progress {
  width: 100px;
  height: 10px;
  margin-left: 5px;
  margin-right: 5px;
  background: crimson;
  border:1px solid;border-color:gray;
}

progress {
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
  border: none;
}

progress::-webkit-progress-bar {
  background:var(--a,grey);
}
progress::-webkit-progress-value {  
  background-color: var(--c,grey);
}