优化 code 预览显示效果，回退 #1359 (#1398)

src/css/modules/code.css

@@ -51,7 +51,7 @@ html #layuicss-skincodecss{display: none; position: absolute; width: 1989px;}
 .layui-code-preview > .layui-tab > .layui-tab-title{border-width: 0;}
 .layui-code-preview .layui-code-item{display: none;}
 .layui-code-preview .layui-code-view > .layui-code-lines > .layui-code-line{}
-.layui-code-item-preview{position: relative; padding: 16px; overflow: auto;}
+.layui-code-item-preview{position: relative; padding: 16px;}
 .layui-code-item-preview > iframe{position: absolute; top: 0; left: 0; width: 100%; height: 100%; border: none;}
 
 /* 工具栏  */
@@ -66,6 +66,7 @@ html #layuicss-skincodecss{display: none; position: absolute; width: 1989px;}
 .layui-code-full .layui-code-item,
 .layui-code-full .layui-code-view,
 .layui-code-full .layui-code-wrap{height: calc(100vh - 51px) !important; box-sizing: border-box;}
+.layui-code-full .layui-code-item-preview{overflow: auto;}
 
 /* 代码高亮重置 */
 .layui-code-view.layui-code-hl{line-height: 20px !important; border-left-width: 1px;}