Good to know that you can't fully style input types: button, submit, reset, file on Symbian3 default browser.

By default they use -webkit-appearance property. This property was introduced in 2004 but then was dropped in CSS3 spec: dropped-css3-features.

In theory, the appearance property is used to make an element look like a standard user interface element on the platform, but it doesn't work that way at all. Moreover, you can't adjust the look of html elements to your project because a property, such as background is ignored.

In the Symbian Browser spec you can find that -webkit-appearance property has a value of push-button.

To resolve the problem you have to change its value to initial, and other CSS properties will work as expected.

    input[type="file"]::-webkit-file-upload-button {
    -webkit-appearance: initial;