[epiphany] Reader mode: Add styling for <mark> elements

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 0beb9b4c711a44e882d8eab1a7f8202fcbb84180
Author: Adrian Perez de Castro <aperez igalia com>
Date:   Tue Sep 11 22:05:38 2018 +0300

    Reader mode: Add styling for <mark> elements
    
    Fixes #46

 src/resources/reader.css | 12 ++++++++++++
 1 file changed, 12 insertions(+)
---
diff --git a/src/resources/reader.css b/src/resources/reader.css
index ce087b582..4d19cdb1c 100644
--- a/src/resources/reader.css
+++ b/src/resources/reader.css
@@ -339,3 +339,15 @@ article {
   font-size: 18px;
   word-wrap: break-word;
 }
+
+mark {
+  padding: 2px;
+  margin: -2px;
+  border-radius: 3px;
+  background: #d7d7d8;
+}
+
+body.dark mark {
+  background: #282828;
+  color: #efefef;
+}