Greater typeset structure can be gained by marking up the proof in more detail, if so desired.
A typical proof consists of individual lines. Each line is numbered, so we can refer to them later. The main "meat" of the line is the "proof step" and there is an optional comment. The proof comment is designed for a comment, to allow an input to ask a question or to act as the second column in a two column proof.
<divclass="proof-comment">Notice we have rearranged the algebra to give us the right hand side of \(P(n+1)\).</div>
</div>
<divclass="proof-line">
<divclass="proof-num">11.</div>
<divclass="proof-step">Hence \(P(n+1)\) is true.</div>
<divclass="proof-comment">This block is the conclusion of the proof.</div>
</div>
</div>
<divclass="proof-block">
<divclass="proof-line">
<divclass="proof-num">12.</div>
<divclass="proof-step">Since \(P(1)\)</span> and \(P(n)\Rightarrow P(n+1)\) it follows that \(P(n)\) is true for all \(n\in\mathbb{N}\) by the principal of mathematical induction.</div>
<divclass="proof-column-2">With further comments.</div>
</div>
<divclass="proof-line">
<divclass="proof-column">This concludes the proof.</div>
</div>
</div>
It is possible to use `proof-column-2` style in the first column, but this looks odd and is not recommended. The `proof-column-2` style is intended for only the second column. The `proof-column` style is intended to be used in both columns.
<divclass="proof-column-2">Notice we have rearranged the algebra to give us the right hand side of \(P(n+1)\).</div>
</div>
<divclass="proof-line">
<divclass="proof-num">11.</div>
<divclass="proof-column">Hence \(P(n+1)\) is true.</div>
<divclass="proof-column-2">This block is the conclusion of the proof.</div>
</div>
</div>
<divclass="proof-block">
<divclass="proof-line">
<divclass="proof-num">12.</div>
<divclass="proof-column">Since \(P(1)\)</span> and \(P(n)\Rightarrow P(n+1)\) it follows that \(P(n)\) is true for all \(n\in\mathbb{N}\) by the principal of mathematical induction.</div>