/* Dark theme styles */
[data-theme="dark"] {
    --background-color: #1a1a1a;
    --card-bg: #2d2d2d;
    --text-color: #ffffff;
    --border-color: #404040;
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
}

[data-theme="dark"] .display {
    background: #1a1a1a;
}

[data-theme="dark"] .num-btn {
    background: #404040;
    color: #ffffff;
    border-color: #555;
}

[data-theme="dark"] .num-btn:hover {
    background: #555;
    border-color: var(--primary-color);
}

[data-theme="dark"] .sci-btn {
    background: #2a2a2a;
    color: var(--primary-color);
    border-color: #404040;
}

[data-theme="dark"] .sci-btn:hover {
    background: #404040;
    border-color: var(--primary-color);
}

[data-theme="dark"] .control-btn {
    background: #3e2723;
    color: #ff9800;
    border-color: #5d4037;
}

[data-theme="dark"] .control-btn:hover {
    background: #5d4037;
    border-color: #ff9800;
}

[data-theme="dark"] .memory-btn {
    background: #1b5e20;
    color: #81c784;
    border-color: #2e7d32;
}

[data-theme="dark"] .memory-btn:hover {
    background: #2e7d32;
    border-color: #81c784;
}

/* Theme transition */
.calculator {
    transition: background-color 0.3s ease, color 0.3s ease;
}

.btn {
    transition: all 0.3s ease;
}