perf(ui): avoid blank space at the bottom of the homepage preview image

When the title of the post has a line break, there will be a blank space at the bottom of the preview image.

_layouts/home.html

@@ -65,7 +65,7 @@ refactor: true
 
           {% assign alt = post.image.alt | default: 'Preview Image' %}
 
-          <img src="{{ src }}" w="15" h="8" alt="{{ alt }}" {{ lqip }}>
+          <img src="{{ src }}" w="17" h="10" alt="{{ alt }}" {{ lqip }}>
         {% endif %}
 
         <div class="card-body d-flex flex-column">

_sass/layout/home.scss

@@ -148,7 +148,7 @@
     .card {
       .preview-img {
         width: 20rem;
-        height: 11.5rem; // can hold 2 lines each for title and content
+        height: 11.55rem; // can hold 2 lines each for title and content
       }
 
       .card-body {