Table formatting breaks if output is piped

[patrislav1]

Describe the bug

Table formatting breaks when stdout is piped to a file or a program. glow seems to detect if stdout is connected to a tty, and leaves out some table formatting if it's not.

I would like to pipe glow output to tools like grep and fzf and still have the correct table formatting.

Setup
Please complete the following information along with version numbers, if applicable.

• OS [e.g. Ubuntu, macOS]: Ubuntu 22.04
• Shell [e.g. zsh, fish]: zsh
• Terminal Emulator [e.g. kitty, iterm]: kitty
• Terminal Multiplexer [e.g. tmux]: Bug reproduces both with and without tmux
• Locale [e.g. en_US.UTF-8, zh_CN.UTF-8, etc.]: en_US.UTF-8

To Reproduce
Steps to reproduce the behavior:

$ glow test.md                                     

                                                                                                                    
    FIRST COLUMN │ SECOND COLUMN                                                                                      
  ───────────────┼────────────────                                                                                    
    Foo          │ Bar                                                                                                
                 │ Baz                                                                                                

$ glow test.md | cat                               


FIRST COLUMN │ SECOND COLUMN
───────────────┼────────────────
Foo          │ Bar
│ Baz

$ socat - EXEC:'glow test.md',pty,setsid,ctty | cat

                                                                            
    FIRST COLUMN │ SECOND COLUMN                                              
  ───────────────┼────────────────                                            
    Foo          │ Bar                                                        
                 │ Baz                                                        

Source Code
Please include source code if needed to reproduce the behavior.

| First column | Second column |
|--------------|---------------|
| Foo          | Bar           |
|              | Baz           |

Expected behavior
Table formatting should be maintained regardless of TTY presence.

Screenshots

Additional context
N/A

[patrislav1]

PS.: After reading main.go it turns out that this bug can be mitigated with explicit style option (e.g. -s dark)

OTOH, it can be reproduced without piping, by selecting the "notty" style

$ glow -s notty test.md     


FIRST COLUMN │ SECOND COLUMN
───────────────┼────────────────
Foo          │ Bar
│ Baz