What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
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We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
That is possible by injecting custom css into your form. Please take a look at this clone form: http://www.jotformpro.com/form/40385353091957
Here's the code that I use:
background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#72922d), color-stop(100%,#4c6d1f));
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#333333', endColorstr='#4A4A4A',GradientType=0 );
If you need further assistance, please let us know.