.narrating { position: relative; z-index: 1; } body.light .narrating { background-color: #ffc; } body.sepia .narrating { background-color: #e0d7c5; } body.dark .narrating { background-color: #242424; } .narrate-word-highlight { position: absolute; display: none; transform: translate(-50%, calc(-50% - 2px)); z-index: -1; border-bottom-style: solid; border-bottom-width: 7px; transition: left 0.1s ease, width 0.1s ease; } .narrating > .narrate-word-highlight { display: inline-block; } .narrate-word-highlight.newline { transition: none; } body.light .narrate-word-highlight { border-bottom-color: #ffe087; } body.sepia .narrate-word-highlight { border-bottom-color: #bdb5a5; } body.dark .narrate-word-highlight { border-bottom-color: #6f6f6f; }