>>>Hmm. Just tried all three(i.e aspx.:

<input type="button" id="button1" value="One" />
>>><button type="button" id="button2">Two</button>
>>><asp:Button runat="server" ID="button3" Text="Three"/>

gives HTML:

<input type="button" id="button1" value="One">
>>><button type="button" id="button3">Two</button>
>>><input type="submit" name="button4" value="Three" id="button4">

in a clean Web Application and they look the same to me. Relevant bit in css:

   input[type="submit"],
>>>    input[type="button"],
>>>    button {
>>>        background-color: #d3dce0;
>>>        border: 1px solid #787878;
>>>        cursor: pointer;
>>>        font-size: 1.2em;
>>>        font-weight: 600;
>>>        padding: 7px;
>>>        margin-right: 8px;
>>>        width: auto;
>>>    }

How does yours differ ?
>>>
>>
>>I will try to create a small test page to see if I get the same results as you. When I tested in my "production" project page, the look was very different. As I said, the standard ASP.NET Web Forms project is using Sites.css (from MS). So it (this .css) could be that made the difference.
>
>The example above is using standard Sites.css. I can see one difference: for the 'button' element Sites.css doesn't override the margin-bottom, -left or -top values. For and 'input' element it overrides all four. But that shouldn't affect the size of the element itself.......
>

One other CSS I have is Bootstrap.css. I am working on learning of how to "examine" the resulting HTML so I can see what affects what. For example, I use a Bootstrap class "table table-bordered" but it does not show the left side of the table correctly (that it, no border on the left). So I will use the IE Development Tool or Firefox or Chrome to figure what is in the "way.". I think (for me) to learn how to use this tools is essential since I am up to my neck in web development. And plan to continue this uphill road. Thank you.