ReactNativeCssElementDescriptorProvider.kt

package com.intellij.StyledComponents

import com.intellij.lang.javascript.psi.JSFile
import com.intellij.psi.PsiElement
import com.intellij.psi.css.CssElementDescriptorProvider
import com.intellij.psi.css.CssPropertyDescriptor
import com.intellij.psi.css.CssSimpleSelector
import com.intellij.psi.impl.source.tree.injected.InjectedLanguageUtil

class MyCssElementDescriptorProvider : CssElementDescriptorProvider() {

    override fun findPropertyDescriptors(propertyName: String, context: PsiElement?): MutableCollection<out CssPropertyDescriptor> {
        val normalizedName = toCssName(propertyName)
        return EP_NAME.extensions.last()
                .findPropertyDescriptors(normalizedName, context)
                .filter { it.browsers.isEmpty() }
                .toMutableList()
    }

    override fun getDeclarationsForSimpleSelector(p0: CssSimpleSelector): Array<PsiElement> {
        return emptyArray()
    }

    override fun shouldAskOtherProviders(context: PsiElement?): Boolean {
        return false
    }

    override fun isMyContext(p0: PsiElement?): Boolean {
        return p0 != null && InjectedLanguageUtil.getTopLevelFile(p0) is JSFile
    }

    override fun getAllPropertyDescriptors(context: PsiElement?): MutableCollection<out CssPropertyDescriptor> {
        return EP_NAME.extensions.last()
                .getAllPropertyDescriptors(context)
                .filter { it.browsers.isEmpty() }
                .map { MyPropertyDescriptor(it, toReactNativeName(it.propertyName)) }
                .toMutableList()
    }

    private fun toReactNativeName(propertyName: String): String {
        return propertyName.foldIndexed(StringBuilder(), { index, acc, c ->
            if (c == '-') {
            } else if (index > 0 && propertyName[index - 1] == '-') {
                acc.append(c.toUpperCase())
            } else {
                acc.append(c)
            }
            acc
        }).toString()
    }

    private fun toCssName(propertyName: String): String {
        return propertyName.fold(StringBuilder(), { acc, c ->
            if (!acc.isEmpty() && c.isUpperCase()) {
                acc.append("-")
                acc.append(c.toLowerCase())
            } else {
                acc.append(c)
            }
            acc
        }).toString()
    }

    class MyPropertyDescriptor(b: CssPropertyDescriptor, private val reactName: String)
        : CssPropertyDescriptor by b {
        override fun getPropertyName(): String {
            return reactName
        }

        override fun getPresentableName(): String {
            return reactName
        }

        override fun getDescription(): String {
            return reactName
        }

        override fun getId(): String {
            return reactName
        }
    }
}

This is a CssElementDescriptorProvider that naively transforms css properties to 'react-native-specific props' in CSS files.
It does not add platform specific props or remove browser-specific properties or take into account difference in schema of some (like top)