* {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    body {
      font-family: 'Monaco', 'Menlo', 'Courier New', monospace;
      background: #1e1e1e;
      color: #d4d4d4;
      height: 100vh;
      display: flex;
      flex-direction: column;
    }

    #app, #app > div {
      display: flex;
      flex-direction: column;
      height: 100vh;
      width: 100%;
    }

    header {
      padding: 0.75rem 1.5rem;
      background: #252526;
      border-bottom: 1px solid #3e3e42;
      display: flex;
      align-items: center;
      justify-content: space-between;
      flex-shrink: 0;
      position: sticky;
      top: 0;
      z-index: 1001;
    }

    .content-wrapper {
      flex: 1;
      display: flex;
      flex-direction: row;
      overflow: hidden;
    }

    h1 {
      font-size: 1.25rem;
      font-weight: 700;
      letter-spacing: 0.05em;
      color: #CE9156;
      display: flex;
      align-items: center;
      gap: 0.5rem;
    }

    .header-actions {
      display: flex;
      gap: 0.5rem;
      align-items: center;
    }

    .icon-button {
      background: transparent;
      border: 1px solid #3e3e42;
      color: #d4d4d4;
      padding: 10px;
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 2px;
      transition: all 0.2s;
      min-width: 44px;
      min-height: 44px;
      text-decoration: none;
    }

    .icon-button:hover {
      background: #3e3e42;
      border-color: #CE9156;
    }

    .icon-button.active {
      background: #CE9156;
      border-color: #CE9156;
      color: #1e1e1e;
      cursor: default;
    }

    .icon-button svg {
      width: 24px;
      height: 24px;
      image-rendering: pixelated;
    }

    .tool-palette {
      background: #252526;
      border-right: 1px solid #3e3e42;
      display: flex;
      flex-direction: column;
      align-items: center;
      padding: 0.75rem;
      gap: 0.5rem;
      width: 64px;
      flex-shrink: 0;
      position: relative;
      z-index: 1001;
    }

    .tool-palette button {
      background: transparent;
      border: 1px solid #3e3e42;
      color: #d4d4d4;
      padding: 10px;
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 2px;
      transition: all 0.2s;
      min-width: 44px;
      min-height: 44px;
      flex-shrink: 0;
    }

    .tool-palette button:hover {
      background: #3e3e42;
      border-color: #CE9156;
    }

    .tool-palette button.active {
      background: #CE9156;
      border-color: #CE9156;
      color: #1e1e1e;
    }

    .tool-palette button svg {
      width: 24px;
      height: 24px;
      image-rendering: pixelated;
    }

    .tool-palette-separator {
      width: 100%;
      height: 1px;
      background: #3e3e42;
      margin: 0.25rem 0;
    }

    #settings-tool {
      margin-top: auto;
    }

    @media (max-width: 767px) {
      .tool-palette {
        display: none;
      }
    }

    .main-wrapper {
      flex: 1;
      display: flex;
      flex-direction: column;
      overflow: hidden;
      min-width: 0;
    }

    .logo {
      height: 32px;
      width: auto;
    }

    main {
      flex: 1;
      padding: 0;
      overflow: hidden;
    }

    .container {
      height: 100%;
      display: flex;
      gap: 0;
      background: #1e1e1e;
      border: none;
      overflow: hidden;
    }

    .editor-wrapper {
      width: 70%;
      position: relative;
      background: #2a2a2a;
    }

    #notepad {
      width: 100%;
      height: 100%;
      background: transparent;
      border: none;
      padding: 1rem 1.5rem;
      font-family: 'Monaco', 'Menlo', 'Courier New', monospace;
      font-size: 1rem;
      line-height: 1.6;
      color: transparent;
      resize: none;
      outline: none;
      position: relative;
      z-index: 3;
      caret-color: #d4d4d4;
      -webkit-text-fill-color: transparent;
    }

    #notepad::placeholder {
      color: #8a8a8a;
      opacity: 1;
      -webkit-text-fill-color: #8a8a8a;
    }

    #highlight-layer {
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      padding: 1rem 1.5rem;
      font-family: 'Monaco', 'Menlo', 'Courier New', monospace;
      font-size: 1rem;
      line-height: 1.6;
      pointer-events: none;
      z-index: 1;
      white-space: pre-wrap;
      word-wrap: break-word;
      overflow: hidden;
    }

    #ghost-layer {
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      padding: 1rem 1.5rem;
      font-family: 'Monaco', 'Menlo', 'Courier New', monospace;
      font-size: 1rem;
      line-height: 1.6;
      pointer-events: none;
      z-index: 2;
      white-space: pre-wrap;
      word-wrap: break-word;
      overflow: hidden;
    }

    .ghost-text {
      color: #6a6a6a;
      opacity: 0.6;
    }

    .token.number { color: #6A9955; }
    .token.operator { color: #a0a0a0; }
    .token.unit { color: #C4A870; }
    .token.punctuation { color: #a0a0a0; }
    .token.comment { color: #8faf85; }

    #results {
      width: 30%;
      padding: 1rem 1.5rem;
      background: #1e1e1e;
      border-left: 1px solid #3e3e42;
      font-family: 'Monaco', 'Menlo', 'Courier New', monospace;
      font-size: 1rem;
      line-height: 1.6;
      color: #858585;
      overflow-y: auto;
    }

    @media (max-width: 374px) {
      .container {
        flex-direction: column;
      }

      .editor-wrapper {
        width: 100%;
        border-bottom: 1px solid #3e3e42;
      }

      #results {
        width: 100%;
        border-left: none;
        border-top: 1px solid #3e3e42;
      }
    }

    @media (min-width: 375px) and (max-width: 767px) {
      .editor-wrapper {
        width: 60%;
      }

      #results {
        width: 40%;
      }
    }

    @media (min-width: 768px) and (max-width: 1023px) {
      .editor-wrapper {
        width: 65%;
      }

      #results {
        width: 35%;
      }
    }

    .result-line {
      min-height: 1.6em;
      text-align: right;
    }

    .result-value {
      color: #CE9156;
    }

    .result-error {
      color: #f48771;
    }

    .results-placeholder span {
      color: #8a8a8a;
    }

    #annotation-canvas {
      position: fixed;
      top: 0;
      left: 0;
      width: 100vw;
      height: 100vh;
      z-index: 1000;
      pointer-events: none;
      cursor: crosshair;
    }

    #annotation-canvas.active {
      pointer-events: auto;
    }

    #annotation-canvas.draw-mode {
      cursor: crosshair;
    }

    #annotation-canvas.erase-mode {
      cursor: pointer;
    }

    /* Accessibility: Focus indicators for keyboard navigation (WCAG 2.4.7) */
    button:focus-visible,
    a:focus-visible,
    input:focus-visible,
    textarea:focus-visible,
    select:focus-visible,
    [tabindex]:focus-visible {
      outline: 2px solid #CE9156;
      outline-offset: 2px;
    }

    button:focus:not(:focus-visible),
    a:focus:not(:focus-visible) {
      outline: none;
    }

    .tool-palette button:focus-visible {
      outline: 2px solid #CE9156;
      outline-offset: 2px;
      background-color: #3a3a3a;
    }

    .modal-close:focus-visible {
      outline: 2px solid #CE9156;
      outline-offset: 2px;
    }

    .checkbox-option:focus-visible {
      outline: 2px solid #CE9156;
      outline-offset: 2px;
    }

    /* Accessibility: Skip link for keyboard users (WCAG 2.4.1) */
    .skip-link {
      position: absolute;
      top: -100%;
      left: 0;
      background: #CE9156;
      color: #1e1e1e;
      padding: 8px 16px;
      z-index: 10000;
      text-decoration: none;
      font-weight: 600;
      transform: translateY(-100%);
    }

    .skip-link:focus {
      top: 0;
      transform: translateY(0);
    }

    /* Accessibility: Screen reader only class */
    .sr-only {
      position: absolute !important;
      width: 1px !important;
      height: 1px !important;
      padding: 0 !important;
      margin: -1px !important;
      overflow: hidden !important;
      clip: rect(0, 0, 0, 0) !important;
      clip-path: inset(50%) !important;
      white-space: nowrap !important;
      border: 0 !important;
    }