.letter-header {
    cursor: pointer;
    padding: 10px;
    background: #3a5371 !important;
    color: #fff;
    width: 100%;
    text-align: left;
    font-weight: bold;
    border-top: 0;
        border-left: 0;
            border-right: 0;
    border-bottom: 1px solid #a0a0a0;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.letter-header:hover {
    background: #000000;
}

.letter-list {
    display: none;
    margin: 0;
    padding: 0 15px;
    list-style: none;
    background: transparent;
}

.letter-list li {
    padding: 8px 0;
    border-bottom: 1px solid #ddd;
}