Make Mark Read button extend across whole document.

src/css/burichan.css

@@ -87,6 +87,11 @@
   background: rgba(255, 255, 255, .33);
 }
 
+/* Unread */
+:root.burichan .unread-mark-read {
+  background-color: rgba(214,218,240,0.5);
+}
+
 /* Thread Watcher */
 :root.burichan .replies-quoting-you > a, :root.burichan #watcher-link.replies-quoting-you {
   color: #F00;

src/css/futaba.css

@@ -87,6 +87,11 @@
   background: rgba(255, 255, 255, .33);
 }
 
+/* Unread */
+:root.futaba .unread-mark-read {
+  background-color: rgba(240,224,214,0.5);
+}
+
 /* Thread Watcher */
 :root.futaba .replies-quoting-you > a, :root.futaba #watcher-link.replies-quoting-you {
   color: #F00;

src/css/photon.css

@@ -85,6 +85,11 @@
   background: rgba(255, 255, 255, .33);
 }
 
+/* Unread */
+:root.photon .unread-mark-read {
+  background-color: rgba(221,221,221,0.5);
+}
+
 /* Thread Watcher */
 :root.photon .replies-quoting-you > a, :root.photon #watcher-link.replies-quoting-you {
   color: #00F !important;

src/css/spooky.css

@@ -152,6 +152,9 @@
   visibility: visible;
   opacity: 1;
 }
+:root.spooky .unread-mark-read {
+  background-color: rgba(23,21,38,0.5);
+}
 
 /* Thread Watcher */
 :root.spooky .replies-quoting-you > a, :root.spooky #watcher-link.replies-quoting-you {

src/css/style.css

@@ -1066,14 +1066,11 @@ span.hide-announcement {
 .unread-mark-read {
   float: right;
   clear: both;
-  height: 0;
   width: 100%;
-  position: relative;
-  top: -1em;
   text-align: right;
 }
 :not(.unread-thread) > .unread-mark-read {
-  visibility: hidden;
+  display: none;
 }
 
 /* Thread Updater */

src/css/tomorrow.css

@@ -157,6 +157,9 @@
 :root.tomorrow .unread-line {
   border-color: rgb(197, 200, 198);
 }
+:root.tomorrow .unread-mark-read {
+  background-color: rgba(40,42,46,0.5);
+}
 
 /* Thread Watcher */
 :root.tomorrow .replies-quoting-you > a, :root.tomorrow #watcher-link.replies-quoting-you {

src/css/yotsuba-b.css

@@ -83,6 +83,11 @@
   background: rgba(255, 255, 255, .33);
 }
 
+/* Unread */
+:root.yotsuba-b .unread-mark-read {
+  background-color: rgba(214,218,240,0.5);
+}
+
 /* Thread Watcher */
 :root.yotsuba-b .replies-quoting-you > a, :root.yotsuba-b #watcher-link.replies-quoting-you {
   color: #F00;

src/css/yotsuba.css

@@ -82,6 +82,11 @@
   background: rgba(255, 255, 255, .33);
 }
 
+/* Unread */
+:root.yotsuba .unread-mark-read {
+  background-color: rgba(240,224,214,0.5);
+}
+
 /* Thread Watcher */
 :root.yotsuba .replies-quoting-you > a, :root.yotsuba #watcher-link.replies-quoting-you {
   color: #F00;

src/main/Main.coffee

@@ -263,7 +263,7 @@ Main =
           s = window.getComputedStyle(d.body)
           bgColor = "#{s.backgroundColor} #{s.backgroundImage} #{s.backgroundRepeat} #{s.backgroundPosition}"
         Main.bgColorStyle.textContent = """
-          .dialog, .suboption-list > div:last-of-type, :root.catalog-hover-expand .catalog-container:hover > .post {
+          .dialog, .suboption-list > div:last-of-type, :root.catalog-hover-expand .catalog-container:hover > .post, .unread-mark-read {
             background: #{bgColor};
           }
         """