:root {
  --ibm-blue: #0f62fe;
  --ibm-blue-dark: #0043ce;
  --gh-dark: #0d1117;
  --gh-dark-2: #161b22;
  --gh-border: #d0d7de;
  --text: #1f2328;
  --muted: #59636e;
  --bg: #ffffff;
  --bg-soft: #f6f8fa;
  --self: #0f62fe;      /* Learn for yourself */
  --deliver: #8250df;   /* Deliver on behalf of GitHub */
  --cert: #1a7f37;      /* Certifications */
  --radius: 10px;
  --max: 1180px;
  font-family: "IBM Plex Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; color: var(--text); background: var(--bg); line-height: 1.55; }
a { color: var(--ibm-blue); }
img { max-width: 100%; }
h1, h2, h3, h4 { line-height: 1.2; margin: 0 0 .5rem; }
p { margin: 0 0 1rem; }

.container { width: min(100% - 2.5rem, var(--max)); margin-inline: auto; }
.section { padding: 4rem 0; }
.section--soft { background: var(--bg-soft); }
.section--dark { background: var(--gh-dark); color: #e6edf3; }
.section--dark a { color: #79c0ff; }
.eyebrow { text-transform: uppercase; letter-spacing: .08em; font-size: .78rem; font-weight: 600; color: var(--muted); }
.section--dark .eyebrow { color: #8b949e; }
.lede { font-size: 1.15rem; color: var(--muted); max-width: 62ch; }
.section--dark .lede { color: #c9d1d9; }

.grid { display: grid; gap: 1.25rem; }
.grid-2 { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
.grid-4 { grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); }

.card {
  background: #fff; border: 1px solid var(--gh-border); border-radius: var(--radius);
  padding: 1.5rem; display: flex; flex-direction: column; gap: .5rem; color: var(--text);
}
.card h3 { font-size: 1.15rem; }
.card ul { margin: 0 0 1rem; padding-left: 1.1rem; }
.card .spacer { flex: 1; }

.btn {
  display: inline-block; padding: .65rem 1.1rem; border-radius: 6px; font-weight: 600;
  text-decoration: none; border: 1px solid transparent; cursor: pointer; font-size: .95rem;
  align-self: flex-start;
}
.btn--primary { background: var(--ibm-blue); color: #fff; }
.btn--primary:hover { background: var(--ibm-blue-dark); }
.btn--ghost { border-color: currentColor; color: inherit; background: transparent; }
.btn--deliver { background: var(--deliver); color: #fff; }
.btn--cert { background: var(--cert); color: #fff; }

.tag {
  display: inline-block; font-size: .72rem; font-weight: 600; padding: .15rem .55rem;
  border-radius: 999px; background: var(--bg-soft); border: 1px solid var(--gh-border); color: var(--muted);
  align-self: flex-start;
}
.tag--self { background: #e5f0ff; border-color: #a6c8ff; color: var(--ibm-blue-dark); }
.tag--deliver { background: #f3eefe; border-color: #c8b3f5; color: #6639ba; }
.tag--cert { background: #e6f4ea; border-color: #9fd6ad; color: var(--cert); }

.placeholder-note {
  font-size: .8rem; color: var(--muted); border-left: 3px solid var(--gh-border); padding-left: .75rem;
}

/* FAQ */
details.faq { border: 1px solid var(--gh-border); border-radius: 8px; background: #fff; margin-bottom: .75rem; }
details.faq summary { cursor: pointer; padding: 1rem 1.25rem; font-weight: 600; list-style: none; }
details.faq summary::-webkit-details-marker { display: none; }
details.faq summary::after { content: "+"; float: right; color: var(--muted); }
details.faq[open] summary::after { content: "-"; }
details.faq > div { padding: 0 1.25rem 1rem; color: var(--muted); }

/* Site header + footer */
.site-header { background: var(--gh-dark); color: #fff; position: sticky; top: 0; z-index: 10; }
.site-header .container { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding: .85rem 0; }
.brand { font-weight: 700; color: #fff; text-decoration: none; }
.brand span { color: #79c0ff; font-weight: 400; }
.site-nav { display: flex; gap: 1.1rem; flex-wrap: wrap; }
.site-nav a { color: #c9d1d9; text-decoration: none; font-size: .9rem; }
.site-nav a:hover { color: #fff; }
.site-footer { background: var(--gh-dark-2); color: #8b949e; padding: 2rem 0; font-size: .85rem; }
.site-footer a { color: #c9d1d9; }

@media (max-width: 760px) {
  .site-nav { display: none; }
  .section { padding: 3rem 0; }
}