:root {
  --app-bg: #f8fafc;
  --app-surface: #ffffff;
  --app-text: #111827;
  --app-muted: #6b7280;
  --app-border: #e5e7eb;
  --app-soft: #f3f4f6;
  --app-accent: #2563eb;
  --app-radius-sm: 6px;
  --app-radius-md: 10px;
  --app-radius-lg: 14px;
  --app-shadow: 0 18px 50px rgba(15, 23, 42, 0.08);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  background: var(--app-bg);
  color: var(--app-text);
  font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 14px;
}

.skip-link {
  position: absolute;
  left: 12px;
  top: -48px;
  z-index: 1000;
  background: var(--app-text);
  color: #fff;
  padding: 8px 10px;
  border-radius: var(--app-radius-sm);
}
.skip-link:focus { top: 12px; }

.app-shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 20px 12px;
}

.phone-frame {
  width: min(100%, 430px);
  min-height: min(860px, calc(100vh - 40px));
  background: var(--app-surface);
  border: 1px solid var(--app-border);
  border-radius: 22px;
  box-shadow: var(--app-shadow);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

.app-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 18px 14px;
  border-bottom: 1px solid var(--app-border);
  background: rgba(255, 255, 255, 0.96);
}

.eyebrow, .label {
  margin: 0 0 4px;
  color: var(--app-muted);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
}

h1, h2, p { margin-top: 0; }
h1 { margin-bottom: 0; font-size: 20px; font-weight: 700; letter-spacing: -0.02em; }
h2 { font-size: 24px; line-height: 1.15; font-weight: 700; letter-spacing: -0.04em; }

.screen {
  display: none;
  flex: 1;
  padding: 18px;
  overflow-y: auto;
}
.screen.active { display: block; }

.hero-card, .status-card, .detail-card, .empty-state, .list-item, .module-card, .parts-box {
  border: 1px solid var(--app-border);
  border-radius: var(--app-radius-lg);
  background: var(--app-surface);
}

.hero-card {
  padding: 22px;
  margin-bottom: 18px;
  background: #fcfcfd;
}

.muted, .empty-state p, small { color: var(--app-muted); }
.stack { display: grid; gap: 14px; }

.form-control, .form-select {
  border-color: var(--app-border);
  border-radius: var(--app-radius-md);
  min-height: 44px;
  font-size: 14px;
}
.form-control:focus, .form-select:focus, .btn:focus-visible, .module-card:focus-visible, .list-item:focus-visible {
  border-color: var(--app-accent);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, .14);
  outline: none;
}

.btn { border-radius: var(--app-radius-md); font-weight: 650; min-height: 40px; }
.btn-dark { background: var(--app-text); border-color: var(--app-text); }

.status-card {
  padding: 14px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
  background: #fcfcfd;
}

.module-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}
.module-card {
  min-height: 112px;
  padding: 14px;
  text-align: left;
  cursor: pointer;
  transition: border-color .16s ease, transform .16s ease, background .16s ease;
}
.module-card:hover { border-color: #cbd5e1; transform: translateY(-1px); }
.module-card.featured { grid-column: span 2; background: #f9fafb; }
.module-card span { display: block; color: var(--app-accent); font-size: 18px; margin-bottom: 12px; }
.module-card strong, .module-card small { display: block; }

.screen-actions {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 14px;
}

.list-stack { display: grid; gap: 10px; }
.list-item {
  width: 100%;
  padding: 13px 14px;
  text-align: left;
  display: grid;
  gap: 4px;
  cursor: pointer;
}
.list-item:hover { background: #f9fafb; }
.list-item-row { display: flex; justify-content: space-between; gap: 10px; align-items: start; }

.empty-state { padding: 18px; text-align: center; background: #fcfcfd; }
.empty-state p { margin: 8px 0 14px; }

.parts-box { padding: 14px; }
.parts-box legend { float: none; width: auto; margin-bottom: 10px; font-size: 13px; font-weight: 700; }
.parts-list { display: grid; gap: 8px; }
.part-choice {
  display: flex;
  gap: 10px;
  align-items: center;
  padding: 10px;
  border: 1px solid var(--app-border);
  border-radius: var(--app-radius-md);
  cursor: pointer;
}
.part-choice:hover { background: #f9fafb; }
.part-choice input { width: 16px; height: 16px; }

.detail-card { padding: 18px; }
.detail-grid { display: grid; gap: 12px; margin-top: 14px; }
.detail-row { padding-bottom: 10px; border-bottom: 1px solid var(--app-border); }
.detail-row:last-child { border-bottom: 0; padding-bottom: 0; }
.detail-row span { display: block; color: var(--app-muted); font-size: 12px; margin-bottom: 2px; }

.toast-region {
  position: absolute;
  width: min(390px, calc(100% - 48px));
  left: 50%;
  transform: translateX(-50%);
  top: 78px;
  z-index: 20;
  display: grid;
  gap: 8px;
}
.app-toast {
  border: 1px solid var(--app-border);
  background: var(--app-text);
  color: #fff;
  border-radius: var(--app-radius-md);
  padding: 10px 12px;
  box-shadow: var(--app-shadow);
  font-size: 13px;
}
.app-toast.error { background: #991b1b; }

.app-footer {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  padding: 12px 18px;
  border-top: 1px solid var(--app-border);
  color: var(--app-muted);
  font-size: 11px;
}

@media (max-width: 460px) {
  .app-shell { padding: 0; }
  .phone-frame { min-height: 100vh; border: 0; border-radius: 0; }
}