docs: improve code comments (#1911)

src/styles/index.scss

@@ -96,14 +96,18 @@ div:focus {
   }
 }
 
-code {
+aside {
   background: #eef1f6;
-  padding: 15px 16px;
+  padding: 8px 24px;
   margin-bottom: 20px;
+  border-radius: 2px;
   display: block;
-  line-height: 36px;
-  font-size: 15px;
-  font-family: "Source Sans Pro", "Helvetica Neue", Arial, sans-serif;
+  line-height: 32px;
+  font-size: 16px;
+  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif;
+  color: #2c3e50;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
 
   a {
     color: #337ab7;
@@ -115,20 +119,6 @@ code {
   }
 }
 
-.warn-content {
-  background: rgba(66, 185, 131, .1);
-  border-radius: 2px;
-  padding: 16px;
-  padding: 1rem;
-  line-height: 1.6rem;
-  word-spacing: .05rem;
-
-  a {
-    color: #42b983;
-    font-weight: 600;
-  }
-}
-
 //main-container全局样式
 .app-container {
   padding: 20px;