.weekly-challenge {
    background: #c3f5d3;
    border: 1px solid #ddd;
    border-left: 5px solid #2d7d46;
    padding: 20px;
    margin: 25px 0;
    border-radius: 6px;
}

    .weekly-challenge h2 {
        margin-top: 0;
        color: #2d7d46;
    }

.challenge-description {
    font-size: 1.1em;
    line-height: 1.6;
}

.challenge-rules {

}

.challenge-dates {
    color: #666;
    margin-top: 15px;
    font-size: .95em;
}