:root {
  --bg: #f7f9fc;
  --surface: #ffffff;
  --text: #1d2635;
  --muted: #637083;
  --primary: #2f6fed;
  --primary-dark: #2457bc;
  --border: #e6ebf2;
  --shadow: 0 10px 30px rgba(18, 38, 63, 0.08);
  --radius: 14px;
  --max-width: 1080px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Inter, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

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

.container {
  width: min(100% - 2rem, var(--max-width));
  margin-inline: auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(247, 249, 252, 0.94);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}

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

.brand {
  font-weight: 700;
  letter-spacing: 0.2px;
}

.nav-toggle {
  display: none;
  border: 1px solid var(--border);
  background: var(--surface);
  border-radius: 10px;
  padding: 0.45rem 0.6rem;
  cursor: pointer;
}

.main-nav {
  display: flex;
  gap: 0.7rem;
}

.main-nav a {
  padding: 0.45rem 0.75rem;
  border-radius: 8px;
  color: var(--muted);
  font-weight: 500;
}

.main-nav a:hover,
.main-nav a.active {
  color: var(--primary);
  background: #edf3ff;
}

main {
  padding-block: 3rem;
}

.hero {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: clamp(1.5rem, 4vw, 3rem);
  display: grid;
  gap: 1.25rem;
}

.hero h1 {
  margin: 0;
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  line-height: 1.2;
}

.hero p {
  margin: 0;
  max-width: 65ch;
  color: var(--muted);
}

.button {
  display: inline-block;
  width: fit-content;
  border: 0;
  border-radius: 10px;
  background: var(--primary);
  color: #fff;
  padding: 0.72rem 1.1rem;
  font-weight: 600;
}

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

.section {
  margin-top: 2rem;
}

.section h2 {
  margin-bottom: 0.4rem;
  font-size: 1.5rem;
}

.section p {
  margin-top: 0;
  color: var(--muted);
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.1rem;
}

.card h3 {
  margin-top: 0;
}

.card p {
  margin-bottom: 0;
  color: var(--muted);
}

.course-tag {
  display: inline-block;
  margin-bottom: 0.6rem;
  background: #edf3ff;
  color: var(--primary);
  font-size: 0.85rem;
  font-weight: 600;
  padding: 0.2rem 0.5rem;
  border-radius: 999px;
}

.contact-grid {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 1rem;
}

.contact-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.contact-list li + li {
  margin-top: 0.5rem;
}

.contact-form {
  display: grid;
  gap: 0.75rem;
}

input,
textarea {
  width: 100%;
  font: inherit;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.72rem 0.8rem;
  background: #fff;
}

textarea {
  min-height: 120px;
  resize: vertical;
}

.site-footer {
  border-top: 1px solid var(--border);
  padding: 1.2rem 0;
  color: var(--muted);
  font-size: 0.95rem;
}

@media (max-width: 900px) {
  .grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .contact-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 700px) {
  .nav-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
  }

  .main-nav {
    position: absolute;
    top: 72px;
    left: 0;
    right: 0;
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    display: none;
    flex-direction: column;
    padding: 0.6rem 1rem 1rem;
  }

  .main-nav.open {
    display: flex;
  }

  .main-nav a {
    width: 100%;
    padding: 0.65rem 0.7rem;
  }

  .grid {
    grid-template-columns: 1fr;
  }
}