:root {
  --primary-color: #fec200;
  --primary-light: #feda00;
  --primary-dark: #e6ac00;
  --dark-900: #111827;
  --dark-800: #1f2937;
  --dark-700: #374151;
  --dark-600: #4b5563;
  --dark-500: #6b7280;
  --dark-400: #9ca3af;
  --dark-300: #d1d5db;
  --light-100: #f3f4f6;
  --light-200: #e5e7eb;
  --success: #10b981;
  --error: #ef4444;
  --warning: #f59e0b;
  --info: #3b82f6;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow: 0 4px 6px rgba(0, 0, 0, 0.1), 0 1px 3px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  --transition: all 0.3s ease;
  --border-radius: 8px;
  --border-radius-lg: 12px;
  --border-radius-xl: 16px;
  --container-width: 1200px;
  --font-main: 'Montserrat', sans-serif;
  --font-secondary: 'Roboto', sans-serif;
}

.back-to-top {
    position: fixed;
    bottom: 1.5rem;
    left: 1.5rem;
    width: 3.5rem;
    height: 3.5rem;
    background: var(--dark-800);
    border: 1px solid var(--dark-700);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
    cursor: pointer;
    z-index: 100;
    transition: var(--transition);
    opacity: 0;
    visibility: hidden;
    box-shadow: var(--shadow);
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background: var(--primary-color);
    color: var(--dark-900);
}