diff --git a/css/styles.css b/css/styles.css
index 77eee41..f048fb5 100644
--- a/css/styles.css
+++ b/css/styles.css
@@ -743,13 +743,33 @@ section { padding: 46px 0; }
 
 /* ---------- Diagram-style project thumb ---------- */
 .project-card .thumb-diagram {
-  background: #13283c;
+  background: #101820;
   display: flex;
   align-items: center;
   justify-content: center;
-  padding: 10px;
+  padding: 18px 8px 8px;
+  position: relative;
+  border-color: #263746;
+  box-shadow: 0 4px 14px rgba(16, 38, 61, 0.10);
+}
+
+.project-card .thumb-diagram::before {
+  content: "";
+  position: absolute;
+  top: 7px;
+  left: 10px;
+  width: 34px;
+  height: 5px;
+  border-radius: 999px;
+  background: rgba(255,255,255,.24);
+}
+
+.project-card .thumb-diagram img {
+  width: 100%;
+  height: 100%;
+  object-fit: contain;
+  border: 1px solid rgba(255,255,255,.10);
 }
-.project-card .thumb-diagram img { width: 100%; height: 100%; object-fit: contain; }
 .project-card .card-link { display: block; color: inherit; }
 .project-card .card-link:hover { text-decoration: none; }