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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen,
    Ubuntu, Cantarell, sans-serif;
  background: #0f172a;
  color: #e2e8f0;
  min-height: 100vh;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 48px 24px;
}

.container {
  width: 100%;
  max-width: 680px;
}

.card {
  background: #1e293b;
  border-radius: 16px;
  padding: 40px;
  box-shadow: 0 25px 50px rgba(0, 0, 0, 0.4);
  border: 1px solid #334155;
}

.header {
  text-align: center;
  margin-bottom: 32px;
}

.header h1 {
  font-size: 28px;
  font-weight: 700;
  color: #f8fafc;
  margin-bottom: 8px;
}

.subtitle {
  color: #94a3b8;
  font-size: 15px;
  line-height: 1.5;
}

.input-group {
  margin-bottom: 16px;
}

.input-group label {
  display: block;
  font-size: 14px;
  font-weight: 500;
  color: #cbd5e1;
  margin-bottom: 8px;
}

.input-group input {
  width: 100%;
  padding: 12px 16px;
  background: #0f172a;
  border: 1px solid #334155;
  border-radius: 8px;
  color: #f1f5f9;
  font-size: 15px;
  transition: border-color 0.2s;
}

.input-group input:focus {
  outline: none;
  border-color: #3b82f6;
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

.input-group input::placeholder {
  color: #475569;
}

#optin-btn,
#generate-btn {
  width: 100%;
  padding: 12px;
  background: #3b82f6;
  color: #fff;
  border: none;
  border-radius: 8px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s;
  margin-top: 4px;
}

#optin-btn:hover,
#generate-btn:hover {
  background: #2563eb;
}

#optin-btn:active,
#generate-btn:active {
  background: #1d4ed8;
}

#optin-btn:disabled {
  background: #475569;
  cursor: not-allowed;
}

.error-msg {
  color: #f87171;
  font-size: 14px;
  margin-bottom: 12px;
}

.privacy-note {
  text-align: center;
  color: #64748b;
  font-size: 13px;
  margin-top: 16px;
}

.result {
  margin-top: 24px;
  padding-top: 24px;
  border-top: 1px solid #334155;
}

.result label {
  display: block;
  font-size: 14px;
  font-weight: 500;
  color: #cbd5e1;
  margin-bottom: 8px;
}

.output-row {
  display: flex;
  gap: 8px;
}

.output-row input {
  flex: 1;
  padding: 12px 16px;
  background: #0f172a;
  border: 1px solid #334155;
  border-radius: 8px;
  color: #67e8f9;
  font-size: 14px;
  font-family: 'SF Mono', 'Fira Code', 'Fira Mono', monospace;
}

.output-row input:focus {
  outline: none;
}

#copy-btn {
  padding: 12px;
  background: #334155;
  border: 1px solid #475569;
  border-radius: 8px;
  color: #e2e8f0;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s;
  min-width: 48px;
}

#copy-btn:hover {
  background: #475569;
}

#copy-btn.copied {
  background: #065f46;
  border-color: #059669;
  color: #34d399;
}

.hint {
  margin-top: 12px;
  font-size: 13px;
  color: #64748b;
}

.hint code {
  background: #0f172a;
  padding: 2px 6px;
  border-radius: 4px;
  color: #94a3b8;
  font-size: 12px;
}

.info-section {
  margin-top: 32px;
  padding-top: 24px;
  border-top: 1px solid #334155;
}

.info-section h2 {
  font-size: 16px;
  font-weight: 600;
  color: #f8fafc;
  margin-bottom: 12px;
}

.info-section ol {
  padding-left: 20px;
}

.info-section li {
  font-size: 14px;
  color: #94a3b8;
  margin-bottom: 8px;
  line-height: 1.5;
}

.info-section li code {
  background: #0f172a;
  padding: 2px 6px;
  border-radius: 4px;
  color: #94a3b8;
  font-size: 12px;
}

.hidden {
  display: none;
}

.shake {
  animation: shake 0.4s ease-in-out;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-6px); }
  75% { transform: translateX(6px); }
}

.seo-content {
  margin-top: 40px;
  padding: 0 8px;
}

.seo-content section {
  margin-bottom: 32px;
}

.seo-content h2 {
  font-size: 22px;
  font-weight: 700;
  color: #f1f5f9;
  margin-bottom: 12px;
}

.seo-content p {
  font-size: 15px;
  color: #94a3b8;
  line-height: 1.75;
  margin-bottom: 12px;
}

.seo-content p code {
  background: #1e293b;
  padding: 2px 6px;
  border-radius: 4px;
  color: #67e8f9;
  font-size: 13px;
}

.seo-content ul {
  padding-left: 20px;
  margin-bottom: 12px;
}

.seo-content ul li {
  font-size: 15px;
  color: #94a3b8;
  line-height: 1.75;
  margin-bottom: 8px;
}

.seo-content ul li strong {
  color: #cbd5e1;
}

.faq {
  margin-bottom: 20px;
  padding: 20px;
  background: #1e293b;
  border-radius: 12px;
  border: 1px solid #334155;
}

.faq h3 {
  font-size: 16px;
  font-weight: 600;
  color: #f1f5f9;
  margin-bottom: 8px;
}

.faq p {
  font-size: 14px;
  color: #94a3b8;
  line-height: 1.65;
  margin-bottom: 0;
}

.faq p code {
  background: #0f172a;
  padding: 2px 6px;
  border-radius: 4px;
  color: #67e8f9;
  font-size: 12px;
}