* {
  padding: 0;
  margin: 0;
}

html {
  display: block;
  font-size: 16px;
  font-size: 100%;
  /* 默认16px */
}

@media (min-width: 600px) {
  html {
    /* font-size: 112.5%; */
    /* 大约18px */
  }
}

@media (min-width: 1200px) {
  html {
    /* font-size: 150%; */
    /* 大约24px  */
  }
}

body {
  font-family: -apple-system-font, BlinkMacSystemFont, Helvetica Neue, PingFang SC, Hiragino Sans GB, Microsoft YaHei UI, Microsoft YaHei, Arial, sans-serif;
  color: rgba(0, 0, 0, .9);
  /* line-height: 1.4; */
}

body,
form,
h1,
h2,
h3,
h4,
h5,
h6,
ul,
ol,
li,
dl,
dd,
dt,
p,
hr,
input,
em {
  margin: 0;
  padding: 0;
  list-style: none;
  -webkit-text-size-adjust: none;
  vertical-align: middle;
  font-weight: normal;
}

ul,
li {
  list-style: none;
  margin: 0;
}

img {
  border: 0
}

div {
  display: block;
  unicode-bidi: isolate;
}

a {
  text-decoration: none;
  cursor: pointer;
  outline: none;
}

.width_center {
  display: flex;
  justify-content: center;
}

.height_center {
  display: inline-flex;
  align-items: center;
}

.pointer {
  cursor: pointer;
}

.item {
  position: relative;
  transition: top 0.5s;
  /* 平滑过渡效果 */
}