dismiss warning when selecting other themes, fix collapsed attachments link color

src/components/attachment/attachment.vue

@@ -130,6 +130,8 @@
   .placeholder {
     margin-right: 8px;
     margin-bottom: 4px;
+    color: $fallback--link;
+    color: var(--postLink, $fallback--link);
   }
 
   .nsfw-placeholder {

src/components/style_switcher/style_switcher.js

@@ -385,6 +385,7 @@ export default {
       origin,
       forceUseSource = false
     ) {
+      this.dismissWarning()
       if (!source && !theme) {
         throw new Error('Can\'t load theme: empty')
       }
@@ -723,6 +724,7 @@ export default {
       }
     },
     selected () {
+      this.dismissWarning()
       if (this.selectedVersion === 1) {
         if (!this.keepRoundness) {
           this.clearRoundness()