Optimize user setting page for mobile browser (#1924)

* Remove overflow because it blocks scrolling on mobile safari.

* Add “-webkit-overflow-scrolling: touch;” to enable smooth scroll on mobile safari and other webkit browsers.

* Use radio buttons in user setting page.

Because select tags with long text are not fit in the width of mobile devices.

* Add flex property to fit labels to devise width.

* Change font size of select.

It causes auto zooming on mobile safari.