Add html namespace and some comments

content/css_scrollbar_width_color.css

@@ -1,4 +1,5 @@
 /* Scrollbar colors and width - applied globally */
+@namespace url("http://www.w3.org/1999/xhtml");
 :root{
   scrollbar-color: rgb(210,210,210) rgb(46,54,69);
   scrollbar-width: thin;

content/limit_css_data_leak.css

@@ -1,4 +1,6 @@
 /* Limit CSS data leak, POTENTIALLY BREAKS SOME SITES */
+@namespace html url("http://www.w3.org/1999/xhtml");
+
 body input:not([value=""])[type],
 body input:not([value=""])[type]:focus ~ *,
 body input:not([value=""])[type] * {

content/newtab_background_color.css

@@ -1,3 +1,5 @@
+@namespace url("http://www.w3.org/1999/xhtml");
+
 @-moz-document url("about:home"),url("about:blank"),url("about:newtab"),url("about:privatebrowsing"){
 	body{background-color: rgb(46,54,69) !important}
 }

content/transparent_reader_toolbar.css

@@ -1,3 +1,7 @@
+/* Toolbar is invisible until hovered */
+
+@namespace html url("http://www.w3.org/1999/xhtml");
+
 @-moz-document url-prefix("about:reader"){
   .reader-toolbar, .reader-toolbar .button:not(:hover) {
     background-color: transparent !important;