#container {
    width: 700px;
    height: 350px;
    border: solid 3px #FF0000;
    margin: auto;
    margin-top: 10%;
    position: relative;
}

h1 {
    display: inline-block;
    position: absolute;
    top: -41px;
    left: -3px;
    margin: 0;
    padding: 0;
    color: #FFFFFF;
    background-color: #FF0000;
    padding: 3px 10px 3px 10px;
    font-size: 28px;
}

form {
    width: 70%;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}
form input {
    display: block;
    width: 100%;
    box-sizing: border-box;
    margin-top: 5px;
    padding: 5px;
    font-size: 1em;
    border: solid 2px #A4A4A4;
}
form input[type="submit"] {
    width: auto;
    background-color: #FF0000;
    color: #FFFFFF;
    border: 0;
    margin-left: 0;
}