:root{
    --header-h : 60px;   
    --banner-h : 120px;  
    --aside-w  : 280px;  
    --ads-w    : 300px;  
    --gap      : 18px;
  
    --bg      : #eef5fb;
    --surf    : #fff;
    --prim    : #0066ff;
    --prim-dk : #0041c4;
    --txt     : #1f2937;
    --muted   : #6b7280;
    --bd      : #e2e8f0;
  
    --rad     : 10px;
    --sh-xs   : 0 1px 3px  rgba(0,0,0,.05);
    --sh-md   : 0 8px 28px rgba(0,0,0,.06);
    /* tipografía */
    --ff-body: "Inter", "Montserrat", system-ui, sans-serif;
    --ff-heading: "Inter", "Montserrat", system-ui, sans-serif;
  
    /* escala fluida: 1rem (min) → 1.25rem (max)  */
    --step-0: clamp(1rem, 0.9rem + 0.4vw, 1.25rem);
    --step-1: clamp(1.25rem, 1.1rem + 0.6vw, 1.75rem);
    --step-2: clamp(1.5rem, 1.2rem + 1vw, 2.25rem);
    --step-3: clamp(1.9rem, 1.4rem + 1.4vw, 2.75rem);
  
    /* colores base */
    --c-bg:      #f9fafb;
    --c-paper:   #ffffff;
    --c-text:    #222;
    --c-text-alt:#64748b;
    --c-border:  #e2e8f0;
    --c-accent:  #0078ff;
    --c-accent-d:#0054b4;


  --code-bg:        #0f172a;   /* gris-azulado muy oscuro */
  --code-border:    #1e293b;   /* borde sutil */
  --code-shadow:    rgba(2,12,27,.35);
  --code-text:      #e2e8f0;   /* texto base (gris 100) */
  --code-comment:   #64748b;   /* gris 400 */
  --code-keyword:   #ff7b72;   /* coral            */
  --code-func:      #fcbf49;   /* ámbar            */
  --code-string:    #7dd3fc;   /* azul claro       */
  --code-number:    #caa6ff;   /* lila            */


  --bg1:#0d1117;
  --aqua:#00eaff;
  --violet:#6c00ff;
  --radius:24px;

  
      --surf:#ffffff;
      --surf2:#f0f5ff;
      --border:#e1e7f3;
      --gap:22px;
      --blue:#1062fe;
  }
  
  *,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
  body{font-family:Inter,Arial,sans-serif;background:var(--bg);color:var(--txt);line-height:1.6}
  a{color:var(--prim);text-decoration:none}
  a:hover{color:var(--prim-dk)}
  
  .wrapper{max-width:1440px;margin:10px auto;padding:0 var(--gap)}
  .layout{display:grid;grid-template-columns:var(--aside-w) 1fr;gap:var(--gap)}
  .container{display:grid;grid-template-columns:1fr var(--ads-w);gap:var(--gap)}
  header{
    position:sticky;top:0;z-index:1000;
    display:flex;align-items:center;justify-content:space-between;
    height:var(--header-h);
    background:var(--surf);padding:0 1.5rem;box-shadow:var(--sh-xs);
    animation:fadeIn .3s ease;
  }
  .logo{display:flex;align-items:center;gap:.55rem;font:700 1rem/1 Inter;color:var(--txt)}
  .logo img{height:28px;width:28px}
  nav{display:flex;align-items:center;gap:1.25rem;font-size:.93rem}
  nav a{color:var(--txt);font-weight:500;position:relative;padding:.15rem 0}
  nav a::after{content:"";position:absolute;bottom:-4px;left:0;width:0;height:2px;background:var(--prim);transition:.25s}
  nav a:hover::after{width:100%}
  
  .toggle-btn{
    position:fixed;top:calc(var(--header-h)+14px);left:0;z-index:1040;
    display:none;align-items:center;gap:.45rem;
    background:var(--prim);color:#fff;border:none;border-radius:0 8px 8px 0;
    padding:.55rem 1.2rem;font-size:.83rem;box-shadow:var(--sh-xs);cursor:pointer;
  }
  .toggle-btn i{font-size:1.25rem}
  .banner{height:var(--banner-h);display:flex;align-items:center;justify-content:center}
  .banner-inside{
    position:relative;
    width:100%;max-width:970px;height:90px;
    /*border:2px dashed var(--prim);border-radius:var(--rad);*/
    display:flex;align-items:center;justify-content:center;
    /*background:#dfe9ff;color:var(--muted);*/font-weight:600;text-align:center;
  }
  .banner-close{position:absolute;top:-2px;right:-2px}
  .sidebar{font-size:.9rem}
  .sidebar h3{font-size:.8rem;font-weight:600;color:var(--muted);text-transform:uppercase;margin-bottom:1rem}
  #asideDesktop{
    position:sticky;top:var(--header-h);
    max-height:calc(100vh - var(--header-h) - var(--banner-h) - var(--gap)*2);
    overflow-y:auto;padding:1.25rem 1rem;
  }
  #asideMobile{
    position:fixed;inset:0 auto 0 0;width:var(--aside-w);
    padding:var(--header-h) 1rem 1.5rem;background:var(--surf);
    transform:translateX(-105%);transition:.35s ease;z-index:1050;
    overflow-y:auto;
  }
  #asideMobile.open{transform:translateX(0)}
  #asideMobile .close{position:absolute;top:14px;left:18px;font-size:1.8rem;color:var(--txt);cursor:pointer}
  .tree, .tree ul{list-style:none;padding-left:0;margin:0}
  .tree ul{margin-left:18px;max-height:0;overflow:hidden;transition:max-height .35s ease}
  li.open>ul{max-height:9999px}
  .section{display:flex;align-items:center;gap:.55rem;padding:.3rem .45rem;font-weight:600;color:var(--txt);cursor:pointer;border-radius:6px}
  .section:hover{background:rgba(0,0,0,.04)}
  .icon{font-size:1.3rem;transition:transform .3s ease}
  .link{display:block;padding:.28rem 0 .28rem 1.55rem;color:var(--muted);font-weight:500;border-radius:6px}
  .link:hover{background:rgba(0,0,0,.04);color:var(--prim)}
  .link.active{background:rgba(0,102,255,.12);color:var(--prim);font-weight:600}
  main{background:var(--surf);border:1px solid var(--bd);border-radius:var(--rad);padding:0;box-shadow:var(--sh-md)}
  .ads{
    position:sticky;top:calc(var(--header-h) + 10px);align-self:start;
    width:var(--ads-w);min-height:600px;
    display:flex;align-items:center;justify-content:center;
    background:none;border:none;border-radius:var(--rad);
    color:var(--muted);text-align:center;padding:0;
  }
  footer{background:var(--surf);border-top:1px solid var(--bd);margin-top:var(--gap);padding:1.5rem var(--gap);font-size:.88rem;color:var(--muted);animation:fadeIn .3s ease}
  .footer-inner{max-width:1440px;margin:0 auto;display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:1rem}
  .socials a{font-size:1.4rem;color:var(--muted);margin-right:.75rem;transition:color .25s}
  .socials a:hover{color:var(--prim)}
  .links a{margin:0 .65rem;color:var(--muted);transition:color .25s}
  .links a:hover{color:var(--prim)}
  .close-btn{
    position:absolute;top:6px;right:6px;z-index:2;
    width:18px;height:18px;font-size:.6rem;font-weight:700;
    border:none;border-radius:50%;background:#fff;color:var(--muted);
    display:flex;align-items:center;justify-content:center;cursor:pointer;box-shadow:var(--sh-xs);
    transition:color .25s;
  }
  .close-btn:hover{color:#f00}
  .search-modal{
    position:fixed;inset:0;z-index:2000;
    background:rgba(0,0,0,.55);backdrop-filter:blur(3px);
    display:none;justify-content:center;padding:10px 0;
  }
  .search-modal.open{display:flex}
  .search-box{
    position:relative;width:min(600px,90%);padding:1.8rem 2rem;
    background:var(--surf);border-radius:var(--rad);box-shadow:var(--sh-md);
  }
  .search-box input{width:100%;padding:.9rem 1.1rem;border:1px solid var(--bd);border-radius:8px;font-size:1rem;outline:0}
  .search-box ul{margin-top:1rem;list-style:none;max-height: calc(100vh - 180px);overflow:auto;padding:0}
  .search-box li a{display:block;padding:.6rem .8rem;border-radius:6px;color:var(--txt)}
  .search-box li a:hover{background:rgba(0,0,0,.04);color:var(--prim)}
  .close-search{position:absolute;top:0;right:14px;border:none;background:none;font-size:1.4rem;color:var(--muted);cursor:pointer}
  
  
  .search-btn{background:none;border:none;font-size:1.4rem;color:var(--txt);cursor:pointer}
  .nav-tutorials i{display:none;font-size:1.25rem}  
  @keyframes fadeIn{from{opacity:0}to{opacity:1}}
  @media (max-width:1200px){
    .toggle-btn{display:flex}
    .layout{grid-template-columns:1fr}
    #asideDesktop{display:none}
  }
  @media (max-width:800px){
    .container{grid-template-columns:1fr}
    .ads{width:100%;max-width:336px;margin:0 auto}
  }
  @media (max-width:600px){
    .banner{height:300px}
    .banner-inside{width:300px;height:300px;max-width:none;border-style:none;flex-direction:column}
    .footer-inner{flex-direction:column;text-align:center}
    .logo span{display:none}
    .nav-tutorials span{display:none}
    .nav-tutorials i{display:inline}
  }

  
  /* ───────────  LAYOUT MAIN  ─────────── */
  main{
    background: var(--c-bg);
    display: flex;
    gap: clamp(1rem, 3vw, 40px);
  }
  
  /* columna central del artículo */
  main .main{
    flex: 1 1 0;
    background: var(--c-paper);
    border-radius: 12px;
    padding: clamp(1.5rem, 4vw, 3rem);
    box-shadow: 0 4px 16px rgba(0,0,0,.05);
    overflow: hidden;
  }
  
  /* (opcional) aside lateral derecho si existiera */
  main .aside{
    flex: 0 0 clamp(220px, 25vw, 300px);
    background: var(--c-paper);
    border-radius: 12px;
    box-shadow: 0 4px 16px rgba(0,0,0,.05);
    max-height: calc(100vh - 120px);
    position: sticky;
    top: 80px;
    overflow: auto;
  }
  
  /* ───────────  TIPOGRAFÍA  ─────────── */
  main{
    font-family: var(--ff-body);
    font-size: var(--step-0);
    color: var(--c-text);
    line-height: 1.7;
  }
  
  main h1, main h2, main h3{
    font-family: var(--ff-heading);
    font-weight: 700;
    line-height: 1.25;
    margin: 0 0 .5em;
  }
  
  main h1{ font-size: var(--step-3); }
  main h2{ font-size: var(--step-2); border-top: 1px solid var(--c-border); padding-top: .75em;}
  main h3{ font-size: var(--step-1); }
  
  main p,
  main li{ margin-block: .75em; }
  
  main a{
    color: var(--c-accent);
    text-decoration: none;
  }
  main a:hover{ text-decoration: underline; color: var(--c-accent-d); }
  
  /* ───────────  COMPONENTES ESPECÍFICOS  ─────────── */
  
  /* fecha */
  main .dateline{
    font-size: .75em;
    letter-spacing: .1em;
    color: var(--c-text-alt);
    margin-block-end: 1.5rem;
    border-block-end: 1px solid var(--c-border);
    padding-block-end: 1rem;
  }
  
  /* tabla de contenido */
  .tabcont{
    background: #f1f5f9;
    border: 1px solid var(--c-border);
    border-radius: 8px;
    padding: 1rem 1.5rem;
    margin-block: 2rem;
  }
  .tab-cont{
    display: block;
    font-weight: 600;
    margin-block-end: .75rem;
    color: var(--c-accent-d);
  }
  .tab-links{
    list-style: none;
    margin: 0; padding: 0;
  }
  .tab-links li{ margin-block: .25rem; }
  .tab-links a{
    color: var(--c-text);
    transition: color .2s;
  }
  .tab-links a:hover{ color: var(--c-accent); }
  
  
  /* tablas genéricas */
  main table{
    width: 100%;
    border-collapse: collapse;
    margin-block: 2rem;
    font-size: .9em;
  }
  main th,
  main td{
    border: 1px solid var(--c-border);
    padding: .6em .8em;
  }
  main th{
    background: var(--c-accent);
    color: #fff;
    font-weight: 600;
  }
  main tr:nth-child(even) td{ background: #f8fafc; }
  
  /* bloques de “Ejemplo” */
  .ejemplo{
    background: #f8fafc;
    border-left: 4px solid var(--c-accent);
    padding: 1rem 1.8rem;
    border-radius: 6px;
    margin-block: 2rem;
  }
  
  /* ecuaciones fraccionarias */
  .fraction{ font-size: .95em; }
  
  /* ───────────  ADAPTABLE  ─────────── */
  @media (max-width: 768px){
    main{
      flex-direction: column;
    }
    main .aside{ position: static; max-height: none; margin-block-start: 2rem; }
  }
  
.fraction {
    display: inline-block;
    vertical-align: middle;
    margin: 0 .2em .4ex;
    text-align: center
}
.fraction > span {
    display: block;
    padding-top: .15em
}
.fraction span.fdn {
    border-top: thin solid
}
.fraction span.bar {
    display: none
}

.centerText {
    margin: auto;
    align-items: center;
    justify-content: center;
    text-align: center;
}
.img300300, .img30080, .img300290 , .img300220 {max-width: 300px;margin: 0 auto;}
.img180100 , .img200130 {max-width: 180px;margin: 0 auto;}
.img200200 {max-width: 200px;margin: 0 auto;}
.img300250 , .img300150 , .img300180 {max-width: 300px;margin: 0 auto;}
.img250220 , .img250250,.img250200 ,.img250180 {max-width: 250px;margin: 0 auto;}
.img600600 {max-width:600px;margin: 0 auto;}
.img141300 {max-width:141px;margin: 0 auto;}
.img450150 {max-width:450px;margin: 0 auto;}
.img220300, .img210180 {max-width:220px;margin: 0 auto;}
.img150180 {max-width:150px;margin: 0 auto;}
.img280180 {max-width:280px;margin: 0 auto;}
.img260210 {max-width:280px;margin: 0 auto;}
.img190300 {max-width:190px;margin: 0 auto;}

img{
  max-width: 100%;   
  height: auto;      
  display:block; 
  border-radius: 9px;   
}


/* ----------  bloque contenedor  ---------- */
.programcodigo{
  background: var(--code-bg);
  color: var(--code-text);
  font-family: "Fira Code", "JetBrains Mono", Consolas, Menlo, monospace;
  font-size: .95rem;
  line-height: 1.55;
  border: 1px solid var(--code-border);
  border-radius: 8px;
  padding: 1.25rem 1.5rem;
  margin-block: 2rem;
  overflow-x: auto;             /* scroll horizontal limpio */
  box-shadow: 0 6px 24px -6px var(--code-shadow);
}

/* quitar viñetas si usas <ul><li> */
.programcodigo ul{
  list-style: none;
  padding: 0;
  margin: 0;
}

/* ----------  “coloreado” rápido  ---------- */
.programcodigo span{ color: var(--code-comment); } /* comentarios */
.programcodigo b   { color: var(--code-keyword);  font-weight: 600; } /* palabras clave */
.programcodigo i   { color: var(--code-string);  font-style: normal; } /* cadenas */
.definec           { color: var(--code-func); }     /* funciones/defines */

/* ejemplo extra: números */
.programcodigo .num{ color: var(--code-number); }

/* ----------  scrollbar sutil (opcional) ---------- */
.programcodigo::-webkit-scrollbar{
  height: 8px;
}
.programcodigo::-webkit-scrollbar-track{
  background: transparent;
}
.programcodigo::-webkit-scrollbar-thumb{
  background: #334155;
  border-radius: 4px;
}

/* ─────────  LAYOUT  ───────── */
    .wrappertutoriales{
      display:grid;
      grid-template-columns:270px 1fr;
      gap:var(--gap);
      min-height:calc(100vh - 60px);   /* alto completo menos header */
      max-width:1600px;
      margin:0 auto;
      padding:var(--gap);
    }
    @media(max-width:900px){
      .wrappertutoriales{grid-template-columns:1fr;grid-template-rows:auto 1fr;}
    }

    /* ─────────  SIDEBAR  ───────── */
    #treeNav{
      background:var(--surf2);
      border:1px solid var(--border);
      border-radius:12px;
      padding:18px;
      overflow-y:auto;
    }
    #treeNav ul{list-style:none;margin:0;padding:0;}
    #treeNav li{margin:4px 0;}
    #treeNav button{all:unset;display:flex;align-items:center;gap:6px;font-size:14px;color:#1a1d22;padding:6px 8px;border-radius:8px;cursor:pointer;}
    #treeNav button:hover{background:#dbe6ff;}
    #treeNav .back{display:flex;align-items:center;gap:6px;font-size:13px;font-weight:500;margin-bottom:10px;cursor:pointer;color:#1a1d22;}
    #treeNav .back:hover{color:var(--blue);}  
    @media(max-width:600px){#treeNav{grid-column:1/-1;max-height:240px;}}

    /* ─────────  MAIN  ───────── */
    main.tutorialespage{
      display:flex;
      flex-direction:column;
      background:var(--surf);
      border:1px solid var(--border);
      border-radius:12px;
      padding:var(--gap);
      overflow:hidden;
    }

    /* header responsive */
    main.tutorialespage .headertutoriales{display:flex;align-items:center;justify-content:space-between;gap:var(--gap);flex-wrap:wrap;}
    main.tutorialespage .headertutoriales h1{margin:0;font-size:clamp(1.7rem,2.2vw+1rem,2.4rem);}  
    main.tutorialespage .headertutoriales p{margin:0;font-size:15px;color:#46515f;max-width:600px;}
    @media(max-width:600px){
      main.tutorialespage .headertutoriales{flex-direction:column;align-items:flex-start;}
      main.tutorialespage .headertutoriales p{display:none;} /* ocultamos texto largo en móvil */
    }

    /* tarjetas */
    #cardsContainer{
      padding-top:var(--gap);
      display:grid;
      grid-template-columns:repeat(auto-fill,minmax(240px,1fr));
      gap:var(--gap);
      overflow-y:auto;
      padding-right:6px;
    }
    @media(max-width:600px){#cardsContainer{grid-template-columns:repeat(auto-fill,minmax(170px,1fr));}}

    .card{
      background:var(--surf2);
      border:1px solid var(--border);
      border-radius:12px;
      padding:18px 20px;
      display:flex;align-items:center;gap:14px;
      text-decoration:none;color:#1a1d22;
      transition:transform .18s,border .18s,box-shadow .18s;
    }
    .card i{font-size:32px;color:var(--blue);}  
    .card span{font-weight:500;font-size:15px;}
    .card:hover{transform:translateY(-3px);border-color:#c6d6fb;box-shadow:0 4px 12px rgba(16,98,254,.12);} 


    
/* ---------- contenedor scroll-snap ---------- */
.snap{
  display:block;overflow-x:hidden;
}
.slide{
  width:100vw;min-height:100vh;margin:0;box-sizing:border-box;
  display:flex;flex-direction:column;justify-content:center;align-items:center;
  text-align:center;scroll-snap-align:start;padding:3.2rem 1rem;
}

/* ---------- fondos ---------- */
.hero{background:#0d1117}
.aqua{background:linear-gradient(135deg,#002d46 0%,#003b55 100%)}
.violet{background:linear-gradient(135deg,#1a0055 0%,#30007e 100%)}
.dark{background:#081018}

/* ---------- HERO ---------- */
.hero-img{
  width:70vw;max-width:300px;height:auto;margin-bottom:1.6rem;
  border-radius:var(--radius);object-fit:cover;
}
.hero h1{
  font-size:clamp(2.6rem,7vw,4.8rem);
  font-weight:700;line-height:1.1;margin:0;
  color:white;
}
.tagline{
  margin:1.1rem 0 3rem;letter-spacing:.8px;
  font-size:clamp(1rem,2.5vw,1.35rem);
  color:white;
}

/* flecha */
.scroll-down{position:absolute;bottom:2.2rem;font-size:2.2rem;color:var(--aqua);animation:bounce 2s infinite}
@keyframes bounce{0%,100%{transform:translateY(0)}50%{transform:translateY(10px)}}

/* ---------- GLASS PANEL ---------- */
.glass{
  width:90vw;max-width:900px;
  background:rgba(0,0,0,.35);          /* + opacidad para mayor contraste */
  border:1px solid rgba(255,255,255,.09);
  backdrop-filter:blur(16px);
  padding:2.6rem 1.4rem;border-radius:var(--radius);
  box-shadow:0 8px 32px rgba(0,0,0,.45);
}
.glass h2{
  font-size:clamp(1.7rem,5vw,2.45rem);margin-bottom:1rem;color:var(--aqua)
}
.glass p,.glass li{color:#d5d5d5}
.bullets{padding-left:1rem;text-align:left}
.bullets li{margin:.6rem 0;line-height:1.7}

/* ---------- CTA ---------- */
.cta{text-align:center;padding:3.5rem 1rem 6rem;
    color: white;
    background: #191919;}
.cta h2{font-size:clamp(1.9rem,5vw,2.6rem);margin-bottom:1rem}

/* ---------- BOTÓN ---------- */
.btn-primary{
  display:inline-flex;align-items:center;gap:.6rem;
  padding:1rem 2.3rem;border-radius:var(--radius);font-weight:600;
  background:linear-gradient(90deg,var(--aqua),var(--violet));color:#000;
  box-shadow:0 8px 18px rgba(0,0,0,.55);transition:transform .25s;
}
.btn-primary:hover{
  transform:translateY(-4px);
  color: rgb(35, 35, 35);
  text-decoration: none;
}