Sass vs Plain CSS: Do You Still Need a Preprocessor in 2025

Sass emerged when plain CSS had no variables, nesting, or functions — a huge productivity gain at the time. Modern CSS has since absorbed many of those features natively, narrowing the gap considerably.

$primary: #3858e9;

@mixin button-base {
    padding: 0.5rem 1rem;
    border-radius: 4px;
    border: none;
}

.card {
    border: 1px solid #eee;

    .title {           // nesting: compiles to .card .title
        color: $primary;
    }

    &:hover {           // parent selector reference
        box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    }
}

.btn-primary {
    @include button-base;
    background: $primary;
}

What Plain CSS Now Has Natively

Custom properties (variables), native nesting, and calc() cover a lot of what once required Sass. What plain CSS still lacks: real mixins with logic, functions beyond calc(), and loops for generating repetitive rules — genuine reasons Sass still earns its place in larger projects.