Fix collapsible categories on index page for iPhone (#43)

- Increase button padding from 0 to 0.5rem with negative margin-left to improve touchable area on mobile
- Add -webkit prefixes for smooth transforms and transitions on iOS Safari
- Increase max-height from 1000px to 2000px to accommodate category content
- Add :active state for better touch feedback
- Prevent text selection on toggle buttons
- Optimize opacity transition timing for smoother collapse animation

Co-authored-by: Claude <noreply@anthropic.com>

Author: streamcode9

assets/site.css

@@ -75,30 +75,40 @@ section {
   color: var(--primary-color);
   font-size: 1rem;
   cursor: pointer;
-  padding: 0;
+  padding: 0.5rem;
   margin-right: 0.5rem;
+  margin-left: -0.5rem;
   vertical-align: middle;
+  -webkit-transition: -webkit-transform 0.2s ease, transform 0.2s ease;
   transition: transform 0.2s ease;
+  -webkit-touch-callout: none;
+  -webkit-user-select: none;
+  user-select: none;
 }
 
-.category-toggle:hover {
+.category-toggle:hover,
+.category-toggle:active {
   opacity: 0.7;
 }
 
 .category-toggle[aria-expanded="false"] {
+  -webkit-transform: rotate(-90deg);
   transform: rotate(-90deg);
 }
 
 .category-content {
   overflow: hidden;
+  -webkit-transition: -webkit-max-height 0.3s ease, max-height 0.3s ease, opacity 0.3s ease;
   transition: max-height 0.3s ease, opacity 0.3s ease;
   opacity: 1;
-  max-height: 1000px;
+  max-height: 2000px;
 }
 
 .category-content.collapsed {
   max-height: 0;
   opacity: 0;
+  -webkit-transition: -webkit-max-height 0.3s ease, max-height 0.3s ease, opacity 0.1s ease 0.1s;
+  transition: max-height 0.3s ease, opacity 0.1s ease 0.1s;
 }
 
 #posts-status {