@keyframes progress-indeterminate { 0% { left: -35%; right: 100% } 100%, 60% { left: 100%; right: -90% } } .progress { appearance: none; line-height: $progress-height; position: relative; width: 100%; &::-webkit-progress-bar { background: $gray-100; } &::-webkit-progress-value { background-color: $primary } &::-moz-progress-bar { background-color: $primary } &::-ms-fill { background-color: $primary; border: none } } .progress-sm { height: .25rem; } .progress-bar-indeterminate { &:after, &:before { content: ''; position: absolute; background-color: inherit; left: 0; will-change: left, right; top: 0; bottom: 0; } &:before { animation: progress-indeterminate 2.1s cubic-bezier(.65, .815, .735, .395) infinite; } }