:root {
  color-scheme: light;
  --ink: #183452;
  --body: #202a34;
  --muted: #68737e;
  --line: #b9c3cc;
  --surface: #f3f5f6;
  --disabled: #eceff1;
  --disabled-ink: #737d86;
  --focus: #ad5b00;
  font-family: Arial, Helvetica, sans-serif;
  font-synthesis: none;
  text-rendering: optimizeLegibility;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: #fff;
  color: var(--body);
  font-size: 16px;
  line-height: 1.5;
}

a { color: inherit; }

a:focus-visible, button:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 3px;
}

.breadcrumbs,
.content {
  width: min(100% - 48px, 680px);
  margin-inline: auto;
}

.breadcrumbs {
  display: flex;
  align-items: center;
  gap: 9px;
  min-height: 48px;
  transform: translateY(14px);
  overflow: hidden;
  white-space: nowrap;
  color: var(--muted);
  font-size: 17px;
}

.crumb {
  display: block;
  min-width: 0;
  max-width: 345px;
  overflow: hidden;
  color: var(--ink);
  text-overflow: ellipsis;
  text-decoration: underline;
}

.crumb[aria-current="page"] {
  color: var(--body);
  font-weight: 600;
}

.crumb-separator { flex: none; color: #87919b; }

.content { padding: 28px 0 64px; }

h2 {
  margin: 34px 0 12px;
  color: var(--ink);
  font-size: 18px;
  font-weight: 600;
}

h2:first-of-type { margin-top: 0; }

.activity-group + .activity-group { margin-top: 32px; }

.phase-list,
.course-grid,
.activity-list,
.file-list {
  margin: 0;
  padding: 0;
  list-style: none;
}

.phase-list,
.activity-list,
.file-list {
  display: grid;
  gap: 10px;
  max-width: 680px;
}

.phase-link,
.course-link,
.activity-link,
.file-link,
.activity-unavailable {
  display: flex;
  min-height: 54px;
  align-items: center;
  border: 2px solid var(--ink);
  padding: 12px 16px;
  background: #fff;
  color: var(--ink);
  font-size: 16px;
  text-decoration: none;
  transition: background-color 120ms ease;
}

.phase-link:hover,
.course-link:hover,
.activity-link:hover,
.file-link:hover { background: var(--surface); }

.phase-list { margin-top: 4px; }

.course-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  max-width: 680px;
}

.course-link { min-height: 58px; }

.activity-link,
.activity-unavailable {
  justify-content: space-between;
  gap: 16px;
}

.activity-link__title,
.file-link__name {
  min-width: 0;
  overflow-wrap: anywhere;
}

.activity-unavailable {
  border-color: #c7cdd2;
  background: var(--disabled);
  color: var(--disabled-ink);
}

.activity-unavailable__note,
.activity-link__version {
  flex: none;
  color: #68737e;
  font-size: 13px;
}

.empty-state {
  color: var(--muted);
}

@media (max-width: 600px) {
  .breadcrumbs,
  .content { width: min(100% - 32px, 960px); }

  .content { padding-top: 24px; }
  .course-grid { grid-template-columns: 1fr; }
  .crumb { max-width: 46.5vw; }
  .activity-link,
  .activity-unavailable { align-items: flex-start; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: 0.01ms !important; }
}