/* Design System: Minimalist, Modern, Neutral */
:root {
    --primary-color: #000000;
    --secondary-color: #666666;
    --bg-color: #ffffff;
    --surface-color: #f9f9f9;
    --border-color: #e0e0e0;
    --text-color: #1a1a1a;
    --text-muted: #717171;
    --error-color: #d32f2f;
    --success-color: #2e7d32;
    --pending-color: #ed6c02;
    --radius: 8px;
    --shadow: 0 2px 4px rgba(0,0,0,0.05);
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

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

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
}

a {
    color: inherit;
    text-decoration: none;
}

/* Layout */
.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 20px;
}

header {
    border-bottom: 1px solid var(--border-color);
    padding: 20px 0;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: -0.5px;
}

.nav-links {
    display: flex;
    gap: 20px;
}

.nav-links a:hover {
    color: var(--secondary-color);
}

main {
    padding: 40px 0;
    min-height: calc(100vh - 160px);
}

footer {
    border-top: 1px solid var(--border-color);
    padding: 40px 0;
    text-align: center;
    color: var(--text-muted);
    font-size: 0.9rem;
}

/* Typography */
h1, h2, h3 {
    margin-bottom: 20px;
    font-weight: 600;
}

p {
    margin-bottom: 15px;
}

/* UI Components */
.card {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 24px;
    margin-bottom: 20px;
    box-shadow: var(--shadow);
}

.btn {
    display: inline-block;
    padding: 10px 20px;
    border-radius: var(--radius);
    border: 1px solid var(--primary-color);
    background: var(--primary-color);
    color: white;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
    text-align: center;
}

.btn:hover {
    background: #333;
    border-color: #333;
}

.btn-secondary {
    background: transparent;
    color: var(--primary-color);
}

.btn-secondary:hover {
    background: #f0f0f0;
}

.btn-danger {
    background: var(--error-color);
    border-color: var(--error-color);
}

.btn-danger:hover {
    background: #b71c1c;
}

/* Forms */
.form-group {
    margin-bottom: 20px;
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
}

input, select, textarea {
    width: 100%;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    font-family: inherit;
    font-size: 1rem;
}

input:focus {
    outline: none;
    border-color: var(--primary-color);
}

/* Tables */
table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 20px;
}

th, td {
    padding: 12px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

th {
    font-weight: 600;
    color: var(--text-muted);
}

/* Badges */
.badge {
    padding: 4px 8px;
    border-radius: 4px;
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
}

.badge-pending { background: #fff3e0; color: var(--pending-color); }
.badge-approved { background: #e8f5e9; color: var(--success-color); }
.badge-rejected { background: #ffebee; color: var(--error-color); }
.badge-completed { background: #e3f2fd; color: #1976d2; }

/* Grid */
.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
}

/* Utils */
.text-center { text-align: center; }
.mt-20 { margin-top: 20px; }
.hidden { display: none; }

/* Responsive */
@media (max-width: 600px) {
    .nav-links {
        display: none; /* In a real app, add a burger menu */
    }
}