/* RESET BÁSICO */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #f4f7fa 0%, #d9e2ec 100%);
  color: #2e3a59;
  line-height: 1.8;
  font-size: 17px;
  overflow-x: hidden;
}

/* HEADER (fijo) */
.site-header {
  position: fixed;
  top: 0;
  width: 100%;
  height: 130px;
  background: rgba(255, 255, 255, 0.75);
  backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid rgba(60, 78, 121, 0.15);
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.05);
  z-index: 1000;
  padding: 0 40px;
  display: flex;
  align-items: center;
  transition: background-color 0.3s ease, height .2s ease;
}

.header-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
}

.logo {
  font-size: 1.6rem;
  font-weight: 600;
  color: #3c4e79;
  user-select: none;
}

.main-nav ul {
  list-style: none;
  display: flex;
  gap: 30px;
  margin: 0;
}

.main-nav a {
  text-decoration: none;
  color: #3c4e79;
  font-weight: 500;
  padding: 6px 10px;
  border-radius: 5px;
  font-size: 0.95rem;
  transition: background-color 0.25s ease, color 0.25s ease;
}

.main-nav a:hover,
.main-nav a.active {
  background-color: #cbd5e0;
  color: #1a1a1a;
}

/* MAIN / CONTENEDOR */
.container {
  /* Empuja el contenido por debajo del header fijo */
  margin-top: 130px;
  /* = .site-header height */
  padding: 0 30px;
}

/* TÍTULO E INTRO (ajuste responsivo del título) */
.metodo-section h1 {
  /* Tamaño fluido y más compacto en móvil */
  font-size: clamp(1.8rem, 4.5vw, 2.5rem);
  color: #1f2a56;
  margin-bottom: 16px;
  font-weight: 700;
  letter-spacing: 0.02em;
  /* un poco menos para legibilidad */
  /* Quitamos el gran margen superior que rompía el layout bajo header fijo */
  margin-top: 8px;
}

.intro {
  font-size: clamp(1rem, 2.2vw, 1.15rem);
  color: #3b4466;
  margin-bottom: 44px;
  max-width: 720px;
  line-height: 1.9;
}

/* SELECTOR DE MÉTODO */
.selector-metodo {
  display: flex;
  justify-content: center;
  gap: 16px;
  margin-bottom: 44px;
  flex-wrap: wrap;
}

.selector-btn {
  background-color: #dbe3fa;
  border: none;
  padding: 12px 22px;
  font-size: 1.02rem;
  font-weight: 600;
  color: #1f2a56;
  border-radius: 12px;
  box-shadow: 0 8px 16px rgba(60, 78, 121, 0.1);
  cursor: pointer;
  transition: all 0.35s ease;
}

.selector-btn:hover {
  background-color: #304ffe;
  color: #fff;
  transform: translateY(-2px);
}

.selector-btn.active {
  background-color: #1f2a56;
  color: #ffe600;
  transform: scale(1.02);
}

/* CONTENIDO DE MÉTODO */
.contenido-metodo {
  background-color: #ffffffdd;
  padding: clamp(24px, 3.5vw, 40px) clamp(18px, 3vw, 30px);
  border-radius: 18px;
  box-shadow: 0 12px 30px rgba(46, 58, 89, 0.12);
  opacity: 0;
  transform: scale(0.96) translateY(20px);
  pointer-events: none;
  transition: all 0.5s ease;
  display: none;
  max-width: 900px;
  margin: 0 auto 36px auto;
}

.contenido-metodo.visible {
  opacity: 1;
  transform: scale(1) translateY(0);
  pointer-events: auto;
  display: block;
}

.contenido-metodo h2 {
  font-size: clamp(1.3rem, 3.5vw, 1.9rem);
  /* más pequeño en móvil */
  color: #1f2a56;
  margin-bottom: 12px;
  line-height: 1.25;
}

.contenido-metodo p {
  font-size: clamp(1rem, 2.2vw, 1.08rem);
  color: #3b4466;
  line-height: 1.8;
}

/* FOOTER */
.site-footer {
  padding: 30px 0;
  background-color: #1f2a56;
  color: #d0d6f9;
  text-align: center;
  font-size: 0.95rem;
  user-select: none;
  box-shadow: inset 0 1px 3px rgba(255, 255, 255, 0.1);
}

/* EFECTO FADE IN AL CARGAR */
.fade-in {
  animation: fadeInMoveUp 0.75s ease forwards;
  opacity: 0;
}

@keyframes fadeInMoveUp {
  from {
    opacity: 0;
    transform: translateY(18px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ===== RESPONSIVE ===== */

/* Tablet */
@media (max-width: 992px) {
  .site-header {
    height: 110px;
  }

  .container {
    margin-top: 110px;
    padding: 0 24px;
  }

  .logo {
    font-size: 1.5rem;
  }

  .main-nav ul {
    gap: 22px;
  }
}

/* Móvil */
@media (max-width: 768px) {
  .site-header {
    height: 100px;
    padding: 0 20px;
  }

  .container {
    margin-top: 100px;
    padding: 0 16px;
  }

  .selector-metodo {
    gap: 12px;
  }

  .selector-btn {
    flex: 1 1 100%;
    text-align: center;
    padding: 12px 18px;
  }

  .contenido-metodo {
    padding: 24px 18px;
    border-radius: 14px;
  }
}

/* Móvil pequeño */
@media (max-width: 400px) {
  .site-header {
    height: 92px;
  }

  .container {
    margin-top: 92px;
  }

  .main-nav ul {
    gap: 14px;
  }

  .logo {
    font-size: 1.4rem;
  }
}