<div style="padding: 100px; text-align: center;">
  <button class="tooltip-container">
    Hover Me
    <span class="tooltip-text">This is a CSS-only tooltip!</span>
  </button>
</div>

.tooltip-container {
  font-family: system-ui, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  position: relative;
  display: inline-block;
  padding: 10px 20px;
  background: #2563eb;
  color: white;
  border: none;
  border-radius: 8px;
  cursor: pointer;
}
.tooltip-text {
  visibility: hidden;
  background-color: #1f2937;
  color: #fff;
  text-align: center;
  padding: 8px 12px;
  border-radius: 6px;
  position: absolute;
  z-index: 1;
  bottom: 125%;
  left: 50%;
  transform: translateX(-50%);
  opacity: 0;
  transition: opacity 0.3s, bottom 0.3s;
  width: 140px;
  font-size: 0.85rem;
  pointer-events: none;
}
.tooltip-text::after {
  content: "";
  position: absolute;
  top: 100%;
  left: 50%;
  margin-left: -5px;
  border-width: 5px;
  border-style: solid;
  border-color: #1f2937 transparent transparent transparent;
}
.tooltip-container:hover .tooltip-text {
  visibility: visible;
  opacity: 1;
  bottom: 140%;
}