How to align text box & button using CSS?

I have a textbox:

output.AddAttribute(HtmlTextWriterAttribute.Class, "_textBox");
output.RenderBeginTag(HtmlTextWriterTag.Div);
(textbox code)
textBox.RenderControl(output);
output.RenderEndTag();

and a button:
output.AddAttribute(HtmlTextWriterAttribute.Class, "_button");
output.RenderBeginTag(HtmlTextWriterTag.Div);
(button code)
button.RenderControl(output);
output.RenderEndTag();
-------------------------------------
How do I align the textbox and the button on the same line using CSS?
._textbox
{
   ?????
}

Thanks in advance for any assistance.
._button
{
   ?????
}