:root {
  color-scheme: light dark;
  --background: #ffffff;
  --surface: #f5f6f7;
  --text: #202124;
  --muted: #5f6368;
  --border: #d9dce1;
  --link: #2457a6;
  --max-width: 980px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --background: #111315;
    --surface: #1b1e21;
    --text: #eceff1;
    --muted: #b0b6bc;
    --border: #363a3f;
    --link: #8ab4f8;
  }
}

* {
  box-sizing: border-box;
}

html {
  font-size: 100%;
}

body {
  margin: 0;
  background: var(--background);
  color: var(--text);
  font-family: "Open Sans", Arial, Helvetica, sans-serif;
  font-size: 1.08rem;
  font-weight: 300;
  line-height: 1.65;
}

a {
  color: var(--link);
}

a:hover,
a:focus {
  text-decoration-thickness: 2px;
}

header,
main,
footer {
  width: min(calc(100% - 2rem), var(--max-width));
  margin-inline: auto;
}

header {
  padding-top: 2rem;
}

h1 {
  margin: 0 0 0.6rem;
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 600;
  line-height: 1.2;
  text-align: center;
}

h2 {
  margin-top: 2.5rem;
  font-size: 1.55rem;
  font-weight: 600;
  line-height: 1.3;
}

h3 {
  margin-top: 1.8rem;
  font-size: 1.2rem;
  font-weight: 600;
}

p,
li {
  max-width: 80ch;
}

nav {
  margin: 1.4rem 0 2rem;
  padding: 0.75rem 1rem;
  border-block: 1px solid var(--border);
}

nav ul {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5rem 1.5rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

nav a {
  font-weight: 600;
}

figure {
  margin: 1.5rem 0;
}

figure.centered {
  text-align: center;
}

figcaption {
  margin-top: 0.4rem;
  color: var(--muted);
  font-size: 0.92rem;
  line-height: 1.45;
}

img {
  display: block;
  max-width: 100%;
  height: auto;
  border-radius: 0.2rem;
}

figure.centered img {
  margin-inline: auto;
}

.hero-diagram img {
  width: 600px;
}

.photo-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 280px), 1fr));
  gap: 1.25rem;
  align-items: start;
}

.photo-grid figure {
  margin: 0;
}

.photo-grid img {
  width: 100%;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 250px), 1fr));
  gap: 1rem;
  margin: 1.5rem 0;
}

.card {
  padding: 1rem 1.15rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 0.35rem;
}

.card h2,
.card h3 {
  margin-top: 0;
}

.card p:last-child {
  margin-bottom: 0;
}

.step,
.part {
  padding-top: 0.5rem;
}

.measurements {
  margin: 1rem 0 1.5rem;
  padding-left: 1.4rem;
}

.references {
  padding-left: 1.5rem;
}

.note {
  padding: 0.9rem 1rem;
  background: var(--surface);
  border-left: 4px solid var(--border);
}

footer {
  margin-top: 3rem;
  padding: 1.25rem 0 2rem;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.9rem;
}

footer p {
  margin: 0;
}

@media (max-width: 640px) {
  body {
    font-size: 1rem;
  }

  header,
  main,
  footer {
    width: min(calc(100% - 1.2rem), var(--max-width));
  }

  nav ul {
    gap: 0.35rem 1rem;
  }
}