Ink Transition Effect (Modern Edition) — модальное окно с анимацией чернил

<style>
/* --------------------------------
  Reset / Base
-------------------------------- */
*,
*::before,
*::after {
  box-sizing: border-box;
}

:root {
  --color-text: #242322;
  --color-bg: #ffffff;
  --color-accent: #a5c4bc;
  --color-main-bg: #e4dcca;
  --color-modal-bg: #402f44;
  --font-body: "PT Sans", system-ui, sans-serif;
  --font-heading: "IM Fell Double Pica", Georgia, serif;
}

html {
  font-size: 62.5%;
}

body {
  margin: 0;
  font-size: 1.6rem;
  font-family: var(--font-body);
  color: var(--color-text);
  background-color: var(--color-bg);
}

a {
  color: var(--color-accent);
  text-decoration: none;
}

/* --------------------------------
  Typography
-------------------------------- */
h1 {
  font-size: clamp(2.6rem, 4vw + 1rem, 5rem);
  line-height: 1.1;
  margin: 0 0 1em;
  font-family: var(--font-heading);
  font-style: italic;
}

/* --------------------------------
  Buttons
-------------------------------- */
.btn {
  display: inline-block;
  padding: 1.6em 2.4em;
  font-size: 1.4rem;
  font-family: inherit;
  letter-spacing: 0.15em;
  color: #ffffff;
  font-weight: 700;
  text-transform: uppercase;
  background-color: var(--color-accent);
  border: none;
  cursor: pointer;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
  transition: box-shadow 0.3s, transform 0.2s;
}

@media (hover: hover) {
  .btn:hover {
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.1);
  }
}

.btn:focus-visible {
  outline: 3px solid #402f44;
  outline-offset: 4px;
}

/* --------------------------------
  Main content
-------------------------------- */
.main-content {
  position: relative;
  z-index: 1;
  width: 100%;
  min-height: 100vh;
  min-height: 100dvh;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-main-bg);
  padding: 2rem;
  text-align: center;
}

/* --------------------------------
  Modal
-------------------------------- */
.modal {
  position: fixed;
  inset: 0;
  z-index: 3;
  height: 100%;
  width: 100%;
  overflow: hidden;
  background: var(--color-modal-bg) url("../effect/img/modal-bg.jpg")
  no-repeat center center;
  background-size: cover;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s 0s, visibility 0s 0.3s;
}

.modal.is-visible {
  opacity: 1;
  visibility: visible;
  transition: opacity 0.7s, visibility 0s;
}

.modal__content {
  height: 100%;
  overflow-y: auto;
  padding: 3em 5%;
  color: var(--color-main-bg);
  -webkit-font-smoothing: antialiased;
  -webkit-overflow-scrolling: touch;
  text-align: center;
}

.modal__content h1::after {
  content: "";
  display: block;
  width: 130px;
  height: 18px;
  background: url("../effect/img/ink-separation.svg") no-repeat center center;
  margin: 0.2em auto 0;
}

.modal__content p {
  line-height: 1.6;
  margin: 2em auto;
  max-width: 800px;
}

.modal__close {
  position: absolute;
  z-index: 1;
  top: 20px;
  right: 5%;
  height: 45px;
  width: 45px;
  padding: 0;
  border: none;
  border-radius: 50%;
  background: rgba(0, 0, 0, 0.3)
  url("../effect/img/cd-icon-close.svg") no-repeat center center;
  cursor: pointer;
  visibility: hidden;
  opacity: 0;
  transform: scale(0);
  transition: transform 0.3s 0s, visibility 0s 0.3s, opacity 0.3s 0s;
}

@media (hover: hover) {
  .modal__close:hover {
  background-color: rgba(0, 0, 0, 0.5);
  }
}

.modal__close:focus-visible {
  outline: 3px solid #fff;
  outline-offset: 3px;
}

.modal.is-visible .modal__close {
  visibility: visible;
  opacity: 1;
  transform: scale(1);
  transition: transform 0.3s 0s, visibility 0s 0s, opacity 0.3s 0s;
}

@media (min-width: 1100px) {
  .modal__content {
  padding: 6em 5%;
  }

  .modal__close {
  height: 60px;
  width: 60px;
  }

  .modal__content p {
  font-size: 2rem;
  }
}

/* --------------------------------
  Transition layer
-------------------------------- */
.transition-layer {
  position: fixed;
  inset: 0;
  z-index: 2;
  height: 100%;
  width: 100%;
  opacity: 0;
  visibility: hidden;
  overflow: hidden;
  pointer-events: none;
}

.transition-layer.is-visible {
  opacity: 1;
  visibility: visible;
}

.transition-layer__bg {
  position: absolute;
  left: 50%;
  top: 50%;
  height: 100%;
  width: 2500%;
  background: url("../effect/img/ink.png") no-repeat 0 0;
  background-size: 100% 100%;
  transform: translate(-2%, -50%);
  will-change: transform;
}

.transition-layer.is-opening .transition-layer__bg {
  animation: cd-sequence 0.8s steps(24) forwards;
}

.transition-layer.is-closing .transition-layer__bg {
  animation: cd-sequence-reverse 0.8s steps(24) forwards;
}

@keyframes cd-sequence {
  0% {
  transform: translate(-2%, -50%);
  }
  100% {
  transform: translate(-98%, -50%);
  }
}

@keyframes cd-sequence-reverse {
  0% {
  transform: translate(-98%, -50%);
  }
  100% {
  transform: translate(-2%, -50%);
  }
}

/* Fallback для пользователей, предпочитающих меньше анимаций */
@media (prefers-reduced-motion: reduce) {
  .transition-layer {
  display: none;
  }
  .modal,
  .modal__close {
  transition-duration: 0.01ms !important;
  }
}

/* --------------------------------
  Utilities
-------------------------------- */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}
</style>

  <link
  href="https://fonts.googleapis.com/css2?family=IM+Fell+Double+Pica:ital@0;1&family=PT+Sans:wght@400;700&display=swap"
  rel="stylesheet"
  />

  <main class="main-content">
  <div class="center">
  <h1>Ink Transition Effect</h1>
  <button type="button" class="btn modal-trigger" aria-haspopup="dialog">
  Start Effect
  </button>
  </div>
  </main>

  <div
  class="modal"
  role="dialog"
  aria-modal="true"
  aria-labelledby="modal-title"
  aria-hidden="true"
  >
  <div class="modal__content">
  <h1 id="modal-title">My Modal Content</h1>
  <p>
  Lorem ipsum dolor sit amet, consectetur adipisicing elit.
  Ad modi repellendus, optio eveniet eligendi molestiae?
  Fugiat, temporibus!
  </p>
  </div>
  <button type="button" class="modal__close" aria-label="Закрыть окно">
  <span class="visually-hidden">Закрыть</span>
  </button>
  </div>

  <div class="transition-layer" aria-hidden="true">
  <div class="transition-layer__bg"></div>
  </div>

<script>
(() => {
  'use strict';

  const modalTrigger = document.querySelector('.modal-trigger');
  const modal = document.querySelector('.modal');
  const modalClose = document.querySelector('.modal__close');
  const transitionLayer = document.querySelector('.transition-layer');
  const transitionBg = transitionLayer.querySelector('.transition-layer__bg');

  const FRAME_PROPORTION = 1.78; // соотношение сторон одного кадра PNG
  const FRAMES = 25; // число кадров спрайта

  let lastFocusedElement = null;
  let isAnimating = false;

  /* ---------- Размеры спрайта ---------- */
  function setLayerDimensions() {
  const w = window.innerWidth;
  const h = window.innerHeight;
  let layerHeight;
  let layerWidth;

  if (w / h > FRAME_PROPORTION) {
  layerWidth = w;
  layerHeight = layerWidth / FRAME_PROPORTION;
  } else {
  layerHeight = h * 1.2;
  layerWidth = layerHeight * FRAME_PROPORTION;
  }

  transitionBg.style.width = `${layerWidth * FRAMES}px`;
  transitionBg.style.height = `${layerHeight}px`;
  }

  /* ---------- Оптимизированный resize ---------- */
  let resizeScheduled = false;
  function scheduleResize() {
  if (resizeScheduled) return;
  resizeScheduled = true;
  requestAnimationFrame(() => {
  setLayerDimensions();
  resizeScheduled = false;
  });
  }

  window.addEventListener('resize', scheduleResize, { passive: true });

  /* ---------- Открытие модального окна ---------- */
  function openModal() {
  if (isAnimating) return;
  isAnimating = true;

  lastFocusedElement = document.activeElement;

  transitionLayer.classList.add('is-visible', 'is-opening');
  modal.setAttribute('aria-hidden', 'false');

  const delay = 600;
  window.setTimeout(() => {
  modal.classList.add('is-visible');
  document.body.style.overflow = 'hidden';
  modalClose.focus();
  isAnimating = false;
  }, delay);
  }

  /* ---------- Закрытие модального окна ---------- */
  function closeModal() {
  if (isAnimating) return;
  isAnimating = true;

  transitionLayer.classList.add('is-closing');
  modal.classList.remove('is-visible');
  modal.setAttribute('aria-hidden', 'true');

  const onEnd = (event) => {
  if (event.target !== transitionBg) return;
  transitionBg.removeEventListener('animationend', onEnd);
  transitionLayer.classList.remove('is-closing', 'is-opening', 'is-visible');
  document.body.style.overflow = '';
  isAnimating = false;
  if (lastFocusedElement) lastFocusedElement.focus();
  };

  transitionBg.addEventListener('animationend', onEnd);
  }

  /* ---------- Ловушка фокуса внутри модального окна ---------- */
  function trapFocus(event) {
  if (event.key !== 'Tab') return;
  const focusable = modal.querySelectorAll(
  'a[href], button:not([disabled]), textarea, input, select, [tabindex]:not([tabindex="-1"])'
  );
  if (!focusable.length) return;

  const first = focusable[0];
  const last = focusable[focusable.length - 1];

  if (event.shiftKey && document.activeElement === first) {
  event.preventDefault();
  last.focus();
  } else if (!event.shiftKey && document.activeElement === last) {
  event.preventDefault();
  first.focus();
  }
  }

  /* ---------- События ---------- */
  modalTrigger.addEventListener('click', openModal);
  modalClose.addEventListener('click', closeModal);

  modal.addEventListener('keydown', trapFocus);

  document.addEventListener('keydown', (event) => {
  if (event.key === 'Escape' && modal.classList.contains('is-visible')) {
  closeModal();
  }
  });

  /* ---------- Инициализация ---------- */
  setLayerDimensions();

  /* ---------- Проверка поддержки CSS-анимаций ---------- */
  const supportsAnimations =
  'animation' in document.documentElement.style ||
  'webkitAnimation' in document.documentElement.style;

  if (!supportsAnimations) {
  transitionLayer.style.display = 'none';
  }
})();
</script>