.tree-grid { 
    display: grid; 
    grid-template-columns: repeat(3, 1fr); 
    gap: 15px; 
    margin-top: 15px; 
}

.node { 
    padding: 15px; 
    background: #2f3542; 
    border-radius: 10px; 
    text-align: center; 
    border: 2px solid transparent; 
    cursor: pointer; 
    opacity: 0.5; 
    transition: 0.2s; 
}

.node.available { 
    border-color: var(--mana); 
    opacity: 1; 
}

.node.purchased { 
    background: #1b2e1b; 
    border-color: var(--unlocked); 
    color: var(--unlocked); 
    opacity: 1; 
    cursor: default; 
}