/* --- THEME & BASE STYLES --- */
:root {
    /* Design System Colors */
    --str-primary-50: #f5fff2;
    --str-primary-100: #ecfee0;
    --str-primary-200: #dafec7;
    --str-primary-300: #c6fba3;
    --str-primary-400: #b3f78f;
    --str-primary-500: #96f26c;
    --str-primary-600: #50b358;
    --str-primary-700: #268a40;
    --str-primary-800: #1a5e2d;
    --str-primary-900: #0d331a;
    --str-secondary-50: #f9fcff;
    --str-secondary-100: #f2f8ff;
    --str-secondary-200: #d9ecff;
    --str-secondary-300: #b6e5ff;
    --str-secondary-400: #93ddff;
    --str-secondary-500: #70d6ff;
    --str-secondary-600: #009ec2;
    --str-secondary-700: #0082ae;
    --str-secondary-800: #00668a;
    --str-secondary-900: #004a66;
    --white: #ffffff;
    --black: #000000;
    --rose-400: #fb7185;
    --rose-600: #e11d48;
    --rose-800: #9f1239;
    --rose-950: #4c0519;
    --amber-400: #F59E0B;
    --amber-600: #D97706;
    --amber-800: #92400E;
    --amber-950: #451A03;
    --teal-400: #2DD4BF;
    --teal-600: #0D9488;
    --teal-800: #115E59;
    --teal-950: #042F2E;
    --success-stroke-light: var(--teal-400);
    --success-surface-light: var(--teal-50);
    --success-stroke-dark: var(--teal-800);
    --success-surface-dark: var(--teal-950);
    --warning-stroke-light: var(--amber-400);
    --warning-surface-light: var(--amber-50);
    --warning-stroke-dark: var(--amber-800);
    --warning-surface-dark: var(--amber-950);
    --error-stroke-light: var(--rose-400);
    --error-surface-light: var(--rose-50);
    --error-stroke-dark: var(--rose-800);
    --error-surface-dark: var(--rose-950);
    --grey-1000: #1a1918;
    --grey-950: #242321;
    --grey-900: #2d2b29;
    --grey-850: #393633;
    --grey-800: #44403d;
    --grey-750: #4f4a46;
    --grey-700: #5b5650;
    --grey-450: #978f86;
    --grey-400: #a49b93;
    --grey-350: #afa8a0;
    --grey-200: #d3cec9;
    --grey-100: #ebe9e6;
  
    /* UI Theme Mapping */
    --bg-main: var(--grey-1000);
    --bg-primary: var(--grey-950);
    --bg-panel: #1A1D21;
    --bg-panel-header: #202428;
    --border-primary: var(--grey-850);
    --border-secondary: var(--grey-800);
    --text-primary: var(--grey-100);
    --text-secondary: var(--grey-400);
    --text-tertiary: var(--grey-450);
    --accent-primary: var(--str-secondary-500);
    --accent-secondary: var(--str-secondary-600);
    --accent-danger: var(--rose-400);
    --shadow: 0 5px 20px rgba(0, 0, 0, 0.4);
  }
  
  * {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
  }
  
  body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica,
      Arial, sans-serif;
    background-color: var(--bg-main);
    color: var(--text-primary);
    font-size: 14px;
    overflow: hidden;
    height: 100vh;
  }
  
  button {
    font-family: inherit;
    font-size: inherit;
    background: none;
    border: none;
    color: inherit;
    cursor: pointer;
  }
  
  .icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 16px;
    height: 16px;
  }

  /* --- MAIN LAYOUT --- */
  #app-container {
    display: flex;
    flex-direction: column;
    height: 100vh;
  }
  
  .main-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 24px;
    height: 60px;
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-primary);
    flex-shrink: 0;
  }
  .header-title {
    font-size: 20px;
    font-weight: 600;
    color: var(--text-primary);
  }
  .header-actions {
    display: flex;
    gap: 24px;
    align-items: center;
  }
  .main-btn {
    padding: 8px 16px;
    border-radius: 6px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    gap: 8px;
  }
  .btn-primary {
    background-color: var(--accent-secondary);
    color: var(--text-primary);
  }
  .btn-primary:hover {
    background-color: var(--str-secondary-500);
  }
  .btn-secondary {
      background-color: #31373D;
      border: 1px solid var(--border-secondary);
      color: var(--text-primary);
      padding: 6px 12px;
  }
  .btn-secondary:hover {
      background-color: #40464C;
      border-color: var(--grey-750);
  }
  
  .main-content {
    display: flex;
    flex-grow: 1;
    overflow: hidden;
    background: var(--bg-main);
  }
  
  /* --- PANELS & EDITORS --- */
  .panel {
    display: flex;
    flex-direction: column;
    background-color: var(--bg-panel);
    overflow: hidden;
  }

  .gutter {
      background-color: var(--bg-main);
  }
  .gutter.gutter-horizontal {
      cursor: col-resize;
  }
  .gutter.gutter-vertical {
      cursor: row-resize;
  }
  
  .editor-container {
      display: flex;
      flex-direction: column;
      flex-grow: 1;
      overflow: hidden;
      min-height: 0;
  }

  .editor-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 8px 12px;
      background: var(--bg-panel-header);
      flex-shrink: 0;
      border-bottom: 1px solid var(--border-primary);
  }
  .editor-title {
      display: flex;
      align-items: center;
      gap: 8px;
      font-size: 13px;
      font-weight: 500;
      color: var(--text-secondary);
  }
  .CodeMirror {
      flex-grow: 1;
      height: 100%;
      font-size: 13px;
  }
  .CodeMirror-gutters {
      background: #1A1D21 !important;
      border-right: 1px solid var(--border-primary);
  }
  
  /* --- Toast Notifications --- */
  #toast-container {
    position: fixed;
    bottom: 20px;
    right: 20px;
    z-index: 1001;
    display: flex;
    flex-direction: column;
    gap: 10px;
  }
  .toast {
    padding: 12px 20px;
    border-radius: 8px;
    font-weight: 600;
    box-shadow: var(--shadow);
    opacity: 0;
    transform: translateX(120%);
    transition: all 0.4s cubic-bezier(0.215, 0.61, 0.355, 1);
  }
  .toast.show {
    opacity: 1;
    transform: translateX(0);
  }
  .toast.success {
    background-color: var(--str-primary-500);
    color: var(--black);
  }
  .toast.error {
    background-color: var(--rose-600);
    color: var(--white);
  }
  .toast.warning {
    background-color: var(--amber-400);
    color: var(--black);
  }
  
  /* --- Custom Checkbox --- */
  .header-option {
    display: flex;
    align-items: center;
    gap: 8px;
  }
  .header-option .option-label {
    font-size: 13px;
    color: var(--text-secondary);
    cursor: pointer;
    user-select: none;
  }
  .custom-checkbox {
    position: absolute;
    opacity: 0;
    width: 0;
    height: 0;
  }
  .custom-checkbox-label {
    display: block;
    width: 16px;
    height: 16px;
    background-color: #31373D;
    border: 1px solid var(--border-secondary);
    border-radius: 4px;
    transition: all 0.2s;
    position: relative;
    cursor: pointer;
  }
  .custom-checkbox-label::after {
    content: '';
    position: absolute;
    display: none;
    left: 4px;
    top: 1px;
    width: 5px;
    height: 10px;
    border: solid var(--white);
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
  }
  .custom-checkbox:hover + .custom-checkbox-label {
    border-color: var(--accent-primary);
  }
  .custom-checkbox:checked + .custom-checkbox-label {
    background-color: var(--accent-primary);
    border-color: var(--accent-primary);
  }
  .custom-checkbox:checked + .custom-checkbox-label::after {
    display: block;
  }
  
  /* Scrollbar Styles */
  * {
    scrollbar-width: thin;
    scrollbar-color: var(--grey-750) var(--bg-panel);
  }
  ::-webkit-scrollbar {
    width: 8px;
    height: 8px;
  }
  ::-webkit-scrollbar-track {
    background: var(--bg-panel);
  }
  ::-webkit-scrollbar-thumb {
    background-color: var(--grey-750);
    border-radius: 4px;
    border: 2px solid var(--bg-panel);
  }
  ::-webkit-scrollbar-thumb:hover {
    background-color: var(--grey-700);
  }