body {
    display: flex;
    flex-direction: column;
    margin: 0;
    padding: 0;
    height: 100vh;
    display: flex;
    justify-content: center;  /* centers content vertically within the div */
    align-items: center;      /* centers content horizontally within the div */
}

#background_picture {
        position: fixed; /* Makes it stick to the screen */
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-size: cover;
        background-position: center;
        opacity: 0.6; /* 60% */
        z-index: -1; /* Pushes the image behind the main content */
    }

#app {
    display: flex;
    flex-direction: column;
    justify-content: center;  /* centers content vertically within the div */
    align-items: center;      /* centers content horizontally within the div */
    z-index: 1;
    background-color: whitesmoke;
    max-width: fit-content;
    border: 5px solid black;
    border-radius: 25px;
    padding: 20px;
    font-family: Verdana, Arial, sans-serif;
    font-weight: bold;
    font-size: 1vw;

}

#city_selector {
    text-align: center;
    font-size: 1.5vw

}


#app_button {
    font-size: 1.5vw;
    padding: 10px;
    border-radius: 15px;
    box-shadow: 5px 5px 5px black;

}

#app_button:hover {   /* Hover = The mouse is hovering over the link. */
    color: blue;
    box-shadow: 5px 5px 5px black;
    text-decoration: black;

}

#app_button:active { /* The link is being clicked (mousedown). */
    color: blue;
    box-shadow: 1px 1px 1px black;
    text-decoration: black;

}

/* ---- Media Queries ----------------------------------------------------------------------------------------------- */

 /* For small to large mobile screens. */
@media only screen and (min-width: 320px) and (max-width: 425px) {
    
    #app_button {
        font-size: 1.5vw;
        padding: 10px;
        border-radius: 15px;
        box-shadow: 5px 5px 5px black;
    }


}