*{
  font-family: -apple-system, BlinkMacSystemFont, 'Helvetica Neue', 'PingFang SC', 'Microsoft YaHei', Arial, Helvetica, sans-serif;
}
.content{
  max-width: 1200px;
  margin: 0 auto;
}
.img-container{
  margin: 10px;
}
img{
  width: 100%;
  height: auto;
}
em, strong{
  font-style: normal;
  font-weight: 600;
}
strong{
  color: #3366ff;
}
p{
  margin: 10px;
  font-size: 16px;
  line-height: 24px;
}
p.tip{
  color: #777;
  font-size: 12px;
  line-height: 20px;
  padding: 10px;
  background-color: #fff9dd;
}

h1{
  text-align: center;
  line-height: 30px;
  font-size: 20px;
  color: #333;
  margin: 20px 0;
}

h3{
  margin: 10px;
  text-align: left;
  line-height: 24px;
  font-size: 16px;
  color: #333;
}

footer{
  margin: 30px 0;
  text-align: center;
  color: #999;
  font-size: 12px;
}