:root {
    --bg-color: #f8f9fa;
    --text-color: #333;
    --card-bg: #ffffff;
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --shadow-color: rgba(0, 0, 0, 0.1);
}

/* Dark theme */
[data-theme="dark"] {
    --bg-color: #1a1a1a;
    --text-color: #e0e0e0;
    --card-bg: #2d2d2d;
    --primary-color: #ecf0f1;
    --secondary-color: #5dade2;
    --accent-color: #ec7063;
    --shadow-color: rgba(0, 0, 0, 0.5);
}

/* Theme toggle button */
#theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    padding: 12px 16px;
    border: 2px solid var(--secondary-color);
    border-radius: 50%;
    background-color: var(--card-bg);
    color: var(--text-color);
    cursor: pointer;
    transition: all 0.3s;
    z-index: 1000;
    box-shadow: 0 2px 8px var(--shadow-color);
    display: flex;
    align-items: center;
    justify-content: center;
}

#theme-toggle:hover {
    transform: scale(1.1);
    box-shadow: 0 4px 12px var(--shadow-color);
}

#theme-toggle:active {
    transform: scale(0.95);
}

/* Theme icon styling */
.theme-icon {
    font-size: 20px;
    color: var(--secondary-color);
    transition: transform 0.3s, color 0.3s;
}

[data-theme="dark"] .theme-icon {
    color: #ffd43b; /* Bright yellow for sun in dark mode */
}

#theme-toggle:hover .theme-icon {
    transform: rotate(20deg);
}