body {
    background: teal;
}

header {
    background: lightskyblue;
    border-radius: 0.5em;
    border: greenyellow dotted 0.2em;
    box-sizing: border-box;
    position: relative;
    top: 0;
    margin: 0;
    padding: 0.1em;
    width: 100%;
    display: flex;
}

header > a {
    margin: auto;
    height: 2em;
    width: 2em;
}
a > img {
    height: 2em;
    width: 2em;
}

header > div#container {
    flex-grow: 1;
    display: flex;
    align-items: center;
    justify-content: end;
}

.big-button {
    height: 2em;
    min-width: 2em;
    margin: auto 0.1em;
    border: none;
    border-radius: 0.1em;
    background: linear-gradient(135deg, white, yellow);
}

.big-button:hover {
    background: linear-gradient(135deg, yellow, orange);
}

span#title {
    display: inline-block;
    font-size: 2em;
    font-weight: 600;
}

div#content {
    margin: 2em 1em;
    padding: 0.5em;
    background: white;
    height: 100%;
    border-radius: 1em;
    border: dimgrey 0.2em solid;
}