html, body {
    height: 100%;
    margin: 0;
    padding: 0;
}

body {
    display: flex;
    align-items: center;
    justify-content: center;

    background-size: 200% 200%;
    background-image: repeating-linear-gradient(-45deg, black, black 20px, red 20px, red 40px);
    animation: scrollBackground 50s linear infinite;
}

@keyframes scrollBackground {
    0% {
        background-position: -100% 0;
    }
    100% {
        background-position: 100% 0;
    }
}

.container {
    border-radius: 10px;
    background-color: red;
    height: calc(100% - 50px);
    width: calc(100% - 50px);

    display: flex;
    justify-content: center;
    align-items: center;
	flex-direction: column;

    animation: changeColor 1s steps(1) infinite;
    text-transform: uppercase;
    text-align: center;
    font-size: 5rem;
    font-family: Arial, sans-serif;
    font-weight: bold;
}

.sub{
	font-size: 3rem;
}

@keyframes changeColor {
    0% {
        color: white;
        background-color: black;
    }
    50% {
        color: black;
        background-color: red;
    }
    100% {
        color: white;
        background-color: black;
    }
}