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

body {
  font-family: 'Poppins', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  background: #f8f9fa;
  min-height: 100vh;
  padding: 20px;
  color: #212529;
  line-height: 1.6;
}

.container {
  max-width: 1000px;
  margin: 0 auto;
  background: white;
  border-radius: 12px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
  overflow: hidden;
}

header {
  background: linear-gradient(to bottom, #ffffff, #f8f9fa);
  border-bottom: 1px solid #e9ecef;
  padding: 40px 30px;
  text-align: center;
}

header h1 {
  font-size: 2.25rem;
  margin-bottom: 10px;
  font-weight: 700;
  color: #212529;
  letter-spacing: -0.5px;
}

.subtitle {
  font-size: 1.05rem;
  color: #6c757d;
  font-weight: 400;
}

main {
  padding: 40px;
}

.form-section {
  margin-bottom: 0;
}

.section-header {
  margin-top: 40px;
  margin-bottom: 24px;
  padding-bottom: 12px;
  border-bottom: 2px solid #e9ecef;
  position: relative;
}

.section-header:first-of-type {
  margin-top: 0;
}

.section-header::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 60px;
  height: 2px;
  background: #212529;
}

.section-header h3 {
  font-size: 1.25rem;
  font-weight: 600;
  color: #212529;
  margin: 0 0 8px 0;
  letter-spacing: -0.3px;
}

.section-description {
  font-size: 0.95rem;
  color: #6c757d;
  margin: 0;
  font-weight: 400;
  line-height: 1.5;
}

.form-group {
  margin-bottom: 24px;
}

.form-group label {
  display: block;
  margin-bottom: 8px;
  font-weight: 500;
  color: #212529;
  font-size: 0.95rem;
  letter-spacing: -0.2px;
}

.form-group input[type="text"],
.form-group input[type="url"],
.form-group input[type="email"],
.form-group select {
  width: 100%;
  padding: 12px 16px;
  border: 1.5px solid #dee2e6;
  border-radius: 8px;
  font-size: 1rem;
  background: white;
  transition: all 0.2s ease;
  color: #212529;
}

.form-group input[type="text"]:focus,
.form-group input[type="url"]:focus,
.form-group input[type="email"]:focus,
.form-group select:focus {
  outline: none;
  border-color: #212529;
  box-shadow: 0 0 0 3px rgba(33, 37, 41, 0.1);
}

.form-group select {
  cursor: pointer;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23333' d='M6 9L1 4h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 40px;
}

.help-text {
  display: block;
  margin-top: 8px;
  font-size: 0.875rem;
  color: #6c757d;
  line-height: 1.4;
}

.checkbox-group {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  margin-top: 12px;
  padding: 20px;
  background: #f8f9fa;
  border: 1.5px solid #e9ecef;
  border-radius: 8px;
}

.checkbox-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px;
  border-radius: 6px;
  transition: background 0.2s ease;
}

.checkbox-item:hover {
  background: rgba(33, 37, 41, 0.03);
}

.checkbox-item input[type="checkbox"] {
  width: 20px;
  height: 20px;
  margin: 0;
  padding: 0;
  flex-shrink: 0;
  cursor: pointer;
  accent-color: #212529;
}

.checkbox-item label {
  margin: 0;
  font-weight: 400;
  cursor: pointer;
  font-size: 0.95rem;
  line-height: 1.5;
  flex: 1;
  color: #212529;
}

.checkbox-single-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px;
  border-radius: 6px;
  transition: background 0.2s ease;
  margin-bottom: 4px;
}

.checkbox-single-item:hover {
  background: rgba(33, 37, 41, 0.03);
}

.checkbox-single-item input[type="checkbox"] {
  width: 18px;
  height: 18px;
  margin: 0;
  cursor: pointer;
  accent-color: #212529;
  flex-shrink: 0;
}

.checkbox-single-item label {
  margin: 0;
  font-weight: 500;
  cursor: pointer;
  font-size: 0.95rem;
  color: #212529;
  flex: 1;
}

code {
  background: #f1f3f5;
  padding: 3px 8px;
  border-radius: 4px;
  font-family: 'SF Mono', 'Monaco', 'Courier New', monospace;
  font-size: 0.875em;
  color: #c92a2a;
  font-weight: 500;
}

.btn-primary {
  width: 100%;
  padding: 14px 24px;
  background: #212529;
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  margin-top: 8px;
  letter-spacing: -0.2px;
}

.btn-primary:hover {
  background: #000000;
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.btn-primary:active {
  transform: translateY(0);
}

.result-section {
  margin-top: 40px;
  padding: 24px;
  background: #f8f9fa;
  border: 1.5px solid #e9ecef;
  border-radius: 12px;
}

.result-section h2 {
  margin-bottom: 20px;
  color: #212529;
  font-size: 1.5rem;
  font-weight: 600;
  letter-spacing: -0.3px;
}

.result-box {
  background: white;
  padding: 24px;
  border-radius: 8px;
  border: 1.5px solid #e9ecef;
}

.result-item {
  margin-bottom: 24px;
}

.result-item:last-child {
  margin-bottom: 0;
}

.result-item label {
  display: block;
  margin-bottom: 10px;
  font-weight: 600;
  color: #212529;
  font-size: 0.95rem;
  letter-spacing: -0.2px;
}

.url-display {
  background: #f8f9fa;
  padding: 14px 16px;
  font-family: 'SF Mono', 'Monaco', 'Courier New', monospace;
  font-size: 0.875rem;
  word-break: break-all;
  margin-bottom: 12px;
  border: 1.5px solid #e9ecef;
  border-radius: 8px;
  color: #212529;
  line-height: 1.6;
}

.url-length-info {
  font-size: 0.9rem;
  color: #6c757d;
  font-weight: 500;
  padding: 8px 12px;
  background: #f8f9fa;
  border-radius: 6px;
  display: inline-block;
}

.url-warning {
  font-size: 0.9rem;
  line-height: 1.6;
  border-radius: 8px;
}

.url-warning-moderate {
  background: #fff3cd;
  border: 1.5px solid #ffc107;
  color: #856404;
}

.url-warning-high {
  background: #ffeaa7;
  border: 1.5px solid #fd7e14;
  color: #b45309;
}

.url-warning-critical {
  background: #f8d7da;
  border: 1.5px solid #dc3545;
  color: #721c24;
}

.btn-copy {
  padding: 10px 20px;
  background: #212529;
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-copy:hover {
  background: #000000;
  transform: translateY(-1px);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
}

.btn-copy:active {
  transform: translateY(0);
}

.error-section {
  margin-top: 24px;
  padding: 16px 20px;
  background: #fff;
  border: 1.5px solid #dc3545;
  border-radius: 8px;
  color: #721c24;
}

.error-message {
  font-weight: 500;
  line-height: 1.5;
}

@media (max-width: 768px) {
  body {
    padding: 12px;
  }

  header {
    padding: 30px 20px;
  }

  header h1 {
    font-size: 1.75rem;
  }
  
  main {
    padding: 24px 20px;
  }

  .checkbox-group {
    grid-template-columns: 1fr;
    gap: 10px;
    padding: 16px;
  }

  .section-header {
    margin-top: 32px;
  }

  .result-section {
    padding: 20px;
  }

  .result-box {
    padding: 20px;
  }
}

@media (max-width: 480px) {
  header h1 {
    font-size: 1.5rem;
  }

  .subtitle {
    font-size: 0.95rem;
  }

  main {
    padding: 20px 16px;
  }
}