remove comments, align-items, and unnecessary height

scss/_progress.scss

-// Progress animations
 @keyframes progress-bar-stripes {
   from { background-position: $progress-height 0; }
   to { background-position: 0 0; }
 }
 
-// Basic progress bar
 .progress {
   display: flex;
-  align-items: center;
   height: $progress-height;
   overflow: hidden; // force rounded corners by cropping it
   font-size: $progress-font-size;
@@ -20,18 +17,15 @@
   display: flex;
   align-items: center;
   justify-content: center;
-  height: 100%;
   color: $progress-bar-color;
   background-color: $progress-bar-bg;
 }
 
-// Striped
 .progress-bar-striped {
   @include gradient-striped();
   background-size: $progress-height $progress-height;
 }
 
-// Animated
 .progress-bar-animated {
   animation: progress-bar-stripes $progress-bar-animation-timing;
 }