html {
    background: #557680;
}

body {
    margin:0;
    font-size: 18px;
    font-family: 'Rubik', sans-serif;
}

.container {
    display: flex;
    justify-content: center;
    width: 720px;
    margin: auto;
}

.header {
    background: #2F6E80;
}

.header .container {
    display: block;
    text-align: center;
    padding: 25px 0 35px;
}

.header h1 {
    font-size: 50px;
    margin-bottom: 10px;
}

.r {color: red;}
.g {color: green;}
.b {color: blue;}

#rgb {
    font-size: 24px;
}

.options {
    background: #fff;
}

.options .container {
    justify-content: space-between;
    padding: 10px 0;
}

#reset {
    cursor: pointer;
}

.dificult span {
    padding: 0 5px;
    cursor: pointer;
}

input {
    opacity: 0;
}

label {
    cursor: pointer;
}

.items .container{
    flex-wrap: wrap;
    justify-content: space-between;
    padding: 40px 10px;
}

.item {
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    width: 200px;
    height: 200px;
    margin-bottom: 35px;
    border: 2px solid #383838;
    border-radius: 20px;
    cursor: pointer;
    transition: .3s;
}

.item img {
    opacity: 0;
}

.item .correct,
.item .incorrect {
    position: absolute;
    opacity: 1;
    transition: .3s;
}


@media (max-width: 750px) {
  
    .container {
        width: 100%;
    }

    .item {
        width: 80px;
        height: 80px;
        margin-bottom: 25px;
    }

    .items .container {
        box-sizing: border-box;
    }

    .item img {
        width: 35px;
        height: auto;
    }

    .options {
        font-size: 12px;
    }

    input {
        width: 1px;
        height: 1px;
        position: absolute;
    }

    .items .container {
        justify-content: space-around;
    }

}