如何通css实现 渐变下划线，以及交互动画

<h2 class="title"><span >围殴围殴我饿我饿我饿哦我饿围围殴围殴我饿我饿我饿哦我饿围殴围殴我饿我饿我饿哦我饿我饿围殴围殴殴围殴我饿我饿我饿哦我饿我饿围殴围殴</span></h2>

.title {
  line-height: 2;
  color: #333;
}
.title span{
  font-weight: 800;
  background: #aaa;
  background: linear-gradient(to right, #ec695c, #61c454) no-repeat left bottom;
  background-size: 0 4px;
  transition: background-size 1s;
}
.title span:hover{
    background-position-x: left;
    background-size: 100% 4px;
 }