:root {
  --bg: #0f1117;
  --surface: #1a1d27;
  --surface-2: #242836;
  --border: #2e3345;
  --text: #e8eaf0;
  --text-muted: #9aa3b5;
  --accent: #6c9eff;
  --accent-hover: #8ab4ff;
  --success: #4ade80;
  --danger: #f87171;
  --radius: 12px;
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.35);
}

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

body {
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.container {
  width: min(1100px, 92%);
  margin: 0 auto;
}

.header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 0;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text);
  text-decoration: none;
}

.logo-icon {
  color: var(--accent);
  font-size: 1.5rem;
}

.nav {
  display: flex;
  gap: 0.5rem;
}

.nav-link {
  color: var(--text-muted);
  text-decoration: none;
  padding: 0.5rem 1rem;
  border-radius: 8px;
  transition: background 0.15s, color 0.15s;
}

.nav-link:hover {
  color: var(--text);
  background: var(--surface-2);
}

.nav-link.active {
  color: var(--accent);
  background: rgba(108, 158, 255, 0.12);
}

main {
  flex: 1;
  padding: 2rem 0 3rem;
}

.page-header {
  margin-bottom: 2rem;
}

.page-header h1 {
  font-size: 1.75rem;
  margin-bottom: 0.35rem;
}

.page-header p {
  color: var(--text-muted);
}

.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  align-items: start;
}

@media (max-width: 800px) {
  .grid-2 {
    grid-template-columns: 1fr;
  }
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--shadow);
}

.card h2 {
  font-size: 1.1rem;
  margin-bottom: 1.25rem;
  color: var(--text-muted);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  font-size: 0.8rem;
}

.form {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  margin-bottom: 1rem;
}

.field-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

.field label {
  font-size: 0.875rem;
  color: var(--text-muted);
}

.hint {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--surface-2);
  font-size: 0.7rem;
  cursor: help;
  margin-left: 0.25rem;
}

input,
select {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  padding: 0.65rem 0.85rem;
  font-size: 1rem;
  width: 100%;
  transition: border-color 0.15s;
}

input:focus,
select:focus {
  outline: none;
  border-color: var(--accent);
}

.actions {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  margin-top: 0.5rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.65rem 1.25rem;
  border: none;
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, transform 0.1s;
}

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

.btn-primary {
  background: var(--accent);
  color: #0f1117;
}

.btn-primary:hover {
  background: var(--accent-hover);
}

.btn-secondary {
  background: var(--surface-2);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--border);
}

.btn-danger {
  background: rgba(248, 113, 113, 0.15);
  color: var(--danger);
  border: 1px solid rgba(248, 113, 113, 0.3);
}

.btn-danger:hover {
  background: rgba(248, 113, 113, 0.25);
}

.file-btn {
  cursor: pointer;
}

.results {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.result-row {
  display: flex;
  justify-content: space-between;
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.95rem;
}

.result-row span:last-child {
  font-variant-numeric: tabular-nums;
  font-weight: 500;
}

.result-row.total {
  margin-top: 0.5rem;
  font-weight: 700;
  font-size: 1.05rem;
  border-bottom: none;
}

.result-row.final {
  background: rgba(108, 158, 255, 0.1);
  border: 1px solid rgba(108, 158, 255, 0.25);
  border-radius: 8px;
  padding: 0.85rem 1rem;
  margin-top: 0.25rem;
  font-size: 1.15rem;
  font-weight: 700;
}

.result-row.final span:last-child {
  color: var(--accent);
}

.config-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 1rem;
}

.materials-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-bottom: 1.25rem;
}

.material-row {
  display: grid;
  grid-template-columns: 140px 1fr;
  align-items: center;
  gap: 1rem;
}

.material-row label {
  font-size: 0.9rem;
  color: var(--text);
}

.add-material {
  display: grid;
  grid-template-columns: 1fr 1fr auto;
  gap: 0.75rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}

@media (max-width: 600px) {
  .material-row {
    grid-template-columns: 1fr;
  }

  .add-material {
    grid-template-columns: 1fr;
  }
}

.footer {
  padding: 1.25rem 0;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.85rem;
  text-align: center;
}

.toast {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.85rem 1.25rem;
  box-shadow: var(--shadow);
  z-index: 200;
  transition: opacity 0.2s, transform 0.2s;
}

.toast.hidden {
  opacity: 0;
  transform: translateY(10px);
  pointer-events: none;
}

.toast.error {
  border-color: rgba(248, 113, 113, 0.4);
  color: var(--danger);
}

.toast.success {
  border-color: rgba(74, 222, 128, 0.4);
  color: var(--success);
}