.theorem {

    display: block;

    margin: 12px 0;

    font-style: italic;

}

.theorem:before {

    content: "Theorem.";

    font-weight: bold;

    font-style: normal;

}

.lemma {

    display: block;

    margin: 12px 0;

    font-style: italic;

}

.lemma:before {

    content: "Lemma.";

    font-weight: bold;

    font-style: normal;

}

.proof {

    display: block;

    margin: 12px 0;

    font-style: normal;

}

.proof:before {

    content: "Proof.";

    font-style: italic;

}

.proof:after {

    content: "\25FC";

    float:right;

}

.definition {

    display: block;

    margin: 12px 0;

    font-style: normal;

}

.definition:before {

    content: "Definition.";

    font-weight: bold;

    font-style: normal;

}