Modern CSS Patterns

CSS has evolved massively. You can build complex layouts and design systems without preprocessors or frameworks.

Custom Properties (CSS Variables)

Define a design system with variables:

:root {
    --color-primary: #6366f1;
    --color-surface: #1e1e2e;
    --color-text: #e2e8f0;
    --radius: 0.5rem;
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.3);
    --transition: 200ms ease;
}

.card {
    background: var(--color-surface);
    color: var(--color-text);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    transition: transform var(--transition);
}

.card:hover {
    transform: translateY(-2px);
}

Grid Layout

CSS Grid handles two-dimensional layouts with minimal code:

/* Responsive card grid — no media queries needed */
.grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
}

/* Dashboard layout */
.dashboard {
    display: grid;
    grid-template-columns: 250px 1fr;
    grid-template-rows: auto 1fr;
    grid-template-areas:
        "sidebar header"
        "sidebar main";
    min-height: 100vh;
}

Container Queries

Style based on the container's size, not the viewport:

.card-container {
    container-type: inline-size;
}

@container (min-width: 400px) {
    .card {
        display: grid;
        grid-template-columns: 200px 1fr;
    }
}

Logical Properties

Write CSS that works in any language direction:

/* Instead of margin-left / margin-right */
.element {
    margin-inline: auto;      /* Centers horizontally */
    padding-block: 1rem;      /* Top and bottom */
    border-inline-start: 3px solid var(--color-primary);
}

The :has() Selector

Parent selection is finally possible:

/* Style a card differently when it contains an image */
.card:has(img) {
    grid-template-rows: 200px 1fr;
}

/* Style a form group when its input is invalid */
.form-group:has(:invalid) {
    border-color: red;
}

Dark Mode

Respect user preferences with prefers-color-scheme:

@media (prefers-color-scheme: light) {
    :root {
        --color-surface: #ffffff;
        --color-text: #1e293b;
    }
}