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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    overflow-x: hidden;
}

.container {
    position: relative;
    max-width: 1200px;
    margin: 0 auto;
    padding: 40px 20px;
}

/* Hiệu ứng sao lấp lánh */
.stars {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 0;
}

.stars::before,
.stars::after {
    content: '✨';
    position: absolute;
    font-size: 20px;
    animation: twinkle 3s infinite;
}

.stars::before {
    top: 20%;
    left: 10%;
    animation-delay: 0s;
}

.stars::after {
    top: 60%;
    right: 15%;
    animation-delay: 1.5s;
}

@keyframes twinkle {
    0%, 100% { opacity: 0; transform: scale(0.5); }
    50% { opacity: 1; transform: scale(1.2); }
}

/* Header */
.header {
    text-align: center;
    margin-bottom: 60px;
    position: relative;
    z-index: 1;
    animation: fadeInDown 1s ease;
}

@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.title {
    font-size: 3.5rem;
    color: white;
    text-shadow: 3px 3px 6px rgba(0, 0, 0, 0.2);
    margin-bottom: 15px;
    animation: bounce 2s infinite;
}

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

.subtitle {
    font-size: 1.3rem;
    color: #f0e6ff;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

/* Cards */
.content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
    margin-bottom: 60px;
    position: relative;
    z-index: 1;
}

.card {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 30px;
    padding: 40px 30px;
    text-align: center;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    transition: all 0.3s ease;
    animation: fadeInUp 1s ease;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.card:nth-child(2) {
    animation-delay: 0.2s;
}

.card:nth-child(3) {
    animation-delay: 0.4s;
}

.card:hover {
    transform: translateY(-10px) scale(1.03);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.3);
}

.emoji-box {
    font-size: 4rem;
    margin-bottom: 20px;
    animation: rotate 3s ease-in-out infinite;
}

@keyframes rotate {
    0%, 100% { transform: rotate(0deg); }
    25% { transform: rotate(-10deg); }
    75% { transform: rotate(10deg); }
}

.card h2 {
    font-size: 1.8rem;
    color: #667eea;
    margin-bottom: 15px;
}

.card p {
    font-size: 1.1rem;
    color: #666;
    line-height: 1.6;
}

/* Interactive Section */
.interactive-section {
    text-align: center;
    margin-bottom: 60px;
    position: relative;
    z-index: 1;
}

.cute-button {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    color: white;
    font-size: 1.3rem;
    font-weight: bold;
    padding: 20px 50px;
    border: none;
    border-radius: 50px;
    cursor: pointer;
    box-shadow: 0 8px 20px rgba(245, 87, 108, 0.4);
    transition: all 0.3s ease;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

.cute-button:hover {
    transform: scale(1.1);
    box-shadow: 0 12px 30px rgba(245, 87, 108, 0.6);
}

.cute-button:active {
    transform: scale(0.95);
}

.message {
    margin-top: 30px;
    font-size: 2rem;
    color: white;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
    min-height: 40px;
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

/* Footer */
.footer {
    text-align: center;
    color: white;
    position: relative;
    z-index: 1;
}

.heart-container {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-bottom: 20px;
    font-size: 2rem;
}

.heart {
    display: inline-block;
    animation: heartbeat 1.5s ease-in-out infinite;
}

.heart:nth-child(1) { animation-delay: 0s; }
.heart:nth-child(2) { animation-delay: 0.2s; }
.heart:nth-child(3) { animation-delay: 0.4s; }
.heart:nth-child(4) { animation-delay: 0.6s; }
.heart:nth-child(5) { animation-delay: 0.8s; }

@keyframes heartbeat {
    0%, 100% { transform: scale(1); }
    10% { transform: scale(1.3); }
    20% { transform: scale(1); }
}

.footer p {
    font-size: 1.1rem;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

/* Responsive Design */
@media (max-width: 768px) {
    .title {
        font-size: 2.5rem;
    }
    
    .subtitle {
        font-size: 1.1rem;
    }
    
    .card {
        padding: 30px 20px;
    }
    
    .cute-button {
        font-size: 1.1rem;
        padding: 15px 35px;
    }
}