@import url('http://fonts.lug.ustc.edu.cn/css?family=Open+Sans:400,600,700,800');

$color: #ea3830;

*, *:before, *:after { box-sizing: border-box; }
body {
  font-family: 'Open Sans', sans-serif;
  font-size: 14pt;
  font-smooth: always;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
a { color: $color; text-decoration: none; }
nav {
  position: relative;
  width: 100%; max-width: 960px; min-width: 400px; height: 50px;
  margin: 25px auto;
  border-bottom: 3px solid #eee;
  .slider {
    position: absolute;
    bottom: 0;
    width: 25%; height: 3px;
    box-shadow: 0 3px $color;
    transition: all .3s ease-in-out;
  }
  ul {
    height: 50px;
    display: flex;
    flex-flow: row nowrap;
    justify-content: space-around;
    align-items: center;
    li {
      width: 25%; height: 50px;
      flex: 25%;
      line-height: 50px;
      a {
        padding: 0 25px;
        display: block;
        font-weight: 600;
      }
    }
  }
}