In short
Maintainable CSS comes from keeping specificity low and flat across the whole codebase (mostly single classes, no ID selectors, minimal nesting), picking one naming convention and applying it consistently, and treating any need for !important as a signal that the specificity structure has already broken down somewhere upstream.
Why CSS starts to "fight back"
CSS itself isn't the problem most teams run into — an escalating specificity war is. One override needs to beat another, so it adds an extra class or an ID selector; the next override needs to beat that one, so it goes further still. A few months into this pattern, changing a single style requires understanding a stack of competing overrides, and every fix risks breaking something else.
Keep specificity flat, on purpose
The fix is a deliberate rule: style almost everything with single class selectors, and avoid ID selectors and deep nesting in your styling entirely. If every rule has roughly the same specificity, the cascade behaves predictably — later rules override earlier ones in source order, without needing an escalating arms race of selector complexity to win.
Pick one naming convention and hold the line
BEM (block__element--modifier), utility classes (Tailwind-style), or a component-scoped approach (CSS Modules, scoped styles in a framework) all work — the actual choice matters less than consistency. A codebase that mixes two or three naming approaches, added by different people at different times, becomes much harder to reason about than one consistently using a single approach, even if that approach isn't your personal favorite.
Treat !important as a symptom, not a tool
!important overrides the cascade instead of working with it, and once one exists, beating it requires another !important with higher priority — recreating the exact specificity war it was meant to solve, one level up. Reaching for it is almost always a sign that specificity has already gotten out of hand somewhere upstream; the actual fix is usually reducing the specificity of the rule causing the conflict, not adding a bigger hammer on top of it.
Structuring styles so they don't accumulate cruft
Organize CSS by component or feature rather than by property type — keep everything related to a button (layout, color, states) together, rather than splitting "all colors" into one file and "all layout" into another. This makes it obvious what to change when a specific component needs updating, and much less likely that an edit in one place has an invisible effect somewhere else.
Design tokens reduce the surface area for drift
Using design tokens (CSS variables for color, spacing, type) instead of hardcoded values throughout your stylesheets means a single value change propagates everywhere it's used, rather than requiring a find-and-replace across dozens of hardcoded instances that may or may not all get updated correctly.
A quick self-check
Open your CSS and search for !important and ID selectors used for styling — a high count of either is a reliable signal of accumulated specificity debt. Fixing the worst offenders first, by reducing their selector specificity rather than adding to it, tends to unwind a surprising amount of the underlying tangle.
Modern CSS features that help
CSS nesting, :where() (which has zero specificity, useful for resets and base styles that should be easy to override), and container queries all reduce the need for the workarounds that used to require heavier tooling or more complex selectors — worth adopting as browser support allows.
Related on Troiana: How to Set Up Design Tokens in Code.
Common questions
Is !important ever acceptable?
In rare, deliberate cases (like overriding a third-party library's inline styles you don't control), but as a general pattern in your own codebase, it signals the specificity structure has already broken down and needs fixing at the source, not patching on top.
Which CSS naming convention is best — BEM, utility classes, or CSS Modules?
Any of them work well; the value comes from picking one and applying it consistently across the whole codebase, not from which specific convention you choose.
How do design tokens help with CSS maintainability?
They centralize values like color and spacing into CSS variables, so a single change propagates everywhere the token is used instead of requiring a manual find-and-replace across hardcoded values.