/* Global Variables */
:root {
    --accent-color: #433D8B;
    --font-color: #C8ACD6;
    --primary-color: #17153B;
    --secondary-color: #2E236C;
}

/* RESET */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html, body {
    background-color: black;
    height: 100%;
    overflow: hidden;
    width: 100vw;
}

/* Background Image Container */
.bg-img-container {
    animation: bg-scroll 20s linear infinite, opacity-control 4s linear infinite alternate;
    height: 300vh;
    left: 0;
    position: relative;
    width: 100%;
}

/* Background Image */
.bg-img {
    height: 100vh;
    margin: 0;
    padding: 0;
    position: relative;
    width: 100vw;
}

/* Animation for the background image */
@keyframes bg-scroll {
    from {
        top: 0;
    }
    to {
        top: -100.2vh;
    }
}

@keyframes opacity-control {
    from {
        opacity: 1;
    }

    to {
        opacity: 0.4;
    }
}

/* Button for viewing earth's orbit/animation */
#action-btn {
    background-color: var(--primary-color);
    border: none;
    border-radius: 0;
    box-shadow: 5px 5px var(--secondary-color);
    color: var(--font-color);
    cursor: pointer;
    height: 80px;
    font-family: 'Courier New', Courier, monospace;
    font-size: 1.6rem;
    font-weight: 500;
    left: 50%;
    margin: -40px -160px;
    position: absolute;
    top: 50%;
    transition: all 0.1s;
    width: 320px;
    z-index: 1;
}

/* The button grows when hovering */
#action-btn:hover {
    transform: scale(1.1);
}

/* The button shrinks and changes color when clicked */
#action-btn:active {
    background-color: var(--accent-color);
    transform: scale(1);
}

/* A class to hide the action button */
.hidden-btn {
    animation: hide-btn 1.5s ease forwards;
}

@keyframes hide-btn {
    to {
        transform: scale(0.05);
        visibility: hidden;
    }
}

.hidden {
    display: none;
}

/* Styles for the sun that is a div */
#sun {
    animation: glowing-sun 1s linear infinite alternate;
    background-image: radial-gradient(rgb(255, 50, 50), orange);
    border-radius: 50%;
    box-shadow: 0 0 50px orange;
    height: 200px;
    left: 50%;
    margin: -100px;
    position: absolute;
    top: 50%;
    width: 200px;
}

@keyframes glowing-sun {
    from {
        box-shadow: 0 0 50px orange;
    }

    to {
        box-shadow: 0 0 30px orange;
    }
}

/* Styles for the earths orbit so that the earth can rotate correctly around the sun */
#earths-orbit {
    animation: revolving-earth 50s linear infinite;
    border-radius: 50%;
    height: 850px;
    left: 50%;
    margin: -425px -350px;
    position: absolute;
    top: 50%;
    width: 700px;
}

@keyframes revolving-earth {
    to {
        transform: rotate(-360deg);
    }
}

/* Styles for the earth image */
#earth {
    animation: rotate-earth 10s linear infinite;
    position: absolute;
    top: 50%;
    width: 80px;
}

@keyframes rotate-earth {
    to {
        transform: rotate(-360deg);
    }
}

/* Styles for the moons orbit */
#moons-orbit {
    animation: revolving-moon 6s linear infinite;
    border-radius: 50%;
    height: 120px;
    margin: -3%;
    position: absolute;
    top: 50%;
    width: 120px;
}

@keyframes revolving-moon {
    to {
        transform: rotate(-360deg);
    }
}

#moon {
    animation: rotate-moon 8s linear infinite;
    margin: -8%;
    position: absolute;
    width: 30px;
}

@keyframes rotate-moon {
    to {
        transform: rotate(360deg);
    }
}

#copyright {
    bottom: 0;
    color: white;
    font-size: 1.1rem;
    padding-bottom: 1rem;
    position: absolute;
    text-align: center;
    width: 100vw;
    z-index: 3;
}

.copyright-link {
    color: white;
    transition: all 0.2s;
}

.copyright-link:hover {
    color: var(--accent-color);
}

@media screen and (max-width: 850px) {
    #sun {
        height: 80px;
        margin: -40px;
        width: 80px;
    }

    #earths-orbit {
        height: 300px;
        margin: -150px -125px;
        width: 250px;
    }

    #earth {
        width: 40px;
    }

    #moons-orbit {
        height: 70px;
        margin: -7%;
        width: 70px;
    }

    #moon {
        width: 20px;
    }
}

@media screen and (max-width: 380px) {
    #action-btn {
        font-size: 1.2rem;
        margin: -40px -125px;
        width: 250px;
    }
}