/* Animations */
.fade-in {
    animation: fadeIn var(--transition-slow) forwards;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes float {
    0% { transform: translateY(0px) rotate(0deg); }
    50% { transform: translateY(-10px) rotate(2deg); }
    100% { transform: translateY(0px) rotate(0deg); }
}

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

.envelope-container {
    text-align: center;
    cursor: pointer;
    transition: transform 0.3s ease;
}
.envelope-container:hover {
    transform: scale(1.05);
}
.envelope-img {
    width: 200px;
    height: auto;
    animation: float 4s ease-in-out infinite;
    mix-blend-mode: multiply;
    filter: contrast(1.3) brightness(1.1);
}
.hint-text {
    margin-top: 20px;
    color: var(--color-accent-pink);
    font-style: italic;
    opacity: 0.8;
}

#intro-date {
    font-size: 3rem;
    color: var(--color-text-main);
    letter-spacing: 2px;
}

.primary-btn {
    margin-top: 30px;
    padding: 10px 30px;
    border: 1px solid var(--color-accent-pink);
    color: var(--color-accent-pink);
    border-radius: 30px;
    font-size: 1.1rem;
    transition: all 0.3s ease;
}
.primary-btn:hover {
    background-color: var(--color-accent-pink);
    color: white;
}

@keyframes envelope-pop {
    0% { transform: scale(1); }
    50% { transform: scale(1.15) rotate(3deg); }
    70% { transform: scale(0.95) rotate(-2deg); }
    100% { transform: scale(1); }
}
.pop-open {
    animation: envelope-pop 0.5s ease-out forwards;
}