/* Visual Learn house style.
   Copy this file's rules into an explainer (inline <style> or its own styles.css);
   never import it across folders. Page-specific rules go after it. */

:root {
  color-scheme: light;

  /* paper and ink */
  --paper: #fcfbf7;
  --wash: #f3f1ea;          /* the only fill for a region that must read as "a thing" */
  --ink: #1c1b18;
  --ink-2: #57544c;         /* secondary text, captions */
  --ink-3: #716d63;         /* tertiary: ticks, meta, disabled */
  --rule: #e2ded3;          /* hairlines, gridlines */
  --rule-2: #c9c4b6;        /* control borders, axis lines */
  --link: #1f4e79;

  /* data colors: muted, colorblind-checked (derived from Okabe-Ito).
     Each page maps entities to these once and never reassigns them. */
  --c-blue:   #2f6ea6;
  --c-orange: #ae5019;
  --c-green:  #23765b;
  --c-purple: #6a51a3;
  --c-red:    #b8433a;
  --c-gold:   #b8901f;
  --c-sky:    #6ea8d6;
  --c-grey:   #a8a396;      /* context data: everything not being discussed */

  --serif: "Source Serif 4", "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --sans: "Source Sans 3", -apple-system, "Segoe UI", system-ui, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;

  /* the grid: a reading column, a gutter, and a margin for notes */
  --text: 37rem;
  --gap: 2.5rem;
  --margin: 15rem;
  --page: calc(var(--text) + var(--gap) + var(--margin));
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-padding-top: 3.5rem; }
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font-family: var(--serif); font-size: 1.1875rem; line-height: 1.58;
  font-optical-sizing: auto; -webkit-font-smoothing: antialiased;
  counter-reset: sidenote figure;
}
::selection { background: #e8dfc3; }
:focus-visible { outline: 3px solid var(--link); outline-offset: 3px; }

/* ---------- page frame ---------- */
.page { max-width: calc(var(--page) + 3rem); margin: 0 auto; padding: 0 1.5rem 6rem; }
.page > :not(section), section > * { max-width: var(--text); }
.page > .wide, section > .wide { max-width: none; }
.page > h1 { max-width: 48rem; }

/* ---------- type ---------- */
h1, h2, h3 { font-weight: 400; color: var(--ink); text-wrap: balance; }
h1 { font-size: clamp(2.5rem, 5.5vw, 3.6rem); line-height: 1.04; letter-spacing: -0.012em; margin: 4.5rem 0 0.6rem; }
.subtitle { font-style: italic; font-size: 1.45rem; line-height: 1.35; color: var(--ink-2); margin: 0 0 2rem; }
h2 { font-size: 1.95rem; line-height: 1.15; letter-spacing: -0.005em; margin: 4.5rem 0 1rem; }
h3 { font-style: italic; font-size: 1.35rem; line-height: 1.25; margin: 2.5rem 0 0.6rem; }
p, ul, ol { margin: 0 0 1.1rem; text-wrap: pretty; }
ul, ol { padding-left: 1.3rem; }
li { margin-bottom: 0.35rem; }
li::marker { color: var(--ink-3); }
strong, b { font-weight: 600; }
em, i { font-style: italic; }
.lede { font-size: 1.3rem; line-height: 1.5; }
.meta { font-family: var(--sans); font-size: 0.8125rem; color: var(--ink-3); letter-spacing: 0.01em; }
.smallcaps { font-variant-caps: all-small-caps; letter-spacing: 0.04em; }
a { color: var(--link); text-decoration-line: underline; text-decoration-thickness: 1px; text-underline-offset: 0.16em; text-decoration-color: color-mix(in srgb, var(--link) 35%, transparent); }
a:hover { text-decoration-color: currentColor; }
hr { border: 0; border-top: 1px solid var(--rule); margin: 3rem 0; }

code, kbd, samp { font-family: var(--mono); font-size: 0.84em; }
pre { font-family: var(--mono); font-size: 0.82rem; line-height: 1.55; margin: 0 0 1.25rem; padding: 0.1rem 0 0.1rem 1rem; border-left: 1px solid var(--rule-2); overflow-x: auto; }
.num, table, svg text, .controls { font-variant-numeric: lining-nums tabular-nums; }

/* ---------- sidenotes and margin notes ----------
   <span class="sn-ref"></span><span class="sidenote">…</span>  numbered, inside the paragraph
   <span class="marginnote">…</span>                              unnumbered
   Wide screens: floated into the margin column. Narrow: an indented block. */
.sidenote, .marginnote {
  float: right; clear: right; width: var(--margin);
  margin: 0.3rem calc(-1 * (var(--margin) + var(--gap))) 1rem 0;
  font-size: 0.875rem; line-height: 1.45; color: var(--ink-2);
  font-style: normal; font-weight: 400;
}
.sn-ref { counter-increment: sidenote; }
.sn-ref::after { content: counter(sidenote); font-family: var(--sans); font-size: 0.66em; font-weight: 600; vertical-align: super; line-height: 0; margin-left: 0.08em; color: var(--ink-2); }
.sidenote::before { content: counter(sidenote) "\2002"; font-family: var(--sans); font-size: 0.8em; font-weight: 600; }
p, li, figure { position: relative; }

/* ---------- figures ----------
   <figure class="fig">          text-column width, caption in the margin on wide screens
   <figure class="fig wide">     full page width, caption below
   Inside: optional .controls, the graphic, then <figcaption>. No borders, no cards. */
figure { margin: 2.25rem 0 2.5rem; padding: 0; }
.fig { counter-increment: figure; }
.fig figcaption { font-size: 0.9375rem; line-height: 1.5; color: var(--ink-2); margin-top: 0.85rem; max-width: var(--text); }
.fig figcaption .fig-n::before { content: "Figure " counter(figure) ". "; font-family: var(--sans); font-weight: 600; font-size: 0.78rem; letter-spacing: 0.02em; color: var(--ink); }
.fig .takeaway { font-style: italic; color: var(--ink); }
.graphic { position: relative; }
.graphic svg { display: block; width: 100%; height: auto; overflow: visible; }
.scroll-x { overflow-x: auto; overscroll-behavior-x: contain; }
.scroll-x > * { min-width: var(--min, 36rem); }

/* ---------- controls: quiet, real, keyboard reachable ---------- */
.controls { display: flex; flex-wrap: wrap; align-items: center; gap: 0.6rem 1.4rem; margin: 0 0 0.9rem; font-family: var(--sans); font-size: 0.875rem; color: var(--ink-2); }
.control { display: inline-flex; align-items: center; gap: 0.55rem; }
.control > .label { color: var(--ink-2); }
.control > output, .readout { font-family: var(--sans); color: var(--ink); font-weight: 600; min-width: 3.2ch; }
.btn {
  font: 500 0.875rem/1 var(--sans); color: var(--ink); background: transparent;
  border: 1px solid var(--rule-2); border-radius: 3px; padding: 0.5rem 0.75rem; min-height: 2.125rem;
  cursor: pointer; display: inline-flex; align-items: center; gap: 0.4rem;
}
.btn:hover { border-color: var(--ink-2); }
.btn:disabled { color: var(--ink-3); border-color: var(--rule); cursor: default; }
.btn.primary { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.seg { display: inline-flex; border: 1px solid var(--rule-2); border-radius: 3px; overflow: hidden; }
.seg > button { font: 500 0.875rem/1 var(--sans); color: var(--ink-2); background: transparent; border: 0; padding: 0.5rem 0.75rem; min-height: 2.125rem; cursor: pointer; }
.seg > button + button { border-left: 1px solid var(--rule); }
.seg > button:hover { color: var(--ink); }
.seg > button[aria-pressed="true"] { background: var(--ink); color: var(--paper); }
.seg > button:focus-visible { outline-offset: -3px; }

input[type="range"] { -webkit-appearance: none; appearance: none; background: transparent; width: 9rem; height: 1.5rem; margin: 0; cursor: pointer; }
input[type="range"]::-webkit-slider-runnable-track { height: 2px; background: var(--rule-2); }
input[type="range"]::-moz-range-track { height: 2px; background: var(--rule-2); }
input[type="range"]::-webkit-slider-thumb { -webkit-appearance: none; width: 14px; height: 14px; margin-top: -6px; border-radius: 50%; background: var(--ink); border: 2px solid var(--paper); box-shadow: 0 0 0 1px var(--ink); }
input[type="range"]::-moz-range-thumb { width: 12px; height: 12px; border-radius: 50%; background: var(--ink); border: 2px solid var(--paper); box-shadow: 0 0 0 1px var(--ink); }
input[type="range"]:focus-visible { outline: 3px solid var(--link); outline-offset: 3px; }
select { font: 0.875rem var(--sans); color: var(--ink); background: var(--paper); border: 1px solid var(--rule-2); border-radius: 3px; padding: 0.4rem 0.5rem; }

/* ---------- tables: booktabs ---------- */
table { border-collapse: collapse; width: 100%; font-family: var(--sans); font-size: 0.9rem; line-height: 1.35; margin: 0 0 1.25rem; }
thead th { font-weight: 600; font-size: 0.78rem; letter-spacing: 0.02em; color: var(--ink-2); text-align: left; border-bottom: 1px solid var(--ink); padding: 0.5rem 0.75rem 0.4rem 0; vertical-align: bottom; }
tbody td, tbody th { padding: 0.45rem 0.75rem 0.45rem 0; border-bottom: 1px solid var(--rule); text-align: left; vertical-align: top; font-weight: 400; }
tbody tr:last-child td, tbody tr:last-child th { border-bottom: 1px solid var(--ink); }
td.n, th.n { text-align: right; }

/* ---------- charts (SVG): data ink only ---------- */
.axis line, .axis path { stroke: var(--rule-2); stroke-width: 1; shape-rendering: crispEdges; }
.grid line { stroke: var(--rule); stroke-width: 1; shape-rendering: crispEdges; }
.tick text, .axis text { font-family: var(--sans); font-size: 11.5px; fill: var(--ink-3); }
.axis-title { font-family: var(--sans); font-size: 12px; fill: var(--ink-2); }
.label { font-family: var(--sans); font-size: 12.5px; fill: var(--ink); }
.label.muted { fill: var(--ink-2); }
.annot { font-family: var(--serif); font-style: italic; font-size: 13.5px; fill: var(--ink-2); }

/* ---------- top bar: back to the collection, sections, reading progress ---------- */
.topbar { position: sticky; top: 0; z-index: 20; background: var(--paper); border-bottom: 1px solid var(--rule); font-family: var(--sans); font-size: 0.8125rem; }
.topbar-inner { max-width: calc(var(--page) + 3rem); margin: 0 auto; padding: 0 1.5rem; display: flex; align-items: center; gap: 1.25rem; height: 2.75rem; }
.topbar .home { color: var(--ink-2); text-decoration: none; white-space: nowrap; }
.topbar .home:hover { color: var(--ink); }
.topbar .title { color: var(--ink); font-weight: 600; white-space: nowrap; }
.topbar nav { display: flex; gap: 1rem; min-width: 0; overflow-x: auto; scrollbar-width: thin; scrollbar-color: var(--rule-2) var(--paper); margin-left: auto; scroll-padding-inline: 0.25rem; }
.topbar nav a { color: var(--ink-3); text-decoration: none; white-space: nowrap; padding: 0.75rem 0.2rem; }
.topbar nav a:hover, .topbar nav a[aria-current="true"] { color: var(--ink); }
.topbar nav a[aria-current="true"] { text-decoration: underline; text-decoration-thickness: 2px; text-underline-offset: 0.35em; }
.topbar nav a:focus-visible { outline-offset: -3px; }
.progress { position: absolute; left: 0; bottom: -1px; height: 1px; background: var(--ink); width: 0; }

/* ---------- colophon ---------- */
.colophon { margin-top: 5rem; padding-top: 1.25rem; border-top: 1px solid var(--rule); font-size: 0.9rem; color: var(--ink-2); }

/* ---------- narrow screens: notes and captions fall into the column ---------- */
@media (min-width: 62rem) {
  .fig:not(.wide) { display: grid; grid-template-columns: var(--text) var(--margin); grid-auto-rows: minmax(min-content, auto); column-gap: var(--gap); max-width: none; align-items: end; }
  .fig:not(.wide) > * { grid-column: 1; }
  .fig:not(.wide) > figcaption { grid-column: 2; grid-row: 1 / span 6; align-self: end; margin: 0; }
}
@media (max-width: 61.99rem) {
  .sidenote, .marginnote { float: none; display: block; width: auto; margin: 0.6rem 0 0.9rem; padding-left: 0.9rem; border-left: 1px solid var(--rule-2); }
}
@media (max-width: 40rem) {
  body { font-size: 1.0625rem; line-height: 1.55; }
  .page, .topbar-inner { padding-left: 1rem; padding-right: 1rem; }
  h1 { margin-top: 3rem; }
  .subtitle { font-size: 1.25rem; }
  .lede { font-size: 1.125rem; }
  h2 { font-size: 1.6rem; margin-top: 3.5rem; }
  .topbar .title { display: none; }
  .btn, .seg > button { min-height: 2.5rem; }
  input[type="range"] { width: 7.5rem; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.01ms !important; animation-iteration-count: 1 !important; transition-duration: 0.01ms !important; scroll-behavior: auto !important; }
}

/* =====================================================================
   Page-specific rules for the quantization-aware training explainer.
   Entity colors, fixed for the whole page:
     full precision (fp32 model, master weight W, real value x)    blue
     quantized value (x̂, Ŵ, int4) and post-training quantization   orange
     quantization-aware training and its straight-through gradient green
     error                                                          red
   ===================================================================== */
:root {
  --fp: var(--c-blue);
  --quant: var(--c-orange);
  --qat: var(--c-green);
  --err: var(--c-red);
}

.c-fp { color: var(--fp); } .c-quant { color: var(--quant); } .c-qat { color: var(--qat); } .c-err { color: var(--err); }
.page > h1 { max-width: 48rem; }

/* SVG text that may sit on a data line gets a paper-colored halo */
.halo { paint-order: stroke; stroke: var(--paper); stroke-width: 4px; stroke-linejoin: round; }
.graphic svg text.val { font-family: var(--sans); font-size: 11.5px; fill: var(--ink-2); }
svg text.tick { font-family: var(--sans); font-size: 11.5px; fill: var(--ink-3); }
.node-t { font-family: var(--sans); font-size: 13px; font-weight: 600; fill: var(--ink); }
.node-f { font-family: var(--mono); font-size: 11.5px; fill: var(--ink-2); }
.node-n { font-family: var(--sans); font-size: 12px; fill: var(--ink-2); }

/* panels inside one figure: small multiples on a shared scale */
.panel + .panel { margin-top: 1.1rem; }
.panel-title { font: 600 0.8125rem/1.3 var(--sans); color: var(--ink); margin: 0 0 0.35rem; }
.panel-title .muted { font-weight: 400; color: var(--ink-2); }
.panel-note { font: 0.8125rem/1.4 var(--sans); color: var(--ink-2); margin: 0.35rem 0 0; font-variant-numeric: lining-nums tabular-nums; }
.panel-note b { color: var(--ink); font-weight: 600; }
.multiples { display: grid; gap: 1.25rem 1.5rem; }
.multiples.three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.multiples.tight { gap: 1rem 0.9rem; }
.multiples.three > .panel + .panel { margin-top: 0; }
@media (max-width: 40rem) {
  .multiples.stack-narrow { grid-template-columns: minmax(0, 1fr); }
}
.lab-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 1.5rem 2rem; }
@media (max-width: 52rem) { .lab-grid { grid-template-columns: minmax(0, 1fr); gap: 2.25rem; } }
.lab-grid .panel + .panel { margin-top: 0.4rem; }

/* one quiet line of numbers under a graphic */
.readout-line { font: 0.875rem/1.5 var(--sans); color: var(--ink-2); margin: 0.6rem 0 0; font-variant-numeric: lining-nums tabular-nums; }
.readout-line b { color: var(--ink); font-weight: 600; }
.readout-line .sep { color: var(--ink-3); margin: 0 0.1rem; }
.readout-line .ro { white-space: nowrap; }

/* legend ramp for the error heatmaps: the color scale is data, so it gets a key */
.ramp { display: flex; align-items: center; gap: 0.5rem; font: 0.8125rem var(--sans); color: var(--ink-2); margin-top: 0.8rem; font-variant-numeric: lining-nums tabular-nums; }
.ramp i { display: inline-block; width: 7rem; height: 0.55rem; }

.controls output { font-family: var(--sans); color: var(--ink); font-weight: 600; min-width: 3.2ch; }
.controls .hint { color: var(--ink-3); }
.status { color: var(--ink-3); font-family: var(--sans); font-size: 0.8125rem; }
#numLine svg { touch-action: none; }
#numLine .drag { cursor: ew-resize; }
#numLine .drag:focus-visible { outline: none; stroke: var(--link); stroke-width: 3px; }

/* review questions: a plain list of disclosures */
.check details { border-top: 1px solid var(--rule); padding: 0.7rem 0; max-width: var(--text); }
.check details:last-of-type { border-bottom: 1px solid var(--rule); }
.check summary { cursor: pointer; font-style: italic; }
.check summary::marker { color: var(--ink-3); }
.check details p { margin: 0.6rem 0 0.2rem; }

table caption { caption-side: bottom; text-align: left; font-size: 0.875rem; color: var(--ink-2); padding-top: 0.5rem; font-family: var(--serif); line-height: 1.45; }
td code { font-size: 0.8em; }
.colophon ul { padding-left: 1.1rem; }