在模态窗口中滚动而不消失效果

body {
    background-color: #16171b;
    margin: 0;
    padding: 0;
}

.container-modal-window-easy-difficult {
    position: absolute;
    top: 190px;
    left: 600px;
}

@property --gradient-angle {
    syntax: "<angle>";
    initial-value: 0deg;
    inherits: false;
}

:root {
    --clr-1: #052b2f;
    --clr-2: #073438;
    --clr-3: #0e4b50;
    --clr-4: #2d578f;
    --clr-5: #0038ad;
}

.modal-window-easy-difficult{
    height: 500px;
    width: 700px;
    background: var(--clr-1);
    border-radius: 0.5rem;

    position: relative;
    /*overflow-y: scroll;*/
}

.modal-window-easy-difficult::before,
.modal-window-easy-difficult::after {
    content: "";
    position: absolute;
    inset: -0.5rem;
    z-index: -1;
    background: conic-gradient(
            from var(--gradient-angle),
            var(--clr-3),
            var(--clr-4),
            var(--clr-5),
            var(--clr-4),
            var(--clr-3)
    );
    border-radius: inherit;
    animation: rotation 5s linear infinite;
}

.modal-window-easy-difficult::after {
    filter: blur(3.5rem);
}

@keyframes rotation {
    0% {
        --gradient-angle: 0deg;
    }
    100% {
        --gradient-angle: 360deg;
    }
}

/* SCROLLBAR */
::-webkit-scrollbar {
    background-color: #0e4b50;
    width: 7px;
}

::-webkit-scrollbar-thumb {
    background-color: #0038ad;
}

/* CONTENT */
.header-easy-difficult {
    display: flex;
    flex-direction: row;
    justify-content: center;
    padding-top: 10px;
    width: 100%;
    height: 40px;

    font-size: 30px;
    color: #0038ad;
    font-weight: bold;
    font-family: 'Kanit', sans-serif;
    letter-spacing: .1em;
    filter: brightness(300%);

    user-select: none;
}


.text-modal-window-easy-difficult {
    padding: 10px 15px 15px;

    font-family: 'Montserrat', sans-serif;
    font-size: 16px;
    color: #c1c1c1;;
    font-weight: bold;
    text-align: justify;
}

/* BUTTON CLOSE */
.container-btn {
    display: flex;
    justify-content: space-around;
    align-items: center;
    max-height: 100px;
    padding-top: 20px;
    font-family: 'Raleway', sans-serif;
}

.close-btn{
    height: 50px;
    width: 100px;
    background-color: #050801;
    color: #03e9f4;
    font-weight: bold;
    border: none;
    border-radius: 5px;
    letter-spacing: 4px;
    overflow: hidden;
    transition: 0.5s;
    cursor: pointer;
}

.close-btn:hover{
    background: #03e9f4;
    color: #050801;
    box-shadow: 0 0 5px #03e9f4,
    0 0 25px red,
    0 0 25px darkred;
    /*0 0 25px #03e9f4;*/
    /*0 0 50px #03e9f4,*/
    /*0 0 200px #03e9f4;*/
    -webkit-box-reflect:below 1px linear-gradient(transparent, #0005);
}

/* BUTTON NEXT */
.next-btn{
    height: 50px;
    width: 100px;
    background-color: #050801;
    color: #03e9f4;
    font-weight: bold;
    border: none;
    border-radius: 5px;
    letter-spacing: 4px;
    overflow: hidden;
    transition: 0.5s;
    cursor: pointer;
}

.next-btn:hover{
    background: #03e9f4;
    color: #050801;
    box-shadow: 0 0 5px #03e9f4,
    0 0 25px #03e9f4,
    0 0 25px #03e9f4;
    /*0 0 50px #03e9f4,*/
    /*0 0 200px #03e9f4;*/
    -webkit-box-reflect:below 1px linear-gradient(transparent, #0005);
}

/* ---> my css below <--- */

.modal-content {
    overflow-y: auto;
    max-height: 100%;
}

.container-btn {
    margin-bottom: 50px;
}

<div class="container-modal-window-easy-difficult">
    <div class="modal-window-easy-difficult">
        <div class="modal-content">
            <div class="header-easy-difficult">EASY</div>
            <div class="content-wrapper">
                <div class="text-modal-window-easy-difficult">
                    The Easy difficulty level on our website is the perfect starting point for those who are just
                    beginning
                    their journey into the world of tasks and challenges. Here, you will find puzzles and tasks that
                    provide an
                    inspiring challenge but won't be overly difficult. With this level of difficulty, you can
                    familiarize
                    yourself with basic concepts and patterns, which will gradually help you develop your skills and
                    move on to
                    more serious challenges. Raise the bar of your knowledge with ease and confidence as you prepare for
                    more
                    complex trials ahead.
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                    corrupti, porro explicabo impedit ad.
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                    quo repellat amet dolorem, nulla, ducimus enim animi vel dicta corporis. Sequi saepe aliquam
                    repellendus.
                    Qui, iste exercitationem, explicabo ab sequi ex odio ipsum hic deleniti soluta quibusdam officia
                    voluptas tempore. Quo cum doloribus assumenda reiciendis, dignissimos, ex necessitatibus nesciunt,
                    inventore totam dolorem numquam excepturi?
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                    quae, quia a, mollitia non unde recusandae? Adipisci incidunt placeat dicta esse hic. Hic, rem?
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                    voluptatem minus.
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                    perferendis dignissimos omnis quibusdam reprehenderit aperiam nemo sunt assumenda iure sequi impedit
                    porro consequatur fuga inventore? Eveniet, culpa.
                </div>
            </div>
            <div class="container-btn">
                <button class="close-btn">CLOSE</button>
                <button class="next-btn">NEXT</button>
            </div>
        </div>
    </div>
</div>