How to resize the jQuery DatePicker control

You don't have to change it in the jquery-ui css file (it can be confusing if you change the default files), it is enough if you add

div.ui-datepicker{
 font-size:10px;
}

in a stylesheet loaded after the ui-files

div.ui-datepicker is needed in case ui-widget is mentioned after ui-datepicker in the declaration

I can't add a comment, so this is in reference to the accepted answer by Keijro. I actually added the following to my stylesheet instead:

    div.ui-datepicker {
    font-size: 62.5%;
}

and it worked as well. This might be preferable to the absolute value of 10px.