Comparative and superlative

What are the rules?
| comparative | superlative | |
| 1 syllable high hot (consonant-vowel-consonant) double last consonant | higher hotter | the highest the hottest |
| 2 syllables -y happy | happier | the happiest |
| 2 syllables modern | more modern | the most modern |
| 3 or 4 syllables dangerous | more dangerous | the most dangerous |
Let’s not forget the irregular forms.
| adjective | comparative | superlative |
| good | better | the best |
| bad | worse | the worst |
| far | farther/further | the farthest/furthest |