Add

src/styles/globals.css

@@ -417,6 +417,105 @@ ol {
   white-space: nowrap;
 }
 
+.lab-content .lab-harness-chooser {
+  display: grid;
+  grid-template-columns: repeat(3, minmax(0, 1fr));
+  gap: 0.9rem;
+  margin: 1rem 0 1.35rem;
+}
+
+.lab-content .lab-harness-card {
+  display: flex;
+  flex-direction: column;
+  gap: 0.38rem;
+  min-height: 100%;
+  padding: 0.95rem 1rem;
+  border: 1px solid #d9e4ed;
+  border-radius: 16px;
+  background:
+    linear-gradient(180deg, rgba(255, 255, 255, 0.98), rgba(244, 249, 253, 0.96)),
+    radial-gradient(circle at top right, rgba(248, 156, 39, 0.12), transparent 32%);
+  box-shadow: 0 12px 28px -28px rgba(15, 23, 42, 0.35);
+  color: #18384f;
+  text-decoration: none;
+}
+
+.lab-content button.lab-harness-card {
+  width: 100%;
+  cursor: pointer;
+  text-align: left;
+  font: inherit;
+}
+
+.lab-content a.lab-harness-card:hover,
+.lab-content button.lab-harness-card:hover {
+  transform: translateY(-1px);
+  border-color: #f1bd70;
+  box-shadow: 0 20px 36px -30px rgba(15, 23, 42, 0.45);
+}
+
+.lab-content .lab-harness-card[aria-pressed="true"] {
+  border-color: #cf7a08;
+  background:
+    linear-gradient(180deg, rgba(255, 251, 243, 0.98), rgba(255, 244, 227, 0.96)),
+    radial-gradient(circle at top right, rgba(248, 156, 39, 0.18), transparent 32%);
+  box-shadow: 0 20px 36px -30px rgba(114, 63, 8, 0.5);
+}
+
+.lab-content .lab-harness-card strong {
+  color: #0f3d58;
+  font-size: 1rem;
+  line-height: 1.35;
+}
+
+.lab-content .lab-harness-card span {
+  color: #486073;
+  font-size: 0.92rem;
+}
+
+.lab-content .lab-harness-card__tag {
+  display: inline-flex;
+  align-items: center;
+  width: fit-content;
+  border-radius: 999px;
+  padding: 0.22rem 0.58rem;
+  background: #e7f2fb;
+  color: #0f5c8b;
+  font-size: 0.72rem;
+  font-weight: 800;
+  letter-spacing: 0.06em;
+  text-transform: uppercase;
+}
+
+.lab-content .lab-harness-branch {
+  margin: 1rem 0 1.4rem;
+  padding: 1rem 1.1rem 1.1rem;
+  border: 1px solid #dce7f0;
+  border-left: 6px solid #0f5c8b;
+  border-radius: 16px;
+  background:
+    linear-gradient(180deg, rgba(250, 252, 254, 0.98), rgba(244, 249, 252, 0.95)),
+    radial-gradient(circle at top right, rgba(248, 156, 39, 0.08), transparent 26%);
+  scroll-margin-top: 1.5rem;
+}
+
+.lab-content .lab-harness-branch__eyebrow {
+  margin: 0 0 0.4rem;
+  color: #9a5f00;
+  font-size: 0.74rem;
+  font-weight: 800;
+  letter-spacing: 0.08em;
+  text-transform: uppercase;
+}
+
+.lab-content .lab-harness-branch > h3 {
+  margin: 0 0 0.45rem;
+}
+
+.lab-content .lab-harness-branch > p:last-child {
+  margin-bottom: 0;
+}
+
 .lab-content hr {
   margin: 2rem 0 1.4rem;
   border-color: #d7dee6;
@@ -1686,6 +1785,15 @@ ol {
     padding: 0.52rem 0.75rem;
   }
 
+  .lab-content .lab-harness-chooser {
+    grid-template-columns: 1fr;
+  }
+
+  .lab-content .lab-harness-card,
+  .lab-content .lab-harness-branch {
+    padding: 0.85rem 0.9rem;
+  }
+
   .lab-content ul.lab-settings-list .lab-setting-value {
     justify-self: start;
   }