/* CSS Variables and base reset */
    :root {
      --color-bg: #ffffff;
      --color-text: #374151; /* Gray 700 */
      --color-text-muted: #6b7280; /* Gray 500 */
      --color-primary: #2563eb; /* Blue 600 */
      --color-primary-hover: #1d4ed8; /* Blue 700 */
      --color-card-bg: #f9fafb; /* Gray 50 */
      --color-input-border: #d1d5db; /* Gray 300 */
      --color-input-border-focus: var(--color-primary);
      --color-error: #dc2626; /* Red 600 */
      --font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
      --radius: 0.75rem;
      --shadow: 0 4px 12px rgba(0,0,0,0.08);
      --transition: 0.3s cubic-bezier(0.4,0,0.2,1);
      --max-width: 480px;
    }
    
    * {
      box-sizing: border-box;
    }
    body, html {
      margin: 0;
      padding: 0;
      height: 100%;
      background: var(--color-bg);
      font-family: var(--font-family);
      color: var(--color-text);
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }
    a {
      color: var(--color-primary);
      text-decoration: none;
      transition: color var(--transition);
    }
    a:hover,
    a:focus {
      color: var(--color-primary-hover);
      outline: none;
    }
    main {
      min-height: 100vh;
      display: flex;
      justify-content: center;
      align-items: center;
      padding: 2rem 1rem;
      position: relative;
      background: var(--color-bg);
      overflow: hidden;
    }
    .container {
      position: relative;
      width: 100%;
      max-width: var(--max-width);
      background: var(--color-card-bg);
      border-radius: var(--radius);
      box-shadow: var(--shadow);
      padding: 2.5rem 2rem 3rem;
      backdrop-filter: saturate(150%) blur(12px);
      -webkit-backdrop-filter: saturate(150%) blur(12px);
      transition: transform var(--transition);
    }
    h1 {
      font-weight: 700;
      font-size: 2.75rem;
      line-height: 1.1;
      margin: 0 0 0.75rem 0;
      user-select: none;
    }
    p.subtitle {
      margin: 0 0 2rem 0;
      color: var(--color-text-muted);
      font-size: 1rem;
      user-select: none;
    }
    form {
      display: flex;
      flex-direction: column;
      gap: 1.25rem;
      margin-top: 0.5rem;
    }
    label {
      font-size: 0.875rem;
      font-weight: 600;
      margin-bottom: 0.25rem;
      color: var(--color-text-muted);
    }
    input[type="email"],
    input[type="password"],
    input[type="text"] {
      padding: 0.75rem 1rem;
      font-size: 1rem;
      border-radius: var(--radius);
      border: 1.5px solid var(--color-input-border);
      transition: border-color var(--transition), box-shadow var(--transition);
      font-family: var(--font-family);
    }
    input[type="email"]:focus,
    input[type="password"]:focus,
    input[type="text"]:focus {
      outline: none;
      border-color: var(--color-input-border-focus);
      box-shadow: 0 0 0 3px rgba(37,99,235,0.3);
    }
    button {
      margin-top: 0.5rem;
      padding: 0.85rem 1rem;
      font-size: 1.125rem;
      font-weight: 700;
      background-color: var(--color-primary);
      color: white;
      border: none;
      border-radius: var(--radius);
      cursor: pointer;
      transition: background-color var(--transition), transform var(--transition);
      user-select: none;
    }
    button:hover,
    button:focus {
      background-color: var(--color-primary-hover);
      outline: none;
      transform: scale(1.02);
    }
    small {
      display: block;
      margin-top: 1rem;
      font-size: 0.875rem;
      color: var(--color-text-muted);
      text-align: center;
      user-select: none;
    }
    small a {
      font-weight: 600;
    }
    /* Page Containers */
    section.page {
      display: none;
      opacity: 0;
      transform: translateY(20px);
      transition: opacity var(--transition), transform var(--transition);
      position: relative;
      z-index: 1;
    }
    section.page.active {
      display: block;
      opacity: 1;
      transform: translateY(0);
    }
    /* Page specific backgrounds with subtle graphics */
    main#login {
      background: linear-gradient(135deg, #e0f2fe 0%, #bae6fd 100%);
      overflow: hidden;
    }
    main#register {
      background: linear-gradient(135deg, #d1fae5 0%, #6ee7b7 100%);
      overflow: hidden;
    }
    main#forgot-password {
      background: linear-gradient(135deg, #fef3c7 0%, #fde68a 100%);
      overflow: hidden;
    }
    /* Background svg container */
    .bg-svg {
      position: absolute;
      top: -40px;
      right: -40px;
      width: 300px;
      height: 300px;
      opacity: 0.15;
      pointer-events: none;
      user-select: none;
      z-index: 0;
      fill: none;
      stroke-linecap: round;
      stroke-linejoin: round;
      stroke-width: 2;
      stroke: #444;
    }
    /* Specific SVG shapes per page */
    main#login .bg-svg path {
      stroke: #2563eb;
    }
    main#register .bg-svg path {
      stroke: #059669;
    }
    main#forgot-password .bg-svg path {
      stroke: #ca8a04;
    }
    /* Links container for forms */
    .form-footer {
      margin-top: 1rem;
      text-align: center;
      font-size: 0.9rem;
      color: var(--color-text-muted);
      user-select: none;
    }
    /* Responsive */
    @media (max-width: 600px) {
      main {
        padding: 1rem;
      }
      .container {
        padding: 2rem 1.5rem 2.5rem;
      }
      h1 {
        font-size: 2rem;
      }
    }