:root {
    --primary: #0ea5e9;
    --primary-hover: #0284c7;
    --secondary: #0f172a;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-main: #334155;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
    --danger: #ef4444;
    --success: #10b981;
    --warning: #f59e0b;
    --font-family: 'Kanit', 'Inter', sans-serif;
    --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);
    --radius: 12px;
}

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

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

/* Typography */
h1, h2, h3, h4, h5, h6 {
    color: var(--secondary);
    font-weight: 600;
}

a {
    color: var(--primary);
    text-decoration: none;
    transition: all 0.2s ease;
}

a:hover {
    color: var(--primary-hover);
}

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

/* Sidebar */
.sidebar {
    width: 260px;
    background-color: var(--card-bg);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    position: fixed;
    height: 100vh;
    z-index: 10;
}

.sidebar-header {
    padding: 24px;
    border-bottom: 1px solid var(--border-color);
}

.logo-text {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary);
}

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

.sidebar-nav {
    flex: 1;
    overflow-y: auto;
    padding: 16px 0;
}

.sidebar-nav ul {
    list-style: none;
}

.nav-header {
    padding: 16px 24px 8px;
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
    font-weight: 600;
}

.sidebar-nav li a {
    display: flex;
    align-items: center;
    padding: 12px 24px;
    color: var(--text-main);
    font-weight: 500;
    border-left: 3px solid transparent;
}

.sidebar-nav li a i {
    font-size: 1.25rem;
    margin-right: 12px;
    color: var(--text-muted);
    transition: color 0.2s;
}

.sidebar-nav li a:hover {
    background-color: var(--bg-color);
    color: var(--primary);
}

.sidebar-nav li a:hover i {
    color: var(--primary);
}

.sidebar-nav li.active a {
    background-color: #f0f9ff;
    color: var(--primary);
    border-left-color: var(--primary);
}

.sidebar-nav li.active a i {
    color: var(--primary);
}

.sidebar-footer {
    padding: 16px 24px;
    border-top: 1px solid var(--border-color);
}

.sidebar-footer a {
    display: flex;
    align-items: center;
    color: var(--text-main);
    font-weight: 500;
}

.sidebar-footer a i {
    margin-right: 12px;
}

/* Main Content */
.main-content {
    flex: 1;
    margin-left: 260px;
    display: flex;
    flex-direction: column;
}

.topbar {
    height: 72px;
    background-color: var(--card-bg);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 32px;
    position: sticky;
    top: 0;
    z-index: 5;
}

.page-title {
    font-size: 1.25rem;
    font-weight: 600;
}

.topbar-right {
    display: flex;
    align-items: center;
    gap: 24px;
}

.lang-switcher a {
    color: var(--text-muted);
    font-weight: 500;
}

.lang-switcher a.active {
    color: var(--primary);
    font-weight: 600;
}

.lang-switcher span {
    margin: 0 8px;
    color: var(--border-color);
}

.user-profile {
    display: flex;
    align-items: center;
    gap: 12px;
    cursor: pointer;
}

.avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background-color: var(--bg-color);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary);
    font-size: 1.25rem;
}

.content-wrapper {
    padding: 32px;
    flex: 1;
}

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

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 8px 16px;
    font-size: 0.875rem;
    font-weight: 500;
    border-radius: 8px;
    border: 1px solid transparent;
    cursor: pointer;
    transition: all 0.2s;
    font-family: inherit;
    gap: 8px;
}

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

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

.btn-secondary {
    background-color: var(--bg-color);
    color: var(--text-main);
    border-color: var(--border-color);
}

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

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

/* Forms */
.form-group {
    margin-bottom: 16px;
}

.form-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: 6px;
    color: var(--secondary);
}

.form-control {
    width: 100%;
    padding: 10px 12px;
    font-size: 0.875rem;
    font-family: inherit;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    transition: border-color 0.2s, box-shadow 0.2s;
    outline: none;
}

.form-control:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(14, 165, 233, 0.1);
}

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

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

.table th, .table td {
    padding: 12px 16px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
    font-size: 0.875rem;
}

.table th {
    font-weight: 600;
    color: var(--text-muted);
    background-color: var(--bg-color);
}

.table tbody tr:hover {
    background-color: #f8fafc;
}

/* Login Page */
.login-body {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    background-color: #f0f9ff;
}

.login-container {
    width: 100%;
    max-width: 400px;
    padding: 24px;
}

.login-box {
    background: var(--card-bg);
    padding: 32px;
    border-radius: 16px;
    box-shadow: var(--shadow-lg);
}

.login-logo {
    text-align: center;
    margin-bottom: 32px;
}

.login-logo h2 {
    color: var(--primary);
    margin-bottom: 4px;
}

.btn-block {
    width: 100%;
    padding: 12px;
    margin-top: 8px;
}

.alert {
    padding: 12px;
    border-radius: 8px;
    margin-bottom: 16px;
    font-size: 0.875rem;
}

.alert-danger {
    background-color: #fef2f2;
    color: var(--danger);
    border: 1px solid #fecaca;
}

/* Grid */
.grid {
    display: grid;
    gap: 24px;
}

.grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
.grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
.grid-cols-4 { grid-template-columns: repeat(4, 1fr); }

/* Badges */
.badge {
    padding: 4px 8px;
    border-radius: 99px;
    font-size: 0.75rem;
    font-weight: 500;
}
.badge-draft { background: #f1f5f9; color: #475569; }
.badge-issued { background: #eff6ff; color: #1d4ed8; }
.badge-paid { background: #dcfce3; color: #15803d; }
.badge-cancelled { background: #fee2e2; color: #b91c1c; }