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

:root {
  --primary: #2563eb;
  --bg: #ffffff;
  --bg-secondary: #f8fafc;
  --text: #1e293b;
  --text-secondary: #64748b;
  --border: #e2e8f0;
  --shadow: 0 1px 3px rgba(0,0,0,0.1);
  --radius: 12px;
}

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

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Header */
header {
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  padding: 40px 0;
  text-align: center;
}

header h1 {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 8px;
}

header .subtitle {
  color: var(--text-secondary);
  font-size: 1.1rem;
}

/* Search */
.search-box {
  margin: 30px 0;
}

.search-box input {
  width: 100%;
  max-width: 500px;
  margin: 0 auto;
  display: block;
  padding: 14px 20px;
  font-size: 1rem;
  border: 2px solid var(--border);
  border-radius: 50px;
  outline: none;
  transition: border-color 0.2s;
}

.search-box input:focus {
  border-color: var(--primary);
}

/* Categories */
.categories {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 30px;
}

.categories button {
  padding: 10px 20px;
  border: none;
  background: var(--bg-secondary);
  border-radius: 50px;
  cursor: pointer;
  font-size: 0.95rem;
  color: var(--text-secondary);
  transition: all 0.2s;
}

.categories button:hover,
.categories button.active {
  background: var(--primary);
  color: white;
}

/* Tools Grid */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 20px;
  margin-bottom: 50px;
}

.tool-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  transition: all 0.2s;
}

.tool-card:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}

.tool-card.hidden {
  display: none;
}

.tool-icon {
  font-size: 2.5rem;
  margin-bottom: 12px;
}

.tool-card h3 {
  font-size: 1.1rem;
  margin-bottom: 8px;
}

.tool-card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: 16px;
}

.tool-card button {
  width: 100%;
  padding: 10px;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.95rem;
  transition: background 0.2s;
}

.tool-card button:hover {
  background: #1d4ed8;
}

/* Modal */
.modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.5);
  z-index: 1000;
  overflow-y: auto;
}

.modal.show {
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 40px 20px;
}

.modal-content {
  background: white;
  border-radius: var(--radius);
  padding: 30px;
  max-width: 600px;
  width: 100%;
  position: relative;
  animation: slideIn 0.2s ease;
}

@keyframes slideIn {
  from { transform: translateY(-20px); opacity: 0; }
  to { transform: translateY(0); opacity: 1; }
}

.close {
  position: absolute;
  top: 15px;
  right: 20px;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-secondary);
}

.close:hover {
  color: var(--text);
}

/* Form Elements */
.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  margin-bottom: 8px;
  font-weight: 500;
}

.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 1rem;
  outline: none;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  border-color: var(--primary);
}

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

.btn {
  padding: 12px 24px;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  font-size: 1rem;
  transition: background 0.2s;
}

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

.btn-secondary {
  background: var(--bg-secondary);
  color: var(--text);
}

.btn-secondary:hover {
  background: #e2e8f0;
}

/* File Upload */
.file-upload {
  border: 2px dashed var(--border);
  border-radius: 8px;
  padding: 30px;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.2s;
}

.file-upload:hover {
  border-color: var(--primary);
}

.file-upload input {
  display: none;
}

.file-upload p {
  color: var(--text-secondary);
}

.file-name {
  margin-top: 10px;
  color: var(--primary);
  font-weight: 500;
}

/* Result */
.result {
  margin-top: 20px;
  padding: 16px;
  background: var(--bg-secondary);
  border-radius: 8px;
  word-break: break-all;
}

.result-label {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 8px;
}

.result-value {
  font-family: monospace;
  background: white;
  padding: 12px;
  border-radius: 6px;
  border: 1px solid var(--border);
}

/* Flex utilities */
.flex {
  display: flex;
  gap: 10px;
}

.flex > * {
  flex: 1;
}

/* Footer */
footer {
  text-align: center;
  padding: 30px;
  color: var(--text-secondary);
  border-top: 1px solid var(--border);
}

/* Checkbox */
.checkbox-group {
  display: flex;
  flex-wrap: wrap;
  gap: 15px;
}

.checkbox-item {
  display: flex;
  align-items: center;
  gap: 6px;
  cursor: pointer;
}

.checkbox-item input {
  width: auto;
}

/* Range slider */
input[type="range"] {
  width: 100%;
  margin-top: 8px;
}

/* Responsive */
@media (max-width: 768px) {
  header h1 {
    font-size: 2rem;
  }
  
  .tools-grid {
    grid-template-columns: 1fr;
  }
  
  .categories {
    justify-content: flex-start;
    overflow-x: auto;
    flex-wrap: nowrap;
    padding-bottom: 10px;
  }
  
  .modal-content {
    margin: 0 10px;
    padding: 20px;
  }
}