What are the reasons for the first and second civil wars in Rome?

In the first century BC. in the Roman Republic there were 2 civil wars. The first of these was for power between the supporters of the dictator Sulla, who wanted to limit the power of the Senate and rule arbitrarily, and the forces of Gaia Maria, who wanted to preserve the republican rule. The second war began almost 30 years later, when all the provinces of Rome were unofficially divided between three people, but Julius Caesar and Pompey the Great fought for absolute power. In the first, Sulla won, in the second – Caesar.