:root {
  --bg: #ffffff;
  --bg-soft: #f6f7f9;
  --bg-card: #ffffff;
  --text: #1a1f2e;
  --text-soft: #5b6472;
  --muted: #8a93a3;
  --border: #e7e9ee;
  --primary: #1f6feb;
  --primary-dark: #1559c4;
  --primary-soft: #e8f0fe;
  --accent: #0a8f7a;
  --wa: #25d366;
  --wa-dark: #1ebe5a;
  --radius: 14px;
  --radius-sm: 10px;
  --shadow-sm: 0 1px 2px rgba(16, 24, 40, 0.06);
  --shadow: 0 8px 24px rgba(16, 24, 40, 0.08);
  --shadow-lg: 0 20px 48px rgba(16, 24, 40, 0.12);
  --maxw: 1080px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Inter", system-ui, -apple-system, sans-serif;
  color: var(--text);
  background-color: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

.container {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text);
  font-weight: 700;
  font-size: 1.05rem;
}
.brand-mark {
  display: inline-grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 9px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff;
  font-weight: 700;
  font-size: 1.1rem;
}
.header-cta { display: inline-flex; }

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 20px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  cursor: pointer;
  border: 1px solid transparent;
  transition: transform 0.15s ease, background-color 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}
.btn:active { transform: translateY(1px); }
.btn-sm { padding: 8px 16px; font-size: 0.88rem; }
.btn-lg { padding: 15px 28px; font-size: 1.05rem; }
.btn-primary {
  background: var(--primary);
  color: #fff;
  box-shadow: var(--shadow-sm);
}
.btn-primary:hover { background: var(--primary-dark); box-shadow: var(--shadow); }
.btn-ghost {
  background: transparent;
  color: var(--text);
  border-color: var(--border);
}
.btn-ghost:hover { background: var(--bg-soft); border-color: #d3d7df; }
.btn-whatsapp {
  background: var(--wa);
  color: #fff;
  box-shadow: 0 8px 20px rgba(37, 211, 102, 0.35);
}
.btn-whatsapp:hover { background: var(--wa-dark); box-shadow: 0 12px 28px rgba(37, 211, 102, 0.45); }

.wa-icon, .wa-icon-lg { width: 20px; height: 20px; flex: none; }
.wa-icon-lg { width: 30px; height: 30px; }

/* Hero */
.hero {
  padding: 72px 0 64px;
  background:
    radial-gradient(1200px 480px at 80% -10%, rgba(31, 111, 235, 0.10), transparent 60%),
    radial-gradient(900px 420px at 0% 0%, rgba(10, 143, 122, 0.08), transparent 55%),
    var(--bg);
}
.hero-inner {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 56px;
  align-items: center;
}
.eyebrow {
  margin: 0 0 14px;
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--accent);
}
.hero h1 {
  margin: 0 0 18px;
  font-size: clamp(2.1rem, 4.4vw, 3.2rem);
  line-height: 1.1;
  font-weight: 700;
  letter-spacing: -0.02em;
}
.accent { color: var(--primary); }
.lead {
  margin: 0 0 28px;
  font-size: 1.12rem;
  color: var(--text-soft);
  max-width: 30em;
}
.hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 36px;
}
.hero-stats {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 32px;
  flex-wrap: wrap;
}
.hero-stats li {
  display: flex;
  flex-direction: column;
}
.hero-stats strong {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text);
}
.hero-stats span {
  font-size: 0.85rem;
  color: var(--muted);
}

/* Hero card */
.hero-card {
  position: relative;
  border-radius: 22px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  box-shadow: var(--shadow-lg);
  padding: 32px;
  overflow: hidden;
}
.card-glow {
  position: absolute;
  inset: -40% -30% auto auto;
  width: 320px;
  height: 320px;
  background: radial-gradient(circle, rgba(31, 111, 235, 0.18), transparent 65%);
  pointer-events: none;
}
.card-content { position: relative; }
.card-tag {
  display: inline-block;
  padding: 5px 12px;
  border-radius: 999px;
  background: var(--primary-soft);
  color: var(--primary-dark);
  font-size: 0.78rem;
  font-weight: 600;
  margin-bottom: 18px;
}
.equation {
  font-family: "Georgia", "Times New Roman", serif;
  font-size: 1.5rem;
  font-style: italic;
  color: var(--text);
  padding: 18px 20px;
  background: var(--bg-soft);
  border-radius: var(--radius-sm);
  margin-bottom: 14px;
}
.card-note {
  margin: 0 0 20px;
  color: var(--text-soft);
  font-size: 0.95rem;
}
.card-steps { display: flex; flex-direction: column; gap: 10px; }
.step {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.92rem;
  color: var(--text-soft);
}
.step span {
  display: inline-grid;
  place-items: center;
  width: 24px;
  height: 24px;
  border-radius: 7px;
  background: var(--primary);
  color: #fff;
  font-size: 0.8rem;
  font-weight: 700;
  flex: none;
}

/* About / Photo */
.about { padding: 80px 0; background: var(--bg); }
.about-inner {
  display: grid;
  grid-template-columns: 0.85fr 1.15fr;
  gap: 56px;
  align-items: center;
}
.about-photo {
  position: relative;
  border-radius: 20px;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  aspect-ratio: 4 / 5;
  background: linear-gradient(135deg, var(--primary-soft), rgba(10, 143, 122, 0.12));
}
.about-photo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
.about-photo::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 20px;
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.4);
  pointer-events: none;
}
.about-copy .eyebrow { margin-bottom: 12px; }
.about-title {
  margin: 0 0 16px;
  font-size: clamp(1.6rem, 3.2vw, 2.2rem);
  font-weight: 700;
  letter-spacing: -0.01em;
}
.about-copy p {
  margin: 0 0 16px;
  color: var(--text-soft);
  font-size: 1.02rem;
}
.about-copy .btn { margin-top: 6px; }

/* Section titles */
.section-title {
  margin: 0 0 36px;
  font-size: clamp(1.6rem, 3vw, 2.1rem);
  font-weight: 700;
  letter-spacing: -0.01em;
  text-align: center;
}

/* Subjects */
.subjects { padding: 80px 0; background: var(--bg-soft); }
.subject-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
.subject {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 24px;
  box-shadow: var(--shadow-sm);
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}
.subject:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow);
  border-color: #d3d7df;
}
.subject-icon {
  display: inline-grid;
  place-items: center;
  width: 48px;
  height: 48px;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--primary-soft), rgba(10, 143, 122, 0.12));
  color: var(--primary-dark);
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 16px;
}
.subject h3 {
  margin: 0 0 8px;
  font-size: 1.15rem;
  font-weight: 600;
}
.subject p {
  margin: 0;
  color: var(--text-soft);
  font-size: 0.95rem;
}

/* How it works */
.how { padding: 80px 0; }
.steps-list {
  list-style: none;
  counter-reset: step;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}
.steps-list li {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px 22px;
  position: relative;
  transition: box-shadow 0.2s ease, transform 0.2s ease;
}
.steps-list li:hover { box-shadow: var(--shadow); transform: translateY(-3px); }
.num {
  display: inline-grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: var(--text);
  color: #fff;
  font-weight: 700;
  margin-bottom: 14px;
}
.steps-list h3 {
  margin: 0 0 6px;
  font-size: 1.05rem;
  font-weight: 600;
}
.steps-list p {
  margin: 0;
  color: var(--text-soft);
  font-size: 0.92rem;
}

/* FAQ */
.faq { padding: 80px 0; }
.faq-inner { max-width: 760px; margin: 0 auto; }
.faq-list { display: flex; flex-direction: column; gap: 12px; }
.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  transition: box-shadow 0.2s ease, border-color 0.2s ease;
}
.faq-item:hover { border-color: #d3d7df; }
.faq-item[open] { box-shadow: var(--shadow); border-color: #cdd3dc; }
.faq-item summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 20px 24px;
  font-weight: 600;
  font-size: 1.02rem;
  color: var(--text);
  cursor: pointer;
  list-style: none;
  -webkit-tap-highlight-color: transparent;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+";
  flex: none;
  font-size: 1.4rem;
  font-weight: 400;
  color: var(--primary);
  transition: transform 0.2s ease;
  line-height: 1;
}
.faq-item[open] summary::after { transform: rotate(45deg); }
.faq-item p {
  margin: 0;
  padding: 0 24px 22px;
  color: var(--text-soft);
  font-size: 0.96rem;
  line-height: 1.6;
}

/* Contact */
.contact {
  padding: 80px 0;
  background: var(--bg-soft);
}
.contact-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 24px;
}
.contact-copy h2 {
  margin: 0 0 10px;
  font-size: clamp(1.7rem, 3.2vw, 2.3rem);
  font-weight: 700;
  letter-spacing: -0.01em;
}
.contact-copy p {
  margin: 0;
  color: var(--text-soft);
  font-size: 1.05rem;
  max-width: 32em;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 24px 0;
  background: var(--bg);
}
.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.88rem;
  color: var(--muted);
}
.footer-link {
  color: var(--primary);
  text-decoration: none;
  font-weight: 500;
}
.footer-link:hover { text-decoration: underline; }

/* Floating WhatsApp */
.wa-float {
  position: fixed;
  right: 22px;
  bottom: 22px;
  z-index: 100;
  display: grid;
  place-items: center;
  width: 60px;
  height: 60px;
  border-radius: 50%;
  background: var(--wa);
  color: #fff;
  box-shadow: 0 10px 26px rgba(37, 211, 102, 0.5);
  transition: transform 0.2s ease, background-color 0.2s ease;
  animation: wa-pop 0.5s cubic-bezier(0.34, 1.56, 0.64, 1) both;
}
.wa-float:hover { background: var(--wa-dark); transform: scale(1.08); }
.wa-float-pulse {
  position: absolute;
  inset: 0;
  border-radius: 50%;
  background: var(--wa);
  opacity: 0.55;
  z-index: -1;
  animation: wa-pulse 2.4s ease-out infinite;
}
@keyframes wa-pop {
  from { transform: scale(0); opacity: 0; }
  to { transform: scale(1); opacity: 1; }
}
@keyframes wa-pulse {
  0% { transform: scale(1); opacity: 0.55; }
  70% { transform: scale(1.8); opacity: 0; }
  100% { transform: scale(1.8); opacity: 0; }
}

/* Reveal on scroll */
.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.is-visible {
  opacity: 1;
  transform: none;
}

/* Responsive */
@media (max-width: 860px) {
  .hero-inner { grid-template-columns: 1fr; gap: 40px; }
  .hero-card { order: -1; max-width: 420px; }
  .about-inner { grid-template-columns: 1fr; gap: 32px; }
  .about-photo { max-width: 360px; margin: 0 auto; }
  .subject-grid { grid-template-columns: 1fr; }
  .steps-list { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 560px) {
  .container { padding: 0 18px; }
  .hero { padding: 48px 0 40px; }
  .subjects, .how, .contact, .about, .faq { padding: 56px 0; }
  .steps-list { grid-template-columns: 1fr; }
  .hero-stats { gap: 22px; }
  .header-cta.btn-sm { padding: 8px 14px; }
  .wa-float { right: 16px; bottom: 16px; width: 54px; height: 54px; }
  .wa-icon-lg { width: 26px; height: 26px; }
  .footer-inner { flex-direction: column; gap: 8px; text-align: center; }
}

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
  .reveal { opacity: 1; transform: none; }
  html { scroll-behavior: auto; }
}