:root {
  --color-primary: #3730A3;
  --color-primary-light: #4F46E5;
  --color-coral: #F97316;
  --color-bg: #FAF9F7;
  --color-surface: #FFFFFF;
  --color-text: #1F2937;
  --color-text-secondary: #6B7280;
  --color-border: #E5E7EB;
  --color-success: #10B981;
  --color-error: #EF4444;
  --font-heading: 'Outfit', sans-serif;
  --font-body: 'DM Sans', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --radius: 8px;
  --shadow: 0 1px 3px rgba(0,0,0,0.1);
  --shadow-lg: 0 4px 12px rgba(0,0,0,0.15);
}

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

body {
  font-family: var(--font-body);
  background: var(--color-bg);
  color: var(--color-text);
  min-height: 100vh;
}

.app-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding: 1rem 2rem;
  position: sticky;
  top: 0;
  z-index: 10;
}

.app-header nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 1200px;
  margin: 0 auto;
}

.logo {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--color-primary);
}

.nav-link {
  color: var(--color-text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
}

.nav-link:hover { color: var(--color-primary); }

.app-container {
  max-width: 900px;
  margin: 2rem auto;
  padding: 0 1rem;
}

.step-section {
  background: var(--color-surface);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  box-shadow: var(--shadow);
}

.step-section h2 {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  margin-bottom: 1rem;
  color: var(--color-text);
}

.hidden { display: none !important; }

/* Upload Zone */
.upload-zone {
  border: 2px dashed var(--color-border);
  border-radius: var(--radius);
  padding: 3rem 2rem;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
  color: var(--color-text-secondary);
}

.upload-zone:hover, .upload-zone.drag-over {
  border-color: var(--color-primary);
  background: rgba(55, 48, 163, 0.03);
}

.upload-zone svg {
  margin-bottom: 0.5rem;
  opacity: 0.5;
}

.upload-zone p { margin: 0.25rem 0; }
.upload-hint { font-size: 0.875rem; }
.upload-formats { font-size: 0.75rem; color: var(--color-text-secondary); margin-top: 0.5rem; }

.error-msg { color: var(--color-error); font-size: 0.875rem; margin-top: 0.5rem; }

/* 3D Viewer */
.viewer-3d {
  width: 100%;
  min-height: 400px;
  background: #E5E7EB;
  border-radius: var(--radius);
  overflow: hidden;
  position: relative;
}

.layer-badge {
  display: inline-block;
  background: var(--color-primary);
  color: white;
  padding: 0.25rem 0.75rem;
  border-radius: 100px;
  font-size: 0.875rem;
  font-family: var(--font-mono);
  margin-top: 0.75rem;
}

/* Parameters */
.params-grid {
  display: grid;
  gap: 1rem;
  margin-bottom: 1rem;
}

.param {
  display: grid;
  grid-template-columns: 160px 1fr 80px;
  align-items: center;
  gap: 0.75rem;
}

.param span {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
}

.param input[type="range"] {
  width: 100%;
  accent-color: var(--color-primary);
}

.param input[type="number"] {
  width: 100%;
  padding: 0.375rem 0.5rem;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 0.875rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.625rem 1.25rem;
  border-radius: var(--radius);
  font-family: var(--font-body);
  font-weight: 500;
  font-size: 0.875rem;
  cursor: pointer;
  border: none;
  transition: background 0.2s, transform 0.1s;
}

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

.btn-primary {
  background: var(--color-primary);
  color: white;
}
.btn-primary:hover { background: var(--color-primary-light); }
.btn-primary:disabled { background: var(--color-border); cursor: not-allowed; }

.btn-secondary {
  background: transparent;
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
}
.btn-secondary:hover { border-color: var(--color-text-secondary); }

.btn-download {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  color: var(--color-text);
}
.btn-download:hover { border-color: var(--color-primary); color: var(--color-primary); }

.slice-status {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  margin: 0.75rem 0;
}

.download-buttons {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}

/* Modal */
.modal {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
}

.modal-content {
  background: var(--color-surface);
  padding: 2rem;
  border-radius: var(--radius);
  max-width: 400px;
  width: 90%;
  text-align: center;
}

.modal-content h2 {
  font-family: var(--font-heading);
  margin-bottom: 0.5rem;
}

.modal-content p {
  color: var(--color-text-secondary);
  font-size: 0.875rem;
  margin-bottom: 1.5rem;
}

.modal-content form {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.modal-content input[type="email"] {
  width: 100%;
  padding: 0.625rem 0.75rem;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  font-size: 0.875rem;
}

.modal-content .btn { width: 100%; }

.modal-content .btn-secondary {
  margin-top: 0.5rem;
  border: none;
  color: var(--color-primary);
  font-size: 0.875rem;
  background: transparent;
}

@media (max-width: 640px) {
  .param { grid-template-columns: 1fr; gap: 0.25rem; }
  .download-buttons { flex-direction: column; }
}