* {
  box-sizing: border-box;
  font-family: Arial, sans-serif;
}

body {
  margin: 0;
  background: #f5f7fb;
  color: #1f2937;
}

.container {
  max-width: 1400px;
  margin: 40px auto;
  padding: 20px;
}

.card {
  background: #ffffff;
  border-radius: 16px;
  padding: 24px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
}

h1 {
  margin-top: 0;
  font-size: 32px;
  margin-bottom: 10px;
}

h2 {
  margin-top: 0;
}

p {
  color: #4b5563;
  margin-bottom: 20px;
}


.site-nav {
  max-width: 1400px;
  margin: 24px auto 0;
  padding: 0 20px;
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.site-nav a {
  text-decoration: none;
  background: #ffffff;
  color: #1f2937;
  padding: 10px 14px;
  border-radius: 10px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
  font-weight: 600;
  display: inline-block;
}

.site-nav a:hover {
  background: #eff6ff;
}

.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
}

.tool-card {
  display: block;
  background: #eff6ff;
  border-radius: 14px;
  padding: 20px;
  text-decoration: none;
  color: inherit;
}

.tool-card:hover {
  background: #dbeafe;
}

input {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid #d1d5db;
  border-radius: 8px;
  font-size: 14px;
}

button {
  padding: 12px 18px;
  border: none;
  border-radius: 10px;
  font-size: 15px;
  cursor: pointer;
  font-weight: 600;
}

.primary-btn {
  background: #2563eb;
  color: white;
}

.primary-btn:hover {
  background: #1d4ed8;
}

.result-box {
  background: #eff6ff;
  padding: 18px;
  border-radius: 12px;
  margin-top: 16px;
}

.seo-section {
  margin-top: 24px;
  line-height: 1.7;
}

@media (max-width: 768px) {
  h1 {
    font-size: 26px;
  }
}

.bottom-content {
  max-width: 1400px;
  margin: 40px auto;
  padding: 0 20px 40px;
}

.seo-card {
  background: #ffffff;
  border-radius: 16px;
  padding: 40px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
}

.seo-card h2 {
  font-size: 28px;
  margin: 0 0 16px;
  color: #1f2937;
}

.seo-card p {
  margin: 0 0 20px;
  color: #4b5563;
  line-height: 1.7;
}

.seo-formula {
  font-weight: 700;
  color: #1f2937;
  margin-bottom: 20px;
}

.ad-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  margin-top: 30px;
}

.ad-box {
  min-height: 250px;
  background: #f3f4f6;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
}