(--bar-ink); }
.menubar > * { flex: 0 0 auto; }
.menubar.more-right { -webkit-mask-image: linear-gradient(to right, #000 calc(100% - 40px), transparent); mask-image: linear-gradient(to right, #000 calc(100% - 40px), transparent); }
.menubar.more-left { -webkit-mask-image: linear-gradient(to left, #000 calc(100% - 40px), transparent); mask-image: linear-gradient(to left, #000 calc(100% - 40px), transparent); }
.menubar.more-left.more-right { -webkit-mask-image: linear-gradient(to right, transparent, #000 40px, #000 calc(100% - 40px), transparent); mask-image: linear-gradient(to right, transparent, #000 40px, #000 calc(100% - 40px), transparent); }
.menubar a, .menubar button {
  color: inherit;
  text-decoration: none;
  font: inherit;
  background: none;
  border: 0;
  padding: 4px 6px;
  cursor: pointer;
}
.menubar a:hover, .menubar button:hover, .menubar a:focus-visible, .menubar button:focus-visible {
  background: var(--sel);
  color: var(--sel-ink);
  outline: none;
}
.menubar nav { display: flex; gap: 4px; flex: 0 0 auto; }
.menubar .logo { font-weight: normal; padding-right: 10px; border-right: var(--px) solid currentColor; }
.mn { color: var(--mn); }

/* ---------------------------------------------------------------- windows */

.desktop {
  display: grid;
  grid-template-columns: 300px minmax(0, 920px);
  justify-content: center;
  gap: 40px;
  padding: 44px 24px 56px;
  align-items: start;
}

.window {
  position: relative;
  background: var(--win);
  color: var(--ink);
  border: var(--px) solid var(--frame);
  box-shadow: calc(var(--px) * 4) calc(var(--px) * 4) 0 var(--shadow);
}
:root[data-style="turbo"] .window {
  border: calc(var(--px) * 3) double var(--frame);
  outline: calc(var(--px) * 3) solid var(--win);
}

.tab {
  font: 16px/16px var(--pixel);
  background: var(--tab);
  color: var(--tab-ink);
  border: var(--px) solid var(--frame);
  border-bottom: 0;
  padding: 3px 10px 2px;
}
.title {
  position: absolute;
  left: 12px;
  bottom: 100%;
  max-width: calc(100% - 24px);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
:root[data-style="turbo"] .tab {
  border: 0;
  padding: 0 8px;
}
:root[data-style="turbo"] .title {
  left: 50%;
  bottom: auto;
  top: -14px;
  transform: translateX(-50%);
}

.main-window { padding: 28px 40px 32px; min-height: 60vh; }

/* The contents window stays in view on wide screens. */
.contents-window {
  position: sticky;
  top: 72px;
  max-height: calc(100vh - 96px);
  overflow: auto;
  scrollbar-width: thin;
}
.contents-window details { padding: 0; }
.contents-window summary {
  position: sticky;
  top: 0;
  list-style: none;
  cursor: pointer;
  border: 0;
  border-bottom: var(--px) solid var(--frame);
  padding: 6px 12px;
}
.contents-window summary::-webkit-details-marker { display: none; }
.toc { margin: 0; padding: 8px 0 12px; list-style: none; counter-reset: ch; font-size: 14px; line-height: 1.35; }
.toc > li { counter-increment: ch; }
.toc > li:first-child { counter-increment: none; }
.toc a { display: block; padding: 3px 12px 3px 16px; color: inherit; text-decoration: none; }
.toc > li > a::before { content: counter(ch) ". "; font-family: var(--pixel); font-size: 12px; color: var(--muted); }
.toc > li:first-child > a::before { content: ""; }
.toc a:hover { background: var(--sel); color: var(--sel-ink); }
.toc a:hover::before { color: inherit; }
.toc li.here > a { background: var(--sel); color: var(--sel-ink); }
.toc li.here > a::before { color: inherit; }
.toc ul { list-style: none; margin: 2px 0 6px; padding: 0 0 0 18px; border-left: var(--px) solid var(--rule); margin-left: 22px; }
.toc ul a { padding: 2px 8px; font-size: 13px; }

/* ---------------------------------------------------------------- text */

article { max-width: 72ch; margin: 0 auto; }
article > :first-child { margin-top: 0; }
h1, h2, h3, h4 { font-family: var(--pixel); font-weight: normal; line-height: 1.25; letter-spacing: 0; }
h1 { font-size: 32px; line-height: 40px; margin: 8px 0 20px; }
h2 { font-size: 24px; margin: 40px 0 16px; }
h2.inline { margin-top: 44px; padding-top: 16px; border-top: var(--px) solid var(--rule); }
h3 {
  font-size: 16px;
  margin: 36px 0 12px;
  padding-bottom: 6px;
  border-bottom: var(--px) solid var(--rule);
}
h4 { font-size: 16px; margin: 28px 0 8px; color: var(--muted); }
:root[data-style="turbo"] h4 { color: #ffff55; }
p, ul, ol, table, pre, figure, blockquote { margin: 0 0 16px; }
li { margin: 2px 0; }
a { color: var(--link); text-underline-offset: 2px; }
a:hover { background: var(--sel); color: var(--sel-ink); text-decoration: none; }
strong { font-weight: 650; }
hr { border: 0; border-top: var(--px) solid var(--rule); margin: 28px 0; }
blockquote {
  margin-left: 0;
  padding: 10px 16px;
  border: var(--px) solid var(--frame);
  border-left-width: calc(var(--px) * 4);
}
blockquote > :last-child { margin-bottom: 0; }

kbd { font-family: var(--pixel); font-size: 16px; }
/* Inline code in running text uses a regular monospace: the 8x8 font is
 * authentic in code blocks and headings but heavy inside sentences. */
:not(pre) > code {
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  background: var(--inline-bg);
  padding: 1px 4px;
  font-size: 0.9em;
  line-height: 1;
  word-break: break-word;
}
/* Code inside headings and table headers takes their colours and font. */
th code, th a { color: inherit; }
th code { font: inherit; background: none; padding: 0; }
h1 code, h2 code, h3 code, h4 code { font-family: var(--pixel); font-size: 1em; background: none; padding: 0; }
kbd {
  border: var(--px) solid var(--frame);
  padding: 0 4px;
  font-size: 14px;
  box-shadow: var(--px) var(--px) 0 var(--shadow);
}
/* Code blocks: a regular monospace for 80-column lines, framed like a VDS
 * window with the language in an 8x8 title tab. */
pre {
  position: relative;
  background: var(--code-bg);
  color: var(--code-ink);
  border: var(--px) solid var(--frame);
  padding: 12px 14px;
  overflow-x: auto;
  font: 14px/1.5 ui-monospace, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  box-shadow: calc(var(--px) * 2) calc(var(--px) * 2) 0 var(--shadow);
  tab-size: 4;
}
pre { margin-top: 34px; overflow: visible; }
pre > code { display: block; overflow-x: auto; }
pre[data-lang]::before {
  content: attr(data-lang);
  position: absolute;
  left: 10px;
  bottom: 100%;
  margin-bottom: var(--px);
  font: 12px/12px var(--pixel);
  padding: 3px 8px 2px;
  background: var(--tab);
  color: var(--tab-ink);
  border: var(--px) solid var(--frame);
  border-bottom: 0;
}
:root[data-style="turbo"] pre[data-lang]::before { background: var(--sel); color: var(--sel-ink); border-color: var(--sel); }
pre code { background: none; padding: 0; font: inherit; }

/* Copy to clipboard: a pixel clipboard icon in a tab at the block's top right. */
pre .copy {
  position: absolute;
  right: 10px;
  bottom: 100%;
  margin-bottom: var(--px);
  display: inline-flex;
  align-items: center;
  gap: 6px;
  height: 21px;
  padding: 2px 7px;
  font: 12px/12px var(--pixel);
  color: var(--tab-ink);
  background: var(--win);
  border: var(--px) solid var(--frame);
  border-bottom: 0;
  cursor: pointer;
}
pre .copy svg { width: 12px; height: 12px; display: block; shape-rendering: crispEdges; fill: currentColor; }
pre .copy:hover, pre .copy:focus-visible { background: var(--sel); color: var(--sel-ink); outline: none; }
pre .copy.done { background: var(--tab); color: var(--tab-ink); }
:root[data-style="turbo"] pre .copy { background: var(--code-bg); color: var(--code-ink); border-color: var(--sel); }


/* Tables look like VDS table widgets: a selection-coloured header row. */
.table-wrap { overflow-x: auto; margin: 0 0 18px; border: var(--px) solid var(--frame); }
table { border-collapse: collapse; width: 100%; font-size: 14.5px; line-height: 1.45; margin: 0; }
th {
  background: var(--sel);
  color: var(--sel-ink);
  font: 14px/18px var(--pixel);
  text-align: left;
  padding: 6px 10px;
  white-space: nowrap;
}
td { padding: 6px 10px; vertical-align: top; border-top: 1px solid var(--rule); }
td code { white-space: nowrap; }
td:nth-child(2) code { white-space: normal; }

/* The word reference uses the whole window width. */
.page-word-reference article, .page-word-reference .filter, .page-word-reference .pager { max-width: none; }
.page-word-reference td:first-child { width: 17%; }
.page-word-reference td:nth-child(2) { width: 24%; }
.page-word-reference td:last-child { width: 8%; font-size: 13px; color: var(--muted); }
.page-word-reference td:first-child code { font-family: var(--pixel); font-size: 16px; background: none; padding: 0; }
tr:target, tr:has(a:target) { background: var(--tab); color: var(--tab-ink); }
:root[data-style="turbo"] tr:has(a:target) { background: #00aaaa; }

/* Screenshots: the real 640x480 frames, pixel-exact. */
figure.shot { margin: 24px 0 28px; text-align: center; }
figure.shot a { display: inline-block; background: none; }
figure.shot img {
  display: block;
  width: 100%;
  max-width: 640px;
  height: auto;
  image-rendering: pixelated;
  border: var(--px) solid var(--frame);
  box-shadow: calc(var(--px) * 4) calc(var(--px) * 4) 0 var(--shadow);
}
figure.shot figcaption { margin-top: 14px; font: 14px/1.4 var(--text); color: var(--muted); }
figure.shot.anim figcaption::before { content: "\25B6  "; font-family: var(--pixel); }

/* Pager: VDS buttons. */
.pager {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  max-width: 72ch;
  margin: 40px auto 0;
  padding-top: 20px;
  border-top: var(--px) solid var(--rule);
}
.button {
  font: 16px/20px var(--pixel);
  color: var(--ink);
  text-decoration: none;
  padding: 4px 6px;
}
.button[rel="next"] { margin-left: auto; text-align: right; }
.button:hover, .button:focus-visible { background: var(--sel); color: var(--sel-ink); outline: none; }

.filter { max-width: 72ch; margin: 0 auto 20px; font-family: var(--pixel); display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.filter input {
  flex: 1 1 240px;
  font: 16px/20px var(--pixel);
  padding: 6px 8px;
  color: var(--ink);
  background: var(--win);
  border: var(--px) solid var(--frame);
  border-radius: 0;
  box-shadow: inset var(--px) var(--px) 0 var(--shadow);
}
.filter input:focus { outline: var(--px) solid var(--sel); outline-offset: 2px; }
.filter .count { color: var(--muted); font-size: 14px; }


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

/* ---------------------------------------------------------------- narrow screens */

@media (max-width: 1100px) {
  .desktop { grid-template-columns: minmax(0, 920px); gap: 36px; padding: 36px 16px 48px; }
  .contents-window { position: relative; top: 0; max-height: none; }
  .contents-window:not(:has(details[open])) { box-shadow: calc(var(--px) * 2) calc(var(--px) * 2) 0 var(--shadow); }
  .toc ul { display: none; }
}

@media (max-width: 640px) {
  :root { --px: 2px; }
  body { font-size: 16px; }
  .desktop { padding: 30px 10px 40px; gap: 30px; }
  .main-window { padding: 22px 16px 24px; }
  .window { box-shadow: calc(var(--px) * 3) calc(var(--px) * 3) 0 var(--shadow); }
  h1 { font-size: 24px; line-height: 32px; }
  h2 { font-size: 20px; }
  pre { margin-left: -6px; margin-right: -6px; padding: 10px; font-size: 13px; }
  .menubar { gap: 8px; padding: 6px 8px; font-size: 14px; }
  .title { font-size: 14px; }
  figure.shot { margin-left: -6px; margin-right: -6px; }
  table { font-size: 14px; }
  article ul, article ol { padding-left: 22px; }
  .page-word-reference td:first-child, .page-word-reference td:nth-child(2) { width: auto; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

@media print {
  html { background: #fff; }
  .menubar, .contents-window, .pager, .filter { display: none; }
  .desktop { display: block; padding: 0; }
  .window { border: 0; box-shadow: none; }
  .title { position: static; }
}