tooltipの最適化

- box-shadowを削除し、代わりにborderで視覚効果を維持
- 複雑なtransitionを簡略化（opacity以外のz-index transitionを削除）

Author: faithandbrave

css/kunai/site/tooltip.css

@@ -4,15 +4,18 @@
   width: max-content; max-width: 40em;
   border: 1px solid black; padding: 0.2rem 0.4rem; margin: 0;
   background-color: white; color: black; text-decoration: none; font-size: 0.9rem;
-  position: fixed; box-shadow: 2px 2px 2px 0 rgba(128, 128, 128, 0.6);
+  position: fixed; /* box-shadow: 2px 2px 2px 0 rgba(128, 128, 128, 0.6); GPUメモリ削減のため無効化 */
+  border: 1px solid #ccc; /* box-shadowの代替として境界線を強化 */
   cursor: default;
   opacity: 0; z-index: -1;
-  transition: opacity .3s linear .5s, z-index 0s linear .8s;
+  /* transition: opacity .3s linear .5s, z-index 0s linear .8s; GPUメモリ削減のため簡略化 */
+  transition: opacity .2s ease-out .3s;
 }
 #kunai-ui-tooltip:before {
   content: attr(data-desc);
 }
 #kunai-ui-tooltip.kunai-ui-tooltip-revealed {
   opacity: 1; z-index: 1000000;
-  transition: opacity .3s linear 0s, z-index 0s linear 0s;
+  /* transition: opacity .3s linear 0s, z-index 0s linear 0s; GPUメモリ削減のため簡略化 */
+  transition: opacity .2s ease-out;
 }