From glum to glam: Sleek Britney bounces back from custody battle for a night with Jim Carrey

Britney Spears stepped out in Los Angeles over the weekend looking better than she has in years.

Just a day after lawyers announced the singer's ex-husband Kevin Federline had won sole custody of their two sons, a smiling Britney stole the show at a charity event.

The 26-year-old singer was the star guest at the Generation Rescue autism charity event, hosted by Jim Carrey and girlfriend Jenny McCarthy at their Brentwood home.

Britney looked sleek in a tight-fitting black halterneck dress and matching high heels.

A fellow partygoer told America's Us Weekly magazine: 'She definitely looked happy.

'She was clapping and smiling a lot.'

Despite Britney's happy and smiling demeanour at the party, the singer looked visibly tired thanks to the bags under her eyes.

Her smile on the night could be due to her excitment at seeing her boys the following night.

On Sunday, Britney enjoyed quality time with her two boys in the Los Angeles sunshine.

And it appears black was the dress code for the night.

Funnyman Jim was dressed in a black suit, while girlfriend Jenny flashed her legs in a dark mini dress.

Other guests at the bash included newlyweds Charlie Sheen and Brooke Mueller and director Robert Rodriguez and actress girlfriend Rose MacGowan.

The party was a rare appearance on the Hollywood party scene for Britney, who has been keeping a low profile this year.

After a rocky start to 2008, which saw the troubled singer hospitalised twice for psychiatric evaluation, Britney has been spending increasing amounts of time at home with her father Jamie Spears, who is currently living with her at her Hollywood Hills mansion.

On Friday, Kevin's lawyer Mark Vincent Kaplan announced Britney and her former spouse had reached a custody agreement over their sons Sean Preston, two; and Jayden James, 22 months.

Back on the Hollywood party scene: Britney poses with party hosts Jim Carrey and Jenny McCarthy at the Generation Rescue event

Former dancer Kevin has sole legal and physical custody of the two boys, while Britney will have visitation rights.

Britney's lawyer Laura Wasser said the agreement will give her more time with her sons. She added that while Federline still has full custody, the singer may get expanded rights by the end of the year.

Now her custody battle with Kevin is out of the way, Britney is free to focus on recording her sixth studio album, a follow-up to last year's Blackout.