.theorem {
    display: block;
    margin: 12px 0;
    font-style: italic;
    content: "Theorem. ";
}
.theorem:before {
    content: inherit;
    font-weight: bold;
    font-style: normal;
}

.lemma {
    display: block;
    margin: 12px 0;
    font-style: italic;
    content: "Lemma. ";
}
.lemma:before {
    font-weight: bold;
    font-style: normal;
    content: inherit;
}

.proof {
    display: block;
    margin: 12px 0;
    font-style: normal;
    content: "Proof. ";
}
.proof:before {
    content: inherit;
    font-style: italic;
}
.proof:after {
    content: "\25FC";
    float:right;
}

.definition {
    display: block;
    margin: 12px 0;
    font-style: normal;
    content: "Definition. ";
}
.definition:before {
    content: inherit;
    font-weight: bold;
    font-style: normal;
}

.example {
    display: block;
    margin: 12px 0;
    font-style: normal;
    content: "Example. ";
}

.example:before {
    content: inherit;
    font-weight: bold;
    font-style: normal;
}