:root {
    --primary-bg: #1a1a2e;
    --secondary-bg: #16213e;
    --tertiary-bg: #0f3460;
    --accent-color: #e94560;
    --text-color: #dcdcdc;
    --element-bg: #2c3e50;
    --element-border: #34495e;
    --feedback-correct: #2ecc71;
    --feedback-incorrect: #e74c3c;
    --font-display: 'Orbitron', sans-serif;
    --font-body: 'Roboto', sans-serif;
}

body {
    font-family: var(--font-body);
    background-color: var(--primary-bg);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    padding: 20px;
    box-sizing: border-box;
}

#game-container {
    width: 100%;
    max-width: 1400px;
    background-color: var(--secondary-bg);
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
    padding: 25px;
    border: 1px solid var(--tertiary-bg);
}

header {
    text-align: center;
    border-bottom: 2px solid var(--tertiary-bg);
    padding-bottom: 20px;
    margin-bottom: 20px;
}

header h1 {
    font-family: var(--font-display);
    color: var(--accent-color);
    font-size: 2.5em;
    margin: 0;
    text-shadow: 0 0 10px var(--accent-color);
}

#game-info {
    display: flex;
    justify-content: space-around;
    font-family: var(--font-display);
    font-size: 1.2em;
    margin-top: 15px;
}

#formula-display-container {
    background-color: var(--primary-bg);
    padding: 20px;
    border-radius: 8px;
    text-align: center;
    margin-bottom: 20px;
}

#current-formula {
    min-height: 60px;
    background: #111;
    border: 2px dashed var(--tertiary-bg);
    border-radius: 5px;
    padding: 10px;
    font-size: 2em;
    font-family: var(--font-display);
    display: flex;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
    margin-top: 10px;
}

#current-formula .formula-part {
    margin: 0 2px;
}

#current-formula .formula-part .symbol {
    color: var(--accent-color);
}

#current-formula .formula-part .count {
    font-size: 0.7em;
    vertical-align: sub;
    color: var(--text-color);
}


#feedback {
    margin-top: 15px;
    font-size: 1.1em;
    font-weight: bold;
    min-height: 24px;
}

.feedback-correct {
    color: var(--feedback-correct);
}

.feedback-incorrect {
    color: var(--feedback-incorrect);
}

#controls {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-bottom: 25px;
}

button {
    font-family: var(--font-display);
    padding: 12px 25px;
    font-size: 1em;
    border-radius: 5px;
    border: none;
    cursor: pointer;
    transition: all 0.3s ease;
    color: white;
}

#submit-btn { background-color: #27ae60; }
#submit-btn:hover { background-color: #2ecc71; box-shadow: 0 0 15px #2ecc71; }

#clear-btn { background-color: #f39c12; }
#clear-btn:hover { background-color: #f1c40f; box-shadow: 0 0 15px #f1c40f; }

#new-game-btn { background-color: var(--accent-color); }
#new-game-btn:hover { background-color: #ff6b81; box-shadow: 0 0 15px #ff6b81;}


#periodic-table-container {
    overflow-x: auto;
}

#periodic-table {
    display: grid;
    grid-template-columns: repeat(18, minmax(60px, 1fr));
    grid-template-rows: repeat(7, minmax(60px, 1fr));
    gap: 5px;
}

.element {
    background-color: var(--element-bg);
    border: 1px solid var(--element-border);
    padding: 5px;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s ease;
    border-radius: 4px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.element:hover {
    transform: scale(1.1);
    box-shadow: 0 0 15px var(--accent-color);
    border-color: var(--accent-color);
    z-index: 10;
}

.element .number {
    font-size: 0.7em;
    align-self: flex-start;
}

.element .symbol {
    font-size: 1.4em;
    font-weight: bold;
}

.element .name {
    font-size: 0.6em;
    word-break: break-all;
}

footer {
    text-align: center;
    margin-top: 25px;
    font-size: 0.9em;
    color: #888;
}

/* Modal Styling */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.7);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.modal-content {
    background: var(--secondary-bg);
    padding: 40px;
    border-radius: 10px;
    text-align: center;
    box-shadow: 0 0 20px rgba(0,0,0,0.5);
    border: 1px solid var(--accent-color);
}
.modal-content h2 {
    font-family: var(--font-display);
    color: var(--accent-color);
    margin-top: 0;
}
.modal-content button {
    background-color: var(--accent-color);
    margin-top: 20px;
}
.modal-content button:hover {
    background-color: #ff6b81;
}

/* Element Category Colors */
.alkali.metal { background-color: #c0392b; }
.alkaline.earth.metal { background-color: #e67e22; }
.lanthanide { background-color: #d35400; }
.actinide { background-color: #e74c3c; }
.transition.metal { background-color: #f1c40f; color: #333; }
.post-transition.metal { background-color: #2ecc71; }
.metalloid { background-color: #1abc9c; }
.polyatomic.nonmetal { background-color: #3498db; }
.diatomic.nonmetal { background-color: #2980b9; }
.noble.gas { background-color: #9b59b6; }
.unknown { background-color: #7f8c8d; }