chore(Chat): Small CSS adjustments (#1937)

Author: gadenbuie

js/chat/chat.scss

@@ -145,7 +145,8 @@ shiny-chat-input {
 
   margin-top: calc(-1 * var(--_input-padding-top));
   position: sticky;
-  bottom: calc(-1 * var(--_input-padding-bottom));
+  bottom: calc(-1 * var(--_input-padding-bottom) + 4px);
+  // 4px: autoscroll adds 2px to height, this keeps input from wiggling when scrolling on top of chat
   padding-block: var(--_input-padding-top) var(--_input-padding-bottom);
 
   textarea {

js/markdown-stream/markdown-stream.scss

@@ -68,7 +68,8 @@ pre:has(.code-copy-button) {
 .markdown-stream-dot {
   // The stream dot is appended with each streaming chunk update, so the pulse animation
   // only shows up when streaming pauses but isn't complete.
-  animation: markdown-stream-dot-pulse 2s infinite cubic-bezier(0.18, 0.89, 0.32, 1.28);
+  animation: markdown-stream-dot-pulse 1.75s infinite cubic-bezier(0.18, 0.89, 0.32, 1.28);
+  animation-delay: 250ms;
   display: inline-block;
   transform-origin: center;
 }