* {
    margin: 0;
    padding: 0;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-repeat: no-repeat;
    background-position: 50% 100%;
    background-size: cover;
    overflow: hidden;
    font-family: Arial, Helvetica, sans-serif;
}

#clock-container {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    width: 50%;
    height: 25%;
    background-color: hsla(0, 0%, 90%, 0.5);
    backdrop-filter: blur(5px);
    border-radius: 10px;
}

#city-selector {
    /* styling */
    background-color: hsla(0, 0%, 75%, 0.6);
    color: rgb(0, 0, 0);
    border: none;
    border-radius: 4px;
    display: inline-block;
    font-size: 2rem;
    line-height: 1.5em;
    padding: 0.1em 3em 0.1em 1em;
    text-align: center;

    /* reset */
    margin: 0;
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
    appearance: none;
    -webkit-appearance: none;
    -moz-appearance: none;

    /* arrows */
    background-image:
        linear-gradient(45deg, transparent 50%, hsl(0, 0%, 35%) 50%),
        linear-gradient(135deg, hsl(0, 0%, 35%) 50%, transparent 50%),
        linear-gradient(to right, hsla(0, 0%, 69%, 0.7), hsla(0, 0%, 69%, 0.7));
    background-position:
        calc(100% - 31px) calc(1em + -7px),
        calc(100% - 21px) calc(1em + -7px),
        100% 0;
    background-size:
        10px 10px,
        10px 10px,
        2em 2em;
    background-repeat: no-repeat;
}

#city-selector.active {
    background-image:
    linear-gradient(135deg, transparent 50%, hsl(0, 0%, 35%) 50%),
    linear-gradient(45deg, hsl(0, 0%, 35%) 50%, transparent 50%),
    linear-gradient(to right, hsla(0, 0%, 69%, 0.7), hsla(0, 0%, 69%, 0.7));
    background-position:
        calc(100% - 31px) calc(1em + -7px),
        calc(100% - 21px) calc(1em + -7px),
        100% 0;
    background-size:
        10px 10px,
        10px 10px,
        2em 2em;
    background-repeat: no-repeat;
    
}

#city-selector:focus{
    outline: 0;
}

#date {
    margin-top: 25px;
    font-size: 2.5rem;
}

#clock {
    font-size: 4rem;
}

@media screen and (max-width: 650px) {
    #clock-container {
        width: 100%;
    }
}

@media screen and (max-width: 400px) {
    #city-selector{
        font-size: 1.7rem;
    }
    #date {
        font-size: 2rem;
    }
    #clock {
        font-size: 3.5rem;
    }
}

@media screen and (max-width: 320px) {
    #date {
        font-size: 1.5rem;
    }

    #clock {
        font-size: 3rem;
    }
}