:root {
  --primary-color: #ff6b9d;
  --secondary-color: #ffeef8;
  --text-color: #6a0572;
  --envelope-color: #ffcce6;
  --accent-color: #ff4081;
  --dark-color: #3a1c47;
}

* {
  box-sizing: border-box;
  -webkit-tap-highlight-color: transparent;
}

body {
  margin: 0;
  padding: 0;
  font-family: "Be Vietnam Pro", "Quicksand", sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background-image: url("https://images.unsplash.com/photo-1525310072745-f49212b5ac6d?q=80&w=1965&auto=format&fit=crop");
  background-size: cover;
  background-position: center;
  overflow: hidden;
  position: relative;
  touch-action: none;
  touch-action: pan-y; /* thay vì touch-action: none */
  -webkit-overflow-scrolling: touch; /* thêm dòng này */
}

.petal {
  position: absolute;
  background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><path d="M50 0 C20 20 20 80 50 100 C80 80 80 20 50 0 Z" fill="%23FFB6C1" opacity="0.8"/></svg>');
  background-size: contain;
  background-repeat: no-repeat;
  width: 20px;
  height: 20px;
  top: -50px;
  animation: fall linear infinite;
  pointer-events: none;
  z-index: 99;
  will-change: transform;
}

@keyframes fall {
  0% {
    transform: translateY(0vh) rotateZ(0deg);
    opacity: 1;
  }
  100% {
    transform: translateY(105vh) rotateZ(720deg);
    opacity: 0;
  }
}

.envelope-wrapper {
  position: relative;
  cursor: pointer;
  transition: all 1.5s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  z-index: 10;
  transform-origin: center;
  animation: bounce 2s infinite;
  max-width: 90vw;
  max-height: 60vh;
}

.envelope-wrapper:hover {
  transform: translateY(-10px);
  animation: none;
}

@keyframes bounce {
  0%,
  20%,
  50%,
  80%,
  100% {
    transform: translateY(0);
  }
  40% {
    transform: translateY(-15px);
  }
  60% {
    transform: translateY(-8px);
  }
}

.envelope {
  position: relative;
  width: 320px;
  height: 200px;
  background-color: var(--envelope-color);
  border-radius: 10px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
  display: flex;
  justify-content: center;
  align-items: center;
  max-width: 90vw;
  max-height: 60vh;
}

.envelope::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  border-top: 100px solid #ff99cc;
  border-left: 160px solid transparent;
  border-right: 160px solid transparent;
  z-index: 3;
  transform-origin: top;
  transition: transform 0.7s cubic-bezier(0.68, -0.55, 0.27, 1.55);
}

.envelope::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--envelope-color);
  border-top: 100px solid transparent;
  border-left: 160px solid #ffe6f2;
  border-right: 160px solid #ffe6f2;
  z-index: 1;
}

.heart {
  position: absolute;
  width: 40px;
  height: 40px;
  background: var(--primary-color);
  transform: rotate(-45deg);
  z-index: 4;
  opacity: 1;
  transition: opacity 0.5s;
}

.heart::before,
.heart::after {
  content: "";
  position: absolute;
  width: 40px;
  height: 40px;
  background: var(--primary-color);
  border-radius: 50%;
}

.heart::before {
  top: -20px;
  left: 0;
}

.heart::after {
  top: 0;
  left: 20px;
}

.open .envelope::before {
  transform: rotateX(180deg);
  z-index: 0;
}

.open .heart {
  opacity: 0;
}

.card {
  position: absolute;
  width: 300px;
  height: 180px;
  background: linear-gradient(135deg, #fff5f8 0%, #ffe6f2 100%);
  border-radius: 8px;
  top: 10px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s 0.7s, transform 0.5s 0.7s;
  pointer-events: none;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  color: var(--text-color);
  font-family: "Be Vietnam Pro", sans-serif;
  font-weight: 500;
  max-width: 85vw;
  max-height: 50vh;
}

.card p {
  margin: 10px 0;
  font-size: 1.1rem;
  font-weight: 600;
}

.card .tap-icon {
  font-size: 2.5rem;
  animation: tap 1s infinite;
  margin-bottom: 10px;
}

@keyframes tap {
  0%,
  100% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.2);
  }
}

.open .card {
  opacity: 1;
  transform: translateY(0);
}

.main-content {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  background: rgba(255, 238, 248, 0.95);
  backdrop-filter: blur(10px);
  opacity: 0;
  visibility: hidden;
  transition: opacity 1.2s, visibility 1.2s;
  z-index: 100;
  padding: 20px;
  box-sizing: border-box;
  overflow-y: auto;
  touch-action: pan-y;
}

.main-content.visible {
  opacity: 1;
  visibility: visible;
}

#greeting {
  font-family: "Dancing Script", cursive;
  font-size: 2.5rem;
  color: var(--primary-color);
  margin-bottom: 20px;
  min-height: 100px;
  text-align: center;
  padding: 0 10px;
}

.swiper-container {
  width: 90%;
  max-width: 700px;
  height: 450px;
  border-radius: 20px;
  box-shadow: 0 15px 50px rgba(0, 0, 0, 0.3);
  margin-bottom: 30px;
  overflow: hidden;
  touch-action: pan-y;
}

.swiper-slide {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  background: linear-gradient(135deg, #fff5f8 0%, #ffe6f2 100%);
  color: var(--text-color);
  text-align: center;
  padding: 30px;
  box-sizing: border-box;
  position: relative;
}

.slide-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  width: 100%;
}

.slide-content h3 {
  font-family: "Dancing Script", cursive;
  font-size: 2.5rem;
  margin-top: 0;
  margin-bottom: 20px;
  color: var(--primary-color);
  font-weight: 700;
}

.slide-content p {
  font-size: 1.15rem;
  line-height: 1.8;
  max-width: 90%;
  margin: 0 auto 20px;
  font-weight: 400;
  color: var(--dark-color);
}

.slide-image {
  width: 100%;
  max-width: 400px;
  height: 200px;
  object-fit: cover;
  border-radius: 15px;
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
  transition: transform 0.3s ease;
}

.slide-image:hover {
  transform: scale(1.03);
}

.swiper-button-next,
.swiper-button-prev {
  display: none;
}

.swiper-pagination-bullet {
  background: var(--primary-color);
  opacity: 0.5;
  width: 12px;
  height: 12px;
}

.swiper-pagination-bullet-active {
  background: var(--primary-color);
  opacity: 1;
  width: 30px;
  border-radius: 6px;
}

.swipe-hint {
  margin-top: 15px;
  color: var(--text-color);
  font-size: 0.95rem;
  display: flex;
  align-items: center;
  gap: 8px;
  animation: fadeInOut 2s infinite;
}

@keyframes fadeInOut {
  0%,
  100% {
    opacity: 0.5;
  }
  50% {
    opacity: 1;
  }
}

.signature {
  margin-top: 25px;
  margin-bottom: 20px;
  text-align: center;
  color: var(--primary-color);
  font-size: 1.2rem;
  font-weight: 600;
  font-family: "Dancing Script", cursive;
  text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.1);
  padding: 0 10px;
}

.footer {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: linear-gradient(to top, rgba(255, 107, 157, 0.9), transparent);
  padding: 15px 20px;
  text-align: center;
  color: white;
  font-size: 0.95rem;
  font-weight: 500;
  z-index: 102;
  backdrop-filter: blur(5px);
}

.footer-hidden {
  display: none;
}

.action-buttons {
  display: none;
}

.action-btn {
  display: none;
}

.share-buttons {
  display: none;
}

.share-btn {
  display: none;
}

.facebook-btn {
  display: none;
}

.zalo-btn {
  display: none;
}

@media (max-width: 768px) {
  body {
    touch-action: pan-y;
  }

  #greeting {
    font-size: 2rem;
    min-height: 80px;
  }

  .swiper-container {
    height: 400px;
    max-width: 95%;
    border-radius: 15px;
  }

  .swiper-slide {
    padding: 25px 20px;
  }

  .slide-content h3 {
    font-size: 2rem;
  }

  .slide-content p {
    font-size: 1rem;
  }

  .slide-image {
    height: 180px;
  }

  .signature {
    font-size: 1rem;
  }

  .swipe-hint {
    font-size: 0.85rem;
  }
}

@media (max-width: 480px) {
  .envelope {
    width: 280px;
    height: 180px;
  }

  .envelope::before {
    border-left-width: 140px;
    border-right-width: 140px;
    border-top-width: 90px;
  }

  .envelope::after {
    border-left-width: 140px;
    border-right-width: 140px;
    border-top-width: 90px;
  }

  .card {
    width: 260px;
    height: 160px;
  }

  .card p {
    font-size: 0.9rem;
  }

  #greeting {
    font-size: 1.5rem;
    min-height: 60px;
  }

  .swiper-container {
    height: 380px;
    max-width: 95%;
  }

  .swiper-slide {
    padding: 20px 15px;
  }

  .slide-content h3 {
    font-size: 1.6rem;
    margin-bottom: 15px;
  }

  .slide-content p {
    font-size: 0.9rem;
    line-height: 1.6;
    margin-bottom: 15px;
  }

  .slide-image {
    height: 160px;
  }

  .signature {
    font-size: 0.95rem;
  }

  .swipe-hint {
    font-size: 0.8rem;
  }

  .footer {
    font-size: 0.85rem;
    padding: 12px 15px;
  }

  .petal {
    width: 15px;
    height: 15px;
  }
}

@media (max-width: 360px) {
  .envelope {
    width: 240px;
    height: 150px;
  }

  .envelope::before {
    border-left-width: 120px;
    border-right-width: 120px;
    border-top-width: 75px;
  }

  .envelope::after {
    border-left-width: 120px;
    border-right-width: 120px;
    border-top-width: 75px;
  }

  .card {
    width: 220px;
    height: 130px;
  }

  .card p {
    font-size: 0.8rem;
  }

  #greeting {
    font-size: 1.3rem;
    min-height: 50px;
  }

  .swiper-container {
    height: 360px;
  }

  .swiper-slide {
    padding: 15px 10px;
  }

  .slide-content h3 {
    font-size: 1.4rem;
  }

  .slide-content p {
    font-size: 0.8rem;
  }

  .slide-image {
    height: 140px;
  }

  .signature {
    font-size: 0.85rem;
  }
}

@media (min-width: 1200px) {
  .swiper-container {
    max-width: 800px;
    height: 500px;
  }

  .slide-content h3 {
    font-size: 2.8rem;
  }

  .slide-content p {
    font-size: 1.25rem;
  }

  .slide-image {
    height: 220px;
  }
}