Change size of text in text input tag?

I would say to set up the font size change in your CSS stylesheet file.

I'm pretty sure that you want all text at the same size for all your form fields. Adding inline styles in your HTML will add to many lines at the end... plus you would need to add it to the other types of form fields such as <select>.

HTML:

<div id="cForm">
    <form method="post">
        <input type="text" name="name" placeholder="Name" data-required="true">
        <option value="" selected="selected" >Choose Category...</option>
    </form>
</div>

CSS:

input, select {
    font-size: 18px;
}

<input style="font-size:25px;" type="text"/>

The above code changes the font size to 25 pixels.

This works, too.

<input style="width:300px; height:55px; font-size:50px;" />

A CSS stylesheet looks better though, and can easily be used over multiple pages.

In your CSS stylesheet, try adding:

input[type="text"] {
    font-size:25px;
}

See this jsFiddle example