css: setup initial font-size

Author: pbrezina

extensions/sssd/io/themes/sssd.io/static/sass/_layout.scss

@@ -1,10 +1,15 @@
+html {
+    font-size: 100%;
+}
+
 /* Put footer on the bottom of the page. */
 body {
     display: flex;
     flex-direction: column;
     justify-content: space-between;
     min-height: 100vh;
     overflow-x: hidden; /* To allow search results animation. */
+    font-size: 1em;
 }
 
 body > * {