.rectangle {
    width: 200px;
    height: 100px;
    background-color: lightblue;
    border: 2px solid blue;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.triangle-down {
    width: 0;
    height: 0;
    border-top: 100px solid transparent;
    border-left: 50px solid transparent;
    border-right: 50px solid transparent;
}