Datepicker comparison ranges uses substandard colors

### Describe the problem that you experienced

Up until V17 (excl.) the Datepicker Docs showed clear distinctions between the primary and accent colors, which made the example at the "Date range picker comparison ranges" section valuable. However, starting with the V17 docs (up until and including the current version), Angular Material started using Material 3 and some of the default themes (especially Azure & Blue) now don't show much of a color distinction (if at all), making the example barely useful with that respective color scheme.

Maybe it gets better with Material 3 Expressive, but I don't have particularly high hopes. Also, older versions will always have a docs page, still.

### Enter the URL of the topic with the problem

https://material.angular.dev/components/datepicker/overview

### Describe what you were looking for in the documentation

_No response_

### Describe the actions that led you to experience the problem

_No response_

### Describe what you want to experience that would fix the problem

More distinction between primary and accent colors, or actually custom defined colors for this example.

### Add a screenshot if that helps illustrate the problem

### If this problem caused an exception or error, please paste it here

```true

```

### If the problem is browser-specific, please specify the device, OS, browser, and version

```true

```

### Provide any additional information here in as much as detail as you can

```true

```

Apri la sezione «Date range picker comparison ranges» della panoramica del datepicker all’indirizzo material.angular.dev/components/datepicker/overview e confronta i colori primario e accent nei Material 3 themes attuali, in particolare Azure e Blue. Segui i punti di ingresso della documentazione e dello styling del theme dell’esempio, quindi verifica che i due intervalli siano visibilmente distinti nei themes documentati e che la documentazione delle versioni precedenti rimanga invariata.

Scritto dal modello di indicizzazione a partire dal testo della issue.