/* screen.css — the HTML edition (site/learn/book/). Shares waldogis.com's
   variables and dark mode (site/index.html :root). Copied to book.css by
   build_book.py. Numbers from course/book/STYLE.md "HTML edition". */

:root {
  --bg: #f7f8f9;
  --card: #ffffff;
  --ink: #1d2529;
  --muted: #5b6a72;
  --accent: #0079c1;
  --accent-ink: #ffffff;
  --line: #dfe5e8;
  --soft: #eef4f8;
  --ring1: #bddbef; --ring2: #7fbce0; --ring3: #1484c6; --ring4: #0079c1;
  --chap: #0079c1;
  --figure-card: transparent;
  --note-bg: #f3f4f5;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14191c;
    --card: #1c2327;
    --ink: #e8edf0;
    --muted: #9fb0b9;
    --accent: #3da5e0;
    --accent-ink: #10161a;
    --line: #2c363c;
    --soft: #212c33;
    --ring1: #24404f; --ring2: #2f6e93; --ring3: #3da5e0; --ring4: #7ccbf5;
    --figure-card: #ffffff;
    --note-bg: #20272b;
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  font-size: 17px;
  line-height: 1.6;
  background: var(--bg);
  color: var(--ink);
}
a { color: var(--accent); }
code { font-family: Consolas, ui-monospace, monospace; font-size: 0.9em; }

.chapter, .matter {
  --chap-ink: var(--chap);
  --chap-tint: color-mix(in srgb, var(--chap) 10%, var(--card));
  --chap-head: color-mix(in srgb, var(--chap) 18%, var(--card));
}
@media (prefers-color-scheme: dark) {
  .chapter, .matter {
    --chap-ink: color-mix(in srgb, var(--chap) 55%, white);
    --chap-tint: color-mix(in srgb, var(--chap) 22%, var(--card));
    --chap-head: color-mix(in srgb, var(--chap) 30%, var(--card));
  }
}

/* header bar */
.site-bar {
  position: sticky; top: 0; z-index: 5;
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  padding: 10px 20px;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.bar-home { display: flex; align-items: center; color: var(--ink); text-decoration: none; font-weight: 600; font-size: 15px; }
.bar-home .mark { width: 26px; height: 26px; margin-right: 10px; flex: none; }
.bar-links { display: flex; gap: 18px; font-size: 14px; }
.bar-links a { text-decoration: none; color: var(--muted); }
.bar-links a:hover { color: var(--accent); }

main.book { max-width: 52rem; margin: 0 auto; padding: 32px 20px 24px; }
main.book > * { max-width: 44rem; margin-left: auto; margin-right: auto; }
.chapter-body > *, .opener > * { max-width: 44rem; margin-left: auto; margin-right: auto; }
.chapter-body > figure, .chapter-body > .fig-row, .opener > figure { max-width: 52rem; }

h1, h2, h3 { line-height: 1.25; }
h2 { font-size: 1.55rem; font-weight: 600; color: var(--chap-ink); margin: 2.2em 0 0.5em; scroll-margin-top: 70px; }
h3 { font-size: 1.15rem; font-weight: 600; margin: 1.6em 0 0.4em; scroll-margin-top: 70px; }
p { margin: 0 0 0.85em; }

/* opener */
.opener { margin-bottom: 2.5rem; }
.chap-label { font-size: 0.8rem; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; color: var(--chap-ink); margin: 0 0 0.3em; }
.chap-title { font-size: 2.6rem; font-weight: 600; margin: 0 0 0.25em; }
.chap-module { color: var(--muted); margin: 0 0 1.6rem; padding-bottom: 0.6rem; border-bottom: 3px solid var(--chap); }
.chap-status {
  display: inline-block; font-size: 0.7rem; font-weight: 600; letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--chap-ink); border: 1px solid var(--chap-ink); padding: 0 6px; margin-left: 8px; vertical-align: 2px;
}
.opener figure.hero img { width: 100%; max-height: 28rem; object-fit: contain; }
.in-this-chapter { background: var(--card); border: 1px solid var(--line); border-radius: 10px; padding: 14px 18px; margin-top: 1.4rem; font-size: 0.95rem; }
.in-this-chapter .itc-label { font-size: 0.75rem; font-weight: 600; letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted); margin: 0 0 0.4em; }
.in-this-chapter ol { margin: 0; padding-left: 1.2em; columns: 2; column-gap: 2rem; }
.in-this-chapter a { text-decoration: none; }

.standalone-band { display: flex; align-items: center; gap: 14px; margin-bottom: 1.5rem; }
.band-mark { width: 44px; height: 44px; }
.band-kicker { font-weight: 600; color: var(--accent); font-size: 1.1rem; }
.band-book { color: var(--muted); font-size: 0.85rem; }

/* figures */
figure { margin: 1.6rem auto 1.8rem; }
figure img { display: block; max-width: 100%; height: auto; margin: 0 auto; background: var(--figure-card); border-radius: 4px; }
figure.vector img { width: 100%; }
figure.raster img { border: 1px solid var(--line); }
figure.screenshot img { border: 0; background: transparent; }
@media (prefers-color-scheme: dark) { figure.vector img, figure.raster img { padding: 10px; } }
figcaption { font-size: 0.85rem; line-height: 1.45; color: var(--ink); margin-top: 0.6em; }
.fig-num { font-weight: 600; color: var(--chap-ink); margin-right: 0.6em; }
.fig-credit { display: block; font-size: 0.75rem; color: var(--muted); margin-top: 0.2em; }
.fig-row { display: flex; gap: 20px; align-items: flex-start; margin: 1.6rem auto 1.8rem; }
.fig-row figure { flex: 1 1 0; margin: 0; }
figure.half { max-width: 26rem; }
@media (max-width: 640px) { .fig-row { flex-direction: column; } figure.half { max-width: 100%; } }
.fig-placeholder {
  border: 2px dashed var(--chap-ink); background: var(--chap-tint); border-radius: 6px;
  min-height: 12rem; display: flex; flex-direction: column; justify-content: center; align-items: center;
  text-align: center; padding: 1.2rem; color: var(--muted);
}
.ph-id { font-family: Consolas, monospace; font-size: 0.85rem; color: var(--chap-ink); }
.ph-caption { font-size: 0.85rem; max-width: 32rem; }
.ph-status { font-size: 0.72rem; font-weight: 600; letter-spacing: 0.12em; text-transform: uppercase; color: var(--chap-ink); margin-top: 0.3em; }

/* callouts */
.callout { border-left: 4px solid var(--accent); border-radius: 0 8px 8px 0; padding: 12px 16px; margin: 1.4rem auto; font-size: 0.95rem; }
.callout p:last-child { margin-bottom: 0; }
.callout-label { font-size: 0.75rem; font-weight: 600; letter-spacing: 0.06em; text-transform: uppercase; margin: 0 0 0.3em !important; }
.callout-why { border-left-color: var(--chap); background: var(--chap-tint); font-size: 1rem; }
.callout-why .callout-label { color: var(--chap-ink); }
.callout-outcomes { border-left-color: var(--chap); background: var(--chap-tint); font-size: 0.9rem; padding: 10px 16px; }
.callout-outcomes .callout-label { color: var(--chap-ink); }
.callout-outcomes ul { margin: 0; padding-left: 1.2em; }
.callout-outcomes li { margin: 0 0 0.2em; }
.callout-outcomes ul:last-child { margin-bottom: 0; }
.callout-reading { border: 1px solid var(--chap); border-left: 4px solid var(--chap); background: transparent; font-size: 0.9rem; }
.callout-reading .callout-label { color: var(--chap-ink); }
.callout-reading ul { margin: 0; padding-left: 1.2em; }
.callout-reading li { margin: 0 0 0.2em; }
.callout-reading ul:last-child { margin-bottom: 0; }
.opener .callout-why + .callout-outcomes { margin-top: -0.6rem; }
.callout-rule { background: var(--soft); }
.callout-rule .callout-label, .callout-pane .callout-label { color: var(--accent); }
.callout-pane { background: var(--card); border: 1px solid var(--ring1); border-left: 4px solid var(--ring2); }
.callout-pane .callout-label::before {
  content: ""; display: inline-block; width: 12px; height: 12px; margin-right: 6px; vertical-align: -1px; border-radius: 50%;
  background: radial-gradient(circle, var(--ring4) 0 27%, transparent 27% 40%, var(--ring3) 40% 58%, transparent 58% 70%, var(--ring2) 70% 86%, transparent 86%);
}
.callout-try { background: var(--card); border: 1px solid var(--chap-ink); border-left: 4px solid var(--chap-ink); }
.callout-try .callout-label { color: var(--chap-ink); }
.callout-note { border-left-color: #8a969c; background: var(--note-bg); }
.callout-note .callout-label { color: var(--muted); }
blockquote { margin: 1.2rem 0 1.2rem 1rem; padding-left: 1rem; border-left: 2px solid var(--line); font-style: italic; }

/* tables */
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; font-size: 0.9rem; margin: 1rem auto 1.4rem; }
th { text-align: left; font-weight: 600; background: var(--chap-head); border-bottom: 2px solid var(--chap-ink); padding: 6px 10px; }
td { border-bottom: 1px solid var(--line); padding: 6px 10px; vertical-align: top; }

/* key terms */
dl.key-terms { display: grid; grid-template-columns: minmax(8rem, 13rem) 1fr; gap: 6px 18px; }
dl.key-terms dt { font-weight: 600; }
dl.key-terms dd { margin: 0; }
@media (max-width: 640px) { dl.key-terms { grid-template-columns: 1fr; } dl.key-terms dd { margin-bottom: 8px; } }
.src { display: none; }

/* matter pages */
.matter h1 { font-size: 2rem; font-weight: 600; border-bottom: 3px solid var(--chap); padding-bottom: 0.3em; }
.toc-entry { display: flex; align-items: baseline; gap: 8px; }
.toc-lead, .toc-page { display: none; }
.toc-chapter { font-weight: 600; font-size: 1.1rem; margin: 1.1rem 0 0.2rem; }
.toc-chapter .toc-num { display: inline-block; min-width: 2.2rem; color: var(--toc-accent, var(--accent)); }
.toc-section { padding-left: 2.2rem; font-size: 0.92rem; }
.toc-section a { color: var(--muted); text-decoration: none; }
.toc-section a:hover { color: var(--accent); }
.toc-chapter a { color: var(--ink); text-decoration: none; }
.toc-matter { margin: 0.9rem 0 0.2rem; font-weight: 600; }
.glossary { columns: 2 22rem; column-gap: 2.5rem; font-size: 0.95rem; }
.gl-entry { break-inside: avoid; margin: 0 0 0.7em; }
.gl-term { font-weight: 600; }
.gl-ch { font-weight: 600; font-size: 0.8rem; margin-left: 4px; }
.gl-def { display: block; padding-left: 0.5em; }
.matter-data-sources td:nth-child(3) { overflow-wrap: anywhere; word-break: break-all; font-size: 0.85em; }
.credits table { font-size: 0.85rem; }

/* footer */
.site-foot { max-width: 44rem; margin: 3rem auto 0; padding: 24px 20px 40px; border-top: 1px solid var(--line); font-size: 0.85rem; color: var(--muted); }
.prevnext { display: flex; justify-content: space-between; gap: 16px; margin-bottom: 1.2rem; font-size: 0.95rem; }
.prevnext a { text-decoration: none; }
.foot-edition, .foot-licence { margin: 0.2em 0; }

/* print-only pages never show on screen */
.cover, .copyright { display: none; }