<!DOCTYPE html>
<html lang="es">
<head>
  <meta charset="UTF-8">
  <title>Flexbox: Alineación y Gap</title>
  <style>
    body {
      font-family: Arial, Helvetica, sans-serif;
      background-color: #f8fafc;
      margin: 0;
      padding: 25px;
      color: #0f172a;
    }

    /* Contenedor flexible con altura fija */
    .caja-escenario {
      display: flex;
      justify-content: space-between;
      align-items: center;
      gap: 16px;
      background-color: #f1f5f9;
      border: 2px dashed #94a3b8;
      border-radius: 12px;
      padding: 20px;
      height: 180px;
      margin-bottom: 20px;
      transition: all 0.3s ease;
    }

    .elemento {
      background: linear-gradient(135deg, #10b981, #059669);
      color: white;
      padding: 16px 20px;
      border-radius: 8px;
      font-weight: bold;
      box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
      text-align: center;
    }

    .btn-opcion {
      background: #0284c7;
      color: white;
      border: none;
      padding: 8px 12px;
      border-radius: 6px;
      cursor: pointer;
      font-size: 0.85rem;
      margin-right: 6px;
      margin-bottom: 6px;
    }
  </style>
</head>
<body>

  <h3>Alineación Flexible (justify-content & align-items)</h3>

  <div id="escenarioFlex" class="caja-escenario">
    <div class="elemento" style="height: 40px; line-height: 40px; padding: 0 20px;">Caja A</div>
    <div class="elemento" style="height: 70px; line-height: 70px; padding: 0 20px;">Caja B</div>
    <div class="elemento" style="height: 50px; line-height: 50px; padding: 0 20px;">Caja C</div>
  </div>

  <div>
    <strong>Eje Principal (justify-content):</strong><br>
    <button class="btn-opcion" onclick="setJustify('center')">center</button>
    <button class="btn-opcion" onclick="setJustify('space-between')">space-between</button>
    <button class="btn-opcion" onclick="setJustify('space-around')">space-around</button>
    <button class="btn-opcion" onclick="setJustify('space-evenly')">space-evenly</button>
    <br><br>
    <strong>Eje Secundario (align-items):</strong><br>
    <button class="btn-opcion" style="background:#475569;" onclick="setAlign('center')">center</button>
    <button class="btn-opcion" style="background:#475569;" onclick="setAlign('flex-start')">flex-start</button>
    <button class="btn-opcion" style="background:#475569;" onclick="setAlign('flex-end')">flex-end</button>
    <button class="btn-opcion" style="background:#475569;" onclick="setAlign('stretch')">stretch</button>
  </div>

  <script>
    const escenario = document.getElementById('escenarioFlex');
    function setJustify(val) { escenario.style.justifyContent = val; }
    function setAlign(val) { escenario.style.alignItems = val; }
  </script>

</body>
</html>