body {
    font-family: sans-serif;
    overflow-x: hidden;
}

a.corner:any-link {
    position: absolute;
    display: inline-block;
    width: 120px;
    line-height: 20px;
    right: -55px;
    top: 25px;
    color: #fff;
    text-decoration: none;
    font-weight: bold;
    padding: 10px 40px;
    transform: rotate(45deg);
    background: #888;
    text-align: center;
    font-size: 15px;
}

section {
    background: #eee;
    padding: 20px;
    width: 1600px;
    border-radius: 20px;
    margin-top: 20px;
    border: 2px solid;
    overflow-x: auto;
    width: 100%;
    box-sizing: border-box;
}

section.valid {
    color: green;
}

section.invalid {
    color: red;
}

h3 {
    margin: 0 0 10px 0;
    border-bottom: 3px solid #ccc;
    padding-bottom: 3px;
    margin-bottom: 10px;
}

#gadget {
    position: sticky;
    background: #fff;
    border: 1px solid #0004;
    border-radius: 10px;
    height: 30px;
    padding: 10px;
    line-height: 30px;
    top: 10px;
    margin: 10px;
    box-shadow: 0 1px 10px -8px #000;
}

#gadget > * {
    vertical-align: middle;
}

#gadget > :not(:last-child) {
    margin-right: 10px;
}