references/jakub-krehel.md

Jakub Krehel's Animation Principles

Jakub Krehel is a design engineer known for his work at jakub.kr. His approach emphasizes subtle production polish—animations that enhance the experience invisibly, designed for real client work where users will interact repeatedly.

Core Philosophy: Invisible Enhancement

"The best animation is that which goes unnoticed."

Jakub's work embodies refinement for production use. His animations are:

• Barely noticeable — If users consciously notice the animation, it's probably too much
• Production-ready — Designed for real client work, not demos
• Contextually appropriate — Adapts to light mode, varied backgrounds, real content
• Subtle over flashy — The goal is to make interfaces feel smooth and responsive, not impressive

The best compliment: "This feels really nice" — not "cool animation!"

The test: If you remove the animation, do users feel something is missing? Good. If users comment "nice animation!" every time they see it? Too prominent.

When to Apply Jakub's Mindset

• Production applications and client work
• Professional/enterprise interfaces
• When users will interact repeatedly (animations must not get tiresome)
• When accessibility and performance are critical
• When you need polish without distraction

Enter Animation Recipe

A standard enter animation combines three properties:

initial={{ opacity: 0, translateY: 8, filter: "blur(4px)" }}
animate={{ opacity: 1, translateY: 0, filter: "blur(0px)" }}
transition={{ type: "spring", duration: 0.45, bounce: 0 }}

Why blur? It creates a "materializing" effect that feels more physical than opacity alone. The element appears to come into focus, not just fade in.

For full container slides, use translateY: "calc(-100% - 4px)" instead of fixed pixels.

Exit Animation Subtlety

Key Insight: Exit animations should be subtler than enter animations.

When a component exits, it doesn't need the same amount of movement or attention as when entering. The user's focus is moving to what comes next, not what's leaving.

// Instead of full exit movement:
exit={{ translateY: "calc(-100% - 4px)" }}

// Use a subtle fixed value:
exit={{ translateY: "-12px", opacity: 0, filter: "blur(4px)" }}

Why this works: Exits become softer, less jarring, and don't compete for attention.

When NOT to use subtle exits:

• When the exit itself is meaningful (user-initiated dismissal)
• When you need to emphasize something leaving (error clearing, item deletion)
• Full-page transitions where directional continuity matters

Spring Animations

Prefer spring animations over linear/ease for more natural-feeling motion:

transition={{ type: "spring", duration: 0.45, bounce: 0 }}
transition={{ type: "spring", duration: 0.55, bounce: 0.1 }}

Why bounce: 0? It gives smooth deceleration without overshoot—professional and refined.

Reserve bounce > 0 for playful contexts only.

Shadows Instead of Borders

In light mode, prefer subtle multi-layer box-shadows over solid borders:

.card {
  box-shadow:
    0px 0px 0px 1px rgba(0, 0, 0, 0.06),
    0px 1px 2px -1px rgba(0, 0, 0, 0.06),
    0px 2px 4px 0px rgba(0, 0, 0, 0.04);
}

/* Slightly darker on hover */
.card:hover {
  box-shadow:
    0px 0px 0px 1px rgba(0, 0, 0, 0.08),
    0px 1px 2px -1px rgba(0, 0, 0, 0.08),
    0px 2px 4px 0px rgba(0, 0, 0, 0.06);
}

Why shadows over borders?

• Shadows adapt to any background (images, gradients, varied colors) via transparency
• Borders are solid colors that may clash with dynamic backgrounds
• Multi-layer shadows create depth; single borders feel flat
• Shadows can be transitioned smoothly

When borders are fine:

• Dark mode (shadows less visible anyway)
• When you need hard edges intentionally
• Simple interfaces where depth isn't needed

Gradients & Color Spaces

Use oklch for gradients to avoid muddy midpoints:

.element {
  background: linear-gradient(in oklch, blue, red);
}

Why oklch? It interpolates through perceptually uniform color space, avoiding the gray/muddy zone that sRGB hits when blending complementary colors.

Color hints control where the blend midpoint appears (different from color stops).

Layer gradients with background-blend-mode for unique effects.

Blur as a Signal

Blur (via filter: blur()) combined with opacity and translate creates a "materializing" effect. Use blur to signal:

• Entering focus: blur → sharp
• Losing relevance: sharp → blur
• State transitions: blur during, sharp after

Optical Alignment

"Sometimes it's necessary to break out of geometric alignment to make things feel visually balanced."

Buttons with Icons

Reduce padding on the icon side so content appears centered:

[  Icon Text  ] ← Geometric (mathematically centered, feels off)
[ Icon Text   ] ← Optical (visually centered, feels right)

Play Button Icons

The triangle points right, creating visual weight on the left. Shift it slightly right to appear centered.

The Rule

If it looks wrong despite being mathematically correct, trust your eyes and adjust.

Icon & State Animations

When icons change contextually (copy → check, loading → done), animate:

• Opacity
• Scale
• Blur

<AnimatePresence mode="wait">
  {isCopied ? (
    <motion.div
      initial={{ opacity: 0, scale: 0.8, filter: "blur(4px)" }}
      animate={{ opacity: 1, scale: 1, filter: "blur(0px)" }}
      exit={{ opacity: 0, scale: 0.8, filter: "blur(4px)" }}
    >
      <CheckIcon />
    </motion.div>
  ) : (
    <motion.div ...>
      <CopyIcon />
    </motion.div>
  )}
</AnimatePresence>

Why animate icon swaps? Instant swaps feel jarring and can be missed. Animated transitions:

• Draw attention to the state change
• Feel responsive and polished
• Give the user confidence their action registered

Shared Layout Animations

FLIP Technique via layoutId

Motion's layoutId prop enables smooth transitions between completely different components:

// In one location:
<motion.div layoutId="card" className="small-card" />

// In another location:
<motion.div layoutId="card" className="large-card" />

Motion automatically animates between them using the FLIP technique (First, Last, Inverse, Play).

Best Practices

• Keep elements with layoutId outside of AnimatePresence to avoid conflicts
• If inside AnimatePresence, initial/exit animations trigger during layout animation (looks bad)
• Multiple elements can animate if each has a unique layoutId
• Works for different heights, widths, positions, and component types

will-change Performance

A hint to the browser: "I'm about to animate these properties, please prepare."

/* Good - specific properties that will animate */
.animated-button {
  will-change: transform, opacity;
}

/* Bad - too broad, wastes resources */
* { will-change: auto; }
.element { will-change: all; }

Properties that benefit from will-change:

• transform
• opacity
• filter (blur, brightness)
• clip-path
• mask

Why it matters: Without the hint, the browser promotes elements to GPU layers only when animation starts, causing first-frame stutter.

When NOT to use:

• On elements that won't animate
• On too many elements (each GPU layer uses memory)
• As a "fix" for janky animations (find the real cause)

Gradient Animation Performance

Cheap to animate (GPU-accelerated):

• background-position
• background-size
• opacity

Expensive to animate:

• Color stops
• Adding/removing gradient layers
• Switching gradient types

Tip: Animate a pseudo-element overlay or use CSS variables that transition indirectly.

Common Mistakes (Jakub's Perspective)

• Making enter and exit animations equally prominent — Exits should be subtler
• Using solid borders when shadows would adapt better — Especially on varied backgrounds
• Forgetting optical alignment — Buttons with icons, play buttons, asymmetric shapes
• Over-animating — If users notice the animation itself, it's too much
• Using the same animation everywhere — Context should drive timing and easing choices
• Ignoring hover state transitions — Even small transitions (150-200ms) feel more polished than instant changes

Jakub's Technique Index

From jakub.kr:

Jakub vs. Emil vs. Jhey

When to use Jakub: You've decided something should animate (passed Emil's gate) and need to make it production-ready and polished.