A basic PHP/MySQL powered forum system

A basic PHP/MySQL powered forum system with a minimal storage footprint.
Test out or discuss Agora forum here: https://agora.evalyn.app/
This is a reference of the currently implemented bbcode tags. This list should be incorporated into a help menu within Agora itself at some point.
[i][/i] - Inner text is italisized.[b][/b] - Inner text is bolded.[u][/u] - Inner text is underlined.[s][/s] - Inner text is crossed out.[color=CSScolor][/color] - Inner text has the specified CSS color applied to it (CSS colors are things like "Red", "Green" "#EEFF33", "rgba(125, 255, 120, 0.8)", "transparent", etc.).[size=fontsize][/size] - Sets the text size to a certain size specified (fontsize is just a number with a unit like 'pt' appended. "20pt", "15px", "2em", etc. are all valid).[url=URL][/url] - Makes the inner elements a link to the specified URL.[iurl=URL][/iurl] - Inline link. Like the previous tag except that the link opens in the same page. Useful for anchor links.[anchor=pageanchor] - Creates a page anchor of the specified name. Refer to one in a link (ie. "[iurl=#pageanchor]click to scroll to the anchor[/iurl]") to create links that navigate to specific parts of the post.[abbr=Text][/abbr] - Inner elements show Text when the mouse is hovered over it.[center][/center] - Inner elements are centered on the page.[left][/left] - Inner elements are aligned to the left of the page.[right][/right] - Inner elements are aligned to the right of the page.[just][/just] - Inner text is justified.[tt][/tt] - Sets a monospace font. (Tag name stands for TeleType)[pre][/pre] - Preformatted text, fully preserves text spacing and sets a monospace font.[code][/code] - Indicates a block of code, sets a monospace font and preserves spacing.[quote Name][/quote] - Creates a blockquote of inner text from Name.[table][/table] - Defines a table. Optional: Add 'border' as a tag argument to create a bordered table.[tr][/tr] - Table row. Must be a child of table.[td][/td] - Table column. Must be a child of tr.[img][/img] - Embeds an image from the url specified by the inner text.[audio][/audio] - Embeds HTML5 audio from the url specified by the inner text. This must link directly to the audio file, much like an img tag.[video][/video] - Embeds an HTML5 video from the url specified by the inner text. This must link directly to the video file, much like the img tag.[youtube][/youtube] - Embeds a video from Youtube using the youtube url specified by the inner text.[vimeo][/vimeo] - Embeds a video from Vimeo using the vimeo url specified by the inner text.[hr] - Creates a horizontal line.[nobbc][/nobbc] - The BBCode parser will skip parsing all text within these tags.[noparse][/noparse] - Alias of [nobbc].