Bootstrap 4 button coloring on pure CSS

my.css

/*
Add this code AFTER importing bootstrap. 
If you add that code to your CSS file, import that file AFTER bootstrap file.
Don't edit bootstrap source code, it's wierd and unkind :)

For defining box-shadows, just get rgb code of main color and write it as rgba with alpha paramenter 0.5
*/

.btn-primary {
  background-color: #FF8A29;
  border-color: #FF8A29;
}

.btn-primary:hover {
  background-color: #E8581A;
  border-color: #E8581A;
}

.btn-primary:focus, .btn-secondary.focus {
  background-color: #E8581A;
  border-color: #E8581A;
  box-shadow: 0 0 0 0.2rem rgba(255, 138, 41, 0.5);
}

.btn-primary:not(:disabled):not(.disabled):active, .btn-secondary:not(:disabled):not(.disabled).active,
.show>.btn-secondary.dropdown-toggle {
  background-color: #FF8A29;
  border-color: #FF8A29;
}

.btn-secondary.disabled, .btn-secondary:disabled {
  background-color: #FF8A29;
  border-color: #FF8A29;
}

.btn-primary:not(:disabled):not(.disabled):active:focus, .btn-secondary:not(:disabled):not(.disabled).active:focus,
.show>.btn-secondary.dropdown-toggle:focus {
  background-color: #FF8A29;
  box-shadow: 0 0 0 0.2rem rgba(255, 138, 41, 0.5);
}