css: standardize font sizes.

Fix various elements to use standard font sizes instead of ad-hoc sizes.

Noticeable changes:

* Tags in autocomplete are slightly smaller.
* The favorite heart icon on posts is slightly smaller.
* Pool titles on thumbnails in the pool gallery page are slightly bigger.
* The page footer is slightly smaller.
* Timestamps on comments and forum posts are very slightly smaller.
* "Pending"/"approved"/"rejected" labels on forum posts are very slightly smaller.

app/components/post_preview_component/post_preview_component.scss

@@ -30,7 +30,7 @@ article.post-preview {
   }
 
   .desc {
-    font-size: 80%;
+    font-size: var(--text-sm);
     margin-bottom: 0;
   }
 

app/components/source_data_component/source_data_component.scss

@@ -16,8 +16,8 @@ div.source-data {
   }
 
   .icon {
-    height: 1rem;
+    height: var(--text-lg);
-    font-size: 1rem;
+    font-size: var(--text-lg);
     vertical-align: bottom;
   }
 

app/javascript/src/styles/base/000_vars.scss

@@ -1,13 +1,13 @@
 :root {
   --text-xs: 0.5625rem; // 9px
-  --text-sm: 0.7875rem; // 12.6px
+  --text-sm: 0.75rem;   // 12px
   --text-md: 0.875rem;  // 14px
-  --text-lg: 1.0208rem; // 16.3333px
+  --text-lg: 1rem;      // 16px
   --text-xl: 1.3125rem; // 21px
   --text-xxl: 1.75rem;  // 28px
   --header-font: Tahoma, Verdana, Helvetica, sans-serif;
   --body-font: Verdana, Helvetica, sans-serif;
-  --monospace-font: 0.85rem monospace; // 13.6px
+  --monospace-font: 0.875rem monospace; // 14px
 }
 
 $h1_padding: 0.8em 0 0.25em 0;

app/javascript/src/styles/base/020_base.scss

@@ -125,10 +125,6 @@ details {
   font-size: 0.8em;
 }
 
-.text-small {
-  font-size: 0.9em;
-}
-
 a.link-plain {
   color: unset;
 

app/javascript/src/styles/common/messages.scss

@@ -21,7 +21,7 @@ div.list-of-messages {
 
       a.message-timestamp {
         font-style: italic;
-        font-size: 0.90em;
+        font-size: var(--text-sm);
         color: var(--muted-text-color);
         &:hover { text-decoration: underline; }
       }
@@ -54,7 +54,7 @@ div.list-of-messages {
         a.message-timestamp {
           display: inline;
           color: var(--muted-text-color);
-          font-size: 0.8em;
+          font-size: var(--text-sm);
         }
       }
     }

app/javascript/src/styles/common/news.scss

@@ -3,7 +3,7 @@ div#news-updates {
   background: var(--news-updates-background);
   border-bottom: 2px solid var(--news-updates-border-color);
   overflow: hidden;
-  font-size: 0.8em;
+  font-size: var(--text-sm);
 
   ul {
     float: left;

app/javascript/src/styles/common/simple_form.scss

@@ -53,7 +53,7 @@ form.simple_form {
         display: block;
         color: var(--form-input-validation-error-text-color);
         font-style: italic;
-        font-size: 0.8em;
+        font-size: var(--text-sm);
       }
     }
 

app/javascript/src/styles/common/utilities.scss

@@ -18,6 +18,7 @@ $spacer: 0.25rem; /* 4px */
 .text-muted { color: var(--muted-text-color); }
 
 .text-xs { font-size: var(--text-xs); }
+.text-sm { font-size: var(--text-sm); }
 
 .leading-none { line-height: 1; }
 

app/javascript/src/styles/specific/forum.scss

@@ -13,7 +13,7 @@ div#c-forum-topics {
 
     &.label {
       display: inline-block;
-      font-size: 0.7em;
+      font-size: var(--text-xs);
       text-transform: uppercase;
       border: 1px solid;
       border-radius: 0.25rem;

app/javascript/src/styles/specific/moderator_dashboard.scss

@@ -12,7 +12,7 @@ div#c-moderator-dashboards {
   }
 
   caption {
-    font-size: 1.1em;
+    font-size: var(--text-lg);
     font-weight: bold;
     text-align: left;
   }

app/javascript/src/styles/specific/posts.scss

@@ -65,7 +65,7 @@
 
 div#c-posts {
   .fav-buttons {
-    font-size: 14pt;
+    font-size: var(--text-lg);
 
     button.ui-button {
       padding: 0.25em 0.75em;

app/javascript/src/styles/specific/uploads.scss

@@ -112,7 +112,7 @@ div#c-uploads {
     }
 
     .caption-top {
-      font-size: 0.8em;
+      font-size: var(--text-sm);
       margin-bottom: 0;
     }
   }

app/javascript/src/styles/specific/z_responsive.scss

@@ -14,7 +14,7 @@
       position: absolute;
       top: 0.5rem;
       right: 0.5rem;
-      font-size: 2em;
+      font-size: var(--text-xxl);
     }
 
     nav#nav {

app/views/static/_footer.html.erb

@@ -1,4 +1,4 @@
-<footer id="page-footer" class="text-small">
+<footer id="page-footer" class="text-sm">
   <span class="page-footer-app-name"><%= Danbooru.config.app_name %></span>
   / <%= link_to "Rules", terms_of_service_path %>
   / <%= link_to "Contact", contact_path %>