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

html {
  scroll-behavior: smooth;
}

body {
  font-family: Arial, Helvetica, sans-serif;
  background: #f6fbff;
  color: #172033;
  line-height: 1.6;
}

a {
  color: inherit;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 22px 7%;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid #dbeafe;
}

.logo {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  font-weight: 900;
  color: #083344;
  font-size: 1.15rem;
}

.logo-mark {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: linear-gradient(135deg, #0891b2, #22c55e);
  color: white;
  display: grid;
  place-items: center;
  font-weight: 900;
  box-shadow: 0 10px 25px rgba(8, 145, 178, 0.3);
}

nav {
  display: flex;
  gap: 22px;
  align-items: center;
}

nav a {
  text-decoration: none;
  color: #334155;
  font-weight: 700;
  font-size: 0.95rem;
}

nav a:hover {
  color: #0891b2;
}

.hero {
  min-height: 88vh;
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 50px;
  align-items: center;
  padding: 90px 7%;
  background:
    radial-gradient(circle at top left, rgba(34, 197, 94, 0.22), transparent 34%),
    radial-gradient(circle at bottom right, rgba(14, 165, 233, 0.28), transparent 38%),
    linear-gradient(135deg, #ecfeff, #ffffff 55%, #f0f9ff);
  overflow: hidden;
}

.eyebrow {
  color: #0891b2;
  font-weight: 900;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  font-size: 0.82rem;
  margin-bottom: 12px;
}

.hero h1 {
  font-size: clamp(3rem, 7vw, 6.5rem);
  line-height: 0.95;
  color: #071a2d;
  letter-spacing: -4px;
  margin-bottom: 28px;
}

.hero-description {
  font-size: 1.25rem;
  max-width: 680px;
  color: #475569;
  margin-bottom: 34px;
}

.hero-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
}

.button {
  display: inline-block;
  padding: 15px 24px;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 900;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.button:hover {
  transform: translateY(-2px);
}

.primary-button {
  background: linear-gradient(135deg, #0891b2, #22c55e);
  color: white;
  box-shadow: 0 15px 30px rgba(8, 145, 178, 0.28);
}

.secondary-button {
  background: white;
  color: #075985;
  border: 1px solid #bae6fd;
}

.chem-visual {
  position: relative;
  min-height: 440px;
  display: grid;
  place-items: center;
}

.chem-visual {
  position: relative;
  min-height: 440px;
  display: grid;
  place-items: center;
}

.hero-circle {
  width: 380px;
  height: 380px;
  border-radius: 50%;
  overflow: hidden;
  background: rgba(255, 255, 255, 0.78);
  border: 1px solid rgba(14, 165, 233, 0.18);
  box-shadow: 0 30px 70px rgba(15, 23, 42, 0.14);
  display: flex;
  align-items: center;
  justify-content: center;
}

.hero-circle-image {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
.visual-card {
  position: absolute;
  right: 0;
  bottom: 26px;
  width: 240px;
  background: #ffffff;
  border-radius: 24px;
  padding: 24px;
  box-shadow: 0 20px 45px rgba(15, 23, 42, 0.16);
  border: 1px solid #e0f2fe;
}

.visual-card p {
  color: #0891b2;
  font-weight: 900;
  margin-bottom: 8px;
}

.visual-card h3 {
  color: #0f172a;
  font-size: 1.4rem;
  line-height: 1.2;
}

.quick-links {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 22px;
  padding: 0 7%;
  margin-top: -55px;
  position: relative;
  z-index: 5;
}

.quick-card {
  background: white;
  border: 1px solid #e0f2fe;
  border-radius: 26px;
  padding: 26px;
  text-decoration: none;
  box-shadow: 0 18px 38px rgba(15, 23, 42, 0.08);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.quick-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 24px 55px rgba(15, 23, 42, 0.13);
}

.icon {
  font-size: 2rem;
  display: block;
  margin-bottom: 14px;
}

.quick-card h3 {
  color: #0f172a;
  margin-bottom: 8px;
}

.quick-card p {
  color: #64748b;
  font-size: 0.95rem;
}

.section {
  padding: 95px 7%;
}

.section-heading {
  max-width: 760px;
  margin-bottom: 42px;
}

.section-heading h2,
.split-section h2,
.about-box h2,
.contact-section h2 {
  color: #071a2d;
  font-size: clamp(2.2rem, 4vw, 3.8rem);
  line-height: 1;
  letter-spacing: -2px;
  margin-bottom: 20px;
}

.section-heading p,
.split-section p,
.about-box p,
.contact-section p {
  color: #526277;
  font-size: 1.08rem;
}

.lesson-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 22px;
}

.lesson-card {
  background: white;
  border: 1px solid #dbeafe;
  border-radius: 28px;
  padding: 30px;
  min-height: 260px;
  box-shadow: 0 14px 35px rgba(15, 23, 42, 0.06);
}

.lesson-number {
  width: 54px;
  height: 54px;
  border-radius: 18px;
  display: grid;
  place-items: center;
  background: #ecfeff;
  color: #0891b2;
  font-weight: 900;
  margin-bottom: 24px;
}

.lesson-card h3 {
  color: #0f172a;
  font-size: 1.45rem;
  margin-bottom: 12px;
}

.lesson-card p {
  color: #64748b;
}

.dark-section {
  background:
    radial-gradient(circle at top right, rgba(34, 197, 94, 0.18), transparent 35%),
    linear-gradient(135deg, #0f172a, #083344);
  color: white;
}

.dark-section .section-heading h2,
.dark-section .section-heading p {
  color: white;
}

.resource-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 22px;
}

.resource-card {
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.16);
  border-radius: 28px;
  padding: 30px;
  backdrop-filter: blur(14px);
}

.resource-card h3 {
  font-size: 1.55rem;
  margin-bottom: 12px;
}

.resource-card p {
  color: #dbeafe;
  margin-bottom: 20px;
}

.text-link {
  color: #67e8f9;
  font-weight: 900;
  text-decoration: none;
}

.split-section {
  display: grid;
  grid-template-columns: 1fr 0.85fr;
  gap: 48px;
  align-items: center;
}

.check-list {
  list-style: none;
  margin: 28px 0;
}

.check-list li {
  margin-bottom: 12px;
  padding-left: 32px;
  position: relative;
  color: #334155;
  font-weight: 700;
}

.check-list li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: #22c55e;
  font-weight: 900;
}

.tutoring-card {
  background:
    linear-gradient(135deg, rgba(8, 145, 178, 0.12), rgba(34, 197, 94, 0.12)),
    #ffffff;
  border: 1px solid #dbeafe;
  border-radius: 34px;
  padding: 38px;
  box-shadow: 0 22px 55px rgba(15, 23, 42, 0.1);
}

.tutoring-card h3 {
  font-size: 1.8rem;
  color: #083344;
  margin-bottom: 22px;
}

.tutoring-card p {
  background: white;
  border-radius: 18px;
  padding: 16px;
  margin-bottom: 12px;
  color: #475569;
  font-weight: 700;
}

.about-section {
  background: #ffffff;
}

.about-box {
  max-width: 920px;
  background:
    radial-gradient(circle at top left, rgba(14, 165, 233, 0.16), transparent 36%),
    #f8fafc;
  border: 1px solid #dbeafe;
  border-radius: 36px;
  padding: 48px;
}

.about-box p {
  margin-bottom: 16px;
}

.insights-section {
  background: #f6fbff;
}

.insight-card {
  display: flex;
  justify-content: space-between;
  gap: 30px;
  align-items: center;
  background: white;
  border: 1px solid #dbeafe;
  border-radius: 32px;
  padding: 36px;
  box-shadow: 0 18px 45px rgba(15, 23, 42, 0.08);
}

.insight-card h3 {
  font-size: 2rem;
  color: #0f172a;
  margin-bottom: 10px;
}

.insight-card p {
  color: #64748b;
  max-width: 720px;
}

.contact-section {
  text-align: center;
  background:
    radial-gradient(circle at top, rgba(34, 197, 94, 0.22), transparent 35%),
    linear-gradient(135deg, #071a2d, #083344);
}

.contact-section h2 {
  color: white;
}

.contact-section p {
  color: #dbeafe;
  max-width: 760px;
  margin: 0 auto 28px;
}

.small-note {
  font-size: 0.9rem;
  margin-top: 18px;
  opacity: 0.8;
}

footer {
  text-align: center;
  padding: 28px;
  background: #020617;
  color: #cbd5e1;
}

@media (max-width: 950px) {
  .site-header {
    flex-direction: column;
    gap: 16px;
  }

  nav {
    flex-wrap: wrap;
    justify-content: center;
  }

  .hero,
  .split-section {
    grid-template-columns: 1fr;
  }

  .hero {
    min-height: auto;
    padding-top: 65px;
  }

  .chem-visual {
    min-height: 360px;
  }

  .quick-links,
  .lesson-grid,
  .resource-grid {
    grid-template-columns: 1fr 1fr;
  }

  .quick-links {
    margin-top: 0;
    padding-top: 28px;
  }
}

@media (max-width: 620px) {
  .site-header {
    padding: 18px 5%;
  }

  nav {
    gap: 14px;
  }

  nav a {
    font-size: 0.86rem;
  }

  .hero,
  .section {
    padding-left: 5%;
    padding-right: 5%;
  }

  .hero h1 {
    letter-spacing: -2px;
  }

  .quick-links,
  .lesson-grid,
  .resource-grid {
    grid-template-columns: 1fr;
    padding-left: 5%;
    padding-right: 5%;
  }

  .hero-circle {
  width: 290px;
  height: 290px;
}

  .visual-card {
    position: relative;
    right: auto;
    bottom: auto;
    margin-top: -30px;
  }

  .insight-card {
    flex-direction: column;
    align-items: flex-start;
  }

  .about-box {
    padding: 32px;
  }
}