:root {
      --bg: #f5f5f7;
      --card: #ffffff;
      --primary: #0071e3;
      --text: #1d1d1f;
      --text-light: #86868b;
      --border: #e5e5e7;
      --radius: 24px;
      --accent: #ff0000;
  }

  * {
      box-sizing: border-box;
  }

  body {
      font-family: 'Plus Jakarta Sans', sans-serif;
      background-color: var(--bg);
      color: var(--text);
      margin: 0;
      display: flex;
      justify-content: center;
      align-items: center;
      min-height: 100vh;
      padding: 20px;
  }

  .container {
      width: 100%;
      max-width: 600px;
      background: var(--card);
      padding: 32px;
      border-radius: 32px;
      /* box-shadow: 0 20px 60px rgba(0,0,0,0.08); */
      border: 1px solid #e5e5e7;
      text-align: center;
      height: auto;
  }

  header {
      margin-bottom: 32px;
  }

  h1 {
      font-weight: 600;
      font-size: 2rem;
      margin: 0;
      letter-spacing: -0.8px;
  }

  header p {
      color: var(--text-light);
      margin-top: 8px;
      font-size: 1rem;
  }

  .workspace {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 20px;
      margin-bottom: 28px;
  }

  .canvas-box {
      background: #fbfbfd;
      border-radius: var(--radius);
      aspect-ratio: 1/1;
      position: relative;
      border: 1px solid var(--border);
      display: flex;
      align-items: center;
      justify-content: center;
      overflow: hidden;
  }

  .canvas-box img {
      max-width: 90%;
      max-height: 90%;
      object-fit: contain;
      border-radius: 12px;
      z-index: 2;
  }

  .label {
      position: absolute;
      top: 12px;
      left: 12px;
      background: rgba(255, 255, 255, 0.8);
      backdrop-filter: blur(10px);
      padding: 4px 10px;
      border-radius: 8px;
      font-size: 0.65rem;
      font-weight: 700;
      color: var(--text-light);
      border: 1px solid rgba(0, 0, 0, 0.03);
      z-index: 3;
  }

  .file-badge {
      position: absolute;
      bottom: 12px;
      font-size: 0.75rem;
      font-weight: 600;
      color: var(--primary);
      background: #fff;
      padding: 4px 10px;
      border-radius: 8px;
      box-shadow: 0 4px 10px rgba(0, 0, 0, 0.04);
      z-index: 3;
  }

  .settings-panel {
      margin-bottom: 28px;
      display: none;
      animation: fadeIn 0.4s ease-out;
      text-align: left;
  }

  @keyframes fadeIn {
      from {
          opacity: 0;
          transform: translateY(10px);
      }

      to {
          opacity: 1;
          transform: translateY(0);
      }
  }

  .settings-header {
      display: flex;
      justify-content: space-between;
      font-size: 0.85rem;
      font-weight: 600;
      margin-bottom: 12px;
      color: var(--text-light);
  }

  /* --- ENHANCED SLIDER UI --- */
  input[type=range] {
      -webkit-appearance: none;
      width: 100%;
      background: transparent;
      cursor: pointer;
  }

  /* Track */
  input[type=range]::-webkit-slider-runnable-track {
      width: 100%;
      height: 8px;
      background: #e5e5e7;
      border-radius: 10px;
      border: none;
  }

  /* Thumb (soprolo Style) */
  input[type=range]::-webkit-slider-thumb {
      -webkit-appearance: none;
      height: 24px;
      width: 24px;
      border-radius: 50%;
      background: #ffffff;
      border: 1px solid rgba(0, 0, 0, 0.1);
      box-shadow: 0 2px 5px rgba(0, 0, 0, 0.15);
      margin-top: -8px;
      /* Centers thumb on track */
      transition: transform 0.1s ease;
  }

  input[type=range]:active::-webkit-slider-thumb {
      transform: scale(1.1);
      background: var(--primary);
  }

  /* Firefox Support */
  input[type=range]::-moz-range-track {
      width: 100%;
      height: 8px;
      background: #e5e5e7;
      border-radius: 10px;
  }

  input[type=range]::-moz-range-thumb {
      height: 22px;
      width: 22px;
      border-radius: 50%;
      background: #fff;
      border: 1px solid rgba(0, 0, 0, 0.1);
  }

  /* Action Buttons */
  .action-bar {
      display: flex;
      gap: 12px;
  }

  .btn {
      flex: 1;
      padding: 16px;
      border-radius: 16px;
      border: none;
      font-family: inherit;
      font-weight: 600;
      font-size: 0.95rem;
      cursor: pointer;
      transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
      display: flex;
      align-items: center;
      justify-content: center;
      text-decoration: none;
  }

  .btn-secondary {
      background: #f2f2f7;
      color: var(--text);
  }

  .btn-primary {
      background: var(--primary);
      color: white;
  }

  .btn-primary:hover {
      transform: translateY(-1px);
      box-shadow: 0 4px 12px rgba(0, 113, 227, 0.2);
  }

  #fileInput {
      display: none;
  }

  .placeholder-text {
      color: #e5e5e7;
      font-size: 2rem;
      font-weight: 800;
      letter-spacing: 2px;
      position: absolute;
      z-index: 1;
  }

  @media (max-width: 600px) {
      body {
          align-items: flex-start;
          padding: 16px 16px 40px 16px;
      }

      .container {
          padding: 24px 16px;
          border-radius: 28px;
      }

      h1 {
          font-size: 1.6rem;
      }

      .workspace {
          grid-template-columns: 1fr;
          gap: 16px;
      }

      .canvas-box {
          aspect-ratio: 4/3;
      }

      .action-bar {
          flex-direction: column;
          gap: 10px;
      }

      .btn {
          width: 100%;
          padding: 18px;
      }
  }