Change inner borders in media galleries in web UI (#31852)

app/javascript/mastodon/components/media_gallery.jsx

@@ -327,7 +327,7 @@ class MediaGallery extends PureComponent {
     }
 
     return (
-      <div className='media-gallery' style={style} ref={this.handleRef}>
+      <div className={`media-gallery media-gallery--layout-${size}`} style={style} ref={this.handleRef}>
         {(!visible || uncached) && (
           <div className={classNames('spoiler-button', { 'spoiler-button--click-thru': uncached })}>
             {spoilerButton}

app/javascript/styles/mastodon/components.scss

@@ -6953,6 +6953,64 @@ a.status-card {
   grid-template-columns: 50% 50%;
   grid-template-rows: 50% 50%;
   gap: 2px;
+
+  &--layout-2 {
+    .media-gallery__item:nth-child(1) {
+      border-end-end-radius: 0;
+      border-start-end-radius: 0;
+    }
+
+    .media-gallery__item:nth-child(2) {
+      border-start-start-radius: 0;
+      border-end-start-radius: 0;
+    }
+  }
+
+  &--layout-3 {
+    .media-gallery__item:nth-child(1) {
+      border-end-end-radius: 0;
+      border-start-end-radius: 0;
+    }
+
+    .media-gallery__item:nth-child(2) {
+      border-start-start-radius: 0;
+      border-end-start-radius: 0;
+      border-end-end-radius: 0;
+    }
+
+    .media-gallery__item:nth-child(3) {
+      border-start-start-radius: 0;
+      border-end-start-radius: 0;
+      border-start-end-radius: 0;
+    }
+  }
+
+  &--layout-4 {
+    .media-gallery__item:nth-child(1) {
+      border-end-end-radius: 0;
+      border-start-end-radius: 0;
+      border-end-start-radius: 0;
+    }
+
+    .media-gallery__item:nth-child(2) {
+      border-start-start-radius: 0;
+      border-end-start-radius: 0;
+      border-end-end-radius: 0;
+    }
+
+    .media-gallery__item:nth-child(3) {
+      border-start-start-radius: 0;
+      border-start-end-radius: 0;
+      border-end-start-radius: 0;
+      border-end-end-radius: 0;
+    }
+
+    .media-gallery__item:nth-child(4) {
+      border-start-start-radius: 0;
+      border-end-start-radius: 0;
+      border-start-end-radius: 0;
+    }
+  }
 }
 
 .media-gallery__item {