Add 18F logo to header

Author: igorkorenfeld

_data/header.yml

@@ -25,6 +25,12 @@ type: extended
 #  alt: 18F
 #  external: true
 
+title: Accessibility Guide
+
+logo:
+  src: /images/18f-logo-black.svg
+  alt: 18f
+
 # this is a key into _data/navigation.yml
 # primary:
 # links: primary
@@ -33,4 +39,4 @@ type: extended
 primary:
   links: primary
 secondary:
-  links: secondary
+  links: secondary

_sass/_uswds-theme-custom-styles.scss

@@ -19,6 +19,8 @@ $color-gray-divider:  color("gray-20");
 
 $color-gray-border:   color("base-dark");
 
+$logo-size-lg: 3rem;
+$logo-size-md: 2rem;
 
 // Typography
 .usa-prose{
@@ -76,6 +78,26 @@ a:hover {
   display: none;
 }
 
+// logo
+.usa-header.usa-header--extended .usa-logo-img {
+  height: $logo-size-md;
+}
+
+.usa-logo__text {
+  line-height: $logo-size-md;
+}
+
+
+@include at-media('desktop') {
+  .usa-header.usa-header--extended .usa-logo-img {
+    height: $logo-size-lg;
+  }
+
+  .usa-logo__text {
+    line-height: $logo-size-lg;
+  }
+}
+
 // usa-sidenav
 
 .usa-sidenav a {