added header for blog post filter tags

src/routes/blog/+page.svelte

@@ -33,6 +33,7 @@
         bannerAlt="View at a tram bridge rising and then curving to the left." />
 
     <!-- TODO descriptions on filter click -->
+    <p class="tag-filter-header"># filter posts by tag:</p>
     <div class="tag-filter-container">
         {#each Object.values(BlogPostTag) as tag}
             {#if tag == filter}
@@ -47,10 +48,19 @@
 </Content>
 
 <style>
+    .tag-filter-header {
+        font-family: var(--font-mono);
+        font-size: 0.9rem;
+        /* margin-left: 10px;    
+        margin-right: 10px; */
+        margin: 12px 10px 4px;
+        color: var(--color-text-highlight-alt);
+    }
+
     .tag-filter-container {
         display: flex;
         gap: 8px 12px;
-        margin: 12px 10px 8px;
+        margin: 0 10px 8px;
         flex-wrap: wrap;
     }