:root {
    --bg: #f5f7fa;
    --surface: #ffffff;
    --surface2: #f0f2f5;
    --accent: #4f46e5;
    --accent-hover: #4338ca;
    --text: #111827;
    --text-muted: #6b7280;
    --border: #e5e7eb;
    --success: #059669;
    --warning: #d97706;
    --danger: #dc2626;
    --radius: 8px;
    --shadow: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.04);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
}

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

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    background: var(--bg);
    color: var(--text);
    font-size: 14px;
    line-height: 1.6;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

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

.sidebar {
    width: 230px;
    background: var(--surface);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    position: fixed;
    top: 0; left: 0; bottom: 0;
    z-index: 100;
    box-shadow: var(--shadow);
}

.sidebar-logo {
    padding: 20px 20px 18px;
    font-size: 15px;
    font-weight: 700;
    color: var(--text);
    border-bottom: 1px solid var(--border);
    letter-spacing: -.3px;
}

.sidebar-logo span { color: var(--accent); }

.sidebar-nav { flex: 1; padding: 10px 0; overflow-y: auto; }

.sidebar-nav a {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 9px 18px;
    color: var(--text-muted);
    font-size: 13.5px;
    font-weight: 500;
    transition: all .12s;
    border-left: 3px solid transparent;
    margin: 1px 0;
}

.sidebar-nav a:hover {
    color: var(--text);
    background: var(--surface2);
    text-decoration: none;
}

.sidebar-nav a.active {
    color: var(--accent);
    background: #eef2ff;
    border-left-color: var(--accent);
    text-decoration: none;
}

.sidebar-footer {
    padding: 14px 18px;
    border-top: 1px solid var(--border);
    font-size: 12px;
    color: var(--text-muted);
}

.sidebar-footer a { color: var(--text-muted); }
.sidebar-footer a:hover { color: var(--danger); }

.main {
    margin-left: 230px;
    flex: 1;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.topbar {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 14px 28px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: sticky;
    top: 0;
    z-index: 50;
}

.topbar h1 { font-size: 17px; font-weight: 600; color: var(--text); }
.topbar-right { display: flex; align-items: center; gap: 10px; }

.content { padding: 28px; flex: 1; }

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

.card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 20px;
}

.card-title { font-size: 15px; font-weight: 600; color: var(--text); }

/* Stats */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
    gap: 16px;
    margin-bottom: 24px;
}

.stat-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px 24px;
    box-shadow: var(--shadow);
}

.stat-value { font-size: 28px; font-weight: 700; margin-bottom: 4px; color: var(--text); }
.stat-label { font-size: 12px; color: var(--text-muted); text-transform: uppercase; letter-spacing: .5px; font-weight: 500; }

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

table { width: 100%; border-collapse: collapse; }

th {
    text-align: left;
    padding: 10px 14px;
    font-size: 11.5px;
    text-transform: uppercase;
    letter-spacing: .5px;
    color: var(--text-muted);
    background: var(--surface2);
    border-bottom: 1px solid var(--border);
    font-weight: 600;
}

th:first-child { border-radius: var(--radius) 0 0 0; }
th:last-child  { border-radius: 0 var(--radius) 0 0; }

td {
    padding: 13px 14px;
    border-bottom: 1px solid var(--border);
    vertical-align: middle;
    color: var(--text);
}

tr:last-child td { border-bottom: none; }
tr:hover td { background: #fafafa; }

/* Badges */
.badge {
    display: inline-block;
    padding: 3px 10px;
    border-radius: 20px;
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: .4px;
}
.badge-success  { background: #d1fae5; color: #065f46; }
.badge-warning  { background: #fef3c7; color: #92400e; }
.badge-danger   { background: #fee2e2; color: #991b1b; }
.badge-secondary{ background: #f3f4f6; color: #6b7280; }

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 16px;
    border-radius: var(--radius);
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    border: 1px solid transparent;
    transition: all .12s;
    text-decoration: none;
    white-space: nowrap;
}

.btn-primary { background: var(--accent); color: #fff; border-color: var(--accent); }
.btn-primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); text-decoration: none; color: #fff; }

.btn-secondary { background: var(--surface); color: var(--text); border-color: var(--border); }
.btn-secondary:hover { background: var(--surface2); text-decoration: none; color: var(--text); }

.btn-danger { background: #fee2e2; color: #991b1b; border-color: #fecaca; }
.btn-danger:hover { background: #fecaca; text-decoration: none; color: #991b1b; }

.btn-success { background: #d1fae5; color: #065f46; border-color: #a7f3d0; }
.btn-success:hover { background: #a7f3d0; text-decoration: none; color: #065f46; }

.btn-sm { padding: 5px 11px; font-size: 12px; }

/* Forms */
.form-group { margin-bottom: 18px; }
.form-group label { display: block; margin-bottom: 6px; font-size: 13px; font-weight: 500; color: var(--text); }

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 9px 12px;
    color: var(--text);
    font-size: 14px;
    transition: border-color .12s, box-shadow .12s;
    font-family: inherit;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(79,70,229,.1);
}

.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }

/* Alerts */
.alert {
    padding: 12px 16px;
    border-radius: var(--radius);
    margin-bottom: 20px;
    font-size: 13px;
    font-weight: 500;
    border: 1px solid;
}
.alert-success { background: #f0fdf4; border-color: #bbf7d0; color: #15803d; }
.alert-error   { background: #fef2f2; border-color: #fecaca; color: #dc2626; }
.alert-warning { background: #fffbeb; border-color: #fde68a; color: #d97706; }
.alert-info    { background: #eef2ff; border-color: #c7d2fe; color: #4338ca; }

/* Login page */
.login-page {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg);
}

.login-card {
    width: 100%;
    max-width: 400px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 40px;
    box-shadow: var(--shadow-md);
}

.login-card h1 { font-size: 22px; margin-bottom: 4px; color: var(--text); }
.login-card p  { color: var(--text-muted); font-size: 14px; margin-bottom: 28px; }

/* Misc */
.text-muted   { color: var(--text-muted); }
.text-right   { text-align: right; }
.text-success { color: var(--success); }
.text-danger  { color: var(--danger); }
.text-warning { color: var(--warning); }
.mt-0  { margin-top: 0; }
.mb-0  { margin-bottom: 0; }
.flex  { display: flex; }
.items-center { align-items: center; }
.gap-2 { gap: 8px; }
.gap-3 { gap: 12px; }
.ml-auto { margin-left: auto; }

/* Empty state */
.empty-state {
    text-align: center;
    padding: 48px 24px;
    color: var(--text-muted);
}
.empty-state h3 { margin-bottom: 8px; font-size: 15px; color: var(--text); }

/* Detail grid */
.detail-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.detail-item label { font-size: 11px; text-transform: uppercase; letter-spacing: .5px; color: var(--text-muted); display: block; margin-bottom: 4px; font-weight: 600; }
.detail-item span  { font-size: 14px; color: var(--text); }

/* Invoice */
.invoice-total { font-size: 24px; font-weight: 700; }