Hi,

here is my contact form: http://+++
How can i Increase the text field for this form? When the page loads, it should immediately have its correct size (500 pixels wide and 250 pixels high) without the user having to manually enlarge the field.
I think, this must added anywhere in the template CSS.
Can you help me?

Please add this css code to your css/custom.css

input, textarea, .uneditable-input {
height: auto !important;
}

Many Thanks. However, this change does nothing. I mean the big text field where you enter the message.

Do you mean this text field?

Yes, this i mean.

But this screenshot above is from your site.
please clean your browser cache and look again.