html {
  font-size: 16px;
}
@media screen and (min-width: 375px) {
  html {
    /* 375px作为16px基准，414px宽度时正好对应18px的根字号大小 */
    font-size: calc(16px + 2 * (100vw - 375px) / 39);
  }
}
@media screen and (min-width: 414px) {
  html {
    /* 屏幕宽度从414px到1000px，根字号大小累积增加4px（18px-22px） */
    font-size: calc(18px + 4 * (100vw - 414px) / 586);
  }
}
@media screen and (min-width: 1000px) {
  html {
    /* 屏幕宽度从1000px往后每增加100px，根字号大小就增加0.5px */
    font-size: calc(22px + 5 * (100vw - 1000px) / 1000);
  }
}
.mod {
  padding-bottom: 58px;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  width: 100%;
}

.long-banner {
  width:80%;
  align-self: center;
}

.long-cover {
  width:80%;
  align-self: center;
}

.long-banner-1 {
  width:80%;
  margin-top: 146px;
  align-self: center;
}

.banner {
  width: 80%;
  margin-top: 65px;
  align-self: center;
}

.long-cover-1 {
  width:80%;
  align-self: center;
}

.long-banner-2 {
  width:80%;
  align-self: center;
}

.cover {
  width:80%;
  margin-top: 41px;
  align-self: center;
}

.long-cover-2 {
  width:80%;
  margin-top: 83px;
  align-self: center;
}

.long-banner-3 {
  width:80%;
  margin-top: 98px;
  align-self: center;
}

.long-cover-3 {
  width:80%;
  align-self: center;
  margin: 56px 0 0 1px;
}