...
* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
    font-family: Arial, Helvetica, sans-serif;
}

body {
    transition: background .5s;
}

.wrapper {
    width: 100%;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.wrapper .container {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    width: 300px;
    border-radius: 15px;
    background: #fff;
    padding: 15px;
    box-shadow: 0px 0px 15px rgba(0, 0, 0, 0.15);
}

.container .content {
    display: flex;
    margin: 15px 0;
}

.content #color_code {
    font-size: 1rem;
    margin-right: 20px;
}

.content i {
    font-size: 18px;
    cursor: pointer;
}

#btn {
    display: block;
    background: #cb5eb1;
    color: #fff;
    width: 100%;
    border: 0;
    outline: none;
    border-radius: 10px;
    padding: 10px;
    cursor: pointer;
}
...