如何让按钮高度填充网站的垂直空间？

I have a mobile website and it has 3 buttons and a couple of lines of text. I have the text centered (horizontally) and the buttons take up the entire width of the screen. However, I need the height of the buttons to scale to take up the entire screen. How do I make the buttons scale vertically?I have a mobile website and it has 3 buttons an