Hi mjamero,
1/ Which file are you adding the CSS code to?
I have checked and see that you using this code:
@media (max-width: 480px) {
.gk-animation .gk-ticket strong {
background: #dfa539;
}
}
Any CSS rules placed within this media query block will only apply when the screen width is 480 pixels or less.
Add the CSS code in the style.css file or Customize > Custom CSS without the screen width.
2/ About the text in the Register button, you can open the /wp-content/themes/Fest/css/mobile.css file, line 188, and replace it with this code:
body .gk-animation .gk-ticket small {
display: block;
max-width: 100%;
}
3/ The Guitar image is hidden on the mobile because it doesn't show well to arrange on the mobile. If you want to show the image, you can open the /wp-content/themes/Fest/css/mobile.css file, line 141, and replace with this CSS code:
.gk-animation .gk-guitar {
display: block !important;
background-size: 90%;
opacity: 0.7 !important;
top: 0 !important;
width: 170px !important;
}
Hope this helps!