body {
    font-family: 'Arial', sans-serif;
    background-color: #f0f2f5;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
}

.container {
    text-align: center;
    width: 100%;
    max-width: 800px;
    padding: 20px;
}

.header-section {
    position: relative;
    margin-bottom: 40px;
    display: flex;
    justify-content: center;
    align-items: center;
}

.header-buttons {
    position: absolute;
    right: 0;
    display: flex;
    gap: 10px;
}

h1 {
    color: #333;
    margin: 0;
}

.btn-rules, .btn-celebrate {
    padding: 8px 16px;
    background-color: #fff;
    border: 1px solid #ddd;
    border-radius: 20px;
    cursor: pointer;
    font-size: 14px;
    color: #555;
    transition: all 0.2s;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
}

.btn-celebrate {
    background: linear-gradient(135deg, #ff9a9e 0%, #fecfef 99%, #fecfef 100%);
    color: #fff;
    border: none;
    font-weight: bold;
}

.btn-rules:hover, .btn-celebrate:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.btn-rules:hover {
    background-color: #f8f9fa;
}

.btn-celebrate:hover {
    filter: brightness(1.05);
}

.cards-container {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
    margin-bottom: 40px;
}

.card {
    background: linear-gradient(135deg, #6e8efb, #a777e3);
    border-radius: 15px;
    height: 150px;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: default;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    transition: transform 0.2s, box-shadow 0.2s;
    color: white;
    font-size: 24px;
    font-weight: bold;
    user-select: none;
    position: relative; /* Required for absolute positioning of controls */
    overflow: hidden;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.2);
}

.card-content {
    transition: opacity 0.3s;
}

/* Hide text content on hover to make room for controls */
.card:hover .card-content {
    opacity: 0.1;
    filter: blur(2px);
}

.card-controls {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 15px;
    opacity: 0;
    transition: opacity 0.3s;
    background-color: rgba(0,0,0,0.2); /* Slight overlay */
}

.card:hover .card-controls {
    opacity: 1;
}

.control-btn {
    background-color: rgba(255, 255, 255, 0.9);
    border: none;
    border-radius: 50%;
    width: 50px;
    height: 50px;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    color: #333;
    transition: transform 0.2s, background-color 0.2s;
    box-shadow: 0 2px 8px rgba(0,0,0,0.2);
}

.control-btn:hover {
    transform: scale(1.1);
    background-color: #fff;
}

.control-btn:active {
    transform: scale(0.95);
}

.hidden {
    display: none !important;
}

/* Different colors for different decades */
.card[data-decade="70"] { background: linear-gradient(135deg, #ff9966, #ff5e62); }
.card[data-decade="80"] { background: linear-gradient(135deg, #fce38a, #f38181); }
.card[data-decade="90"] { background: linear-gradient(135deg, #42275a, #734b6d); }
.card[data-decade="00"] { background: linear-gradient(135deg, #11998e, #38ef7d); }
.card[data-decade="10"] { background: linear-gradient(135deg, #00b09b, #96c93d); }
.card[data-decade="20"] { background: linear-gradient(135deg, #8E2DE2, #4A00E0); }

/* Modal Styles */
.modal {
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
    display: flex;
    justify-content: center;
    align-items: center;
    animation: fadeIn 0.3s;
}

.modal-content {
    background-color: white;
    padding: 30px;
    border-radius: 15px;
    width: 90%;
    max-width: 500px;
    position: relative;
    box-shadow: 0 5px 30px rgba(0,0,0,0.3);
    animation: slideIn 0.3s;
}

.close {
    position: absolute;
    top: 15px;
    right: 20px;
    font-size: 28px;
    font-weight: bold;
    color: #aaa;
    cursor: pointer;
    transition: color 0.2s;
}

.close:hover {
    color: #333;
}

.modal-content h2 {
    margin-top: 0;
    color: #333;
    text-align: center;
    margin-bottom: 25px;
    border-bottom: 2px solid #f0f2f5;
    padding-bottom: 15px;
}

.rules-list {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.rule-item {
    display: flex;
    align-items: flex-start;
    gap: 15px;
}

.rule-icon {
    font-size: 24px;
    background-color: #f0f2f5;
    width: 45px;
    height: 45px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-shrink: 0;
}

.rule-text h3 {
    margin: 0 0 5px 0;
    font-size: 16px;
    color: #333;
}

.rule-text p {
    margin: 0;
    color: #666;
    font-size: 14px;
    line-height: 1.5;
}

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

@keyframes slideIn {
    from { transform: translateY(-20px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

.footer {
    margin-top: 60px;
    font-size: 14px;
    color: #7f8c8d;
    font-weight: 500;
    letter-spacing: 1px;
    opacity: 0.8;
}