:root {
      --bg-primary: #0d1117;
      --bg-secondary: #161b22;
      --text-primary: #c9d1d9;
      --text-secondary: #8b949e;
      --accent: #5e72e4;
      --accent-hover: #4a5fc1;
      --link: #58a6ff;
      --border: #30363d;
      --border-hover: #484f58;
      --shadow: 0 4px 12px rgba(1, 4, 9, 0.8);
      --radius-sm: 4px;
      --radius-md: 6px;
      --radius-lg: 8px;
      --transition: all 0.2s cubic-bezier(0.3, 0, 0.5, 1);
      --success: #238636;
      --error: #f85149;
    }
    
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    
    body {
      font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
      line-height: 1.6;
      color: var(--text-primary);
      background-color: var(--bg-primary);
      min-height: 100vh;
      padding: 2rem;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }
    
    .container {
      max-width: 600px;
      margin: 0 auto;
    }
    
    .card {
      background: var(--bg-secondary);
      border-radius: var(--radius-md);
      box-shadow: var(--shadow);
      border: 1px solid var(--border);
      padding: 2rem;
      margin-bottom: 2rem;
      transition: var(--transition);
    }
    
    h1 {
      color: var(--text-primary);
      text-align: center;
      margin-bottom: 1rem;
      font-weight: 600;
      font-size: 1.8rem;
    }
    
    .subtitle {
      text-align: center;
      color: var(--text-secondary);
      margin-bottom: 1.5rem;
      font-size: 1rem;
    }
    
    .upload-area {
      border: 2px dashed var(--border);
      border-radius: var(--radius-md);
      padding: 2.5rem 1rem;
      text-align: center;
      margin-bottom: 1.5rem;
      cursor: pointer;
      transition: var(--transition);
      position: relative;
      overflow: hidden;
    }
    
    .upload-area:hover {
      border-color: var(--accent);
      background: rgba(94, 114, 228, 0.05);
    }
    
    .upload-area i {
      font-size: 2.5rem;
      color: var(--accent);
      margin-bottom: 1rem;
    }
    
    .upload-area h3 {
      margin-bottom: 0.5rem;
      font-weight: 600;
      color: var(--text-primary);
    }
    
    .upload-area p {
      color: var(--text-secondary);
      font-size: 0.9rem;
    }
    
    #file-name {
      margin-top: 1rem;
      font-size: 0.9rem;
      color: var(--accent);
      font-weight: 500;
      word-break: break-all;
    }
    
    #file-size {
      font-size: 0.8rem;
      color: var(--text-secondary);
      margin-top: 0.25rem;
    }
    
    input[type="file"] {
      display: none;
    }
    
    .dimensions-container {
      display: flex;
      gap: 1rem;
      margin-bottom: 1rem;
    }
    
    .dimension-input {
      flex: 1;
    }
    
    .dimension-input label {
      display: block;
      margin-bottom: 0.5rem;
      font-size: 0.9rem;
      color: var(--text-secondary);
      font-weight: 500;
    }
    
    .dimension-input input {
      width: 100%;
      padding: 0.75rem 1rem;
      border: 1px solid var(--border);
      border-radius: var(--radius-sm);
      font-size: 1rem;
      transition: var(--transition);
      background-color: var(--bg-primary);
      color: var(--text-primary);
    }
    
    .dimension-input input:focus {
      outline: none;
      border-color: var(--accent);
      box-shadow: 0 0 0 3px rgba(94, 114, 228, 0.3);
    }
    
    .aspect-ratio-controls {
      display: flex;
      align-items: center;
      margin-bottom: 1.5rem;
      gap: 0.5rem;
    }
    
    .checkbox-container {
      display: flex;
      align-items: center;
    }
    
    .checkbox-container input[type="checkbox"] {
      margin-right: 0.5rem;
      width: 1rem;
      height: 1rem;
      accent-color: var(--accent);
    }
    
    .checkbox-container label {
      font-size: 0.9rem;
      color: var(--text-secondary);
      cursor: pointer;
    }
    
    .btn {
      background: var(--accent);
      color: white;
      border: none;
      padding: 0.75rem 1.5rem;
      border-radius: var(--radius-sm);
      font-size: 1rem;
      font-weight: 500;
      cursor: pointer;
      transition: var(--transition);
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 0.5rem;
      width: 100%;
    }
    
    .btn:hover {
      background: var(--accent-hover);
      transform: translateY(-1px);
      text-decoration: none;
    }
    
    .btn:active {
      transform: translateY(0);
    }
    
    .btn-secondary {
      background: var(--bg-secondary);
      color: var(--accent);
      border: 1px solid var(--accent);
      margin-top: 1rem;
    }
    
    .btn-secondary:hover {
      background: rgba(94, 114, 228, 0.1);
    }
    
    #result {
      margin-top: 1.5rem;
      padding: 1rem;
      border-radius: var(--radius-sm);
      font-weight: 500;
      text-align: center;
      display: none;
      border: 1px solid transparent;
    }
    
    .preview-container {
      margin: 1.5rem 0;
      text-align: center;
      display: none;
    }
    
    .preview-container h4 {
      margin-bottom: 0.5rem;
      font-weight: 600;
      color: var(--text-primary);
    }
    
    #preview {
      max-width: 100%;
      border-radius: var(--radius-sm);
      border: 1px solid var(--border);
      background-color: var(--bg-primary);
    }
    
    .original-size {
      font-size: 0.9rem;
      color: var(--text-secondary);
      margin-top: 0.5rem;
    }
    
    @media (max-width: 768px) {
      body {
        padding: 1.5rem;
      }
      
      .card {
        padding: 1.5rem;
      }
      
      .dimensions-container {
        flex-direction: column;
        gap: 1rem;
      }
      
      h1 {
        font-size: 1.5rem;
      }
    }