body {
    text-align: center;
    font-family: sans-serif;
    margin: 0;
    padding: 20px 0;
}

img {
    min-height: calc(80vw * (9 / 16)); /* should be around the height of the image */
    width: 80%;
}

input.url {
    width: 80%;
    padding: 5px;
    border: none;
    background-color: #ddd;
    text-align: center;
    box-sizing: border-box;
}

form {
    margin-top: 50px;
    width: 80%;
    text-align: center;
    display: inline-block;
}

form > textarea {
    width: 100%;
    height: 10vh;
    padding: 5px;
    box-sizing: border-box;
    resize: none;
}

form > input.submit {
    width: 100%;
    display: block;
    padding: 10px;
    background-color: #3070a0;
    border: 1px solid #275070;
    color: white;
    cursor: pointer;
    font-size: 18px;
}

form > input.submit:hover {
    background-color: #206090;
}
body {
    text-align: center;
    font-family: sans-serif;
    margin: 0;
    padding: 20px 0;
}

img {
    min-height: calc(80vw * (9 / 16)); /* should be around the height of the image */
    width: 80%;
}

input.url {
    width: 80%;
    padding: 15px;
    border: none;
    background-color: #ddd;
    text-align: center;
    box-sizing: border-box;
}

form {
    margin-top: 50px;
    width: 80%;
    text-align: center;
    display: inline-block;
}

form > textarea {
    width: 100%;
    height: 10vh;
    padding: 5px;
    box-sizing: border-box;
    resize: none;
}

form > input.submit {
    width: 100%;
    display: block;
    padding: 10px;
    background-color: #3070a0;
    border: 1px solid #275070;
    color: white;
    cursor: pointer;
    font-size: 18px;
}

form > input.submit:hover {
    background-color: #206090;
}
Add more padding around the image url
Add more padding around the image url

This makes it a little easier to copy text on mobile devices
