fix thread icon size and color (#26288)

webapp/channels/src/components/threading/global_threads_link/global_threads_link.scss

@@ -11,15 +11,21 @@
 
         .icon {
             padding: 3px;
-            margin-right: 8px;
-            margin-left: 1px;
+            margin-right: 7px;
+            margin-left: -1px;
 
             svg {
-                fill: rgba(var(--sidebar-text-rgb), 0.75);
+                fill: rgba(var(--sidebar-text-rgb), 0.64);
                 vertical-align: middle;
             }
         }
 
+        &.unread-title {
+            svg {
+                fill: var(--sidebar-text);
+            }
+        }
+
         &:hover {
             padding-right: 16px;
 

webapp/channels/src/components/threading/global_threads_link/threads_icon.tsx

@@ -7,8 +7,8 @@ import type {HTMLAttributes} from 'react';
 const ThreadsIcon = (attrs: HTMLAttributes<SVGElement>) => {
     return (
         <svg
-            width='14'
-            height='13'
+            width='18'
+            height='18'
             viewBox='0 0 14 13'
             fill='none'
             xmlns='http://www.w3.org/2000/svg'