:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --purple: #7c3aed;
  --dark: #111827;
  --text: #4b5563;
  --light: #f5f7fb;
  --white: #ffffff;
  --border: #e5e7eb;
  --success: #15803d;
}

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

body {
  font-family: Arial, Helvetica, sans-serif;
  color: var(--dark);
  background: var(--white);
  line-height: 1.6;
}

a {
  text-decoration: none;
  color: inherit;
}

.container {
  width: min(1120px, 92%);
  margin: auto;
}

.site-header {
  background: var(--white);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}

.nav-wrapper {
  min-height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-size: 20px;
  font-weight: 700;
  color: var(--dark);
}

.logo span {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  margin-right: 8px;
  border-radius: 10px;
  color: var(--white);
  background: linear-gradient(135deg, var(--primary), var(--purple));
}

nav {
  display: flex;
  gap: 25px;
}

nav a {
  color: var(--text);
  font-weight: 600;
  padding: 8px 0;
}

nav a:hover,
nav a.active {
  color: var(--primary);
}

.menu-toggle {
  display: none;
  border: 0;
  background: transparent;
  font-size: 26px;
  cursor: pointer;
}

.hero {
  background: linear-gradient(135deg, #eff6ff, #f5f3ff);
  padding: 90px 0;
}

.hero-content {
  display: grid;
  grid-template-columns: 1.3fr 0.7fr;
  gap: 60px;
  align-items: center;
}

.tagline {
  color: var(--primary);
  font-size: 14px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 10px;
}

h1 {
  font-size: clamp(36px, 6vw, 64px);
  line-height: 1.1;
  margin-bottom: 20px;
}

h2 {
  font-size: 32px;
  margin-bottom: 15px;
}

h3 {
  margin-bottom: 8px;
}

.hero-text {
  color: var(--text);
  font-size: 18px;
  max-width: 600px;
}

.hero-buttons {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  margin-top: 30px;
}

.btn {
  display: inline-block;
  border: 0;
  border-radius: 8px;
  padding: 13px 21px;
  font-weight: 700;
  cursor: pointer;
}

.primary-btn {
  color: var(--white);
  background: var(--primary);
}

.primary-btn:hover {
  background: var(--primary-dark);
}

.secondary-btn {
  color: var(--primary);
  background: var(--white);
  border: 1px solid var(--primary);
}

.hero-card {
  padding: 40px 30px;
  text-align: center;
  background: var(--white);
  border-radius: 20px;
  box-shadow: 0 15px 40px rgba(37, 99, 235, 0.12);
}

.card-icon {
  font-size: 65px;
  margin-bottom: 15px;
}

.section {
  padding: 75px 0;
}

.section-heading {
  text-align: center;
  margin-bottom: 35px;
}

.class-grid,
.feature-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 25px;
}

.feature-grid {
  grid-template-columns: repeat(3, 1fr);
}

.class-card {
  display: flex;
  gap: 20px;
  align-items: center;
  padding: 28px;
  border: 1px solid var(--border);
  border-radius: 15px;
  transition: 0.25s;
}

.class-card:hover {
  border-color: var(--primary);
  transform: translateY(-4px);
  box-shadow: 0 12px 30px rgba(17, 24, 39, 0.08);
}

.class-card p,
.feature-card p,
.content-box p,
.contact-info p {
  color: var(--text);
}

.class-card span {
  display: inline-block;
  color: var(--primary);
  font-weight: 700;
  margin-top: 12px;
}

.class-number {
  min-width: 70px;
  height: 70px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 18px;
  color: var(--white);
  background: var(--primary);
  font-size: 28px;
  font-weight: bold;
}

.class-number.purple {
  background: var(--purple);
}

.features-section {
  background: var(--light);
  padding: 75px 0;
}

.feature-card {
  padding: 28px;
  background: var(--white);
  border-radius: 14px;
  border: 1px solid var(--border);
}

.feature-icon {
  width: 42px;
  height: 42px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 15px;
  border-radius: 50%;
  color: var(--white);
  background: var(--primary);
  font-weight: bold;
}

.page-banner {
  padding: 70px 0;
  color: var(--white);
  background: linear-gradient(135deg, var(--primary), var(--purple));
}

.page-banner h1 {
  font-size: 45px;
  margin-bottom: 10px;
}

.page-banner .tagline,
.page-banner p {
  color: #dbeafe;
}

.subject-tabs {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 30px;
}

.subject-btn {
  padding: 11px 17px;
  border: 1px solid var(--border);
  border-radius: 7px;
  color: var(--text);
  background: var(--white);
  cursor: pointer;
  font-weight: bold;
}

.subject-btn.active,
.subject-btn:hover {
  color: var(--white);
  background: var(--primary);
  border-color: var(--primary);
}

.question-area h2 {
  margin-bottom: 22px;
}

.question-card {
  margin-bottom: 22px;
  padding: 25px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--white);
}

.question-card > p {
  margin-bottom: 15px;
  font-size: 17px;
}

.question-card label {
  display: block;
  margin: 9px 0;
  color: var(--text);
}

.answer-btn {
  margin-top: 15px;
  padding: 9px 14px;
  border: 0;
  border-radius: 6px;
  color: var(--white);
  background: var(--dark);
  cursor: pointer;
}

.answer {
  margin-top: 12px;
  color: var(--success);
  font-weight: bold;
}

.hidden {
  display: none;
}

.content-box {
  max-width: 800px;
}

.notice {
  margin-top: 25px;
  padding: 18px;
  border-left: 4px solid var(--primary);
  color: var(--text);
  background: #eff6ff;
}

.contact-layout {
  display: grid;
  grid-template-columns: 0.8fr 1.2fr;
  gap: 50px;
}

.contact-form {
  padding: 30px;
  border: 1px solid var(--border);
  border-radius: 15px;
}

.contact-form label {
  display: block;
  margin: 14px 0 6px;
  font-weight: bold;
}

.contact-form input,
.contact-form textarea {
  width: 100%;
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: 7px;
  font: inherit;
}

.contact-form textarea {
  resize: vertical;
}

.contact-form button {
  margin-top: 18px;
}

.form-message {
  margin-top: 15px;
  color: var(--success);
  font-weight: bold;
}

.footer {
  padding: 35px 0;
  color: #d1d5db;
  background: var(--dark);
}

.footer-content {
  display: flex;
  justify-content: space-between;
  gap: 25px;
}

@media (max-width: 760px) {
  .menu-toggle {
    display: block;
  }

  nav {
    display: none;
    position: absolute;
    top: 72px;
    left: 0;
    right: 0;
    padding: 20px;
    flex-direction: column;
    gap: 10px;
    background: var(--white);
    border-bottom: 1px solid var(--border);
  }

  nav.show {
    display: flex;
  }

  .hero-content,
  .contact-layout,
  .class-grid,
  .feature-grid {
    grid-template-columns: 1fr;
  }

  .hero {
    padding: 60px 0;
  }

  .page-banner h1 {
    font-size: 37px;
  }

  .footer-content {
    flex-direction: column;
  }
}