* {
    box-sizing: border-box;
}

html,
body {
    margin: 0;
}
html {
    scroll-behavior: smooth;
}

body {
    font-family: Helvetica, Arial, sans-serif;
    background: linear-gradient(#3e5ae2, #00ffff) fixed;
    font-size: 18px;
}

a {
    text-decoration: none;
}

a:hover {
    color: #f90;
    text-decoration: underline;
}

h1,
h2,
h3 {
    margin: 0;
    padding: 5px 0;
}

header {
    background: url(../img/sky.jpg) no-repeat fixed;
    background-size: cover; /* contain */
    background-position: 50%;
    height: 200px;
    color: #fff;
    text-align: center;
    border-bottom: 2px solid #333c;
}
header h1 {
    padding-top: 54px;
}

main {
    max-width: 1024px;
    margin: 0 auto;
    box-shadow: 0px 10px 10px rgba(0, 0, 0, 0.5);
    padding: 10px;
    background-color: #333c;
}

.welcome {
    background: white;
    border-radius: 2px;
    padding: 20px;
}
.welcome h2 {
    color: #999;
}

nav {
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1;
}
nav div {
    max-width: 1024px;
    margin: 20px auto;

    text-align: right;
}
nav a {
    display: inline-block;
    min-width: 80px;
    text-align: center;
    text-transform: uppercase;
    margin: 0 10px 0 0;
    line-height: 30px;
    border-radius: 5px;
    border: solid #fff 2px;
    color: #fff;
    background-color: #000;
    transition: 0.5s;
}

nav a:hover {
    text-decoration: none;
    border: solid #f90 2px !important;
    color: #f90 !important;
}

footer {
    max-width: 1024px;
    margin: 0 auto;
    padding: 10px 0;
}

@media (max-width: 768px) {
    main {
        grid-template-columns: 1fr 1fr;
    }
    nav div {
        text-align: center;
    }
    nav a {
        margin: 0 5px;
    }
}

@media (max-width: 520px) {
    main {
        grid-template-columns: 1fr;
    }
}