Answer 1

The animation property in CSS can be used to animate many other CSS properties such as color, background-color, height, or width. Each animation needs to be defined with the @keyframes at-rule which is then called with the animation.

.element {
animation: pulse 5s infinite;
}

@keyframes pulse {
0% {
background-color: #001F3F;
}
100% {
background-color: #FF4136;
}
}

the webkit prefix is for specific browsers: Chrome, Safari, Android, iOs

you have some prefix:
-webkit
-moz (firefox)
-o (opera)
-ms (ie)