autoprefixer 和 cssnext

a {
    display: flex;
}

a {
    display: -webkit-box;
    display: -webkit-flex;
    display: -ms-flexbox;
    display: flex
}

/* custom selectors */
@custom-selector --heading h1, h2, h3, h4, h5, h6;
--heading { margin-top: 0 }

/* filters */
.blur {
  filter: blur(4px);
}

/* custom selectors */
h1,
h2,
h3,
h4,
h5,
h6 { margin-top: 0 }

/* filters */
.blur {
  filter: url(‘data:image/svg+xml;charset=utf-8,<svg xmlns="http://www.w3.org/2000/svg"><filter id="filter"><feGaussianBlur stdDeviation="4" /></filter></svg>#filter‘);
  -webkit-filter: blur(4px);
          filter: blur(4px);
}