:root {
  color-scheme: light;
  --ink: #14213d;
  --muted: #5a6478;
  --line: #d8dfeb;
  --paper: #ffffff;
  --page: #f3f6fb;
  --blue: #1756a9;
  --blue-soft: #eaf2ff;
  --code: #111827;
  --code-text: #e5edf8;
  --content: 72rem;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }

body {
  min-height: 100vh;
  margin: 0;
  color: var(--ink);
  background: var(--page);
}

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

a:focus-visible,
button:focus-visible {
  outline: 3px solid #f5b82e;
  outline-offset: 3px;
}

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

.site-header { padding-block: 1.25rem; }

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: .55rem;
  color: var(--muted);
  font-size: .9rem;
}

main { margin-block: 3.5rem 5rem; }

.course-intro {
  max-width: 54rem;
  margin-bottom: 2.5rem;
}

.eyebrow {
  margin: 0 0 .8rem;
  color: var(--blue);
  font-size: .82rem;
  font-weight: 800;
  letter-spacing: .12em;
  text-transform: uppercase;
}

h1 {
  max-width: 18ch;
  margin: 0;
  font-size: clamp(2.5rem, 7vw, 5rem);
  line-height: .98;
  letter-spacing: -.055em;
}

.lead {
  max-width: 46rem;
  margin: 1.5rem 0 0;
  color: var(--muted);
  font-size: 1.12rem;
  line-height: 1.6;
}

.notice {
  margin: 0 0 2rem;
  padding: 1rem 1.2rem;
  border-left: 4px solid var(--blue);
  background: var(--blue-soft);
  line-height: 1.55;
}

.steps {
  display: grid;
  gap: 1rem;
  counter-reset: lab-step;
}

.step {
  position: relative;
  padding: clamp(1.35rem, 4vw, 2.25rem);
  padding-left: clamp(4.5rem, 9vw, 6.4rem);
  border: 1px solid var(--line);
  border-radius: .8rem;
  background: var(--paper);
  box-shadow: 0 10px 30px rgba(20, 33, 61, .04);
  counter-increment: lab-step;
}

.step::before {
  content: counter(lab-step);
  position: absolute;
  top: 1.35rem;
  left: 1.35rem;
  display: grid;
  width: 2.2rem;
  height: 2.2rem;
  place-items: center;
  border-radius: 50%;
  color: #fff;
  background: var(--blue);
  font-weight: 800;
}

.step h2 { margin: 0 0 .7rem; font-size: 1.35rem; }

.step p,
.step li { color: var(--muted); line-height: 1.6; }

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

code {
  padding: .12rem .32rem;
  border-radius: .25rem;
  color: var(--code-text);
  background: var(--code);
}

.button-link {
  display: inline-block;
  padding: .7rem .9rem;
  border-radius: .4rem;
  color: #fff;
  background: var(--blue);
  font-weight: 750;
  text-decoration: none;
}

.boundary-table {
  width: 100%;
  border-collapse: collapse;
  color: var(--muted);
}

.boundary-table th,
.boundary-table td {
  padding: .7rem;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

.boundary-table th { color: var(--ink); }

.site-footer {
  padding: 1.5rem 0 2rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: .75rem;
  text-align: center;
}

@media (max-width: 520px) {
  main { margin-top: 2rem; }
  .step { padding-left: 1.25rem; padding-top: 4.5rem; }
  .step::before { left: 1.25rem; }
  .boundary-table { font-size: .9rem; }
}