How I can enable i3-gaps?

I started to use i3 and I love it so far, and then I tried to enable i3-gaps on i3 but when I tried to enable it I receive this error I don't understand at all...

ERROR: CONFIG: (in file /home/$USER/.config/i3/config)
ERROR: CONFIG: Line 214: # Gaps
ERROR: CONFIG: Line 215: for_window [class="^.*"] border pixel 2
ERROR: CONFIG: Line 216: gaps inner 10
ERROR: CONFIG:           ^^^^^^^^^^^^^
ERROR: CONFIG: Line 217: gaps outer 10
ERROR: CONFIG: Line 218: 
ERROR: CONFIG: Expected one of these tokens: <end>, '#', 'set ', 'set   ', 'set_from_resource', 'include', 'bindsym', 'bindcode', 'bind', 'bar', 'font', 'mode', 'floating_minimum_size', 'floating_maximum_size', 'floating_modifier', 'default_orientation', 'workspace_layout', 'default_border', 'new_window', 'default_floating_border', 'new_float', 'hide_edge_borders', 'for_window', 'assign', 'no_focus', 'focus_follows_mouse', 'mouse_warping', 'focus_wrapping', 'force_focus_wrapping', 'force_xinerama', 'force-xinerama', 'disable_randr15', 'disable-randr15', 'workspace_auto_back_and_forth', 'fake_outputs', 'fake-outputs', 'force_display_urgency_hint', 'focus_on_window_activation', 'title_align', 'show_marks', 'workspace', 'ipc_socket', 'ipc-socket', 'ipc_kill_timeout', 'restart_state', 'popup_during_fullscreen', 'exec_always', 'exec', 'client.background', 'client.focused_inactive', 'client.focused', 'client.unfocused', 'client.urgent', 'client.placeholder'
ERROR: CONFIG: (in file /home/$USER/.config/i3/config)
ERROR: CONFIG: Line 215: for_window [class="^.*"] border pixel 2
ERROR: CONFIG: Line 216: gaps inner 10
ERROR: CONFIG: Line 217: gaps outer 10
ERROR: CONFIG:           ^^^^^^^^^^^^^
ERROR: CONFIG: Line 218: 
ERROR: FYI: You are using i3 version 4.20.1 (2021-11-03)

According to Debian i3 wiki, you just need to add 'gaps inner 10' to your config file to make it work, but I do exactly that and it didn't work, I receive the same exact message.