svg边框线围绕一圈动画

html部分：

<a id="a5" href="#" class="know_thiye">
    <svg>
        <rect x="0" y="0" fill="none" width="100%" height="100%"></rect>
    </svg>
    <span>MORE</span>
</a>

css部分：

.know_thiye {
  display: block;
  font-size: 0.22rem;
  font-weight: 400;
  text-align: center;
  margin: 0.6rem 0;
  width: 1.5rem;
  height: 0.4rem;
  position: relative;
  transition: all 450ms linear 0s;  // *过渡
  color: #313944;
}

.know_thiye span {
  line-height: 0.5rem;
}

.know_thiye svg {
  height: 0.5rem;
  left: 0;
  position: absolute;
  top: 0;
  width: 100%;
}

/* 动画部分 */
.know_thiye rect {
  fill: none;
  stroke: #078fdf;
  stroke-width: 5;
  stroke-dasharray: 422, 0;
  transition: all 450ms linear 0s;
}

.know_thiye:hover rect {
  stroke-width: 5;
  stroke-dasharray: 22, 323;
  stroke-dashoffset: 80;
  transition: all 1s cubic-bezier(0.19, 1, 0.22, 1);
}
/* 动画部分 end */

.know_thiye:hover {
  font-weight: 900;
  letter-spacing: 1px;
}