Edit in JSFiddle

<table class="mod-table-01 mod-table-01--line-color-green">
    <tr>
        <th>foo</th>
        <th>bar</th>
    </tr>
    <tr>
        <td>baz</td>
        <td>foobar</td>
    </tr>
</table>

<table class="mod-table-02--line-color-green">
    <tr>
        <th>foo</th>
        <th>bar</th>
    </tr>
    <tr>
        <td>baz</td>
        <td>foobar</td>
    </tr>
</table>

/* multiple class (503 byte), full-width=2byte, half-width=1byte, break=2byte */
.mod-table-01 {
    border: 1px solid black;
    border-collapse: collapse;
    margin: 10px auto;
}

.mod-table-01 th,
.mod-table-01 td {
    padding: 5px;
    border: 1px solid black;
}

.mod-table-01 th {
    font-weight: bold;
}

.mod-table-01--line-color-green {
    border: 1px solid green;  
}

.mod-table-01--line-color-green th,
.mod-table-01--line-color-green td {
    border: 1px solid green;
}

.mod-table-01--line-color-green th {
    background-color: #01ff70;
}

/* single class (648 byte), full-width=2byte, half-width=1byte, break=2byte */
.mod-table-02,
.mod-table-02--line-color-green {
    border: 1px solid black;
    border-collapse: collapse;
    margin: 10px auto;
}

.mod-table-02 th,
.mod-table-02--line-color-green th,
.mod-table-02 td,
.mod-table-02--line-color-green td {
    padding: 5px;
    border: 1px solid black;
}

.mod-table-02 th,
.mod-table-02--line-color-green th {
    font-weight: bold;
}

.mod-table-02--line-color-green {
    border: 1px solid green;  
}

.mod-table-02--line-color-green th,
.mod-table-02--line-color-green td {
    border: 1px solid green;
}

.mod-table-02--line-color-green th {
    background-color: #01ff70;
}