/*  LIGHT & DARK THEMES */
:root{
  --bg:#f5f7fa;--surface:#ffffff;--text:#374151;
  --primary:#21468b;--accent:#c8af2f;
}
body.dark{
  --bg:#0f172a;--surface:#1e293b;--text:#f3f4f6;
  --primary:#1d4ed8;--accent:#eab308;
}

/*  RESET & BASE  */
*{margin:0;padding:0;box-sizing:border-box}
body{
  font-family:"Poppins",sans-serif;background:var(--bg);color:var(--text);
  line-height:1.6;transition:background .3s,color .3s
}
a{text-decoration:none;color:inherit}
img{max-width:100%;display:block}

/*  UTILITIES  */
.btn-primary{background:var(--accent);color:#fff;padding:.75rem 1.5rem;
  border:none;border-radius:.375rem;font-weight:600;cursor:pointer}
.section{padding:4rem 2rem;max-width:1200px;margin:0 auto}
.section-title{text-align:center;font-size:2rem;color:var(--primary);margin-bottom:2rem}
.cards{display:grid;gap:1.5rem;grid-template-columns:repeat(auto-fit,minmax(260px,1fr))}
.card{background:var(--surface);padding:1.5rem;border-radius:.5rem;
  box-shadow:0 4px 14px rgba(0,0,0,.08);text-align:center}
.card i{font-size:2.3rem;color:var(--primary);margin-bottom:.75rem}
.surface{background:var(--surface)}
/* === NAVBAR === */
header{
  background:var(--primary);color:#fff;
  padding:1rem 1.25rem;
  display:flex;justify-content:space-between;align-items:center;
  position:sticky;top:0;z-index:1020; /* asegura que quede encima del hero */
  box-shadow:0 2px 6px rgba(0,0,0,.15);
}
.logo img{width: 46px}
.logo{
  background-color: #fff;
  width: 50px;
  height: 50px;
  display: flex;
  justify-content: center;
  border-radius: 100%;
}
.header-controls{display:flex;width: 100%; justify-content: end; align-items:center;gap:.75rem}
nav ul{list-style:none;display:flex;gap:1.25rem}
nav a{color:#fff;font-weight:600}
.menu-toggle{display:none; background:none;border:none;color:#fff;
             font-size:1.7rem;cursor:pointer;}
             
button#modeToggle{
              
              margin-right: 10px;
             }
/* ---- Mobile ---- */
@media (max-width:760px){
  nav ul{
    flex-direction:column;
    background:var(--primary);
    position:absolute;left:0;top:100%;
    width:100%;
    overflow:hidden;
    max-height:0;                /* cerrado por defecto */
    transition:max-height .35s ease;
    border-top:1px solid rgba(255,255,255,.25);
  }
  nav ul.open{max-height:340px;} /* suficiente para 6 links */
  nav li{padding:.85rem 22px;border-bottom:1px solid rgba(255,255,255,.15);}
  .menu-toggle{display:block;}
}


/*  HERO  */
.hero{
  background:linear-gradient(rgba(0,0,0,.55),rgba(0,0,0,.55)),
            url('../lab-hero.png') center/cover no-repeat;
  color:#fff;text-align:center;padding:6rem 2rem
}
.hero h1{font-size:2.4rem;margin-bottom:1rem}
.hero p{max-width:640px;margin:0 auto 2rem}
@media(min-width:600px){.hero h1{font-size:3rem}}

/*  ABOUT  */
.founders{display:flex;gap:1.5rem;justify-content:center;flex-wrap:wrap;margin-top:2rem}
.founders img{width:190px;height:190px;object-fit:cover;border-radius:50%;
  box-shadow:0 4px 14px rgba(0,0,0,.1)}
.values ul{display:flex;flex-wrap:wrap;gap:.75rem;justify-content:center;margin-top:1rem}
.values li{background:var(--surface);padding:.5rem .9rem;border-radius:.4rem;font-weight:600}

/*  TESTIMONIALS  */
.testimonials{display:grid;gap:1.5rem;grid-template-columns:repeat(auto-fit,minmax(300px,1fr))}
.testimonial{background:var(--surface);border-left:4px solid var(--accent);padding:1.5rem;border-radius:.4rem}

/*  CONTACT  */
.contact-grid{display:grid;gap:2rem;grid-template-columns:repeat(auto-fit,minmax(280px,1fr))}
input,textarea{width:100%;padding:.75rem;border:1px solid #cbd5e1;border-radius:.4rem;font-family:inherit}

/*  FOOTER  */
footer{background:var(--primary);color:#fff;padding:3rem 2rem}
.footer-grid{display:grid;gap:2rem;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));
             max-width:1200px;margin:0 auto 2rem}
.footer-grid h3{margin-bottom:1rem;font-size:1.25rem}
.socials a{color:#fff;margin-right:.5rem;font-size:1.3rem}
.copy{text-align:center;font-size:.875rem}