:root {
    --color-theme-primary: #1e40af;
    --color-theme-secondary: #3b82f6;
}

body.dark-mode {
    --color-theme-primary: #3b82f6;
    --color-theme-secondary: #60a5fa;
}

.btn-toggle-theme {
    position: fixed;
    top: 20px;
    right: 20px;
    background: var(--color-theme-primary);
    color: white;
    border: none;
    border-radius: 50%;
    width: 45px;
    height: 45px;
    font-size: 1.2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 999;
    cursor: pointer;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.25);
    transition: all 0.3s ease;
}

.btn-toggle-theme:hover {
    background: var(--color-theme-secondary);
    transform: scale(1.1);
    box-shadow: 0 6px 16px rgba(30, 64, 175, 0.35);
}