* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.container {
    width: 90%;
    max-width: 500px;
    perspective: 1000px;
}

.card {
    width: 100%;
    height: 500px;
    position: relative;
    cursor: pointer;
    transition: transform 0.5s;
    transform-style: preserve-3d;
}

.card.flipped {
    transform: rotateY(180deg);
}

.card-front {
    position: absolute;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #ff6b6b 0%, #ee5a6f 100%);
    color: white;
    border-radius: 20px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 40px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    backface-visibility: hidden;
    transform: rotateY(0deg);
}

.card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    color: white;
    border-radius: 20px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 40px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    transform: rotateY(180deg);
    backface-visibility: hidden;
}

.card-front h1 {
    font-size: 2.5em;
    margin-bottom: 20px;
    animation: pulse 2s infinite;
}

.card-back h2 {
    font-size: 2em;
    margin-bottom: 20px;
}

.card-back p {
    font-size: 1.2em;
    line-height: 1.8;
    margin-bottom: 15px;
}

.signature {
    margin-top: 30px;
    font-size: 1.3em;
    font-style: italic;
}

@keyframes pulse {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.1);
    }
    100% {
        transform: scale(1);
    }
}

.hearts {
    margin-top: 30px;
    display: flex;
    gap: 15px;
}

.hearts span {
    font-size: 2em;
    animation: float 2s ease-in-out infinite;
}

.hearts span:nth-child(1) {
    animation-delay: 0s;
}

.hearts span:nth-child(2) {
    animation-delay: 0.5s;
}

.hearts span:nth-child(3) {
    animation-delay: 1s;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-15px);
    }
}

@media (max-width: 600px) {
    .card {
        height: 400px;
    }
    
    .card-front h1 {
        font-size: 2em;
    }
    
    .card-back h2 {
        font-size: 1.5em;
    }
    
    .card-back p {
        font-size: 1em;
    }
}