:root {
    --blue: #2563eb;
    --blue-light: #3b82f6;
    --blue-pale: #eff6ff;
    --blue-mid: #bfdbfe;
    --blue-dark: #1d4ed8;
    --navy: #1e3a8a;
    --white--100: #ffffff;
    --gray--50: #f8fafc;
    --gray--100: #f1f5f9;
    --gray--200: #e2e8f0;
    --gray--400: #94a3b8;
    --gray--600: #475569;
    --gray--800: #1e293b;
    --radius: 12px;
    --radius-sm: 8px;
    --shadow: 0 4px 24px rgba(37,99,235,0.10);
    --shadow-lg: 0 8px 40px rgba(37,99,235,0.16);
  }
 
  /* TAB SWITCHER */
  .tab {
    display: flex;
    justify-content: center;
    gap: 6px;
    margin-bottom: 36px;
  }
 
  .tab-btn {
    font-family: 'Syne', sans-serif;
    font-size: 0.88rem;
    font-weight: 700;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    padding: 9px 28px;
    border-radius: 999px;
    border: 2px solid var(--blue-mid);
    background: var(--white--100);
    color: var(--blue);
    cursor: pointer;
    transition: all 0.18s ease;
  }
 
  .tab-btn:hover { background: var(--blue-pale); }
 
  .tab-btn.active {
    background: var(--blue);
    border-color: var(--blue);
    color: #fff;
    box-shadow: 0 2px 12px rgba(37,99,235,0.25);
  }
 
  /* PANEL LAYOUT */
  .panel { display: none; }
  .panel.active { display: block; }
 
  .generator-layout {
    display: grid;
    grid-template-columns: 340px 1fr;
    gap: 28px;
    max-width: 1100px;
    margin: 0 auto;
    align-items: start;
  }
 
  @media (max-width: 850px) {
    .generator-layout { grid-template-columns: 1fr; }
	.preview-card {min-height:360px;}
  }
 
  /* PREVIEW CARD */
  .preview-card {
    background: var(--gray--50);
    border: 1px solid var(--gray--200);
    border-radius: var(--radius);
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 24px;
    padding: 32px;
    position: relative;
    overflow: hidden;
  }
 
  .preview-card::before {
    content: '';
    position: absolute;
    inset: 0;
    background:
      linear-gradient(rgba(37,99,235,0.04) 1px, transparent 1px),
      linear-gradient(90deg, rgba(37,99,235,0.04) 1px, transparent 1px);
    background-size: 32px 32px;
    pointer-events: none;
  }
 
  .preview-label {
    font-family: monospace;
    font-size: 0.85rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--gray--600);
    position: absolute;
    top: 14px;
    left: 18px;
  }
 
  .preview-box {
    width: 110px;
    height: 110px;
    background: linear-gradient(135deg, var(--blue-light), var(--navy));
    border-radius: 16px;
    box-shadow: 0 6px 24px rgba(37,99,235,0.30);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 700;
    font-size: 0.8rem;
    letter-spacing: 0.05em;
    transition: transform 0.05s linear;
    position: relative;
    z-index: 1;
  }
 
  /* 3D scene */
  .scene-3d {
    perspective: 600px;
    display: flex;
    align-items: center;
    justify-content: center;
  }
 
  /* CONTROLS CARD */
  .controls-card {
    background: var(--white--100);
    border: 1.5px solid var(--gray--200);
    border-radius: var(--radius);
    padding: 28px;
    display: flex;
    flex-direction: column;
    gap: 20px;
  }
 
  .controls-card h2 {
    font-size: 1rem;
    font-weight: 700;
    letter-spacing: 0.04em;
    color: var(--blue);
    text-transform: uppercase;
    display: flex;
    align-items: center;
    gap: 8px;
  }
 
  .controls-card h2::before {
    content: '';
    display: block;
    width: 12px;
    height: 12px;
    background: var(--blue);
    border-radius: 3px;
  }
 
  /* SLIDER GROUP */
  .slider-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
  }
 
  .slider-label {
    display: flex;
    justify-content: space-between;
    align-items: center;
  }
 
  .slider-label span:first-child {
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--gray--600);
    letter-spacing: 0.04em;
    text-transform: uppercase;
  }
 
  .slider-val {
    font-family: 'DM Mono', monospace;
    font-size: 0.82rem;
    color: var(--blue);
    font-weight: 500;
    background: var(--blue-pale);
    padding: 2px 10px;
    border-radius: 999px;
    min-width: 60px;
    text-align: center;
  }
 
  input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 5px;
    border-radius: 999px;
    background: var(--gray--200);
    outline: none;
    cursor: pointer;
  }
 
  input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--blue);
    box-shadow: 0 0 0 3px var(--blue-pale), 0 2px 8px rgba(37,99,235,0.3);
    cursor: pointer;
    transition: box-shadow 0.15s;
  }
 
  input[type="range"]:hover::-webkit-slider-thumb {
    box-shadow: 0 0 0 5px var(--blue-mid), 0 2px 8px rgba(37,99,235,0.3);
  }
 
  /* divider */
  .divider {
    height: 1px;
    background: var(--gray--200);
    margin: 4px 0;
  }
 
  /* UNIT + ORIGIN SELECT */
 
  .select-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
  }
 
  .select-group label {
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--gray--600);
    letter-spacing: 0.04em;
    text-transform: uppercase;
  }
 
  .select-group select {
    font-family: 'DM Mono', monospace;
    font-size: 0.82rem;
    padding: 8px 12px;
    border: 1.5px solid var(--gray--200);
    border-radius: var(--radius-sm);
    background: var(--gray--50);
    color: var(--gray--800);
    cursor: pointer;
    outline: none;
    transition: border-color 0.15s;
  }
 
  .select-group select:focus {
    border-color: var(--blue);
  }
 
  /* CODE OUTPUT */
  .code-output {
    position: relative;
	grid-column: 1 / -1
  }

  /* ABOUT SECTION */
  .about-section {

  }
 
  .about-section .about-header {
    display: flex;
    align-items: center;
    gap: 14px;
    margin-bottom: 16px;
  }
 
  .about-section .about-header h2 {
    font-size: clamp(1.4rem, 3vw, 1.9rem);
    font-weight: 800;
    letter-spacing: -0.02em;
    color: var(--gray--800);
  }
 
  .about-section .about-header h2 span { color: var(--blue); }
 
  .about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 36px;
  }
 
  @media (max-width: 640px) {
    .about-grid { grid-template-columns: 1fr; }
    .intro-features { flex-direction: column; align-items: center; }
  }
 
  .about-card {
    background: var(--gray--50);
    border: 1.5px solid var(--gray--200);
    border-radius: var(--radius);
    padding: 22px 24px;
  }
 
  .about-card h3 {
    font-size: 0.88rem;
    font-weight: 700;
    color: var(--blue);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    gap: 8px;
  }
 
  .about-card h3 .icon {
    font-size: 1rem;
    line-height: 1;
  }
 
  .about-card p, .about-card li {
    font-size: 0.88rem;
    color: var(--gray--600);
    line-height: 1.7;
  }
 
  .about-card ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 5px;
  }
 
  .about-card ul li::before {
    content: '→ ';
    color: var(--blue);
    font-weight: 700;
  }
 
  .about-prose {
    font-size: 0.93rem;
    color: var(--gray--600);
    line-height: 1.8;
    display: flex;
    flex-direction: column;
    gap: 14px;
  }
 
  .about-prose p strong {
    color: var(--gray--800);
    font-weight: 700;
  }
 
  .about-prose .inline-code {
    font-family: 'DM Mono', monospace;
    font-size: 0.82rem;
    background: var(--blue-pale);
    color: var(--blue-dark);
    padding: 1px 7px;
    border-radius: 5px;
    border: 1px solid var(--blue-mid);
  }
 

 
  .toggle-row {
    display: flex;
    align-items: center;
    gap: 10px;
  }
 
  .toggle-row label {
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--gray--600);
    letter-spacing: 0.04em;
    text-transform: uppercase;
    cursor: pointer;
  }
 
  .toggle {
    position: relative;
    width: 40px;
    height: 22px;
    cursor: pointer;
  }
 
  .toggle input { opacity: 0; width: 0; height: 0; }
 
  .toggle-track {
    position: absolute;
    inset: 0;
    background: var(--gray--200);
    border-radius: 999px;
    transition: background 0.2s;
  }
 
  .toggle input:checked ~ .toggle-track { background: var(--blue); }
 
  .toggle-thumb {
    position: absolute;
    top: 3px;
    left: 3px;
    width: 16px;
    height: 16px;
    background: white;
    border-radius: 50%;
    transition: transform 0.2s;
    box-shadow: 0 1px 4px rgba(0,0,0,0.15);
  }
 
  .toggle input:checked ~ .toggle-thumb { transform: translateX(18px); }
 
  /* 3D Perspective control (only in 3D panel) */
  .persp-row { display: flex; flex-direction: column; gap: 6px; }