perf: performance optimization

src/layouts/default/multitabs/index.less

@@ -34,6 +34,12 @@
           color: inherit;
         }
 
+        > div {
+          display: flex;
+          justify-content: center;
+          align-items: center;
+        }
+
         svg {
           fill: @text-color-base;
         }