tu-view-plus/es/src/resize-box/style/resize-box.css

.tu-resize-box {
  position: relative;
  width: 100%;
  overflow: hidden;
  box-sizing: border-box;
}
.tu-resize-box__left, .tu-resize-box__right, .tu-resize-box__top, .tu-resize-box__bottom {
  position: absolute;
  top: 0;
  left: 0;
  box-sizing: border-box;
  -webkit-user-select: none;
  -moz-user-select: none;
  user-select: none;
}

.tu-resize-box__left {
  border-left: 1px solid var(--tu-color-line, rgba(128, 128, 128, 0.18));
}

.tu-resize-box__right {
  right: 0;
  left: unset;
  border-right: 1px solid var(--tu-color-line, rgba(128, 128, 128, 0.18));
}

.tu-resize-box__top {
  border-top: 1px solid var(--tu-color-line, rgba(128, 128, 128, 0.18));
}

.tu-resize-box__bottom {
  top: unset;
  bottom: 0;
  border-bottom: 1px solid var(--tu-color-line, rgba(128, 128, 128, 0.18));
}