html, body {
    margin: 0;
    padding: 0;
    height: 100vh;
    overflow: hidden;
}

body {
    background-image: url("background/background.png");
    background-position: center;
    background-size: cover;
    background-attachment: fixed;
}

#clockContainer {
    height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    position: relative;
}

#clock {
    font-family: monospace;
    font-size: 8em;
    font-weight: bold;
    text-align: center;
    color: white;
    backdrop-filter: blur(5px);
    background-color: hsla(175, 100%, 54%, 0.12);
    width: 100%;
    padding: 20px;
    box-sizing: border-box;
}

#toggleFormatBtn {
    position: absolute;
    top: 12px;
    left: 12px;
    font-size: 20px;
    font-weight: bold;
    background-color: rgba(0, 200, 255, 0.8);
    border: none;
    border-radius: 20px;
    padding: 10px 20px;
    cursor: pointer;
    z-index: 10;
}

#toggleFormatBtn:hover {
    background-color: rgba(0, 200, 255);
}

#toggleFormatBtn:active {
    transform: scale(0.98);
}

/* tablets */
@media screen and (max-width: 768px) {
    #clock {
        font-size: 4em;
        padding: 15px;
    }
    
    #toggleFormatBtn {
        font-size: 16px;
        padding: 8px 16px;
        top: 8px;
        left: 8px;
    }
}

/* mobiles */
@media screen and (max-width: 480px) {
    #clock {
        font-size: 3em;
        padding: 10px;
    }
    
    #toggleFormatBtn {
        font-size: 14px;
        padding: 6px 12px;
        top: 6px;
        left: 6px;
    }
}

/* small mobiles */
@media screen and (max-width: 320px) {
    #clock {
        font-size: 2em;
        padding: 8px;
    }
}