:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-text: #1f2937;
  --color-text-light: #6b7280;
  --color-bg: #ffffff;
  --color-bg-gray: #f3f4f6;
  --max-width: 1100px;
  --radius: 10px;
}

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

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

img {
  max-width: 100%;
  display: block;
}

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

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* Header */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-bg);
  border-bottom: 1px solid #e5e7eb;
}

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 70px;
}

.logo {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--color-primary);
}

.nav {
  display: flex;
  gap: 28px;
}

.nav a {
  font-weight: 500;
  color: var(--color-text);
  transition: color 0.2s;
}

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

.burger {
  display: none;
  flex-direction: column;
  justify-content: space-between;
  width: 26px;
  height: 20px;
  background: none;
  border: none;
  cursor: pointer;
}

.burger span {
  display: block;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
}

/* Hero */
.hero {
  background: linear-gradient(135deg, #eff6ff, #f9fafb);
  padding: 100px 0;
  text-align: center;
}

.hero h1 {
  font-size: 2.6rem;
  margin-bottom: 16px;
  color: #111827;
}

.hero p {
  font-size: 1.15rem;
  color: var(--color-text-light);
  max-width: 600px;
  margin: 0 auto 28px;
}

.btn {
  display: inline-block;
  background: var(--color-primary);
  color: #fff;
  padding: 12px 28px;
  border-radius: var(--radius);
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: background 0.2s, transform 0.2s;
}

.btn:hover {
  background: var(--color-primary-dark);
  transform: translateY(-2px);
}

/* Sections */
.section {
  padding: 80px 0;
}

.section--gray {
  background: var(--color-bg-gray);
}

.section h2 {
  font-size: 2rem;
  margin-bottom: 20px;
  text-align: center;
}

.section > .container > p {
  max-width: 700px;
  margin: 0 auto;
  color: var(--color-text-light);
  text-align: center;
}

/* Cards */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 24px;
  margin-top: 40px;
}

.card {
  background: #fff;
  padding: 28px;
  border-radius: var(--radius);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
  text-align: center;
  transition: transform 0.2s, box-shadow 0.2s;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.08);
}

.card h3 {
  color: var(--color-primary);
  margin-bottom: 10px;
}

.card p {
  color: var(--color-text-light);
}

/* Form */
.form {
  max-width: 500px;
  margin: 40px auto 0;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.form input,
.form textarea {
  padding: 12px 14px;
  border: 1px solid #d1d5db;
  border-radius: var(--radius);
  font-size: 1rem;
  font-family: inherit;
  resize: vertical;
}

.form input:focus,
.form textarea:focus {
  outline: none;
  border-color: var(--color-primary);
}

.form .btn {
  align-self: center;
  min-width: 160px;
}

.form__status {
  text-align: center;
  margin-top: 16px;
  color: var(--color-primary);
  font-weight: 500;
}

/* Footer */
.footer {
  background: #111827;
  color: #9ca3af;
  text-align: center;
  padding: 24px 0;
  font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 768px) {
  .nav {
    position: absolute;
    top: 70px;
    left: 0;
    right: 0;
    background: var(--color-bg);
    flex-direction: column;
    align-items: center;
    gap: 0;
    border-bottom: 1px solid #e5e7eb;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
  }

  .nav.open {
    max-height: 300px;
  }

  .nav a {
    padding: 16px;
    width: 100%;
    text-align: center;
  }

  .burger {
    display: flex;
  }

  .hero h1 {
    font-size: 2rem;
  }
}