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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: #f0f2f5;
  color: #1a1a2e;
  min-height: 100vh;
}

header {
  background: #1a1a2e;
  color: #fff;
  padding: 1.25rem 2rem;
}

header h1 {
  font-size: 1.6rem;
  letter-spacing: 0.05em;
}

header p {
  font-size: 0.85rem;
  opacity: 0.7;
  margin-top: 0.25rem;
}

.layout {
  display: flex;
  gap: 1.5rem;
  padding: 2rem;
  max-width: 1100px;
  margin: 0 auto;
  align-items: flex-start;
}

.card {
  background: #fff;
  border-radius: 12px;
  padding: 1.75rem;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
}

.form-panel {
  flex: 0 0 340px;
}

.preview-panel {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 420px;
}

/* Form fields */
.field {
  margin-bottom: 1.25rem;
}

.field label {
  display: block;
  font-size: 0.82rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: #555;
  margin-bottom: 0.4rem;
}

.hint {
  font-weight: 400;
  text-transform: none;
  letter-spacing: 0;
  color: #888;
}

input[type="url"],
input[type="text"] {
  width: 100%;
  padding: 0.55rem 0.75rem;
  border: 1.5px solid #d0d5dd;
  border-radius: 8px;
  font-size: 0.95rem;
  transition: border-color 0.2s;
  outline: none;
}

input[type="url"]:focus,
input[type="text"]:focus {
  border-color: #4f6ef7;
}

.radio-group {
  display: flex;
  gap: 1rem;
}

.radio-label {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.9rem;
  cursor: pointer;
  font-weight: 400;
  text-transform: none;
  letter-spacing: 0;
  color: #333;
}

.radio-label input[type="radio"] {
  accent-color: #4f6ef7;
}

.color-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

input[type="color"] {
  width: 44px;
  height: 36px;
  border: 1.5px solid #d0d5dd;
  border-radius: 8px;
  padding: 2px;
  cursor: pointer;
  background: none;
}

#color-val {
  font-size: 0.9rem;
  font-family: monospace;
  color: #555;
}

/* Buttons */
.btn {
  display: inline-block;
  width: 100%;
  padding: 0.65rem 1rem;
  border: none;
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: opacity 0.15s, transform 0.1s;
  text-align: center;
}

.btn:active {
  transform: scale(0.98);
}

.btn-primary {
  background: #4f6ef7;
  color: #fff;
}

.btn-primary:hover {
  opacity: 0.88;
}

.btn-secondary {
  background: #e8ecfd;
  color: #4f6ef7;
}

.btn-secondary:hover {
  background: #d5dcfc;
}

.download-form {
  margin-top: 0.75rem;
}

/* Preview */
.qr-preview {
  max-width: 100%;
  width: 420px;
  height: auto;
  border-radius: 8px;
  display: block;
}

.scan-hint {
  margin-top: 0.75rem;
  font-size: 0.8rem;
  color: #888;
}

.placeholder {
  text-align: center;
  color: #bbb;
}

.placeholder-icon {
  font-size: 5rem;
  line-height: 1;
  margin-bottom: 1rem;
}

.placeholder p {
  font-size: 0.9rem;
}

.error {
  background: #fff1f1;
  color: #c0392b;
  border: 1px solid #f5c6cb;
  border-radius: 8px;
  padding: 0.75rem 1rem;
  font-size: 0.9rem;
  width: 100%;
  text-align: center;
}

/* Responsive */
@media (max-width: 720px) {
  .layout {
    flex-direction: column;
    padding: 1rem;
  }

  .form-panel {
    flex: none;
    width: 100%;
  }
}