19.纯 CSS 创作一种有削铁如泥感觉的菜单导航特效

原文地址：https://segmentfault.com/a/1190000014836748

感想： 把原元素隐藏，利用伪元素::before 和 ::after 各取上下一半 clip-path 切割图片

HTML代码：

<ul class="menu">
  <li data-text="New Game">New Game</li>
  <li data-text="Load Game">Load Game</li>
  <li data-text="Options">Options</li>
  <li data-text="Exit">Exit</li>
</ul>

CSS代码：

html,
body {
    margin: 0;
    padding: 0;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: black;
}
.menu li {
    position: relative;
    list-style-type: none;
    color: transparent;
    font-size: 3em;
    text-transform: uppercase;
    text-align: center;
    line-height: 1em;
    width: 7em;
    margin: 0.5em;
    /* 画出文字的分割线 */
    border-top: 1px solid transparent;
    transition: 0.3s;
}
.menu li:hover{
    border-top: 1px solid yellow;
}
/* 用伪元素添加文本 */
.menu li::before,
.menu li::after{
    position: absolute;
    /* 插入元素的属性值 */
    content: attr(data-text);
    top: 0;
    left: 0;
    width: 100%;
    color: silver;
}
/* 把伪元素文本向上移，竖跨分割线 */
.menu li::before,
.menu li::after {
    top: -0.5em;
    transition: 0.3 ease-out;
}
/* 用遮罩切出分割线上下二部分的文本 */
.menu li::before{
    clip-path: polygon(0 0, 100% 0, 100% 50%, 0 50%);
}
.menu li::after{
    clip-path: polygon(0 50%, 100% 50%, 100% 100%, 0 100%);
}
.menu li:hover::before,
.menu li:hover::after{
    color: yellow;
    transition: left 0.3s ease-out;
    transition-delay: 0.2s;
}
.menu li:nth-child(odd):hover::before,
.menu li:nth-child(even):hover::after{
    left: -0.15em;
}
.menu li:nth-child(even):hover::before,
.menu li:nth-child(odd):hover::after{
    left: 0.15em;
}