How can I modify the height and width (or shape, too, if possible) of an input form in HTML??

Answer 1

Oh its a easy way I try to explain it for you:

Example: <form id="name"></form>

In CSS:

#name{
width: 200px; (width of block element)
height: 50px; (height of block element)
border-radius: 20px; (circle-like borders)
}

In JS:
(load function when window ready)

window.onload = function(){

var handler = document.getElementById('name');

(access to html element like to other object)

handler.style.width= 200px;
handler.style.height=50px;
handler.style.borderRadius= 20px;
};

If you have questions I'll try answer ! :))

Answer 2

Thank you, Wiktor. I will try this.

Answer 3

in CSS you write: background-color, font-size

And if you styling elements in JS remember that:
You need to use camelCase letters :)
-> backgroundColor
-> fontSize

etc :)