Faux bold / faux italic
Fake bold thickens a regular font; fake italic tilts it. Both happen when the real style is missing, and both distort the intended drawing.
See it
What it is
Faux bold and faux italic are styles a browser synthesizes when CSS asks for a face that was not loaded. Synthetic bold thickens the available outlines instead of using a weight drawn by the type designer. Synthetic italic slants the roman instead of switching to a real italic with redrawn forms. Photoshop is blunt enough to label the same trick honestly: its Character panel menu lists Faux Bold and Faux Italic as their own options, separate from the real styles in the font menu.
They can keep emphasis visible when a font file fails, but they are a poor production substitute. Faux bold can clog counters, flatten stroke contrast, and make punctuation too heavy. Faux italic preserves upright forms and spacing, so it looks pushed over rather than drawn for the angle.
Gotcha: declaring 'font-weight: 700' or 'font-style: italic' does not prove those faces exist. Load each required file or variable-font range through '@font-face', then use 'font-synthesis: none' to expose missing styles instead of letting the browser quietly manufacture them.
Ask AI for it
Audit this webfont setup for synthetic styles. Define separate '@font-face' sources for weights 400 and 700 and for 'font-style: normal' and 'font-style: italic', or declare the complete weight range of the variable font. Apply 'font-synthesis: none' to the specimen, then render regular, bold, italic, and bold italic. Report any style that falls back instead of loading its real face, and do not use CSS transforms or text shadows to imitate it.