:root {
      --bg: #020617;
      --card: #020617;
      --accent: #38bdf8;
      --accent-soft: rgba(56, 189, 248, 0.12);
      --accent-2: #a855f7;
      --text: #e5e7eb;
      --muted: #9ca3af;
      --danger: #fecaca;
      --radius-lg: 22px;
      --radius-md: 12px;
      --shadow-soft: 0 22px 55px rgba(15, 23, 42, 0.9);
    }

    * {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      min-height: 100vh;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
      background:
        radial-gradient(circle at top, #1d4ed8 0, #020617 45%, #000 100%);
      color: var(--text);
      display: flex;
      align-items: center;
      justify-content: center;
      padding: 1.5rem;
    }

    .shell {
      width: 100%;
      max-width: 1040px;
      background:
        radial-gradient(circle at top left, rgba(56, 189, 248, 0.18), transparent 55%),
        radial-gradient(circle at bottom right, rgba(168, 85, 247, 0.22), transparent 60%),
        rgba(15, 23, 42, 0.95);
      border-radius: 28px;
      box-shadow: var(--shadow-soft);
      border: 1px solid rgba(148, 163, 184, 0.35);
      display: grid;
      grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
      overflow: hidden;
    }

    @media (max-width: 880px) {
      .shell {
        grid-template-columns: minmax(0, 1fr);
      }
    }

    .main {
      padding: 1.9rem 2.1rem 1.7rem;
    }

    @media (max-width: 600px) {
      .main {
        padding: 1.6rem 1.4rem;
      }
    }

    .aside {
      padding: 1.7rem 1.8rem;
      background:
        radial-gradient(circle at top, rgba(56, 189, 248, 0.2), transparent 55%),
        radial-gradient(circle at bottom, rgba(15, 23, 42, 1), #020617);
      border-left: 1px solid rgba(148, 163, 184, 0.4);
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 1rem;
    }

    @media (max-width: 880px) {
      .aside {
        border-left: none;
        border-top: 1px solid rgba(148, 163, 184, 0.4);
      }
    }

    .header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      gap: 1rem;
      margin-bottom: 1.4rem;
    }

    .brand {
      display: flex;
      align-items: center;
      gap: 0.8rem;
    }

    .brand-logo {
      width: 38px;
      height: 38px;
      border-radius: 999px;
      background:
        radial-gradient(circle at 30% 30%, #e0f2fe 0, #38bdf8 40%, #020617 100%);
      display: flex;
      align-items: center;
      justify-content: center;
      color: #0f172a;
      font-size: 1rem;
      font-weight: 700;
      box-shadow: 0 0 26px rgba(56, 189, 248, 0.8);
    }

    .brand-title {
      font-size: 0.95rem;
      font-weight: 600;
    }

    .brand-sub {
      font-size: 0.75rem;
      color: var(--muted);
    }

    .tag {
      font-size: 0.72rem;
      border-radius: 999px;
      border: 1px solid rgba(148, 163, 184, 0.7);
      padding: 0.18rem 0.7rem;
      text-transform: uppercase;
      letter-spacing: 0.08em;
      color: var(--muted);
      background: rgba(15, 23, 42, 0.8);
    }

    h1 {
      margin: 0 0 0.35rem;
      font-size: 1.7rem;
    }

    @media (max-width: 600px) {
      h1 {
        font-size: 1.45rem;
      }
    }

    .subtitle {
      font-size: 0.9rem;
      color: var(--muted);
      max-width: 36rem;
    }

    .form-grid {
      margin-top: 1.6rem;
      display: grid;
      gap: 1.1rem;
    }

    label {
      display: block;
      font-size: 0.8rem;
      color: var(--muted);
      margin-bottom: 0.2rem;
    }

    .field {
      background: rgba(15, 23, 42, 0.96);
      border-radius: var(--radius-md);
      border: 1px solid rgba(148, 163, 184, 0.5);
      padding: 0.6rem 0.8rem;
      display: flex;
      align-items: center;
      gap: 0.45rem;
    }

    .field span.icon {
      font-size: 0.9rem;
      color: var(--muted);
    }

    input[type="url"],
    input[type="text"],
    select {
      flex: 1;
      border: none;
      outline: none;
      background: transparent;
      color: var(--text);
      font: inherit;
    }

    input::placeholder {
      color: #6b7280;
    }

    input[type="file"] {
      font-size: 0.76rem;
      color: var(--muted);
    }

    .hint {
      margin-top: 0.25rem;
      font-size: 0.75rem;
      color: var(--muted);
    }

    .hint strong {
      color: var(--text);
    }

    .row-2cols {
      display: grid;
      grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
      gap: 0.8rem;
    }

    @media (max-width: 700px) {
      .row-2cols {
        grid-template-columns: minmax(0, 1fr);
      }
    }

    .actions {
      margin-top: 1.2rem;
      display: flex;
      align-items: center;
      gap: 0.8rem;
      flex-wrap: wrap;
    }

    button.primary {
      border: none;
      border-radius: 999px;
      padding: 0.55rem 1.5rem;
      font-size: 0.9rem;
      font-weight: 500;
      cursor: pointer;
      background: linear-gradient(135deg, #3b82f6, #22c55e);
      color: white;
      display: inline-flex;
      align-items: center;
      gap: 0.35rem;
      box-shadow: 0 14px 32px rgba(59, 130, 246, 0.6);
      transition: transform 0.15s ease, box-shadow 0.15s ease, filter 0.15s ease;
    }

    button.primary:hover {
      transform: translateY(-1px);
      filter: brightness(1.05);
      box-shadow: 0 18px 40px rgba(59, 130, 246, 0.8);
    }

    button.primary:active {
      transform: translateY(0);
      box-shadow: 0 12px 26px rgba(59, 130, 246, 0.7);
    }

    .secondary-text {
      font-size: 0.78rem;
      color: var(--muted);
    }

    .secondary-text strong {
      color: var(--text);
    }

    .output {
      margin-top: 1.4rem;
      padding: 0.9rem 1rem;
      border-radius: var(--radius-md);
      background: rgba(15, 23, 42, 0.96);
      border: 1px solid rgba(148, 163, 184, 0.4);
      font-size: 0.8rem;
      display: none;
    }

    .output-label {
      font-size: 0.75rem;
      color: var(--muted);
      text-transform: uppercase;
      letter-spacing: 0.08em;
      margin-bottom: 0.25rem;
    }

    .output-url {
      word-break: break-all;
      color: var(--text);
    }

    .badge {
      display: inline-flex;
      align-items: center;
      gap: 0.28rem;
      margin-top: 0.4rem;
      font-size: 0.72rem;
      padding: 0.18rem 0.6rem;
      border-radius: 999px;
      background: var(--accent-soft);
      color: #bfdbfe;
      border: 1px solid rgba(59, 130, 246, 0.6);
    }

    .error {
      margin-top: 0.6rem;
      font-size: 0.8rem;
      color: var(--danger);
    }

    /* Aside (preview) */
    .preview-card {
      width: 100%;
      max-width: 280px;
      background: rgba(15, 23, 42, 0.96);
      border-radius: var(--radius-lg);
      padding: 1.1rem 1.05rem 1rem;
      border: 1px solid rgba(148, 163, 184, 0.55);
      box-shadow: 0 18px 40px rgba(15, 23, 42, 0.95);
      backdrop-filter: blur(18px);
    }

    .preview-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      gap: 0.6rem;
      margin-bottom: 0.8rem;
    }

    .preview-title {
      font-size: 0.9rem;
      font-weight: 500;
    }

    .preview-sub {
      font-size: 0.75rem;
      color: var(--muted);
    }

    .preview-chip {
      font-size: 0.72rem;
      padding: 0.15rem 0.5rem;
      border-radius: 999px;
      background: rgba(56, 189, 248, 0.12);
      color: #e0f2fe;
      border: 1px solid rgba(56, 189, 248, 0.6);
    }

    .qr-preview-wrapper {
      display: flex;
      justify-content: center;
    }

    .qr-preview {
      position: relative;
      display: inline-block;
      padding: 0.45rem;
      border-radius: 18px;
      background: #020617;
    }

    #qrcode {
      background: white;
      border-radius: 14px;
      padding: 0.4rem;
      display: inline-block;
      min-width: 220px;
      min-height: 220px;
    }

    #qrcode canvas {
      width: 220px;
      height: 220px;
      image-rendering: pixelated;
      display: block;
    }

    .qr-logo-overlay {
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      width: 32%;
      height: 32%;
      object-fit: contain;
      border-radius: 10px;
      background: white;
      padding: 4px;
      box-shadow: 0 0 18px rgba(15, 23, 42, 0.7);
      display: none;
    }

    .preview-footer {
      margin-top: 0.8rem;
      font-size: 0.72rem;
      color: var(--muted);
      display: flex;
      justify-content: space-between;
      gap: 0.5rem;
      flex-wrap: wrap;
    }

    .status-dot {
      width: 7px;
      height: 7px;
      border-radius: 999px;
      background: #22c55e;
      box-shadow: 0 0 10px rgba(34, 197, 94, 0.95);
    }

    .download-actions {
      margin-top: 0.8rem;
      display: flex;
      justify-content: flex-start;
      gap: 0.4rem;
      align-items: center;
      flex-wrap: wrap;
    }

    .btn-ghost {
      border-radius: 999px;
      border: 1px solid rgba(148, 163, 184, 0.7);
      background: rgba(15, 23, 42, 0.9);
      color: var(--text);
      font-size: 0.78rem;
      padding: 0.35rem 0.9rem;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 0.3rem;
      transition: background 0.15s ease, border-color 0.15s ease, opacity 0.15s ease;
    }

    .btn-ghost:hover:enabled {
      background: rgba(30, 64, 175, 0.8);
      border-color: rgba(129, 140, 248, 0.9);
    }

    .btn-ghost:disabled {
      opacity: 0.45;
      cursor: default;
    }

    .download-select {
      border-radius: 999px;
      border: 1px solid rgba(148, 163, 184, 0.7);
      background: rgba(15, 23, 42, 0.9);
      color: var(--text);
      font-size: 0.76rem;
      padding: 0.3rem 0.7rem;
      outline: none;
    }

    /* Bloque de colores personalizados */
    .custom-colors {
      margin-top: 0.5rem;
    }

    .custom-colors .field {
      margin-bottom: 0.3rem;
    }