.research-section {
    padding: 4rem 0;
}

.dropdown-toggle-custom {
    background-color: #0f253d;
    color: #ffffff;
    border: none;
    border-radius: 8px;
    padding: 0.8rem 1.5rem;
    font-size: 1.1rem;
    display: inline-flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    transition: background-color 0.3s ease;
    position: relative;
    z-index: 9;
    margin: 2rem 0 1rem 0;
}

    .dropdown-toggle-custom:hover,
    .dropdown-toggle-custom:focus {
        background-color: #0f253d;
        color: #ffffff;
        box-shadow: none;
    }

    .dropdown-toggle-custom i {
        margin-left: 1rem;
        transition: transform 0.3s ease;
    }

    .dropdown-toggle-custom[aria-expanded="true"] i {
        transform: rotate(-180deg);
    }

.dropdown-menu-custom {
    background-color: #ffffff;
    border-radius: 8px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    padding: 0;
    border: none;
    transform-origin: top center;
    z-index: 9;
    overflow: hidden;
    width: calc(100% - 1.5rem);
}

.dropdown-menu[data-bs-popper] {
    top: calc(100% + 0.5rem) !important;
    left: 0 !important;
    margin-top: 0 !important;
}

.dropdown-item-custom {
    color: #0f253d;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
}

    .dropdown-item-custom:hover,
    .dropdown-item-custom:focus {
        background-color: #0f253d;
        color: #ffffff;
    }

    .dropdown-item-custom.active {
        background-color: #0f253d;
        color: #ffffff;
    }

.card-grid2 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    max-width: 1200px;
    margin: 0 auto;
    padding-bottom: 30px;
}

.video-section {
    padding: 4rem 0;
}

    .video-section h2 {
        padding: 0 0 2rem 0;
    }

.year-filter-bar {
    background-color: #ffffff;
    border-radius: 8px;
    padding: 0.5rem;
    margin-bottom: 3rem;
}

    .year-filter-bar .year-link {
        display: inline-block;
        color: #0f253d;
        font-size: 1rem;
        padding: 0.5rem 1rem;
        text-decoration: none;
        transition: all 0.3s ease;
    }

        .year-filter-bar .year-link:hover,
        .year-filter-bar .year-link.active {
            color: #0f253d;
        }

        .year-filter-bar .year-link.active {
            text-decoration: underline;
            text-underline-offset: 8px;
            text-decoration-thickness: 1px;
        }

@media (max-width: 575px) {
    .research-section,
    .video-section {
        padding: 30px 0;
    }
}