Set the {@link #fieldStyle CSS style} of the {@link #inputEl field input element}.
@param {String/Object/Function} style The style(s) to apply. Should be a valid argument to {@link
Ext.Element#applyStyles}.
function(style) {
        var me = this,
            inputEl = me.inputEl;
        if (inputEl) {
            inputEl.applyStyles(style);
        }
        me.fieldStyle = style;
    }