* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}

a {
  text-decoration: none;

}

body {
  min-width: 1400px;
}

header {
  width: 100%;
  background-image: url('../images/picture2.jpg');
  height: 650px;
  background-size: 100% 100%;
  position: relative;
}

@media screen and (min-width:1600px) {
  header {
    height: 1100px;
  }

}

@media screen and (min-width:1920px) {
  header {
    height: 1400px;
  }

}

nav {
  position: fixed;
  right: 0;
  left: 0;
  top: 0;
  line-height: 80px;
  padding: 0 40px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  /* background: rgba(255, 255, 255, .7); */
  background: rgba(255, 255, 255);
  z-index: 99;
  font-size: 17px;
}

nav ul {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
}

nav li {
  list-style: none;
}

nav ul a {
  color: rgb(72, 112, 164);
  display: inline-block;
  padding: 0 20px;
  line-height: 80px;
}

nav ul a:hover {
  color: white;
  background: rgba(72, 112, 164, 0.5);
}

header .active {
  color: white;
  background: rgb(72, 112, 164);
}

.logo {
  width: 150px;
  height: 70px;

}

.header_title {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  color: white;
  text-align: center;
}

.header_title h1 {
  margin-bottom: 30px;
  font-size: 45px;
}

.header_title p {
  font-size: 20px;
}

.login {
  cursor: pointer;
  color: white;
  line-height: 50px;
  border-radius: 25px;
  padding: 0 20px;
  background: #54a0ff;
  transition: box-shadow 0.5s;
}

.login:hover {
  box-shadow: 0 0 10px rgb(72, 112, 164);
}

.login_active {
  cursor: pointer;
  color: white;
  line-height: 50px;
  border-radius: 25px;
  padding: 0 20px;
  background: #54a0ff;
  transition: box-shadow 0.5s;
  box-shadow: 0 0 10px rgb(72, 112, 164);
}

/* 主内容 */
.box {
  width: 1200px;
  margin: auto;
  padding: 40px 0;
}

/* 页脚 */
footer {
  margin-top: 40px;
  background: rgb(72, 112, 164);
  line-height: 70px;
  text-align: center;
  color: white;
}