Stefani is a female mouse, with brown and white patches of fur and a pink snout.
According to the model sheets, she is 5 1/2 ft tall.
She wears a collared shirt in different shades of lavender with cut out sleeves at the shoulders, a pair of black shorts that are above her thigh, a gold collar lapel pin. She also wears black and lavender sneakers.
In Season 3, her top was dark purple and lilac.
Stefani was raised in an environment, where she was never said 'no' to, so she often cannot process the expression of refusal or the word "no" as a concept.
She is often pressuring Diane to write more content, and she strives to expand Girl Croosh in Season 5.
Stefani becomes Diane's new boss after Princess Carolyn suggests blogging work for her. She is the sister of Ralph Stilton.
Diane later meets with Stefani for a job interview. Stefani tests her loyalty, by asking if she would be willing to write something negative, towards her husband (ex-husband in Season 5) Mr. Peanutbutter if she had to. It is unknown what she said to this question, but she ended up getting the job.
In See Mr. Peanutbutter Run, Diane is now working at Girl Croosh.
In Hooray! Todd Episode!, While Todd is trying to distract her from looking at social media, Stefani addresses Diane about her articles. Stefani finds it inspiring, that Diane knows no one reads the stuff she writes, about but she does it anyway.
In Commence Fracking, Diane is at a Girl Croosh meeting. One member is pitching an article about having a healthy sex life. Diane asks why they don't write an article about people who aren't having sex. Stefani pulls her aside and asks her if she isn't having sex with her husband.
Diane says that the campaign has been testing their marriage and that she can't wait for it to go back to normal. Stephanie encourages her to speak up but Diane says that she doesn't want to go against her husband. Stephanie says that she needs to "do you" and that right now no one is.
In Thoughts and Prayers, Diane writes a Girl Croosh article pushing gun ownership as a means of female empowerment. This article quickly gets the most hits on Girl Croosh.
In The Judge, Princess Carolyn, Ralph, and Stefani are on their way to Stilton Acres. Stefani tells her how much she'll love it there, and Ralph tells her how much she'll love The Feast of St Squeaky, the holiest of all mouse holidays.
Ralph hopes his parents will like her. Princess Carolyn assures him they will love her, and the two agree they'll wait to tell his family she is pregnant. Stefani is not a problem as she is completely distracted by social media and her phone.
Princess Carolyn, Ralph, and Stefani have arrived at Stilton Acres. Ralph's parents introduce themselves and the rest of the family. They offer her numerous things you shouldn't eat or do when you're pregnant. Ralph is able to change the subject.
In The Dog Days Are Over, Diane arrives in Vietnam but gets a call from Stefani, telling her she wants more content for Girl Croosh. Diane tells her that she'll write a piece while she's in Vietnam. She calls it 10 Reasons to go to Vietnam: A Girl Croosh Personal Travel Guide.
Before Diane goes to Vietnam, it is also shown Stefani calls an exterminator when her cockroach IT staff try to unionize against her, referring to it as "negotiations."
In BoJack the Feminist, at Girl Croosh, Stefani tells Diane in disgust of the news of Vance Waggoner getting a Forgivie. Diane is also disgusted by this. Stefani wants Diane to go the award show, to take Vance down and do some "Hollywoo hob-nobbing," and ask BoJack why Vance is going to star on his new show—a fact that shocks Diane.
In The Stopped Show, Diane meets with Stefani at Sandro's Place. Stefani explains that Girl Croosh is moving to video format and that she wants Diane to be the face of it. Diane says no to the offer, which shocks and confuses Stefani as she literally has never been said "no" to before—and she doesn't quite understand the concept of the word "no," because she was spoiled, from the time she was young.
Diane then explains, how she's an untrustworthy news source and a hypocrite after her actions. Stefani then explains to Diane what her problem is; that she often holds people and even herself at a very high, almost impossible standard.
This allows her to write juicy take-downs but is harrowing for her self worth. She explains, that the world is already very unforgiving and standardized. In the end, it's best to forgive each other. Diane asks if the content on Girl Croosh should be more forgiving. Stefani however, blows off the idea.
In Feel-Good Story, Diane and the cameraman Guy are out filming for a segment of Girl Croosh called Crooshing USA. The farmer they are interviewing asks what does that mean. Diane tells him "Crooshness" is hard to define. She also says she doesn't know it when she sees it.
The farmer then says he's always trying to get more girls interested in agriculture. Diane says his farm is also a front for a sex trafficking ring. Diane then questions how he got into sex trafficking, and the farmer then runs off. Guy then says he's probably not getting his microphone back.
They then go on to cover other stories.
Guy and Diane are eating lunch at Parmadillo's. Guy asks what she thinks of the sandwich. Diane says it isn't bad. Stefani then calls asking Diane, saying that while she loves the serious stories Diane is covering, she would like some more feel-good stories as well. Diane counters this, by saying the stories they are covering are really making a difference. Stefani tells Diane that the serious news is bumming her out.
Diane and Guy then go and cover the Every Animal Girl Company. The ladies who own it tell Diane they are two best friends who started a doll company because they got tired of seeing dolls, that showed unrealistic beauty standards. Diane then asks if their dolls are made from recyclable materials. The ladies both start giggling nervously and talking over each other. They tell Diane, they were purchased by Toys Galore, which is a subsidiary of Whitewhale.
She then wakes up the next morning and gets a call from Stefani. Stefani tells Diane made a big impression with the guys at Whitewhale. She says they bought Girl Croosh, to Diane's shock. She then goes on to say they technically bought Fuddrucker's, and merged it with Dow Chemical, to create a new media venture called Spronk! She then says Spronk! acquired Univision, which will include Girl Croosh in the Gizmodo-branded mist of advertorial.
Diane says that's terrible. Stefani says not for her, she'll be rich. Diane reminds her she already is rich. Stefani wishes her good luck with Spronk!, which is currently rebranding as Content Spew. Diane then says, "Oh, Spronk me."