/* NoteBeam responsive stylesheet */

*,
*::before,
*::after {
    box-sizing: border-box;
}

html,
body {
    margin: 0;
    padding: 0;
}

body {
    background-color: #fffffd;
    color: #575757;
    font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
    font-size: 14pt;
}

header {
    position: relative;
}

/* Banner */

.banner {
    position: relative;
    width: 100%;
    min-height: 200px;
    background-color: #4682B4;
    box-shadow: 0 8px 10px grey;
}

.siteName h1 {
    position: absolute;
    top: 35px;
    left: 14%;
    width: 350px;
    height: 1.2em;
    margin: 0;
    border: none;
    color: #fffffd;
    font-family: "Times New Roman", serif;
    text-align: center;
}

.sitePurpose h2 {
    position: absolute;
    top: 92px;
    left: 14%;
    width: 350px;
    margin: 0;
    border: none;
    color: #fffffd;
    font-family: "Times New Roman", serif;
    font-size: 1.5em;
    text-align: center;
}

/* Navigation */

.nav {
    position: absolute;
    right: 5%;
    bottom: 24px;
    width: 55%;
    margin: 0;
}

.nav ul {
    display: flex;
    align-items: stretch;
    justify-content: space-between;
    margin: 0;
    padding: 0;
    list-style: none;
}

.nav li {
    display: flex;
    flex: 1 1 0;
}

.nav li a {
    display: block;
    width: 100%;
    padding: 8px 10px;
    border-right: 1px solid #fffffd;
    background: transparent;
    color: #fffffd;
    text-align: center;
    text-decoration: none;
}

.nav li:last-child a {
    border-right: none;
}

a:link,
a:visited {
    color: #fffffd;
}

a:hover,
.nav li a:hover {
    background: #fffffd;
    color: #4682B4;
    text-decoration: overline;
}

a:focus-visible {
    outline: 2px solid #fffffd;
    outline-offset: 3px;
}

/* Tablet */

@media screen and (max-width: 900px) and (min-width: 601px) {
    .siteName h1,
    .sitePurpose h2 {
        left: 4%;
        width: 300px;
    }

    .nav {
        right: 3%;
        width: 58%;
    }

    .nav li a {
        padding-right: 6px;
        padding-left: 6px;
        font-size: 0.9em;
    }
}

/* Mobile */

@media screen and (max-width: 600px) {

    .banner {
        min-height: 100px;
        box-shadow: none;
    }

    .siteName h1 {
        top: 8px;
        left: 0;
        width: 100%;
        font-size: 1.8em;
    }

    .sitePurpose h2 {
        top: 52px;
        left: 0;
        width: 100%;
        font-size: 1.05em;
    }

    .nav {
        position: static;
        width: 100%;
        margin: 0;
        padding: 4px 14px;
        background-color: #4682B4;
    }

    .nav ul {
        flex-direction: column;
        gap: 0;
    }

    .nav li {
        display: block;
        width: 100%;
    }

    .nav li a {
        width: 100%;
        padding: 9px 10px;
        border-right: none;
        border-bottom: 1px solid rgba(255, 255, 255, 0.55);
        text-align: center;
    }

    .nav li:last-child a {
        border-bottom: none;
    }
}



What I'm aiming for
The result should be a more compact header:
-