One common problem for developers is styling the file input field. Here is one ridiculously simple method that works for IE10+ and all other browsers. Just style the label as you want the input to look.
<label class="my-button-class" style="background-color: green;" for="my-file-selector"> <input id="my-file-selector" type="file" style="display:none;"> Select a File </label>
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