styles.css

html {height: 100%;}

* {
    outline: none;
}

body {
    margin: 0;
    padding: 0;
    height: 100%;
    width: 100%;
    box-sizing: border-box;
}

header {
    border-left:2px solid gray;
    border-bottom:2px solid gray;
    border-right:2px solid gray;
    width: 85%;
    height: 80px;
    position: relative;
    margin:0 auto;
}

.header_container {
    width: 100%;
    height: 100%;
}

.header_container-search {
    position: absolute;
}

.header_container nav ul {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    top: 0;
    height: 61%;
    position: absolute;
    padding: 0;
    width: 100%;
    z-index: 1;
}

.header_container nav ul li {
    margin:0px 20px;
    font-size: 17px;
}

.header_container nav ul li:hover {
    text-decoration: underline;
}

.header_container nav ul li:last-child {
    margin-right: 200px;
}

.header_container nav ul li a {
    color:dodgerblue;
    text-decoration: none;
}

.header_container-search {
    position: absolute;
    left: 28%;
    bottom: 29px;
    z-index: 2;
    border-radius: 3px;
    border: 1px solid gray;
}

.header_container-search:focus {
    border:2px solid dodgerblue;
}

.header_container-logo {
    margin-left: 200px;
    width: 150px;
    position: absolute;
    top: 9%;
}



.header_input {
    position: relative;
    width: 175px;
    height: 24px;
    margin: 50px;
    margin: 10px auto;
}

.input_icon {
    width: 13px;
    position: absolute;
    bottom: 20%;
    left:8px;
}

.header_search {
    border-radius: 4px;
    border:1px solid gray;
    height: 20px;
    background-image: ;
    outline: none;
    position: absolute;
    width: 175px;
    font-size: 14px;
    vertical-align: middle;
}

input:focus {
    border:1px solid dodgerblue;
    outline: none;
}