style(css): ✨ use of new CSS features (@import and nested CSS)

www/static/styles/toc.css

@@ -0,0 +1,41 @@
+.table_of_contents {
+  position: sticky;
+  float: left;
+  
+  top: 3em;
+  
+  width: 20em;
+  
+  & a {
+    display: inline-block;
+    
+    transition: all 0.5s !important;
+    
+    line-height: 1em;
+    text-align: justify;
+    font-size: 0.9rem;
+    
+    padding-left: 0.2em;
+    padding-right: 0.2em;
+    padding-bottom: 0.2em;
+    
+    border-radius: 0.2em;
+  }
+  
+  & .active {
+    background-color: var(--highlight_1);
+    color: var(--bg_1);
+  }
+  
+  & ol {
+    padding-left: 0.5em;
+    
+    list-style: none;
+    
+    border-left: 1px solid #FFFFFF44;
+  }
+  
+  & li {
+    margin-bottom: 0.2em;
+  }
+}