css: explicit code for color

more reproducible

browser/css/dark.less

@@ -14,7 +14,7 @@
 @message_green1 : #DFF0D8;
 @message_green2 : #F2DEAE;
 @message_red : #F2DEDE;
-@message_border_red : darkred;
+@message_border_red : #8b0000;
 
 @background : #000000; 
 @border: #333333;

browser/css/light.css

@@ -816,7 +816,7 @@ span .end-codon {
   transition-delay: 0s, 0s;
 }
 #add_clone_menu > #addclone_input.error {
-  border: 1px solid darkred;
+  border: 1px solid #8b0000;
 }
 .buttonSelector {
   background: #ffffff;
@@ -1843,7 +1843,7 @@ table.log textarea {
   text-align: center;
 }
 .urgent_message {
-  border: 2px solid darkred;
+  border: 2px solid #8b0000;
   margin: 3px;
   font-weight: bold;
   background-color: #F2DEDE;

browser/css/segmenter_page.css

@@ -816,7 +816,7 @@ span .end-codon {
   transition-delay: 0s, 0s;
 }
 #add_clone_menu > #addclone_input.error {
-  border: 1px solid darkred;
+  border: 1px solid #8b0000;
 }
 .buttonSelector {
   background: #ffffff;