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

body {
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    font-family: 'Courier New', monospace;
    background: linear-gradient(
        135deg,
        #667eea 0%,
        #764ba2 25%,
        #f093fb 50%,
        #4facfe 75%,
        #00f2fe 100%
    );
    background-size: 400% 400%;
    animation: gradientShift 15s ease infinite;
    overflow: hidden;
}

@keyframes gradientShift {
    0% {
        background-position: 0% 50%;
    }
    50% {
        background-position: 100% 50%;
    }
    100% {
        background-position: 0% 50%;
    }
}

.container {
    text-align: center;
    padding: 2rem;
}

.envelope-wrapper {
    margin-bottom: 2rem;
}

.envelope {
    width: 200px;
    height: 150px;
    filter: drop-shadow(0 10px 30px rgba(0, 0, 0, 0.3));
    animation: bounce 2s ease-in-out infinite;
}

@keyframes bounce {
    0%, 100% {
        transform: translateY(0) rotate(0deg);
    }
    25% {
        transform: translateY(-20px) rotate(-2deg);
    }
    50% {
        transform: translateY(-30px) rotate(0deg);
    }
    75% {
        transform: translateY(-20px) rotate(2deg);
    }
}

.envelope-body {
    fill: #ffffff;
    stroke: #333;
    stroke-width: 2;
}

.envelope-flap {
    fill: #ffeb3b;
    stroke: #333;
    stroke-width: 2;
    animation: flapColor 3s ease-in-out infinite;
}

@keyframes flapColor {
    0%, 100% {
        fill: #ffeb3b;
    }
    33% {
        fill: #ff6b6b;
    }
    66% {
        fill: #4ecdc4;
    }
}

.envelope-line {
    stroke: #333;
    stroke-width: 2;
}

.text-content {
    color: white;
    text-shadow: 2px 2px 8px rgba(0, 0, 0, 0.5);
}

.greeting {
    font-size: 3rem;
    font-weight: bold;
    margin-bottom: 1rem;
    color: white;
    animation: textFloat 3s ease-in-out infinite;
}

@keyframes textFloat {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-10px);
    }
}

.ascii-face {
    font-size: 4rem;
    font-weight: bold;
    letter-spacing: 0.5rem;
    animation: faceWiggle 1s ease-in-out infinite;
}

@keyframes faceWiggle {
    0%, 100% {
        transform: scale(1);
    }
    25% {
        transform: scale(1.05) rotate(-3deg);
    }
    75% {
        transform: scale(1.05) rotate(3deg);
    }
}

/* Responsive design */
@media (max-width: 768px) {
    .greeting {
        font-size: 2rem;
    }

    .ascii-face {
        font-size: 3rem;
    }

    .envelope {
        width: 150px;
        height: 112.5px;
    }
}

@media (max-width: 480px) {
    .greeting {
        font-size: 1.5rem;
    }

    .ascii-face {
        font-size: 2rem;
        letter-spacing: 0.3rem;
    }

    .envelope {
        width: 120px;
        height: 90px;
    }
}