404 Colegio

<!doctype html>
<html lang="es">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <meta name="robots" content="noindex" />
    <title>404 · Página no encontrada</title>
    <style>
      body { margin: 0; background: #000; }
      .n4-school {
        --accent: #fde68a;
        --k: 1;
        position: fixed;
        inset: 0;
        z-index: 0;
        overflow: hidden;
        container-type: size;
        display: grid;
        place-items: center;
        background: #000;
        color: #f5f5f7;
        font-family: -apple-system,BlinkMacSystemFont,"SF Pro Display","Inter","Segoe UI",system-ui,sans-serif;
        -webkit-font-smoothing: antialiased;
        text-align: center;
        line-height: 1.4;
      }
      
      .n4-school *,.n4-school *::before,.n4-school *::after {
        box-sizing: border-box;
      }
      
      .n4-school .n4-copy {
        position: relative;
        z-index: 5;
        display: flex;
        flex-direction: column;
        align-items: center;
        gap: 1.6cqmin;
        width: 100%;
        max-width: 680px;
        padding: 0 6cqw;
      }
      
      .n4-school .n4-title {
        margin: 0;
        font-size: clamp(17px,4.2cqmin,36px);
        font-weight: 600;
        letter-spacing: -.02em;
        line-height: 1.15;
        text-wrap: balance;
      }
      
      .n4-school .n4-sub {
        margin: 0;
        max-width: 34em;
        font-size: clamp(13px,2.4cqmin,18px);
        color: #a1a1a6;
        text-wrap: balance;
      }
      
      .n4-school .n4-tag {
        font: 600 clamp(10px,1.9cqmin,13px)/1 ui-monospace,"SF Mono",Menlo,Consolas,monospace;
        letter-spacing: .16em;
        text-transform: uppercase;
        color: var(--accent);
      }
      
      .n4-school .n4-cta {
        margin-top: 1.8cqmin;
        display: inline-flex;
        align-items: center;
        gap: .5em;
        padding: .85em 1.5em;
        border-radius: 999px;
        background: #f5f5f7;
        color: #000;
        font-size: clamp(13px,2.2cqmin,16px);
        font-weight: 600;
        text-decoration: none;
        transition: transform .3s cubic-bezier(.25,.1,.25,1),box-shadow .3s cubic-bezier(.25,.1,.25,1);
      }
      
      .n4-school .n4-cta:hover {
        transform: translateY(-2px);
        box-shadow: 0 12px 32px -10px var(--accent);
      }
      
      .n4-school .n4-cta:focus-visible {
        outline: 2px solid var(--accent);
        outline-offset: 3px;
      }
      
      .n4-school .n4-stars,.n4-school .n4-stars2 {
        position: absolute;
        inset: -4%;
        pointer-events: none;
      }
      
      .n4-school .n4-stars {
        background-image: radial-gradient(1px 1px at 8% 12%,#fff 60%,transparent),radial-gradient(1px 1px at 22% 68%,#fff 60%,transparent),radial-gradient(1.5px 1.5px at 35% 24%,#fff 60%,transparent),radial-gradient(1px 1px at 48% 82%,#fff 60%,transparent),radial-gradient(1px 1px at 57% 9%,#fff 60%,transparent),radial-gradient(1.5px 1.5px at 66% 44%,#fff 60%,transparent),radial-gradient(1px 1px at 74% 72%,#fff 60%,transparent),radial-gradient(1px 1px at 86% 18%,#fff 60%,transparent),radial-gradient(1.5px 1.5px at 93% 58%,#fff 60%,transparent),radial-gradient(1px 1px at 14% 42%,#fff 60%,transparent),radial-gradient(1px 1px at 40% 55%,#fff 60%,transparent),radial-gradient(1px 1px at 81% 90%,#fff 60%,transparent),radial-gradient(1px 1px at 4% 88%,#fff 60%,transparent),radial-gradient(1px 1px at 62% 30%,#fff 60%,transparent);
        opacity: .75;
        animation: n4-school-tw calc(5s / var(--k)) ease-in-out infinite alternate;
      }
      
      .n4-school .n4-stars2 {
        background-image: radial-gradient(2px 2px at 18% 30%,rgba(255,255,255,.9) 50%,transparent),radial-gradient(1.5px 1.5px at 72% 20%,rgba(255,255,255,.8) 50%,transparent),radial-gradient(2px 2px at 30% 85%,rgba(255,255,255,.7) 50%,transparent),radial-gradient(1.5px 1.5px at 88% 70%,rgba(255,255,255,.8) 50%,transparent),radial-gradient(2px 2px at 52% 60%,rgba(255,255,255,.6) 50%,transparent),radial-gradient(1.5px 1.5px at 6% 55%,rgba(255,255,255,.8) 50%,transparent);
        opacity: .55;
        animation: n4-school-tw calc(7s / var(--k)) ease-in-out infinite alternate-reverse;
      }
      
      .n4-school [data-depth] {
        transition: transform .9s cubic-bezier(.2,.7,.2,1);
      }
      
      @keyframes n4-school-tw {
        from {
          opacity: .3;
        }
      }
      
      @keyframes n4-school-spin {
        to {
          transform: rotate(1turn);
        }
      }
      
      @keyframes n4-school-fade {
        from {
          opacity: 0;
          transform: translateY(10px);
        }
      }
      
      @media (prefers-reduced-motion:reduce) {
        .n4-school *,.n4-school *::before,.n4-school *::after {
          animation: none!important;
          transition: none!important;
        }
      }
      
      .n4-school {
        background: linear-gradient(180deg,#f5ead7 0 84%,#c9a77c 84%);
        color: #2b2118;
      }
      
      .n4-school .n4-slate {
        position: relative;
        width: min(80cqmin,560px);
        aspect-ratio: 16/8;
        margin-bottom: 3cqmin;
        padding: 4cqmin 5cqmin;
        border: min(2.2cqmin,15px) solid #8b5a2b;
        border-radius: .6cqmin;
        background: radial-gradient(40% 30% at 30% 40%,rgba(255,255,255,.06),transparent),radial-gradient(30% 25% at 75% 65%,rgba(255,255,255,.05),transparent),#23463a;
        box-shadow: inset 0 0 3cqmin rgba(0,0,0,.45),0 2cqmin 3cqmin -1cqmin rgba(0,0,0,.35);
        text-align: left;
        font-family: "Chalkboard SE","Chalkduster","Segoe Print","Comic Sans MS",cursive;
        color: #f8fafc;
      }
      
      .n4-school .n4-slate p {
        margin: 0;
        width: max-content;
        font-size: clamp(14px,4.2cqmin,34px);
        line-height: 1.35;
        text-shadow: 0 0 1px rgba(255,255,255,.6);
        clip-path: inset(0 100% 0 0);
        animation: n4-school-write calc(1.4s / var(--k)) steps(16) forwards;
      }
      
      .n4-school .n4-l2 {
        animation-delay: calc(1.5s / var(--k))!important;
      }
      
      .n4-school .n4-l3 {
        color: var(--accent);
        animation-delay: calc(3s / var(--k))!important;
      }
      
      .n4-school .n4-circ {
        position: absolute;
        left: 3cqmin;
        top: 1.6cqmin;
        width: min(34cqmin,240px);
        height: auto;
        overflow: visible;
      }
      
      .n4-school .n4-circ path {
        fill: none;
        stroke: var(--accent);
        stroke-width: 2.2;
        stroke-linecap: round;
        stroke-dasharray: 1;
        stroke-dashoffset: 1;
        opacity: .85;
        animation: n4-school-circ calc(1s / var(--k)) calc(4.4s / var(--k)) ease-out forwards;
      }
      
      .n4-school .n4-ledge {
        position: absolute;
        left: -2.2cqmin;
        right: -2.2cqmin;
        bottom: calc(-1 * min(2.2cqmin,15px) - 1.6cqmin);
        height: 1.6cqmin;
        background: #6b4423;
        border-radius: .3cqmin;
      }
      
      .n4-school .n4-chalk {
        position: absolute;
        left: 18%;
        bottom: 100%;
        width: 5cqmin;
        height: 1.1cqmin;
        border-radius: .5cqmin;
        background: #f8fafc;
      }
      
      .n4-school .n4-eraser {
        position: absolute;
        right: 16%;
        bottom: 100%;
        width: 10cqmin;
        height: 2.6cqmin;
        border-radius: .4cqmin;
        background: linear-gradient(#7c5b3d 55%,#cbd5e1 55%);
      }
      
      .n4-school .n4-title {
        font-size: clamp(20px,5cqmin,42px);
        font-weight: 700;
        letter-spacing: -.02em;
      }
      
      .n4-school .n4-sub {
        color: #5b4636;
      }
      
      .n4-school .n4-cta {
        background: #23463a;
        color: #f8fafc;
      }
      
      @keyframes n4-school-write {
        to {
          clip-path: inset(0 0 0 0);
        }
      }
      
      @keyframes n4-school-circ {
        to {
          stroke-dashoffset: 0;
        }
      }
      
      @media (prefers-reduced-motion:reduce) {
        .n4-school .n4-slate p {
          clip-path: none;
        }
        .n4-school .n4-circ path {
          stroke-dashoffset: 0;
        }
      }
    </style>
  </head>
  <body>
    <main class="n4-school">
      <div class="n4-copy">
        <div class="n4-slate" aria-hidden="true">
          <p class="n4-l1">404 − 0 = 404</p>
          <p class="n4-l2"><span>página</span> = ?</p>
          <p class="n4-l3"><span>Deberes: encontrarla</span></p>
          <svg class="n4-circ" viewBox="0 0 120 60"><path pathLength="1" d="M10 34C8 14 50 6 84 10s30 30-6 38-70 4-64-16"/></svg>
          <i class="n4-ledge"><i class="n4-chalk"></i><i class="n4-eraser"></i></i>
        </div>
        <h1 class="n4-title">Esta lección no está en el temario.</h1>
        <p class="n4-sub">La página que buscas se ha borrado de la pizarra. Saca el cuaderno y vuelve al índice del curso.</p>
        <a class="n4-cta" href="/">Volver al aula</a>
      </div>
    </main>
  </body>
</html>