Observation Details
Text elements use px values for font-size, making it impossible to resize text to 200%.
E.g. the heading "Mehr Datenvolumen, gleicher Preis" starts with a font size of 43px (Viewport 1024×768px, Zoom 100%) and even gets smaller on larger viewports.
Remediation Notes
Text content must not use fixed px values for font sizes. Instead, use relative units (rem, em) to set font sizes.
Even better, evaluate the use of a responsive fluid type scale. More information about fluid type scales can be found at utopia.fyi.