Answers for "how to disable default styles for input css"

remove default input style css

input:focus, textarea:focus, select:focus{
        outline: none;
    }

css disable input

<input type="text" name="username" value="admin" tabindex="-1" >

 <style type="text/css">
  input[name=username] {
    pointer-events: none;
   }
 </style>