sync course b label color to petrol blue (#1e5f8a)

scripts/dev-server.sh

@@ -55,7 +55,7 @@ generate_index() {
     a.course{display:block;background:#fff;border-radius:12px;padding:1.5rem;text-decoration:none;color:inherit;box-shadow:0 1px 3px rgba(0,0,0,0.08);transition:all .2s ease;cursor:pointer}
     a.course:hover{transform:translateY(-2px);box-shadow:0 4px 12px rgba(0,0,0,0.12)}
     .course-label{font-size:.7rem;font-weight:600;text-transform:uppercase;letter-spacing:.05em}
-    .course-b .course-label{color:#5da9e9}
+    .course-b .course-label{color:#1e5f8a}
     .course-c .course-label{color:#d63384}
     .course-title{font-size:1.15rem;font-weight:500;color:#1d1d1f;margin:.25rem 0}
     .course-info{font-size:.85rem;color:#86868b}