CSS Animations and Transitions

/* Simple hover transition */
.button {
    background-color: blue;
    transition: background-color 0.3s ease;
}

.button:hover {
    background-color: darkblue;
}

/* Multiple properties */
.card {
    transform: scale(1);
    opacity: 1;
    transition: transform 0.3s ease, opacity 0.3s ease;
}

.card:hover {
    transform: scale(1.05);
    opacity: 0.9;
}

/* Shorthand - all properties */
.box {
    transition: all 0.3s ease;
}

/* Different timings for different properties */
.element {
    transition: 
        transform 0.3s ease-out,
        opacity 0.5s ease-in,
        background-color 0.2s linear;
}

/* Transition with delay */
.delayed {
    transition: opacity 0.5s ease 0.2s;
    /* opacity, 0.5s duration, ease timing, 0.2s delay */
}

/* Specific properties only */
.specific {
    transition-property: transform, opacity;
    transition-duration: 0.3s;
    transition-timing-function: ease-out;
}

/* Staggered transitions */
.menu-item {
    opacity: 0;
    transform: translateX(-20px);
    transition: opacity 0.3s ease, transform 0.3s ease;
}

.menu-item:nth-child(1) { transition-delay: 0.1s; }
.menu-item:nth-child(2) { transition-delay: 0.2s; }
.menu-item:nth-child(3) { transition-delay: 0.3s; }

.menu.open .menu-item {
    opacity: 1;
    transform: translateX(0);
}

/* Bi-directional transitions (different in/out) */
.modal {
    opacity: 0;
    transform: scale(0.8);
    transition: opacity 0.3s ease-out, transform 0.3s ease-out;
}

.modal.open {
    opacity: 1;
    transform: scale(1);
    /* Fast opening: ease-out */
    transition: opacity 0.2s ease-out, transform 0.2s ease-out;
}

/* When closing, slower with ease-in */
.modal.closing {
    transition: opacity 0.4s ease-in, transform 0.4s ease-in;
}

/* Custom cubic-bezier easing */
.bouncy {
    transition: transform 0.5s cubic-bezier(0.68, -0.55, 0.265, 1.55);
    /* Bouncy overshoot effect */
}

/* Material Design easing */
.material-standard {
    transition: all 0.3s cubic-bezier(0.4, 0.0, 0.2, 1);
}

.material-decelerate {
    transition: all 0.3s cubic-bezier(0.0, 0.0, 0.2, 1);
}

.material-accelerate {
    transition: all 0.3s cubic-bezier(0.4, 0.0, 1, 1);
}

/* Stepped animation (sprite sheet) */
.sprite {
    background: url('sprite.png');
    width: 50px;
    height: 50px;
    transition: background-position 1s steps(10);
    /* 10 frames */
}

.sprite:hover {
    background-position: -500px 0;  /* 10 frames * 50px */
}

/* Simple fade in */
@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

.fade-element {
    animation: fadeIn 1s ease;
}

/* Multi-step animation with percentages */
@keyframes bounce {
    0% {
        transform: translateY(0);
    }
    25% {
        transform: translateY(-30px);
    }
    50% {
        transform: translateY(0);
    }
    75% {
        transform: translateY(-15px);
    }
    100% {
        transform: translateY(0);
    }
}

.bounce-element {
    animation: bounce 1s ease;
}

/* Infinite spinning loader */
@keyframes spin {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}

.loader {
    animation: spin 1s linear infinite;
}

/* Pulse animation */
@keyframes pulse {
    0%, 100% {
        transform: scale(1);
        opacity: 1;
    }
    50% {
        transform: scale(1.1);
        opacity: 0.8;
    }
}

.pulse-button {
    animation: pulse 2s ease-in-out infinite;
}

/* Slide in from left */
@keyframes slideInLeft {
    from {
        transform: translateX(-100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

.slide-in {
    animation: slideInLeft 0.5s ease-out;
}

/* Animation with fill-mode */
@keyframes slideUp {
    from {
        transform: translateY(100%);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.slide-up {
    /* Keep final state after animation */
    animation: slideUp 0.5s ease-out forwards;
}

/* Alternating direction */
@keyframes sway {
    0%, 100% {
        transform: rotate(-5deg);
    }
    50% {
        transform: rotate(5deg);
    }
}

.swaying {
    animation: sway 3s ease-in-out infinite alternate;
    /* Plays forward then backward */
}

/* Multiple animations */
.multi-animated {
    animation: 
        fadeIn 1s ease-out,
        slideUp 1s ease-out,
        pulse 2s ease-in-out 1s infinite;
    /* Third animation starts after 1s delay */
}

/* Paused animation (controlled by JS or hover) */
@keyframes scroll {
    from {
        transform: translateX(0);
    }
    to {
        transform: translateX(-100%);
    }
}

.scrolling-text {
    animation: scroll 10s linear infinite;
}

.scrolling-text:hover {
    animation-play-state: paused;
}

/* Complex multi-property animation */
@keyframes complexEntry {
    0% {
        transform: translateY(50px) scale(0.8) rotate(-5deg);
        opacity: 0;
        filter: blur(10px);
    }
    50% {
        transform: translateY(-10px) scale(1.05) rotate(2deg);
        filter: blur(0px);
    }
    100% {
        transform: translateY(0) scale(1) rotate(0deg);
        opacity: 1;
        filter: blur(0px);
    }
}

.complex-entry {
    animation: complexEntry 0.8s cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* Typing effect with steps */
@keyframes typing {
    from {
        width: 0;
    }
    to {
        width: 100%;
    }
}

@keyframes blink {
    50% {
        border-color: transparent;
    }
}

.typewriter {
    overflow: hidden;
    border-right: 2px solid;
    white-space: nowrap;
    animation: 
        typing 3.5s steps(40) 1s forwards,
        blink 0.75s step-end infinite;
}

/* Bouncy button press */
.bouncy-button {
    transition: transform 0.3s cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

.bouncy-button:active {
    transform: scale(0.9);
}

/* Material Design motion */
.material-card {
    transition: all 0.3s cubic-bezier(0.4, 0.0, 0.2, 1);
}

/* Elastic menu */
@keyframes elasticSlide {
    0% {
        transform: translateX(-100%);
    }
    60% {
        transform: translateX(10%);
    }
    75% {
        transform: translateX(-5%);
    }
    90% {
        transform: translateX(2%);
    }
    100% {
        transform: translateX(0);
    }
}

.elastic-menu {
    animation: elasticSlide 0.8s;
}

/* Or with cubic-bezier */
.elastic-simple {
    animation: slideIn 0.8s cubic-bezier(0.68, -0.75, 0.265, 1.75);
}

/* Stepped animation for sprite */
@keyframes walk {
    to {
        background-position: -480px;  /* 8 frames * 60px */
    }
}

.character-walk {
    width: 60px;
    height: 60px;
    background: url('walk-sprite.png');
    animation: walk 0.8s steps(8) infinite;
}

/* Counter flip animation */
@keyframes flip {
    to {
        transform: translateY(-100%);
    }
}

.flip-counter {
    animation: flip 0.5s steps(10);
}

/* Smooth natural easing (iOS-style) */
.ios-sheet {
    transition: transform 0.5s cubic-bezier(0.32, 0.72, 0, 1);
}

/* Anticipation effect (pull back before forward) */
@keyframes anticipate {
    0% {
        transform: translateX(0);
    }
    20% {
        transform: translateX(-20px);
    }
    100% {
        transform: translateX(100%);
    }
}

.anticipate-exit {
    animation: anticipate 0.6s cubic-bezier(0.6, -0.28, 0.735, 0.045);
}

/* Entry animations: use ease-out (fast start, slow end) */
.enter {
    animation: fadeIn 0.3s ease-out;
}

/* Exit animations: use ease-in (slow start, fast end) */
.exit {
    animation: fadeOut 0.3s ease-in;
}

/* Movement: use ease-in-out */
.move {
    transition: transform 0.5s ease-in-out;
}

/* Quick feedback: use shorter durations */
.button-press {
    transition: transform 0.1s ease-out;
}

/* Attention-grabbing: use bounce */
.notification {
    animation: bounce 0.6s cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

/* Smooth infinite loop: use ease-in-out */
@keyframes float {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-20px);
    }
}

.floating {
    animation: float 3s ease-in-out infinite;
}

/* Custom spring animation */
.spring {
    animation: springIn 0.6s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

/* Stepped loading animation */
@keyframes loadingSteps {
    to {
        background-position: -200px 0;
    }
}

.loading-bar {
    animation: loadingSteps 1s steps(10) infinite;
}

/* Easing visualizer helper classes */
.easing-linear { animation-timing-function: linear; }
.easing-ease { animation-timing-function: ease; }
.easing-ease-in { animation-timing-function: ease-in; }
.easing-ease-out { animation-timing-function: ease-out; }
.easing-ease-in-out { animation-timing-function: ease-in-out; }
.easing-bounce { animation-timing-function: cubic-bezier(0.68, -0.55, 0.265, 1.55); }

/* Fade in as element enters viewport */
@keyframes fadeInScroll {
    from {
        opacity: 0;
        transform: translateY(50px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.scroll-reveal {
    animation: fadeInScroll linear;
    animation-timeline: view();
    animation-range: entry 0% entry 100%;
}

/* Parallax effect with scroll */
@keyframes parallax {
    to {
        transform: translateY(-100px);
    }
}

.parallax-bg {
    animation: parallax linear;
    animation-timeline: scroll();
}

/* Scale based on scroll position */
@keyframes scaleOnScroll {
    from {
        transform: scale(0.8);
    }
    to {
        transform: scale(1);
    }
}

.scale-scroll {
    animation: scaleOnScroll linear;
    animation-timeline: view();
    animation-range: entry 0% cover 50%;
}

/* Header shrink on scroll */
@keyframes shrinkHeader {
    to {
        transform: scale(0.9);
        padding: 0.5rem 1rem;
    }
}

.header {
    animation: shrinkHeader linear;
    animation-timeline: scroll(root block);
    animation-range: 0 100px;
}

/* Rotate on scroll */
@keyframes rotateScroll {
    to {
        transform: rotate(360deg);
    }
}

.rotate-element {
    animation: rotateScroll linear;
    animation-timeline: scroll();
}

/* Progress bar based on scroll */
.progress-bar {
    position: fixed;
    top: 0;
    left: 0;
    height: 4px;
    background: blue;
    transform-origin: 0 50%;
    animation: scaleProgress linear;
    animation-timeline: scroll(root block);
}

@keyframes scaleProgress {
    from {
        transform: scaleX(0);
    }
    to {
        transform: scaleX(1);
    }
}

/* CSS animation classes */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.reveal {
    opacity: 0;
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.active {
    animation: fadeInUp 0.6s ease forwards;
}

/* JavaScript (Intersection Observer) */
/*
const observer = new IntersectionObserver((entries) => {
    entries.forEach(entry => {
        if (entry.isIntersecting) {
            entry.target.classList.add('active');
        }
    });
}, {
    threshold: 0.1,
    rootMargin: '0px 0px -100px 0px'
});

document.querySelectorAll('.reveal').forEach(el => {
    observer.observe(el);
});
*/

/* Staggered scroll reveals */
.reveal-stagger {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease;
}

.reveal-stagger.active {
    opacity: 1;
    transform: translateY(0);
}

.reveal-stagger:nth-child(1) { transition-delay: 0.1s; }
.reveal-stagger:nth-child(2) { transition-delay: 0.2s; }
.reveal-stagger:nth-child(3) { transition-delay: 0.3s; }

/* Parallax sections */
.parallax-section {
    transform: translateY(calc(var(--scroll-progress) * -50px));
    transition: transform 0.1s linear;
}

/* Scroll-linked opacity */
.fade-on-scroll {
    opacity: calc(1 - var(--scroll-progress));
}

/* Pin element during scroll (with scroll-timeline) */
@keyframes pinSticky {
    0% {
        transform: translateY(0);
    }
    100% {
        transform: translateY(0);
    }
}

.pin-element {
    position: sticky;
    top: 0;
    animation: pinSticky linear;
    animation-timeline: view();
}

/* Mark elements for view transitions */
.card {
    view-transition-name: card-1;
}

.title {
    view-transition-name: title;
}

/* Customize transition animation */
::view-transition-old(card-1),
::view-transition-new(card-1) {
    animation-duration: 0.5s;
}

/* Custom animation for specific transition */
@keyframes slide-from-right {
    from {
        transform: translateX(100%);
    }
}

::view-transition-new(card-1) {
    animation: slide-from-right 0.5s ease-out;
}

/* Fade transition */
::view-transition-old(root) {
    animation: 0.3s ease-out both fade-out;
}

::view-transition-new(root) {
    animation: 0.3s ease-out both fade-in;
}

@keyframes fade-out {
    to {
        opacity: 0;
    }
}

@keyframes fade-in {
    from {
        opacity: 0;
    }
}

/* JavaScript usage */
/*
// Simple transition
function updateView() {
    document.startViewTransition(() => {
        // Update DOM here
        document.querySelector('.content').textContent = 'New content';
    });
}

// With promise handling
async function animatedUpdate() {
    const transition = document.startViewTransition(() => {
        // DOM updates
        updateDOMState();
    });
    
    await transition.finished;
    console.log('Transition complete');
}

// Conditional transitions
function conditionalTransition() {
    if (document.startViewTransition) {
        document.startViewTransition(() => updateDOM());
    } else {
        updateDOM();  // Fallback without animation
    }
}
*/

/* Different transitions for different elements */
.hero {
    view-transition-name: hero;
}

.sidebar {
    view-transition-name: sidebar;
}

/* Hero expands */
::view-transition-new(hero) {
    animation: scaleUp 0.5s ease-out;
}

@keyframes scaleUp {
    from {
        transform: scale(0.8);
    }
}

/* Sidebar slides in */
::view-transition-new(sidebar) {
    animation: slideInLeft 0.4s ease-out;
}

@keyframes slideInLeft {
    from {
        transform: translateX(-100%);
    }
}

/* Morph between layouts */
.grid-item {
    view-transition-name: attr(data-id);  /* Dynamic names */
}

/* Smooth color transitions */
::view-transition-group(root) {
    animation-duration: 0.5s;
    animation-timing-function: ease-in-out;
}

/* Page transition (SPA navigation) */
::view-transition-old(root) {
    animation: fadeOutScale 0.3s ease-in;
}

::view-transition-new(root) {
    animation: fadeInScale 0.3s ease-out;
}

@keyframes fadeOutScale {
    to {
        opacity: 0;
        transform: scale(0.95);
    }
}

@keyframes fadeInScale {
    from {
        opacity: 0;
        transform: scale(1.05);
    }
}

/* Disable transition for specific elements */
.no-transition {
    view-transition-name: none;
}

/* Cross-fade between images */
.image-container {
    view-transition-name: main-image;
}

::view-transition-old(main-image),
::view-transition-new(main-image) {
    animation-duration: 0.4s;
    height: 100%;
    object-fit: cover;
}

/* Custom easing for smooth transitions */
::view-transition-group(*) {
    animation-timing-function: cubic-bezier(0.4, 0.0, 0.2, 1);
}

/* GOOD: GPU-accelerated */
.optimized {
    transition: transform 0.3s, opacity 0.3s;
}

.optimized:hover {
    transform: translateY(-5px);
    opacity: 0.8;
}

/* BAD: Triggers layout */
.bad {
    transition: top 0.3s, height 0.3s;
}

.bad:hover {
    top: -5px;
    height: 150px;
}

/* will-change optimization */
.about-to-animate {
    will-change: transform, opacity;
}

.about-to-animate.animating {
    animation: slideIn 0.5s;
}

/* Remove will-change after animation */
.about-to-animate.done {
    will-change: auto;
}

/* Contain for isolated animations */
.animated-card {
    contain: layout paint;
    /* Animation won't affect outside elements */
}

/* Efficient loader */
.loader {
    width: 40px;
    height: 40px;
    border: 4px solid #f3f3f3;
    border-top: 4px solid #3498db;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    /* Only animates transform - GPU accelerated */
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Efficient pulse effect */
.pulse {
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
        opacity: 1;
    }
    50% {
        transform: scale(1.05);
        opacity: 0.9;
    }
}

/* Reduce animation on low-end devices */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Efficient stagger without JavaScript */
.stagger-item {
    animation: fadeIn 0.5s ease-out backwards;
}

.stagger-item:nth-child(1) { animation-delay: 0.1s; }
.stagger-item:nth-child(2) { animation-delay: 0.2s; }
.stagger-item:nth-child(3) { animation-delay: 0.3s; }

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
}

/* Layer promotion for complex animations */
.complex-animation {
    transform: translateZ(0);  /* Force GPU layer */
    will-change: transform;
}

/* Clean up will-change after animation */
/*
element.addEventListener('animationend', () => {
    element.style.willChange = 'auto';
});
*/

/* Efficient scroll animations */
.scroll-animate {
    transition: transform 0.1s ease-out;
    /* Short duration for responsiveness */
}

/* Throttle expensive updates */
/*
let ticking = false;

window.addEventListener('scroll', () => {
    if (!ticking) {
        requestAnimationFrame(() => {
            updateAnimation();
            ticking = false;
        });
        ticking = true;
    }
});
*/

/* Reduce animation complexity for mobile */
@media (max-width: 768px) {
    .complex-animation {
        animation: simpleAnimation 0.3s ease;
    }
}

/* Pause animations when not visible */
/*
const observer = new IntersectionObserver((entries) => {
    entries.forEach(entry => {
        if (entry.isIntersecting) {
            entry.target.style.animationPlayState = 'running';
        } else {
            entry.target.style.animationPlayState = 'paused';
        }
    });
});
*/

/* Efficient color transitions */
.color-change {
    /* Background-color is paint-only, relatively cheap */
    transition: background-color 0.2s ease;
}

/* Avoid filter animations on mobile */
@media (hover: none) {
    .filtered {
        /* Remove expensive filter animations on touch devices */
        filter: none;
    }
}

/* Use animation instead of transition for loops */
.infinite-loop {
    /* Animation is more efficient than transitioning back and forth */
    animation: rotate 2s linear infinite;
}

@keyframes rotate {
    to { transform: rotate(360deg); }
}

/* Batch DOM reads and writes */
/*
// BAD: Causes layout thrashing
elements.forEach(el => {
    const height = el.offsetHeight;  // Read
    el.style.height = height * 2 + 'px';  // Write
});

// GOOD: Batch reads, then writes
const heights = elements.map(el => el.offsetHeight);  // All reads
heights.forEach((height, i) => {
    elements[i].style.height = height * 2 + 'px';  // All writes
});
*/