observer javascript proplem

i want to add an observer so it can add a class when viewed and remove it when it get out of view what is wrong? the proplem is : The code adds the class but doesnt remove The class when the section gets out of viewed

const options = {
    threshold: 0.75,
}
const observer = new IntersectionObserver(function (enteries ,observer) {
    enteries.forEach(entry => {
        if (entry.isIntersecting > 0) {
            entry.target.classList.add("StyleSection");
            console.log(entry.target);
           
        }
        else if (entry.isIntersecting === 0){
            sections.classList.remove("StyleSection");
            console.log(entry.target);
            observer.unobserve(section);
        }
        
    });
}, options);`enter code here`
sections.forEach(section => {
    observer.observe(section);
});