.form-select .dropdown-menu {
    margin-top: 10px;
    max-height: 274px;
    overflow-x: hidden;
    padding: 0.25rem 0;
    width: 100%;
}

.form-select .dropdown-menu-arrow {
    width: 0;
    height: 0;
    border-width: 0 6px 6px;
    border-style: solid;
    border-color: transparent transparent rgba(0,0,0,.15);
    position: absolute;
    left: 20px;
    margin-top: 4px;
    z-index: 1001;
    display: none;
}

    .form-select .dropdown-menu-arrow:after {
        content: " ";
        width: 0;
        height: 0;
        border-width: 0 6px 6px;
        border-style: solid;
        border-color: transparent transparent #fff;
        position: absolute;
        top: 1px;
        left: -6px;
    }

.form-select .form-select-input[readonly] {
    background-color: #fff;
}

.form-select.show .dropdown-menu-arrow {
    display: block;
}

.form-select.show .form-select-append i {
    transform: rotate(0);
}

.form-select.is-disabled .form-select-input {
    background-color: #f5f7fa;
    border-color: #e4e7ed;
    color: #c0c4cc;
    cursor: not-allowed;
}

.form-select.is-disabled .form-select-append {
    color: #c0c4cc;
}

.form-select-input {
    color: #606266;
    outline: none;
    padding-right: 30px;
    cursor: pointer;
}

    .form-select-input:hover, .form-select-input:focus {
        border-color: #c0c4cc;
    }

    .form-select-input:focus {
        box-shadow: none;
    }

    .form-select-input.border-primary:hover {
        box-shadow: inset 0 1px 1px rgba(0,0,0,.075), 0 0 8px rgba(102,175,233,.6);
    }

    .form-select-input.border-info:hover {
        box-shadow: inset 0 1px 1px rgba(0,0,0,.075), 0 0 8px rgba(23, 162, 184, 0.5);
    }

    .form-select-input.border-success:hover {
        box-shadow: inset 0 1px 1px rgba(0,0,0,.075), 0 0 8px rgba(40, 167, 69, 0.5);
    }

    .form-select-input.border-warning:hover {
        box-shadow: inset 0 1px 1px rgba(0,0,0,.075), 0 0 8px rgba(255, 193, 7, 0.5);
    }

    .form-select-input.border-danger:hover {
        box-shadow: inset 0 1px 1px rgba(0,0,0,.075), 0 0 8px rgba(220, 53, 69, 0.5);
    }

    .form-select-input.is-valid, .form-select-input.is-invalid {
        background-image: none;
    }

        .form-select-input.is-invalid:hover {
            border-color: #dc3545;
        }

        .form-select-input.is-invalid + .form-select-append {
            color: #dc3545;
        }

        .form-select-input.is-valid:hover {
            border-color: #28a745;
        }

        .form-select-input.is-valid + .form-select-append {
            color: #28a745;
        }

.form-select-append {
    position: absolute;
    height: 100%;
    width: 30px;
    right: 0;
    top: 0;
    color: #c0c4cc;
    pointer-events: none;
    display: flex;
    align-items: center;
    justify-content: center;
}

    .form-select-append i {
        transition: all .3s;
        transform: rotate(180deg);
    }