react/packages/react-devtools-scheduling-profiler/src/EventTooltip.css

.Tooltip {
  position: fixed;
  display: inline-block;
  border-radius: 0.125rem;
  max-width: 300px;
  padding: 0.25rem;
  user-select: none;
  pointer-events: none;
  background-color: #ffffff;
  border: 1px solid #ccc;
  box-shadow: 1px 1px 2px rgba(0, 0, 0, 0.2);
  font-size: 11px;
}

.Divider {
  height: 1px;
  background-color: #aaa;
  margin: 0.5rem 0;
}

.DetailsGrid {
  display: grid;
  padding-top: 5px;
  grid-gap: 2px 5px;
  grid-template-columns: min-content auto;
}

.DetailsGridLabel {
  color: #666;
  text-align: right;
}

.DetailsGridURL {
  word-break: break-all;
  max-height: 50vh;
  overflow: hidden;
}

.FlamechartStackFrameName {
  word-break: break-word;
  margin-left: 0.4rem;
}

.ComponentName {
  font-weight: bold;
  word-break: break-word;
  margin-right: 0.4rem;
}

.ComponentStack {
  overflow: hidden;
  max-width: 35em;
  max-height: 10em;
  margin: 0;
  font-size: 0.9em;
  line-height: 1.5;
  -webkit-mask-image: linear-gradient(
    180deg,
    #fff,
    #fff 5em,
    transparent
  );
  mask-image: linear-gradient(
    180deg,
    #fff,
    #fff 5em,
    transparent
  );
  white-space: pre;
}

.ReactMeasureLabel {
  margin-left: 0.4rem;
}

.UserTimingLabel {
  word-break: break-word;
}