:root {
    --bg: #f4f6f8;
    --panel: #ffffff;
    --text: #17202a;
    --muted: #667085;
    --line: #d9dee7;
    --primary: #0f5f9f;
    --primary-dark: #0a4778;
    --danger: #b42318;
    --success: #067647;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font-family: Arial, Helvetica, sans-serif;
}

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

.topbar {
    align-items: center;
    background: var(--panel);
    border-bottom: 1px solid var(--line);
    display: flex;
    height: 64px;
    padding: 0 24px;
}

.brand {
    align-items: center;
    display: flex;
    font-size: 18px;
    font-weight: 700;
    gap: 12px;
}

.brand-logo {
    height: 38px;
    object-fit: contain;
    width: auto;
}

.brand-mark {
    background: var(--primary);
    border-radius: 6px;
    color: #fff;
    padding: 8px 10px;
}

.app-shell {
    display: grid;
    grid-template-columns: 240px 1fr;
    min-height: calc(100vh - 64px);
}

.sidebar {
    background: #102235;
    color: #d9e3ee;
    padding: 20px;
}

.sidebar-nav {
    display: grid;
    gap: 8px;
}

.sidebar-nav a {
    border-radius: 6px;
    padding: 12px 14px;
}

.sidebar-nav a.active,
.sidebar-nav a:hover {
    background: #1d3854;
    color: #fff;
}

.main-content {
    padding: 28px;
}

.page-header {
    align-items: center;
    display: flex;
    gap: 18px;
    justify-content: space-between;
    margin-bottom: 22px;
}

.page-header h1 {
    margin: 4px 0 0;
}

.eyebrow {
    color: var(--muted);
    font-size: 12px;
    font-weight: 700;
    letter-spacing: .08em;
    margin: 0;
    text-transform: uppercase;
}

.btn {
    border: 1px solid transparent;
    border-radius: 6px;
    cursor: pointer;
    display: inline-flex;
    font: inherit;
    font-weight: 700;
    justify-content: center;
    padding: 10px 14px;
}

.btn-sm {
    padding: 7px 10px;
}

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

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

.btn-secondary {
    background: #e8f1fa;
    color: var(--primary-dark);
}

.btn-light {
    background: #fff;
    border-color: var(--line);
    color: var(--text);
}

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

.toolbar {
    display: flex;
    gap: 10px;
    margin-bottom: 18px;
}

.toolbar input {
    max-width: 420px;
}

input,
select,
textarea {
    border: 1px solid var(--line);
    border-radius: 6px;
    font: inherit;
    padding: 10px 12px;
    width: 100%;
}

textarea {
    resize: vertical;
}

label span {
    color: #344054;
    display: block;
    font-size: 13px;
    font-weight: 700;
    margin-bottom: 6px;
}

.required-label::after {
    color: var(--danger);
    content: " *";
}

.form-card {
    background: var(--panel);
    border: 1px solid var(--line);
    border-radius: 8px;
    padding: 22px;
}

.form-grid {
    display: grid;
    gap: 16px;
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.span-2 {
    grid-column: span 2;
}

.form-actions {
    display: flex;
    gap: 10px;
    justify-content: flex-end;
    margin-top: 20px;
}

.form-error {
    color: var(--danger);
    font-size: 13px;
    margin: 6px 0 0;
}

.alert {
    align-items: center;
    border-radius: 6px;
    display: flex;
    font-weight: 700;
    justify-content: space-between;
    gap: 14px;
    margin-bottom: 18px;
    padding: 12px 14px;
    transition: opacity .35s ease, transform .35s ease;
}

.alert-success {
    background: #dcfae6;
    color: var(--success);
}

.alert-error {
    background: #fee4e2;
    color: var(--danger);
}

.alert.is-hiding {
    animation: flashFadeOut .35s ease forwards;
}

.alert-close {
    background: transparent;
    border: 0;
    color: inherit;
    cursor: pointer;
    font: inherit;
    font-weight: 800;
    line-height: 1;
    padding: 4px;
}

@keyframes flashFadeOut {
    to {
        opacity: 0;
        transform: translateY(-6px);
    }
}

.table-wrap {
    overflow-x: auto;
}

.data-table {
    background: var(--panel);
    border: 1px solid var(--line);
    border-collapse: collapse;
    width: 100%;
}

.data-table th,
.data-table td {
    border-bottom: 1px solid var(--line);
    padding: 12px;
    text-align: left;
    vertical-align: top;
}

.data-table th {
    background: #eef3f8;
    font-size: 13px;
}

.action-group {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.empty-state {
    background: #fff;
    border: 1px dashed var(--line);
    border-radius: 8px;
    color: var(--muted);
    padding: 20px;
}

.status-badge {
    border-radius: 999px;
    display: inline-flex;
    font-size: 13px;
    font-weight: 800;
    padding: 6px 12px;
    text-transform: uppercase;
}

.status-paid {
    background: #dcfae6;
    color: #067647;
}

.status-unpaid {
    background: #fee4e2;
    color: #b42318;
}

.detail-grid,
.dashboard-grid {
    display: grid;
    gap: 16px;
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.detail-grid div,
.dashboard-card {
    background: #fff;
    border: 1px solid var(--line);
    border-radius: 8px;
    padding: 18px;
}

.detail-grid span,
.dashboard-card span {
    color: var(--muted);
    display: block;
    font-size: 13px;
    margin-bottom: 6px;
}

.customer-tools,
.section-heading {
    align-items: center;
    display: flex;
    justify-content: space-between;
    margin: 18px 0;
}

.customer-preview {
    margin-bottom: 18px;
}

.items-section {
    margin-top: 12px;
}

.section-heading h2 {
    margin: 0;
}

.calculation-summary {
    background: #f8fafc;
    border: 1px solid var(--line);
    border-radius: 8px;
    display: grid;
    gap: 8px;
    margin-top: 18px;
    margin-left: auto;
    max-width: 360px;
    padding: 16px;
}

.calculation-summary div {
    display: flex;
    justify-content: space-between;
}

.modal {
    align-items: center;
    background: rgba(16, 34, 53, .55);
    display: none;
    inset: 0;
    justify-content: center;
    padding: 20px;
    position: fixed;
    z-index: 20;
}

.modal.is-open {
    display: flex;
}

.modal-panel {
    background: #fff;
    border-radius: 8px;
    max-width: 760px;
    padding: 20px;
    width: 100%;
}

.modal-header {
    align-items: center;
    display: flex;
    justify-content: space-between;
}

.icon-button {
    background: transparent;
    border: 0;
    cursor: pointer;
    font-size: 18px;
    font-weight: 700;
}

.modal-errors {
    color: var(--danger);
    margin-top: 12px;
}

nav[role="navigation"] {
    margin-top: 18px;
}

@media (max-width: 860px) {
    .app-shell,
    .form-grid,
    .detail-grid,
    .dashboard-grid {
        grid-template-columns: 1fr;
    }

    .sidebar {
        padding: 12px;
    }

    .sidebar-nav {
        grid-template-columns: repeat(3, 1fr);
    }

    .span-2 {
        grid-column: span 1;
    }

    .page-header,
    .toolbar {
        align-items: stretch;
        flex-direction: column;
    }
}