在HTML选择下拉选项中设置下拉元素的宽度

I am working on a website that involves automatically populating a select box using a PHP script. This all works fine except the problem is that what I am using to populate the text box have very long titles (they are journal articles and presentation titles). The dropdown box extends to the width of the longest element, which stretches off the edge of the screen, therefore making the scrollbar impossible to reach. I have tried various methods of trying to manually set the dropdown box using CSS to a particular width, but so far to no avail. The best I have accomplished it to set the Select box to a certain width but the dropdown menu itself is much, much wider.I am working on a website that involves automat