:root {
  /* Color Palette - Industrial & Professional */
  --color-primary: #1e293b;
  --color-accent: #3b82f6;
  --color-accent-soft: rgba(59, 130, 246, 0.1);
  --color-success: #10b981;
  --color-warning: #f59e0b;
  --color-danger: #ef4444;
  --color-bg: #f8fafc;
  --color-surface: #ffffff;
  --color-border: #e2e8f0;
  --color-text-main: #0f172a;
  --color-text-muted: #64748b;
  
  /* Typography */
  --font-main: 'Instrument Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-display: 'Inter', sans-serif;
  
  /* Spacing & Borders */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2.5rem;
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

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

body {
  font-family: var(--font-main);
  background-color: var(--color-bg);
  color: var(--color-text-main);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

/* Layout */
.app-container {
  display: flex;
  min-height: 100vh;
}

.sidebar {
  width: 260px;
  background-color: var(--color-primary);
  color: white;
  padding: var(--spacing-md);
  display: flex;
  flex-direction: column;
  position: sticky;
  top: 0;
  height: 100vh;
}

.main-content {
  flex: 1;
  padding: var(--spacing-lg);
  overflow-y: auto;
}

/* Typography Helpers */
h1 { font-size: 1.875rem; font-weight: 700; margin-bottom: var(--spacing-md); color: var(--color-text-main); }
h2 { font-size: 1.25rem; font-weight: 600; margin-bottom: var(--spacing-sm); }
.text-muted { color: var(--color-text-muted); font-size: 0.875rem; }

/* Navigation */
.nav-brand {
  font-size: 1.5rem;
  font-weight: 800;
  margin-bottom: var(--spacing-lg);
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
}

.nav-links {
  list-style: none;
  flex: 1;
}

.nav-item {
  margin-bottom: var(--spacing-xs);
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 16px;
  color: #94a3b8;
  text-decoration: none;
  border-radius: var(--radius-sm);
  transition: all 0.2s;
  font-weight: 500;
}

.nav-link:hover, .nav-link.active {
  background-color: rgba(255, 255, 255, 0.1);
  color: white;
}

/* Cards & Stats */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
}

.stat-card {
  background: var(--color-surface);
  padding: var(--spacing-md);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.stat-value {
  font-size: 1.5rem;
  font-weight: 700;
  margin: 4px 0;
}

/* Components */
.card {
  background: var(--color-surface);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
  margin-bottom: var(--spacing-lg);
  overflow: hidden;
}

.card-header {
  padding: var(--spacing-md);
  border-bottom: 1px solid var(--color-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.card-body {
  padding: var(--spacing-md);
}

/* Tables */
.table-container {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}

th {
  background: var(--color-bg);
  padding: 12px 16px;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-muted);
  border-bottom: 1px solid var(--color-border);
}

td {
  padding: 16px;
  border-bottom: 1px solid var(--color-border);
  font-size: 0.875rem;
}

tr:hover {
  background-color: #f8fafc;
}

/* Badges & UI Elements */
.badge {
  padding: 4px 8px;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 600;
}

.badge-success { background: #dcfce7; color: #166534; }
.badge-warning { background: #fef9c3; color: #854d0e; }
.badge-danger { background: #fee2e2; color: #991b1b; }
.badge-info { background: #dbeafe; color: #1e40af; }

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 20px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.875rem;
  cursor: pointer;
  transition: all 0.2s;
  border: none;
  gap: 8px;
  text-decoration: none;
}

.btn-primary { background: var(--color-accent); color: white; }
.btn-primary:hover { background: #2563eb; }

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

/* Custom UI Pieces */
.staff-avatar-group {
  display: flex;
  align-items: center;
}

.placeholder-avatar {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: #cbd5e1;
  border: 2px solid white;
  margin-left: -8px;
}

.placeholder-avatar:first-child { margin-left: 0; }

.icon-box {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-accent-soft);
  color: var(--color-accent);
  margin-bottom: var(--spacing-sm);
}

/* Forms */
.form-group { margin-bottom: var(--spacing-sm); }
.label { display: block; margin-bottom: 4px; font-weight: 500; font-size: 0.875rem; }
.input {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-family: inherit;
}

/* Page Specific: PO View */
.po-details {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: var(--spacing-lg);
}

.resource-list {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.resource-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-sm);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
}