How to use newline within a table cell

Question

I have made a table with the following structure

\begin{center}
\begin{tabular}{ ||c|c|c|| } 
 \hline
 \textbf{Embedding} & {BiLSTM+attn} & {BiLSTM+CNN+attn} \\
 \hline
 BERT & 89.9\% & 89.8\% \\
 \hline
 DistilBERT & 89.6\% & 90.8\%  \\ 
 \hline
 RoBERTa & \textbf{90.5}\% & \textbf{90.8\% } \\ 
 \hline
\end{tabular}
\end{center}

With the output as this

The problem is it is getting overlapped with the right side column of paper. I also used the \\ command for newline but it is giving a totally distorted table.

I want the +attn in both the columns to appear below BiLSTM and BiLSTM+CNN respectively. But I can't find a way. Please help.

Answer 1

It’s easy peasy with tblr environment of tabularray package:

\documentclass{article}

\usepackage{tabularray}

\begin{document}

\begin{center}
\begin{tblr}{ ||c|c|c|| } 
 \hline
 \textbf{Embedding} & {BiLSTM\\+attn} & {BiLSTM+CNN\\+attn} \\
 \hline
 BERT & 89.9\% & 89.8\% \\
 \hline
 DistilBERT & 89.6\% & 90.8\%  \\ 
 \hline
 RoBERTa & \textbf{90.5}\% & \textbf{90.8\% } \\ 
 \hline
\end{tblr}
\end{center}

\end{document} 

Answer 2

You could just break the +attn into their own row.

\documentclass{article}

\begin{document}

\begin{center}
\begin{tabular}{ ||c|c|c|| } 
 \hline
 \textbf{Embedding} & {BiLSTM} & {BiLSTM+CNN} \\[-0.25ex]
                    &  +attn   &    +attn     \\
 \hline
 BERT & 89.9\% & 89.8\% \\
 \hline
 DistilBERT & 89.6\% & 90.8\%  \\ 
 \hline
 RoBERTa & \textbf{90.5}\% & \textbf{90.8\% } \\ 
 \hline
\end{tabular}
\end{center}

\end{document} 

Note that I added a small adjustment to pull the extra row up for better spacing.