The CSS if() function proposal has evolved quickly in recent years. This article digs into how it works and how to apply it in practice.

Basic Concepts

See the following code for specific usage:

:root {
  --primary: #2563eb;
  --surface: #f8fafc;
  --text: #1e293b;
  --radius: 8px;
  --shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.component {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: clamp(1rem, 3vw, 2rem);
  color: var(--text);
}

@media (prefers-color-scheme: dark) {
  :root {
    --surface: #1e293b;
    --text: #f1f5f9;
  }
}

It is recommended to unify conventions within the team to reduce inconsistency.

Core Implementation

Let's look at the specific implementation:

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
}

.card {
  container-type: inline-size;
  border-radius: 12px;
  overflow: hidden;
  transition: transform 0.2s ease;
}

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

@container (min-width: 400px) {
  .card__body {
    display: grid;
    grid-template-columns: 120px 1fr;
    gap: 1rem;
  }
}

This implementation is concise and efficient, suitable for most scenarios.

Practical Application

Here is a practical example:

:root {
  --primary: #2563eb;
  --surface: #f8fafc;
  --text: #1e293b;
  --radius: 8px;
  --shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.component {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: clamp(1rem, 3vw, 2rem);
  color: var(--text);
}

@media (prefers-color-scheme: dark) {
  :root {
    --surface: #1e293b;
    --text: #f1f5f9;
  }
}

In real projects, you need to make appropriate adjustments based on specific requirements.

Best Practices

The core code is as follows:

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
}

.card {
  container-type: inline-size;
  border-radius: 12px;
  overflow: hidden;
  transition: transform 0.2s ease;
}

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

@container (min-width: 400px) {
  .card__body {
    display: grid;
    grid-template-columns: 120px 1fr;
    gap: 1rem;
  }
}

Be sure to handle edge cases and exceptions properly.

Summary

• Base performance optimization on real data and avoid premature optimization
• CSS if() 函数提案的核心在于理解底层原理，而非仅仅记住 API
• In real projects, choosing the right solution matters more than chasing the newest technology