since the days of rudolph of habsburg and the 1283 treaty of rheinfelden, the combination of red-white-red was widely considered to be the austrian (later also inner-austrian) colours used by the ruling habsburg dynasty. black and yellow later became the family colours of the imperial house of habsburg, as they held the title of holy roman emperor over centuries and were themselves in part derived from the banner of the holy roman empire. the original form of this flag featured a yellow background with a black double-headed eagle. however, this proved to be a complicated design and was hard to reproduce. in the 18th century, the simpler form with the yellow and black bars started to appear in the habsburg monarchy. with the end of the holy roman empire in 1804, this flag was approved for use as a civil flag. the black-yellow flag was used in a way similar to a modern "national flag" of the austrian habsburg monarchy within the holy roman empire, the later austrian empire and the austrian part of austria-hungary, sometimes still even used for the entire empire, until 1918.