:root {
    --bg-top: #030712;
    --bg-mid: #0b1326;
    --bg-bottom: #050a15;
    --glow-cyan: rgba(14, 165, 233, 0.28);
    --glow-teal: rgba(34, 211, 238, 0.2);
    --glow-rose: rgba(251, 113, 133, 0.2);
    --text-main: #e5e7eb;
    --text-muted: #cbd5e1;
    --surface: rgba(15, 23, 42, 0.7);
    --surface-border: rgba(148, 163, 184, 0.35);
    --cross-surface: rgba(15, 23, 42, 0.58);
    --cross-surface-border: rgba(148, 163, 184, 0.42);
    --cross-highlight-start: #dff7ff;
    --cross-highlight-mid: #a7defc;
    --cross-highlight-end: #7cc8f7;
    --cross-highlight-border: #0284c7;
    --cross-hor-start: #dcfce7;
    --cross-hor-mid: #86efac;
    --cross-hor-end: #22c55e;
    --cross-hor-border: #16a34a;
    --cross-lat-start: #fee2e2;
    --cross-lat-mid: #fca5a5;
    --cross-lat-end: #ef4444;
    --cross-lat-border: #dc2626;
    /* Cross size used by the 2D cube diagrams */
    --cross-face-size: 150px;
    --cross-gap: 6px;
    --cross-padding: 14px;
  }

  body {
    margin: 0;
    min-height: 100vh;
    overflow-x: hidden;
    background: var(--color-bg);
    color: var(--color-text);
  }

  body.app-embedded .cube16-header {
    position: sticky;
    padding: 10px 16px;
  }

  body.app-embedded .nav-links {
    display: none;
  }

  body.app-embedded .logo {
    height: 34px;
  }

  body.app-embedded .brand {
    font-size: 1rem;
  }

  .howto-content {
    position: relative;
    padding: 2rem;
    border-radius: 16px;
    background: linear-gradient(135deg, var(--color-bg), var(--color-bg-alt));
    border: 1px solid var(--color-border);
    box-shadow: 0 18px 40px rgba(0, 0, 0, 0.55);
    color: var(--text-main);
    overflow-x: hidden;
  }

  .howto-content > * {
    position: relative;
    z-index: 1;
  }

  h1, h2 {
    margin-top: 2rem;
    color: #f8fafc;
  }

  p {
    color: var(--text-muted);
  }

  hr {
    border: 0;
    border-top: 1px solid rgba(148, 163, 184, 0.3);
    margin: 2rem 0;
  }

  .conclusion-highlight {
    margin-top: 1.25rem;
    padding: 1rem 1.25rem;
    background: linear-gradient(140deg, rgba(30, 41, 59, 0.88), rgba(15, 23, 42, 0.96));
    border: 1px solid rgba(56, 189, 248, 0.45);
    border-left: 6px solid #22d3ee;
    border-radius: 10px;
    font-weight: 600;
    color: #f8fafc;
    box-shadow: 0 10px 24px rgba(2, 6, 23, 0.35);
  }

  /* --- CROIX 2D EN MODE PORTRAIT --- */
  .layout {
    display: grid;
    grid-template-columns: repeat(3, var(--cross-face-size));
    grid-template-rows: repeat(4, var(--cross-face-size));
    gap: var(--cross-gap);
    margin: 1.5rem auto;
    width: max-content;
    max-width: 100%;
    overflow: hidden;
    padding: var(--cross-padding);
    border-radius: 14px;
    background: var(--cross-surface);
    border: 1px solid var(--cross-surface-border);
    box-shadow: 0 14px 34px rgba(2, 6, 23, 0.5), inset 0 0 0 1px rgba(148, 163, 184, 0.14);
  }

  /* Positionnement portrait */
  .face.up    { grid-column: 2; grid-row: 1; }
  .face.left  { grid-column: 1; grid-row: 2; }
  .face.front { grid-column: 2; grid-row: 2; }
  .face.right { grid-column: 3; grid-row: 2; }
  .face.down  { grid-column: 2; grid-row: 3; }
  .face.back  { grid-column: 2; grid-row: 4; }

  /* Style des faces */
  .face {
    background: #f8fafc;
    border: 2px solid #334155;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: repeat(4, 1fr);
    font-size: 0.7rem;
    box-shadow: 0 4px 10px rgba(15, 23, 42, 0.22);
  }

  .cell {
    border: 1px solid #94a3b8;
    color: #0f172a;
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
  }

      /* --- MISE EN ÉVIDENCE DES CASES D'UNE FACE--- */
  .facefront .face.front .cell:nth-child(1),
  .facefront .face.front .cell:nth-child(2),
  .facefront .face.front .cell:nth-child(3),
  .facefront .face.front .cell:nth-child(4),
  .facefront .face.front .cell:nth-child(5),
  .facefront .face.front .cell:nth-child(6),    
  .facefront .face.front .cell:nth-child(7),
  .facefront .face.front .cell:nth-child(8),
  .facefront .face.front .cell:nth-child(9),
  .facefront .face.front .cell:nth-child(10),
  .facefront .face.front .cell:nth-child(11),
  .facefront .face.front .cell:nth-child(12),
  .facefront .face.front .cell:nth-child(13),
  .facefront .face.front .cell:nth-child(14),
  .facefront .face.front .cell:nth-child(15),
  .facefront .face.front .cell:nth-child(16)
 { 
  background: linear-gradient(135deg, var(--cross-highlight-start) 0%, var(--cross-highlight-mid) 48%, var(--cross-highlight-end) 100%);
  border-color: var(--cross-highlight-border);
  }

    /* --- MISE EN ÉVIDENCE DES LIGNES VERTICALES--- */
  .ver .face.up    .cell:nth-child(1),
  .ver .face.up    .cell:nth-child(5),
  .ver .face.up    .cell:nth-child(9),
  .ver .face.up    .cell:nth-child(13),
  .ver .face.front .cell:nth-child(1),
  .ver .face.front .cell:nth-child(5),
  .ver .face.front .cell:nth-child(9),
  .ver .face.front .cell:nth-child(13),
  .ver .face.down  .cell:nth-child(1),
  .ver .face.down  .cell:nth-child(5),
  .ver .face.down  .cell:nth-child(9),
  .ver .face.down  .cell:nth-child(13),
  .ver .face.back  .cell:nth-child(1),
  .ver .face.back  .cell:nth-child(5),
  .ver .face.back  .cell:nth-child(9),
  .ver .face.back  .cell:nth-child(13)
 { 
    background: linear-gradient(135deg, var(--cross-highlight-start) 0%, var(--cross-highlight-mid) 48%, var(--cross-highlight-end) 100%);
    border-color: var(--cross-highlight-border);
  }

    /* --- MISE EN ÉVIDENCE DES LIGNES HORIZONTALES (INVERSION SUR BACK) --- */
  .hor .face.left  .cell:nth-child(1),
  .hor .face.left  .cell:nth-child(2),
  .hor .face.left  .cell:nth-child(3),
  .hor .face.left  .cell:nth-child(4),
  .hor .face.front .cell:nth-child(1),
  .hor .face.front .cell:nth-child(2),
  .hor .face.front .cell:nth-child(3),
  .hor .face.front .cell:nth-child(4),
  .hor .face.right .cell:nth-child(1),
  .hor .face.right .cell:nth-child(2),
  .hor .face.right .cell:nth-child(3),
  .hor .face.right .cell:nth-child(4),
  .hor .face.back  .cell:nth-child(13),
  .hor .face.back  .cell:nth-child(14),
  .hor .face.back  .cell:nth-child(15),
  .hor .face.back  .cell:nth-child(16) {
    background: linear-gradient(135deg, var(--cross-hor-start) 0%, var(--cross-hor-mid) 48%, var(--cross-hor-end) 100%);
    border-color: var(--cross-hor-border);
  }

  /* --- MISE EN ÉVIDENCE DES LIGNES LATÉRALES --- */
  .lat .face.up    .cell:nth-child(1),
  .lat .face.up    .cell:nth-child(2),
  .lat .face.up    .cell:nth-child(3),
  .lat .face.up    .cell:nth-child(4),
  .lat .face.left  .cell:nth-child(1),
  .lat .face.left  .cell:nth-child(5),
  .lat .face.left  .cell:nth-child(9),
  .lat .face.left  .cell:nth-child(13),
  .lat .face.down  .cell:nth-child(13),
  .lat .face.down  .cell:nth-child(14),
  .lat .face.down  .cell:nth-child(15),
  .lat .face.down  .cell:nth-child(16),
  .lat .face.right .cell:nth-child(4),
  .lat .face.right .cell:nth-child(8),
  .lat .face.right .cell:nth-child(12),
  .lat .face.right .cell:nth-child(16) { 
    background: linear-gradient(135deg, var(--cross-lat-start) 0%, var(--cross-lat-mid) 48%, var(--cross-lat-end) 100%);
    border-color: var(--cross-lat-border);
  }


  /* --- SECTION INITIATION --- */
  .initiation-intro {
    margin: 1rem 0 1.5rem;
    padding: 1rem 1.25rem;
    background: linear-gradient(140deg, rgba(30, 41, 59, 0.88), rgba(15, 23, 42, 0.96));
    border: 1px solid rgba(56, 189, 248, 0.35);
    border-left: 6px solid #22d3ee;
    border-radius: 10px;
    color: var(--text-muted);
    font-size: 0.97rem;
    line-height: 1.65;
  }

  .initiation-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 2rem;
    margin-top: 1.5rem;
  }

  @media (max-width: 780px) {
    .initiation-grid {
      grid-template-columns: minmax(0, 1fr);
    }
  }

  .anim-block h3 {
    margin: 0 0 0.5rem;
    font-size: 1.05rem;
    color: #f8fafc;
  }

  .anim-block p {
    margin: 0 0 0.75rem;
    font-size: 0.88rem;
  }

  .anim-slideshow {
    position: relative;
    width: 100%;
    border-radius: 14px;
    overflow: hidden;
    background: #f0f4f8;
    border: 2px solid rgba(148, 163, 184, 0.35);
    box-shadow: 0 14px 34px rgba(2, 6, 23, 0.55);
    line-height: 0;
  }

  .anim-frame {
    display: block;
    width: 100%;
    opacity: 0;
    position: absolute;
    top: 0;
    left: 0;
    transition: opacity 0.55s ease-in-out;
    pointer-events: none;
  }

  .anim-frame:first-child {
    position: relative; /* établit la hauteur du conteneur */
  }

  .anim-frame.active {
    opacity: 1;
    pointer-events: auto;
  }

  .anim-footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-top: 0.6rem;
    padding: 0 0.25rem;
    line-height: 1;
  }

  .anim-caption {
    font-size: 0.8rem;
    color: var(--text-muted);
  }

  .anim-dots {
    display: flex;
    gap: 6px;
  }

  .anim-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: rgba(148, 163, 184, 0.3);
    transition: background 0.3s, transform 0.3s;
  }

  .anim-hor .anim-dot.active  { background: #22c55e; transform: scale(1.3); }
  .anim-lat .anim-dot.active  { background: #fb7185; transform: scale(1.3); }

  .anim-badge-hor {
    display: inline-block;
    padding: 3px 10px;
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 600;
    background: rgba(34, 197, 94, 0.15);
    border: 1px solid rgba(34, 197, 94, 0.45);
    color: #86efac;
    margin-bottom: 0.6rem;
  }

  .anim-badge-lat {
    display: inline-block;
    padding: 3px 10px;
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 600;
    background: rgba(251, 113, 133, 0.15);
    border: 1px solid rgba(251, 113, 133, 0.45);
    color: #fda4af;
    margin-bottom: 0.6rem;
  }

  /* --- SECTION INTERFACE --- */
  .ui-layout {
    display: grid;
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 1.4fr);
    gap: 2rem;
    align-items: start;
    margin-top: 1.5rem;
  }

  @media (max-width: 780px) {
    .ui-layout {
      grid-template-columns: minmax(0, 1fr);
    }
  }

  .ui-screen-wrap {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    position: sticky;
    top: 1rem;
  }

  @media (max-width: 780px) {
    .ui-screen-wrap { position: static; }
  }

  .ui-desc {
    display: flex;
    flex-direction: column;
    gap: 0.85rem;
  }

  .ui-group-title {
    font-size: 0.78rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.12em;
    color: #22d3ee;
    padding-bottom: 0.25rem;
    border-bottom: 1px solid rgba(34, 211, 238, 0.25);
  }

  /* --- SECTION CONFIGURATION --- */
  .settings-layout {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.35fr);
    gap: 2rem;
    align-items: start;
    margin-top: 1.5rem;
  }

  @media (max-width: 780px) {
    .settings-layout {
      grid-template-columns: minmax(0, 1fr);
    }
  }

  @media (max-width: 700px) {
    :root {
      --cross-face-size: 108px;
      --cross-gap: 5px;
      --cross-padding: 10px;
    }
  }

  @media (max-width: 480px) {
    :root {
      --cross-face-size: 86px;
      --cross-gap: 4px;
      --cross-padding: 8px;
    }
  }

  .settings-screen-wrap {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
  }

  .settings-screen-label {
    font-size: 0.78rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.1em;
  }

  .settings-screen {
    background: #f8fafc;
    border-radius: 18px;
    overflow: hidden;
    border: 2px solid rgba(148, 163, 184, 0.35);
    box-shadow: 0 16px 40px rgba(2, 6, 23, 0.6), 0 0 0 1px rgba(148, 163, 184, 0.1);
    width: 100%;
  }

  .settings-screen img {
    display: block;
    width: 100%;
    height: auto;
  }

  .settings-desc {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
  }

  .settings-item {
    display: flex;
    gap: 0.85rem;
    align-items: flex-start;
    padding: 0.9rem 1rem;
    background: linear-gradient(140deg, rgba(30, 41, 59, 0.75), rgba(15, 23, 42, 0.9));
    border: 1px solid rgba(148, 163, 184, 0.25);
    border-radius: 12px;
  }

  .settings-item > div:not(.settings-item-icon) {
    flex: 1;
    min-width: 0;
  }

  .settings-item-icon {
    font-size: 1.5rem;
    line-height: 1;
    flex-shrink: 0;
    margin-top: 2px;
  }

  .settings-item strong {
    display: block;
    color: #f8fafc;
    margin-bottom: 0.3rem;
    font-size: 1rem;
  }

  .settings-item p {
    margin: 0;
    font-size: 0.875rem;
    color: var(--text-muted);
    line-height: 1.6;
  }

  .settings-apply-note {
    padding: 0.75rem 1rem;
    background: rgba(34, 211, 238, 0.08);
    border: 1px solid rgba(34, 211, 238, 0.35);
    border-radius: 10px;
    font-size: 0.88rem;
    color: #a5f3fc;
    line-height: 1.5;
  }

  .curve-green {
    color: #86efac;
  }

  .curve-red {
    color: #fda4af;
  }

  .settings-section-title {
    margin-top: 1rem;
  }

  .settings-preview-frame {
    margin-top: 10px;
    border-radius: 10px;
    overflow: hidden;
    border: 1px solid rgba(148, 163, 184, 0.3);
    max-width: 280px;
  }

  .settings-preview-image {
    display: block;
    width: 100%;
    height: auto;
  }

  .clickable-image {
    cursor: pointer;
    transition: opacity 0.2s ease;
  }

  .clickable-image:hover {
    opacity: 0.8;
  }

  .modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.85);
    z-index: 9999;
    justify-content: center;
    align-items: center;
    padding: 1rem;
  }

  .modal.active {
    display: flex;
  }

  .modal-image {
    max-width: 90%;
    max-height: 90%;
    width: auto;
    height: auto;
    border-radius: 10px;
    box-shadow: 0 0 40px rgba(56, 189, 248, 0.3);
  }

  @media print {
    body {
      background: #ffffff !important;
      color: #000000 !important;
      padding: 0;
    }

    .modal {
      display: none !important;
    }

    .print-page-break {
      break-before: page;
      page-break-before: always;
    }

    .print-page-break-marker {
      display: block;
      break-before: page;
      page-break-before: always;
      height: 0;
      margin: 0;
      padding: 0;
    }

    .ui-layout {
      display: block;
    }

    .ui-screen-wrap {
      position: static !important;
      width: 46%;
      max-width: 46%;
      margin-bottom: 1rem;
    }

    .ui-screen {
      width: 100%;
      max-width: 100%;
    }

    .ui-screen img {
      display: block;
      width: 100%;
      max-width: 100%;
      max-height: 95mm;
      object-fit: contain;
    }

    .initiation-grid {
      display: block;
    }

    .anim-block {
      margin-bottom: 0;
      break-inside: avoid;
      page-break-inside: avoid;
      width: 100%;
    }

    .anim-hor {
      break-after: page;
      page-break-after: always;
    }

    .anim-lat {
      break-before: page;
      page-break-before: always;
    }

    .anim-block h3 {
      margin-bottom: 0.35rem;
      font-size: 0.95rem;
    }

    .anim-block p {
      margin-bottom: 0.5rem;
      font-size: 0.8rem;
      line-height: 1.45;
    }

    .anim-slideshow {
      width: 100%;
      height: 58mm;
      max-height: 58mm;
      break-inside: avoid;
      page-break-inside: avoid;
    }

    .anim-frame {
      height: 58mm;
      object-fit: contain;
    }

    .anim-footer {
      margin-top: 0.45rem;
    }

  }