Support Matrix a11y tool

\begin{align} (x+1)^2 &\cssId{Step1}{= (x+1)(x+1)}\ &\cssId{Step2}{= x(x+1) + 1(x+1)}\ &\cssId{Step3}{= (x^2+x) + (x+1)}\ &\cssId{Step4}{= x^2 + (x + x) + 1}\ &\cssId{Step5}{= x^2+2x+1}\ \end{align}

\begin{array}{l}I=\int_0^R{\rho(r)r^2\hspace{0.2em}2\pi r\hspace{0.2em}dr\hspace{0.2em}L=\int_0^R{(\rho_0+\alpha r)r^2}}\hspace{0.2em}2\pi r\hspace{0.2em}dr\hspace{0.2em}L\\hspace{0.2em}\hspace{0.2em}=\frac12\rho_0\pi R^4L+\frac25\alpha\pi R^5L\end{array}