Apply purgecss (#443)

* purge footer css: remove link column

* purge posts css: remove mathjax spacing

* purge styles css: remove hero-headline, feature-card, and mt-30

Author: stefanv

assets/theme-css/footer.css

@@ -98,13 +98,6 @@
   background: var(--colorPrimaryDark);
 }
 
-.link-column {
-  display: block;
-  flex-basis: 0;
-  flex-grow: 1;
-  flex-shrink: 1;
-}
-
 .copyright {
   font-size: 12px;
   color: var(--colorSecondary);

assets/theme-css/posts.css

@@ -76,11 +76,6 @@
   padding-top: 0.5rem;
 }
 
-div.MathJax_Display {
-  margin-top: 0;
-  margin-bottom: 0;
-}
-
 .post-featuredImage img {
   /* FIXME: Use color variable. */
   border: 1px #bbb solid;

assets/theme-css/styles.css

@@ -67,11 +67,6 @@ a > code {
   line-height: 1.5;
 }
 
-.hero-headline {
-  display: flex;
-  flex-direction: row;
-}
-
 .hero-title {
   align-items: center;
   display: flex;
@@ -129,18 +124,10 @@ a > code {
 .cta-button:hover {
   color: var(--colorPrimaryLight);
 }
-
-#feature-card {
-  height: 475px;
-}
 #backtotop.visible #backtotop-color:hover {
   background: var(--colorYellow);
 }
 
-.mt-30 {
-  margin-top: 30px;
-}
-
 @media only screen and (max-width: 1090px) {
   .hero-content {
     flex-direction: column;