Update intro-header.html

Author: TwperBody

_includes/intro-header.html

@@ -8,13 +8,14 @@
     header.intro-header{
         position: relative;
         background-image: url('{{ site.baseurl }}/{% if page.header-img %}{{ page.header-img }}{% else %}{{ site.header-img }}{% endif %}');
+        background-size: cover;
         background: {{ page.header-bg-css }};
     }
 
     {% if page.header-mask %}
     header.intro-header .header-mask{
-        width: 80%;
-        height: 80%;
+        width: 100%;
+        height: 100%;
         position: absolute;
         background: rgba(0,0,0, {{ page.header-mask }});
     }