You need to add media in CSS, understand how to add media into css and make your website responsive.
/*------------------------------------------
Responsive Grid Media Queries - 1280, 1024, 768, 480
1280-1024 - desktop (default grid)
1024-768 - tablet landscape
768-480 - tablet
480-less - phone landscape & smaller
--------------------------------------------*/
@media all and (min-width: 1024px) and (max-width: 1280px) { }
@media all and (min-width: 768px) and (max-width: 1024px) { }
@media all and (min-width: 480px) and (max-width: 768px) { }
@media all and (max-width: 480px) { }
/* Portrait */
@media screen and (orientation:portrait) { /* Portrait styles here */ }
/* Landscape */
@media screen and (orientation:landscape) { /* Landscape styles here */ }
/* CSS for iPhone, iPad, and Retina Displays */
/* Non-Retina */
@media screen and (-webkit-max-device-pixel-ratio: 1) {
}
/* Retina */
@media only screen and (-webkit-min-device-pixel-ratio: 1.5),
only screen and (-o-min-device-pixel-ratio: 3/2),
only screen and (min--moz-device-pixel-ratio: 1.5),
only screen and (min-device-pixel-ratio: 1.5) {
}
/* iPhone Portrait */
@media screen and (max-device-width: 480px) and (orientation:portrait) {
}
/* iPhone Landscape */
@media screen and (max-device-width: 480px) and (orientation:landscape) {
}
/* iPad Portrait */
@media screen and (min-device-width: 481px) and (orientation:portrait) {
}
/* iPad Landscape */
@media screen and (min-device-width: 481px) and (orientation:landscape) {
}
You just need to check which resolution you want to make responsive and particular CSS into that media. You need to use more inspect element for testing. One more thing you also use percentage for padding or margin so according to width of your DOM your button will be adjust.