/* Limit main text width for readability 
main.content {
  max-width: 65ch;
}
*

/* Book cover styling */
img.book-cover {
  width: 100%;
  max-width: 220px;
  border: 1px solid #ccc;
  box-shadow: 0 8px 24px rgba(0,0,0,0.08);
  border-radius: 4px;
  margin-right: 1.5rem;
}

.start-icons a{
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.4rem;
  border-radius: 0.9rem;

  background: rgba(0,0,0,0.04);
  border: 1px solid rgba(0,0,0,0.12);

  transition: transform 120ms ease, box-shadow 120ms ease, background 120ms ease, border-color 120ms ease;
}

.start-icons a:hover{
  transform: translateY(-1px);
  background: rgba(0,0,0,0.06);
  border-color: rgba(0,0,0,0.18);
  box-shadow: 0 6px 18px rgba(0,0,0,0.10);
}

.start-icons a:focus-visible{
  outline: 2px solid rgba(0,0,0,0.35);
  outline-offset: 2px;
}

.start-icons img{
  height: 54px;   /* tweak */
  width: auto;
  display: block;
}

@media (prefers-color-scheme: dark){
  .start-icons a{
    background: rgba(255,255,255,0.06);
    border-color: rgba(255,255,255,0.16);
  }
  .start-icons a:hover{
    background: rgba(255,255,255,0.10);
    border-color: rgba(255,255,255,0.22);
    box-shadow: 0 10px 24px rgba(0,0,0,0.35);
  }
}


/* CTA buttons */
.cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: .75rem;
  margin-top: 1rem;
  margin-bottom: 1.5rem;
}

.columns.hero {
  gap: 4rem; 
}

.columns.book-blurb img {
  display: block;
  max-width: 100%;
  margin-bottom: 4rem;
}
.columns.book-blurb .column:first-child {
  padding-right: 0.5rem;
}

a.btn {
  display: inline-block;
  padding: .6rem .9rem;
  border-radius: .4rem;
  font-weight: 500;
  text-decoration: none;
  line-height: 1.2;
  border: 1px solid transparent;
}

a.btn-primary {
  background: #000;
  color: #fff;
}

a.btn-secondary {
  background: #f5f5f5;
  color: #000;
  border-color: #d0d0d0;
}

/* Under construction note */
.note-under-construction {
  font-size: 0.8rem;
  color: #666;
  display: block;
  margin-top: 2rem;
  border-left: 3px solid #ccc;
  padding-left: .75rem;
}


/* Grid layout */
.dataset-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 1rem;
  margin: 1.5rem 0;
}

/* Base card */
.dataset-card {
  border-radius: 10px;
  padding: 1rem;
  border: 1px solid #ddd;
  background-color: #f9f9f9;
}

/* Card types */
.dataset-card.callout {
  background-color: #eef5ff;
  border-left: 6px solid #3b82f6;
}

.dataset-card.exercise {
  background-color: #f0fdf4;
  border-left: 6px solid #22c55e;
}

/* Title */
.dataset-card h4 {
  font-size: 1.05rem;
  margin-top: 0;
  margin-bottom: 0.4rem;
  line-height: 1.2;
}

.dataset-card p {
  font-size: 0.9rem;
  margin-bottom: 0.4rem;
}

/* Buttons */
.dataset-links a {
  display: inline-block;
  margin-right: 0.5rem;
  margin-top: 0.5rem;
  padding: 0.3rem 0.6rem;
  font-size: 0.85rem;
  border-radius: 5px;
  text-decoration: none;
  border: 1px solid #ccc;
  background-color: white;
}

.dataset-links a:hover {
  background-color: #eee;
}