.header {
  position: relative;
  height: 110px;
  width: 100%;
  background: linear-gradient(
    to right,
    rgb(0, 61, 191),
    rgb(18, 98, 218),
    rgb(59, 63, 221)
  );}

.logo {
  position: absolute;
  left: 25px;
  top: 22px;
  background: url(../imgs/logo.jpg) no-repeat;
  height: 65px;
  width: 215px;}

.menu {
  margin: 0 auto;
  width: 1200px;
  display: flex;
  justify-content:space-between;
  line-height: 110px;
  font-size: 18px;
  cursor: pointer;}

.menu-item {
  color: #fff;
  width: 150px;
  text-align: center;
flex-shrink:0;
  }
.menu-item > a {
  display: block;
  width: 150px;
  height: 110px;
  }
.menu-item:hover {
  background-color: rgb(0, 67, 170);}

.menu-item:hover > .menu-submenu {
  display: block;}

.menu-submenu {
  position: fixed;
  width: 150px;
  z-index: 9999;
  display: none;
  background-color: rgba(43, 118, 221, 0.7);
  }

.menu-submenu-item {
  font-size: 16px;
  line-height: 50px;
  width: 150px;
  }

.menu-submenu-item:hover {
  background-color: rgb(0, 70, 200);}

.banner {
  height: 300px;
  width: 100%;
  position: relative;}
.banner img {
  height: 250px;
  width: 100%;
  object-fit: cover;}
.layer {
  position: absolute;
  background-color: rgb(0, 0, 0, 0.5);
  top: 0;
  left: 0;
  height: 250px;
  width: 100%;}