ck-ops/code/grafana/public/sass/components/_popover-box.scss

.popover-box {
  background-color: $popover-bg;
  color: $popover-color;
  border: 1px solid $popover-border-color;
  border-radius: $border-radius;
  max-width: 500px;
}

.popover-box__header {
  background-color: $popover-border-color;
  padding: 6px 10px;
  display: flex;
}

.popover-box__title {
  font-weight: $font-weight-semi-bold;
  padding-right: $spacer;
  overflow: hidden;
  display: inline-block;
  white-space: nowrap;
  text-overflow: ellipsis;
  flex-grow: 1;
}

.popover-box__body {
  padding: 20px 10px 10px 10px;
}

.popover-box__close {
  cursor: pointer;
}