fix: switch popover back to position:absolute with dynamic max-height

position:fixed pinned the popover to the viewport layer, so scrolling
the page could never reveal off-screen content. Revert to absolute
positioning (scrolls with the page) and dynamically compute max-height
based on available viewport space so the popover fits and scrolls
internally when content exceeds the available area.

Co-authored-by: Cursor <cursoragent@cursor.com>

content/styles/badges.css

@@ -86,7 +86,7 @@ html.rt-enabled .thing.link .flat-list li:has(> .comments) {
 
 /* --- Color popover --- */
 .rt-color-popover {
-  position: fixed;
+  position: absolute;
   z-index: 10000;
   background: #fff;
   border: 1px solid #ccc;
@@ -94,7 +94,6 @@ html.rt-enabled .thing.link .flat-list li:has(> .comments) {
   box-shadow: 0 4px 16px rgba(0, 0, 0, 0.18);
   padding: 12px;
   width: 260px;
-  max-height: calc(100vh - 20px);
   overflow-y: auto;
   font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
   font-size: 13px;