Go to the App Store and search for "video DVD". You'll get a number of potential candidates, some free. I recommend you get one that can save the project as a disk image so you canfollow this workflow to help assure the best qualty video DVD:
Once you have the project as you want it save it as a disk image via the File ➙ Save as Disk Image menu option. This will separate the encoding process from the burn process.
To check the encoding mount the disk image, launch DVD Player and play it. If it plays OK with DVD Player the encoding is good.
Then burn to disk with Disk Utility or Toast at the slowest speed available (2x-4x) to assure the best burn quality. Always use top quality media: Verbatim, Maxell or Taiyo Yuden DVD-R are the most recommended in these forums.
Give DVD Creator Pro Burn Video a look as it does have a number of themes, can burn to an iso file (disk image). There may be a free version of it at the App Store.
None of them, I repeat, none have the versatility of iDVD. Once you've used iDVD nothing can come anywhere close to it.