Fix background image ref when urlpath is set

Signed-off-by: Yukai Huang <yukaihuangtw@gmail.com>

public/js/lib/editor/markdown-lint/index.js

@@ -2,7 +2,6 @@
 
 // load CM lint plugin explicitly
 import '@hackmd/codemirror/addon/lint/lint'
-import './lint.css'
 
 window.markdownit = require('markdown-it')
 // eslint-disable-next-line

public/markdown-lint/css/lint.css

@@ -31,11 +31,11 @@
 }
 
 .CodeMirror-lint-mark-error {
-  background-image: url(/images/lint/mark-error.png);
+  background-image: url(../images/mark-error.png);
 }
 
 .CodeMirror-lint-mark-warning {
-  background-image: url(/images/lint/mark-warning.png);
+  background-image: url(../images/mark-warning.png);
 }
 
 .CodeMirror-lint-marker-error, .CodeMirror-lint-marker-warning {
@@ -58,15 +58,15 @@
 }
 
 .CodeMirror-lint-marker-error, .CodeMirror-lint-message-error {
-  background-image: url(/images/lint/message-error.png);
+  background-image: url(../images/message-error.png);
 }
 
 .CodeMirror-lint-marker-warning, .CodeMirror-lint-message-warning {
-  background-image: url(/images/lint/message-warning.png);
+  background-image: url(../images/message-warning.png);
 }
 
 .CodeMirror-lint-marker-multiple {
-  background-image: url(/images/lint/mark-multiple.png);
+  background-image: url(../images/mark-multiple.png);
   background-repeat: no-repeat;
   background-position: right bottom;
   width: 100%; height: 100%;

public/views/codimd/head.ejs

@@ -22,3 +22,4 @@
 <link rel="stylesheet" href='<%- serverURL %>/build/fork-awesome/css/fork-awesome.min.css'>
 <%- include ../build/index-pack-header %>
 <% } %>
+<link rel="stylesheet" href='<%- serverURL %>/markdown-lint/css/lint.css'>