自留按钮动画

十字形劈开

.btn {
  margin: 80px;
  width: 400px;
  height: 80px;
  position: relative;
  font-size: 4rem;
  background-color: #f2f2f2;
  color: black;
  z-index: 1;
  transition: 1s;
}

.btn::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: #262626;
  transform: rotateX(90deg);
  transition: 1s;
  z-index: -1;
}

.btn:hover::before {
  transform: rotateX(0deg);
}

.btn::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: #262626;
  transform: rotateY(90deg);
  transition: 1s;
  z-index: -1;
}

.btn:hover::after {
  transform: rotateY(0deg);
}

.btn:hover {
  color: #fff;
}

十字形黑到白,原理是通过旋转x和y轴得到

自上而下倒塌

.roate {
  margin: 5px;
  width: 400px;
  height: 50px;
  margin-top: 200px;
  position: relative;
  overflow: hidden;
  background-color: inherit;
}
.roate::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  background-color: yellowgreen;
  z-index: -1;
  width: 100%;
  height: 100%;
  transform-origin: bottom left;
  transform: rotate(-90deg);
  transition: transform 1s ease-in-out;
}
.roate:hover::before {
  transform: rotate(0deg);
}

原理是before里画一团颜色，用transform旋转让他塌下来

填充

.btn2 {
  margin: 5px;
  width: 400px;
  height: 50px;
  margin-top: 200px;
  position: relative;
  background-color: inherit;
  overflow: hidden;
  color: burlywood;
  transition: all 1.5s;
  font-size: 1rem;
}

.btn2::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  background-color: burlywood;
  width: 100%;
  height: 100%;
  z-index: -1;
  transform-origin: left;
  transform: translateX(-100%);
  transition: transform 1s ease-in-out;
}

.btn2:hover::before {
  transform: translateX(0);
}
.btn2:hover {
  color: white;
}

悬浮放大

.btn {
  padding: 10px;
  position: relative;
  background-color: inherit;
  text-transform: uppercase;
  color: black;
  transition: all 1.5s;
  font-size: 1.25rem;
  border: 3px solid black;
  font-weight: 300;
  letter-spacing: 2px;
}

.btn:hover {
  font-weight: 900;
  letter-spacing: 5px;
  border: 5px solid black;
}

想不出来怎么形容

a {
    font-size: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    color: black;
    text-decoration: none;
    margin: 25px;
    width: 160px;
    height: 60px;
    line-height: 60px;
    position: relative;
    transition: all 0.2s;
    letter-spacing: 3px;
    user-select: none;
    &::before {
        content: "";
        position: absolute;
        width: 160px;
        height: 90px;
        top: -15px;
        left: 0;
        border-left: 4px solid #ff717f;
        border-right: 4px solid #353d81;
        transition: all 1s;

    }

    &:hover::before {
        transform: rotateY(180deg);
    }

    &:hover::after {
        transform: rotateX(180deg);
    }

    &::after {
        content: "";
        position: absolute;
        width: 200px;
        height: 60px;
        top: 0;
        left: -15px;
        border-top: 4px solid #ff717f;
        border-bottom: 4px solid #353d81;
        transition: all 1s;
        transition-delay: 0.2s;
    }