fix(style): nowrap => pre-wrap, fixed #228

Author: QingWei-Li

Diff for: src/themes/buble.css

@@ -132,7 +132,7 @@ $sidebar-width: 16rem;
   border-radius: 3px;
   font-family: Inconsolata;
   padding: 0.2em 0.4rem;
-  white-space: pre;
+  white-space: nowrap;
 }
 
 .markdown-section pre {

Diff for: src/themes/dark.css

@@ -134,7 +134,7 @@ body {
   font-size: 0.8rem;
   margin: 0 2px;
   padding: 3px 5px;
-  white-space: nowrap;
+  white-space: pre-wrap;
 }
 
 .markdown-section pre {

Diff for: src/themes/vue.css

@@ -145,7 +145,7 @@ body {
   font-size: 0.8rem;
   margin: 0 2px;
   padding: 3px 5px;
-  white-space: nowrap;
+  white-space: pre-wrap;
 }
 
 .markdown-section pre {