NEBRASKA By Ron Hansen (Vintage, $102) IN the plain-spoken age of modern fiction, it's not so often that style is an interesting topic. Novels that limp along with loose language, dull metaphors, unreconstructed Hemingway-esque curt sentences are said to be stylish. Really rich writers, like Toni Morrison, are hardly the rule, and exceptions from the standard marketplace prose leave lazy readers reaching for romances whose style is mere steam. Ron Hansen is a stylist of a different sort. His writing is not sumptuous, not heightened, rarely ever acute. Indeed, the scope of his language is rather narrow. But it is altogether apt, often perfectly fitted to his subject. His book of short stories is called Nebraska. Like Nebraska, his writing is solid, flat, fertile and topographically dull - until you look very closely at the land and the ''league of sober folk'' who dwell there. Once you grasp the relationship between the stolid solidity of Mr Hansen's prose and the world he portrays, the stories become worth the harvest. Mr Hansen was born in Nebraska. He was educated at the Iowa Writers Workshop and at Stanford where he held the Wallace Stegner Writing Fellowship (now there's a stylist; Stegner is among the strongest American stylists, a writer well worth the whistle). So Mr Hansen has good training, and he writes solid, stylistically accurate stories. But, I'm afraid, the collection of stories is very uneven in quality. Three of the first four stories seem downright bad, workshop exercises in pastiche, character sketch, and gratuitous shock effects. But Can I Just Sit Here For A While is a fine story on a mundane theme. A middle-aged American, tired of selling medical equipment for a large company, decides to set up a business for himself. He moves back to his college town, South Bend, home of Notre Dame - and finds himself in pointless competition for success with two former classmates who have ''made it'' but who have never grown up. Is success worth the effort when your model friend defends middle-agedness by karate punching teenagers in their high school football jackets? Sleepless is a brilliant story. Here a black woman, Avis, moves into an all-white neighbourhood. Her neighbours peer out at her as she walks home from the grocery, silently reviling her for having had the audacity to intrude on their white primacy. Avis is clearly out of place. To make matters worse, she is a skilled psychic. Strangers telephone her for help; she appears on television talk shows to explain that she sees the world the way intelligent people see ''dear'' in the word ''read''. She begins to receive phone calls from a disturbed young man who may, she thinks, have murdered his mother in a bloody mercy killing. He calls frequently, and his presence looms so large in Avis' new house that even her daughter begins spontaneously to draw pictures of the boy's crimes. Avis begins to feel him, to hear him, finally to see him in the house. The house itself begins to manifest changes; the furniture and dishes and clothes in the closet don't belong to Avis. As she pieces the young man's story together - two murders plus his suicide - it becomes suddenly clear (not portentously, inevitably clear) that the murders occurred in this house, in the house that Avis has now devalued by her black presence. And in the house of outcasts, the young ghost telephones her, appears to her, attempts to recreate his crimes through her until she can defuse his grief and agony. The words are simple enough: ''Don't hate anymore. Give up. Go to sleep. You're a ghost. . . Everybody's forgotten.'' Sleepless is wonderful because the surreal scene of the changing house and the overlapping times and lives is perfectly matched and balanced with the deceptively calm realism of the American suburb. The balance is so effective that one begins to see all of America differently. Sleepless is the best story, and it is happily joined by another five that are well worth reading. Nebraska is a slight book, under 200 pages. You won't find the slow development of style from beginner to master as you would expect in a collected stories, but you will find sufficient diversity to keep you reading.