body {
    font-family: "Arial", sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    margin: 0;
    padding: 20px;
    min-height: 100vh;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 20px;
    padding: 30px;
    backdrop-filter: blur(10px);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
}

h1 {
    text-align: center;
    color: white;
    font-size: 2.5em;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

.subtitle {
    text-align: center;
    color: rgba(255, 255, 255, 0.8);
    margin-bottom: 30px;
    font-size: 1.2em;
}

.stats {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin-bottom: 30px;
}

.stat {
    background: rgba(255, 255, 255, 0.2);
    padding: 15px 25px;
    border-radius: 15px;
    color: white;
    text-align: center;
    backdrop-filter: blur(5px);
}

.stat-number {
    font-size: 2em;
    font-weight: bold;
    display: block;
}

.input-section {
    text-align: center;
    margin-bottom: 30px;
}

.input-group {
    display: inline-flex;
    gap: 15px;
    align-items: center;
    background: rgba(255, 255, 255, 0.2);
    padding: 20px;
    border-radius: 15px;
    backdrop-filter: blur(5px);
}

input {
    padding: 12px 20px;
    border: none;
    border-radius: 10px;
    font-size: 16px;
    background: rgba(255, 255, 255, 0.9);
    color: #333;
    min-width: 120px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

input:focus {
    outline: none;
    box-shadow: 0 0 20px rgba(255, 255, 255, 0.5);
}

button {
    padding: 12px 30px;
    background: linear-gradient(45deg, #ff6b6b, #ff8e8e);
    color: white;
    border: none;
    border-radius: 10px;
    font-size: 16px;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(255, 107, 107, 0.3);
}

button:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(255, 107, 107, 0.4);
}

.periodic-table {
    display: grid;
    grid-template-columns: repeat(18, 1fr);
    gap: 3px;
    margin: 0 auto;
    max-width: 1200px;
    background: rgba(255, 255, 255, 0.1);
    padding: 20px;
    border-radius: 15px;
    backdrop-filter: blur(5px);
}

.element {
    aspect-ratio: 1;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    font-size: 12px;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    min-height: 60px;
    background: rgba(255, 255, 255, 0.05);
}

.element.empty {
    background: rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.5);
}

.element.filled {
    background: linear-gradient(135deg, #4caf50, #45a049);
    color: white;
    border-color: #4caf50;
    box-shadow: 0 4px 15px rgba(76, 175, 80, 0.3);
}

.element.selected {
    background: linear-gradient(135deg, #2196f3, #1976d2);
    color: white;
    border-color: #2196f3;
    box-shadow: 0 4px 15px rgba(33, 150, 243, 0.4);
    transform: scale(1.1);
}

.element:hover:not(.filled) {
    background: rgba(255, 255, 255, 0.2);
    transform: scale(1.05);
}

.atomic-number {
    font-size: 10px;
    position: absolute;
    top: 2px;
    left: 4px;
    color: rgba(255, 255, 255, 0.7);
}

.symbol {
    font-size: 18px;
    font-weight: bold;
}

.name {
    font-size: 8px;
    text-align: center;
    margin-top: 2px;
    opacity: 0.9;
}

.feedback {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    padding: 20px 40px;
    border-radius: 15px;
    color: white;
    font-size: 18px;
    font-weight: bold;
    z-index: 1000;
    display: none;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
    backdrop-filter: blur(10px);
}

.feedback.correct {
    background: linear-gradient(135deg, #4caf50, #45a049);
}

.feedback.incorrect {
    background: linear-gradient(135deg, #f44336, #d32f2f);
}

.reset-btn {
    background: linear-gradient(45deg, #9c27b0, #673ab7);
    margin-left: 15px;
}

.reset-btn:hover {
    box-shadow: 0 8px 25px rgba(156, 39, 176, 0.4);
}

@media (max-width: 768px) {
    .periodic-table {
        grid-template-columns: repeat(18, minmax(30px, 1fr));
        gap: 2px;
        padding: 10px;
    }

    .element {
        min-height: 40px;
        font-size: 10px;
    }

    .symbol {
        font-size: 14px;
    }

    .name {
        font-size: 7px;
    }

    .input-group {
        flex-direction: column;
        gap: 10px;
    }

    .stats {
        flex-direction: column;
        gap: 15px;
    }
}