main.css

body{
    margin: 0;
    padding: 0;
    background-size: cover;
    background-position: center;
    font-family: 'Oswald', sans-serif;
}

.loginbox{
    width: 320px;
    height: 360px;
    background: #fff;
    border-radius:5px;
    color: #000;
    top: 50%;
    left: 50%;
    position: absolute;
    transform: translate(-50%,-50%);
    box-shadow: 10px 10px 5px grey;
    box-sizing: border-box;
    padding: 70px 30px;
}
h1{
    margin: 0;
    padding: 0 0 20px;
    text-align: center;
    font-size: 22px;
}


.loginbox input{
    width: 100%;
    margin-bottom: 20px;
}

.loginbox input[type="text"], input[type="password"]
{
    border:none;
    border-bottom: 1px solid black;
    background: transparent;
    outline: none;
    height: 40px;
    color: #000;
    font-size: 16px;
}
.loginbox input[type="submit"]
{
    border: none;
    border-radius: 5px;
    outline: none;
    height: 40px;
    background-image:linear-gradient(to right,rgb(1,84,186),#f4b800);
    color: #fff;
    font-size: 18px;
    box-shadow: 5px 5px 5px grey;
}