style: modify input checkbox style.

Author: jaywcjlove

src/styles/markdown.less

@@ -982,8 +982,7 @@ body[data-color-mode*='light'] {
       display: none;
     }
   }
-  .task-list-item-checkbox,
-  input[type='checkbox'] {
+  .task-list-item-checkbox {
     margin: 0 0.2em 0.25em -1.6em;
     vertical-align: middle;
   }