/* DipGrid site: tokens for both themes, type, page layout, plain sections.
   Pictures live in art.css, the top of the page in hero.css.
   Reasons — web/site-notes/DESIGN.md.
   No inline styles anywhere: the page's CSP allows only these files. */

/* Archivo, served from here (licence: assets/fonts/OFL.txt). Same files and
   ranges as Google Fonts gives for wdth 62..125, wght 400..800; the browser
   fetches latin-ext only if the page has such letters. */
@font-face {
  font-family: "Archivo";
  font-style: normal;
  font-weight: 400 800;
  font-stretch: 62% 125%;
  font-display: swap;
  src: url("../fonts/archivo-latin-ext.woff2") format("woff2");
  unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C0, U+2113, U+2C60-2C7F, U+A720-A7FF;
}
@font-face {
  font-family: "Archivo";
  font-style: normal;
  font-weight: 400 800;
  font-stretch: 62% 125%;
  font-display: swap;
  src: url("../fonts/archivo-latin.woff2") format("woff2");
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}

:root {
  color-scheme: light dark;
  --paper: #F3F6F5;         /* engineering paper */
  --paper-2: #E9EFEC;       /* a panel laid on the paper */
  --grid-minor: #E6ECE9;
  --grid-major: #D9E2DE;
  --ruling: #D3DEDA;
  --ruling-strong: #BCCBC5;
  --ink: #1A2744;           /* blue-black ink */
  --graphite: #4B566B;
  --muted: #737F96;
  --cobalt: #2447C8;        /* bought */
  --cobalt-tint: #C9D4F6;
  --amber: #B06A00;         /* sold */
  --amber-tint: #F1DDBA;
  --on-ink: #F3F6F5;        /* text on an ink button */

  /* the Safety band and its drawing stay dark in both themes */
  --band: #1A2744;
  --band-2: #22325A;
  --band-text: #F3F6F5;
  --band-dim: #B9C4D8;
  --band-line: #3A4A70;
  --band-cobalt: #8FA8FF;
  --band-amber: #F2B441;

  --font: "Archivo", "Helvetica Neue", Arial, sans-serif;
  --wrap: 72rem;
  --gutter: clamp(1rem, 4vw, 3rem);
  --dash: repeating-linear-gradient(to right, var(--ruling) 0 8px, transparent 8px 14px);
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper: #0F1729;
    --paper-2: #16213A;
    --grid-minor: #141E34;
    --grid-major: #1B273F;
    --ruling: #25324F;
    --ruling-strong: #34446A;
    --ink: #E6ECEF;
    --graphite: #A7B2C6;
    --muted: #7D8AA6;
    --cobalt: #8FA8FF;
    --cobalt-tint: #25366A;
    --amber: #F2B441;
    --amber-tint: #4A3818;
    --on-ink: #0F1729;
    --band: #16213A;
    --band-2: #1F2D52;
  }
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 1rem; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font);
  font-size: 1.125rem;
  line-height: 1.55;
  font-kerning: normal;
  -webkit-text-size-adjust: 100%;
}

h1, h2, h3, h4, p, ul, ol, dl, dd, figure, fieldset { margin: 0; }
ul, ol { padding: 0; list-style: none; }
fieldset { padding: 0; border: 0; min-width: 0; }
img, svg, canvas { display: block; max-width: 100%; }

a { color: var(--cobalt); text-underline-offset: .18em; text-decoration-thickness: 1px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--cobalt); outline-offset: 3px; border-radius: 2px; }

.wrap {
  max-width: calc(var(--wrap) + 2 * var(--gutter));
  margin-inline: auto;
  padding-inline: var(--gutter);
}
/* full width background, content lined up with .wrap */
.bleed { padding-inline: max(var(--gutter), calc((100% - var(--wrap)) / 2)); }

.skip {
  position: absolute; z-index: 10; left: var(--gutter); top: -4rem;
  padding: .5rem 1rem; background: var(--ink); color: var(--paper);
}
.skip:focus { top: .75rem; }
.small { font-size: .9375rem; color: var(--graphite); }

/* ---------- header ---------- */

.top {
  position: relative; z-index: 2;
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between;
  gap: .75rem 2rem; padding-block: 1.25rem;
}
.brand {
  display: inline-flex; align-items: center; gap: .55rem;
  color: var(--ink); text-decoration: none;
  font-stretch: 125%; font-weight: 800; font-size: 1.3125rem; letter-spacing: -.01em;
}
.top ul { display: flex; flex-wrap: wrap; gap: .25rem 1.5rem; }
.top nav a { color: var(--graphite); text-decoration: none; font-size: 1rem; }
.top nav a:hover { color: var(--ink); text-decoration: underline; }

/* ---------- buttons and sliders ---------- */

.button {
  display: inline-block; padding: .8rem 1.35rem; border: 2px solid var(--ink);
  border-radius: .35rem; background: var(--ink); color: var(--on-ink);
  font: inherit; font-weight: 600; font-size: 1.0625rem; text-decoration: none; cursor: pointer;
}
.button:hover { background: var(--cobalt); border-color: var(--cobalt); color: var(--on-ink); }
.button-quiet { background: transparent; color: var(--ink); }
.button-quiet:hover { background: transparent; color: var(--cobalt); }

input[type="range"] { width: 100%; margin: .35rem 0 0; accent-color: var(--cobalt); cursor: pointer; }
input[type="radio"] { accent-color: var(--cobalt); }
.range { display: block; font-weight: 600; font-size: 1rem; }
.range output { float: right; font-weight: 700; font-variant-numeric: tabular-nums; }

/* ---------- sections: each one sits on its own level ---------- */

.level { position: relative; display: grid; gap: 1.5rem; padding-block: clamp(3rem, 8vw, 5.5rem); }
.level::before {
  content: ""; position: absolute; top: 0; left: var(--gutter); right: var(--gutter);
  height: 2px; background: var(--dash);
}
.level.flush::before { display: none; }
h2 {
  font-stretch: 125%; font-weight: 800; font-size: clamp(1.75rem, 3.4vw, 2.25rem);
  line-height: 1.08; letter-spacing: -.01em;
}
h2.h2-small { font-size: clamp(1.5rem, 2.6vw, 1.75rem); }
h3 { font-size: 1.3125rem; line-height: 1.3; font-weight: 700; }

.body > * + * { margin-top: 1.5rem; }
.body p { max-width: 38rem; }

@media (min-width: 960px) {
  .level { grid-template-columns: minmax(0, 15rem) minmax(0, 1fr); column-gap: clamp(2.5rem, 5vw, 5rem); }
}

/* short term + plain explanation */
.facts { display: grid; gap: 1.5rem 2.5rem; }
.facts dt { font-weight: 700; }
.facts dd { color: var(--graphite); }
@media (min-width: 640px) { .facts { grid-template-columns: 1fr 1fr; } }
.aside { padding-left: 1rem; border-left: 3px solid var(--ink); font-weight: 600; }

/* ---------- fit, risks, opening ---------- */

.fit { display: grid; gap: 2rem 2.5rem; }
.fit > * + * { margin-top: 0; }
.fit ul { margin-top: .75rem; }
.fit li { position: relative; padding-left: 1.25rem; color: var(--graphite); }
.fit li + li { margin-top: .5rem; }
.fit li::before { content: ""; position: absolute; left: 0; top: .72em; width: .6rem; height: 2px; background: var(--ink); }
@media (min-width: 640px) { .fit { grid-template-columns: 1fr 1fr; } }

.risks li { padding-block: 1rem; border-top: 1px solid var(--ruling); color: var(--graphite); max-width: 42rem; }
.risks li:last-child { border-bottom: 1px solid var(--ruling); }
.risks strong { color: var(--ink); }

.timeline { display: grid; gap: 1.5rem; }
.timeline li { position: relative; padding-left: 1.75rem; }
.timeline li::before {
  content: ""; position: absolute; left: 0; top: .45em;
  width: .75rem; height: .75rem; border-radius: 50%; box-shadow: inset 0 0 0 2px var(--ink); background: var(--paper);
}
.timeline li:first-child::before { background: var(--ink); }
.timeline p { color: var(--graphite); }
@media (min-width: 640px) {
  .timeline {
    grid-template-columns: repeat(3, minmax(0, 1fr)); padding-top: 1.75rem;
    background: linear-gradient(var(--ink), var(--ink)) 0 .35rem / 100% 2px no-repeat;
  }
  .timeline li { padding-left: 0; }
  .timeline li::before { top: -1.75rem; }
}
.facts-short { padding-top: .5rem; }

/* ---------- footer ---------- */

.foot { font-size: .9375rem; color: var(--graphite); }
.foot .wrap { position: relative; padding-block: 2.5rem 3.5rem; }
.foot .wrap::before { content: ""; position: absolute; top: 0; left: var(--gutter); right: var(--gutter); height: 2px; background: var(--dash); }
.foot p { max-width: 50rem; }
.foot p + p { margin-top: .75rem; }
.foot strong { color: var(--ink); }

@media (max-width: 480px) {
  body { font-size: 1.0625rem; }
  .top ul { gap: .25rem .9rem; }
  .top nav a { font-size: .875rem; }
}