easy-going-rails/app/assets/stylesheets/css/tooltip.css

[data-tooltip] {
  --arrow-size: 5px;
  position: relative;
  z-index: 10;
}

/* Positioning and visibility settings of the tooltip */
[data-tooltip]:before,
[data-tooltip]:after {
  position: absolute;
  visibility: hidden;
  opacity: 0;
  left: 50%;
  bottom: calc(100% + var(--arrow-size));
  pointer-events: none;
  transition: 0.2s;
  will-change: transform;
}

/* The actual tooltip with a dynamic width */
[data-tooltip]:before {
  content: attr(data-tooltip);
  padding: 10px 18px;
  min-width: 50px;
  max-width: 300px;
  width: max-content;
  width: -moz-max-content;
  border-radius: 6px;
  font-size: 14px;
  background-color: rgba(59, 72, 80, 0.9);
  background-image: linear-gradient(30deg,
      rgba(59, 72, 80, 0.44),
      rgba(59, 68, 75, 0.44),
      rgba(60, 82, 88, 0.44));
  box-shadow: 0px 0px 24px rgba(0, 0, 0, 0.2);
  color: #fff;
  text-align: center;
  white-space: pre-wrap;
  transform: translate(-50%, calc(0px - var(--arrow-size))) scale(0.5);
}

/* Tooltip arrow */
[data-tooltip]:after {
  content: '';
  border-style: solid;
  border-width: var(--arrow-size) var(--arrow-size) 0px var(--arrow-size);
  /* CSS triangle */
  border-color: rgba(55, 64, 70, 0.9) transparent transparent transparent;
  transition-duration: 0s;
  /* If the mouse leaves the element, 
                              the transition effects for the 
                              tooltip arrow are "turned off" */
  transform-origin: top;
  /* Orientation setting for the
                              slide-down effect */
  transform: translateX(-50%) scaleY(0);
}

/* Tooltip becomes visible at hover */
[data-tooltip]:hover:before,
[data-tooltip]:hover:after {
  visibility: visible;
  opacity: 1;
}

/* Scales from 0.5 to 1 -> grow effect */
[data-tooltip]:hover:before {
  transition-delay: 0.3s;
  transform: translate(-50%, calc(0px - var(--arrow-size))) scale(1);
}

/* 
  Arrow slide down effect only on mouseenter (NOT on mouseleave)
*/
[data-tooltip]:hover:after {
  transition-delay: 0.5s;
  /* Starting after the grow effect */
  transition-duration: 0.2s;
  transform: translateX(-50%) scaleY(1);
}

/*
  That's it for the basic tooltip.

  If you want some adjustability
  here are some orientation settings you can use:
*/

/* LEFT */
/* Tooltip + arrow */
[data-tooltip-location="left"]:before,
[data-tooltip-location="left"]:after {
  left: auto;
  right: calc(100% + var(--arrow-size));
  bottom: 50%;
}

/* Tooltip */
[data-tooltip-location="left"]:before {
  transform: translate(calc(0px - var(--arrow-size)), 50%) scale(0.5);
}

[data-tooltip-location="left"]:hover:before {
  transform: translate(calc(0px - var(--arrow-size)), 50%) scale(1);
}

/* Arrow */
[data-tooltip-location="left"]:after {
  border-width: var(--arrow-size) 0px var(--arrow-size) var(--arrow-size);
  border-color: transparent transparent transparent rgba(55, 64, 70, 0.9);
  transform-origin: left;
  transform: translateY(50%) scaleX(0);
}

[data-tooltip-location="left"]:hover:after {
  transform: translateY(50%) scaleX(1);
}



/* RIGHT */
[data-tooltip-location="right"]:before,
[data-tooltip-location="right"]:after {
  left: calc(100% + var(--arrow-size));
  bottom: 50%;
}

[data-tooltip-location="right"]:before {
  transform: translate(var(--arrow-size), 50%) scale(0.5);
}

[data-tooltip-location="right"]:hover:before {
  transform: translate(var(--arrow-size), 50%) scale(1);
}

[data-tooltip-location="right"]:after {
  border-width: var(--arrow-size) var(--arrow-size) var(--arrow-size) 0px;
  border-color: transparent rgba(55, 64, 70, 0.9) transparent transparent;
  transform-origin: right;
  transform: translateY(50%) scaleX(0);
}

[data-tooltip-location="right"]:hover:after {
  transform: translateY(50%) scaleX(1);
}



/* BOTTOM */
[data-tooltip-location="bottom"]:before,
[data-tooltip-location="bottom"]:after {
  top: calc(100% + var(--arrow-size));
  bottom: auto;
}

[data-tooltip-location="bottom"]:before {
  transform: translate(-50%, var(--arrow-size)) scale(0.5);
}

[data-tooltip-location="bottom"]:hover:before {
  transform: translate(-50%, var(--arrow-size)) scale(1);
}

[data-tooltip-location="bottom"]:after {
  border-width: 0px var(--arrow-size) var(--arrow-size) var(--arrow-size);
  border-color: transparent transparent rgba(55, 64, 70, 0.9) transparent;
  transform-origin: bottom;
}