.noi-dung-thu-gon-inner {
    overflow: hidden;
    position: relative;
    transition: max-height 0.4s ease;
}

.noi-dung-thu-gon:not(.expanded) .noi-dung-thu-gon-inner {
    max-height: 200px; /* Chiều cao thu gọn */
}

.noi-dung-thu-gon:not(.expanded) .noi-dung-thu-gon-inner::after {
    content: "";
    position: absolute;
    left: 0;
    bottom: 0;
    width: 100%;
    height: 150px;
    background: linear-gradient(to bottom, transparent 10%, var(--container-bg, #fff) 100%);
    pointer-events: none;
    transition: opacity 0.4s ease;
    opacity: 1;
}

/* Khi container mở rộng */
.noi-dung-thu-gon.expanded .noi-dung-thu-gon-inner::after {
    opacity: 0;
}

/* Khi nội dung không vượt quá chiều cao collapse, ẩn pseudo-element */
.noi-dung-thu-gon.not-overflow .noi-dung-thu-gon-inner::after {
    display: none;
}

.readmore-button {
    display: none;
    margin: -20px auto 0 auto;
    animation: updown 2s ease infinite;
    cursor: pointer;
    height: 30px;
    width: 40px;
    padding: 5px;
    background: #ffffff;
    border-radius: 10px;
    text-align: center;
}

@keyframes updown {
    0% { transform: translateY(-30%); }
    50% { transform: translateY(30%); }
    100% { transform: translateY(-30%); }
}