selection.css

#categoryDiv {
    display: flex;
    width: 80%;
    margin: auto;
    margin-top: 20px;
    overflow: hidden;
    overflow-x: scroll;
    border: none;
    border-bottom: 1px solid rgba(128, 128, 128, 0.345);
    /* border: 2px solid gray; */
}

#categoryDiv::-webkit-scrollbar {
    display: none;
}

.category-item {
    margin-left: 35px;
    cursor: pointer;
    font-size: 17px;
    font-weight: 600;
    padding-bottom: 12px;
    position: relative;
    top: 2px;
}

#plus-icon {
    margin-right: -15px;
    font-size: 20px;
    cursor: pointer;
}

.switch {
    display: inline-block;
    background-color: gray;
    height: 32px;
    width: 55px;
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: flex-start;
    cursor: pointer;
}

.switch>div {
    background-color: white;
    height: 20px;
    width: 20px;
    border-radius: 50%;
    margin-left: 7px;
    transition: 0.2s ease-in-out;
}

.categoryDivToggle {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-top: 20px;
}

.categoryDivToggle>div {
    margin-left: 20px;
    font-size: 22px;
    font-weight: 600;
    letter-spacing: 0.3px;
}

#categorySelectionBox {
    width: 30%;
    height: 600px;
    border: 1px solid rgba(128, 128, 128, 0.395);
    background-color: white;
    border-radius: 9px;
    padding: 15px 45px 20px 45px;
    overflow: hidden;
    overflow-y: scroll;
    display: none;
    position: fixed;
    left: calc((100vw - 347px)/2);
    top: calc((90vh - 500px)/2);
    z-index: 3;
}

#saveBtn {
    margin: auto;
    margin-top: 30px;
    width: 80%;
    display: block;
}