:root {
    --nli-primary: #1B4F72;
    --nli-primary-dark: #143B56;
    --nli-primary-light: #2A5F82;
    --nli-accent: #3498db;
    --nli-success: #27ae60;
    --nli-warning: #f39c12;
    --nli-danger: #e74c3c;
    --nli-gray-100: #f8f9fa;
    --nli-gray-200: #e9ecef;
    --nli-gray-300: #dee2e6;
    --nli-gray-400: #ced4da;
    --nli-gray-500: #adb5bd;
    --nli-gray-600: #6c757d;
    --nli-gray-700: #495057;
    --nli-gray-800: #343a40;
    --nli-gray-900: #212529;
    --safe-area-inset-top: env(safe-area-inset-top);
    --safe-area-inset-bottom: env(safe-area-inset-bottom);
}

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

/* Light mode (default) */
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--nli-gray-100);
    color: var(--nli-gray-900);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    padding-top: var(--safe-area-inset-top);
    padding-bottom: var(--safe-area-inset-bottom);
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    :root {
        --nli-gray-100: #1a1a1a;
        --nli-gray-200: #2a2a2a;
        --nli-gray-300: #3a3a3a;
        --nli-gray-400: #4a4a4a;
        --nli-gray-500: #6a6a6a;
        --nli-gray-600: #8a8a8a;
        --nli-gray-700: #aaa;
        --nli-gray-800: #ccc;
        --nli-gray-900: #eee;
    }

    body {
        background-color: #000;
        color: var(--nli-gray-900);
    }

    body .header {
        background: var(--nli-gray-100);
        border-bottom-color: var(--nli-gray-300);
    }

    body .screen {
        background: var(--nli-gray-100);
    }

    body .login-screen,
    body .header,
    body .status-card,
    body .action-card,
    body .bottom-nav,
    body .bill-details,
    body .payment-method,
    body .profile-header,
    body .profile-section {
        background: var(--nli-gray-100);
    }

    body .login-screen {
        background: #000;
        color: var(--nli-gray-900);
    }

    .form-input {
        background: var(--nli-gray-200);
        border-color: var(--nli-gray-300);
        color: var(--nli-gray-900);
    }

    body .btn-social {
        background: var(--nli-gray-200);
        border-color: var(--nli-gray-300);
        color: var(--nli-gray-900);
    }

    body .btn-social.btn-apple {
        background: #000;
        color: #fff;
        border-color: #333;
    }

    body .divider span {
        background: #000;
    }

    body .payment-card {
        background: var(--nli-gray-200);
    }

    body .card-icon {
        background: var(--nli-gray-300);
    }

    /* Service screen specific styles */
    body .service-section {
        background: var(--nli-gray-100);
        border: 1px solid var(--nli-gray-300);
    }

    body .usage-card {
        background: var(--nli-gray-200);
        border: 1px solid var(--nli-gray-300);
    }

    body .usage-period {
        color: var(--nli-gray-700);
    }

    body .usage-value {
        color: var(--nli-accent);
    }

    body .usage-bar {
        background: var(--nli-gray-300);
        border: 1px solid var(--nli-gray-400);
    }

    body .usage-bar-fill {
        background: var(--nli-accent);
    }

    body .speed-test-item {
        background: var(--nli-gray-200);
        border: 1px solid var(--nli-gray-300);
    }

    body .test-date {
        color: var(--nli-gray-700);
    }

    body .ticket-item {
        background: var(--nli-gray-200);
    }

    body .ticket-item:hover {
        background: var(--nli-gray-300);
    }

    /* Status card improvements */
    body .status-card {
        background: var(--nli-gray-100);
        border: 1px solid var(--nli-gray-300);
    }

    body .speed-info {
        border-top-color: var(--nli-gray-300);
        border-bottom-color: var(--nli-gray-300);
    }

    body .info-label {
        color: var(--nli-gray-700);
    }

    body .info-value {
        color: var(--nli-gray-900);
    }

    /* Action cards */
    body .action-card {
        background: var(--nli-gray-100);
        border: 1px solid var(--nli-gray-300);
    }

    body .action-card:hover {
        background: var(--nli-gray-200);
        border-color: var(--nli-gray-400);
    }

    body .action-icon {
        background: var(--nli-gray-200);
        border: 1px solid var(--nli-gray-300);
    }

    /* Header improvements for dark mode */
    body .icon-btn {
        color: var(--nli-gray-900);
    }

    body .icon-btn:active {
        background: var(--nli-gray-200);
    }

    body .icon-btn svg {
        stroke: var(--nli-gray-900);
    }

    /* Bottom nav */
    body .bottom-nav {
        background: var(--nli-gray-100);
        border-top-color: var(--nli-gray-300);
    }

    body .nav-item {
        color: var(--nli-gray-700);
    }

    body .nav-item.active {
        color: var(--nli-accent);
    }

    /* Profile screen */
    body .profile-header {
        background: var(--nli-gray-100);
        border-bottom-color: var(--nli-gray-300);
    }

    body .profile-avatar {
        background: var(--nli-primary);
        color: white;
    }

    body .profile-item {
        border-top-color: var(--nli-gray-300);
    }

    body .profile-item:active {
        background: var(--nli-gray-200);
    }

    body .profile-item-icon {
        background: var(--nli-gray-200);
        border: 1px solid var(--nli-gray-300);
    }

    /* Support screen specific styles */
    body .support-section {
        background: var(--nli-gray-100);
        border: 1px solid var(--nli-gray-300);
    }

    body .quick-diagnostics {
        background: var(--nli-gray-100);
        border: 1px solid var(--nli-gray-300);
    }

    body .help-article {
        background: var(--nli-gray-100);
        border: 1px solid var(--nli-gray-300);
    }

    body .help-article:hover {
        background: var(--nli-gray-200);
        border-color: var(--nli-primary);
    }

    body .ping-result {
        background: var(--nli-gray-200);
        border: 1px solid var(--nli-gray-300);
    }

    body .article-icon {
        background: var(--nli-primary);
        color: white;
    }

    body .btn-text {
        color: var(--nli-primary);
    }

    body .btn-text:hover {
        background: var(--nli-gray-200);
    }

    /* Navigation icons for better contrast */
    body .nav-item svg {
        stroke: var(--nli-gray-700);
    }

    body .nav-item.active svg {
        stroke: var(--nli-accent);
    }

    /* Billing Details Card for dark mode */
    body .billing-details-card {
        background: var(--nli-gray-100);
        border: 1px solid var(--nli-gray-300);
    }

    body .billing-details-card .section-title {
        color: var(--nli-gray-900);
    }

    body .billing-details-card .billing-label {
        color: var(--nli-gray-700);
    }

    body .billing-details-card .billing-value {
        color: var(--nli-gray-900);
    }

    body .billing-details-card .billing-item {
        border-bottom-color: var(--nli-gray-300);
    }

    /* WiFi Management for dark mode */
    body .wifi-management-item:hover {
        background: var(--nli-gray-200);
    }

    body .wifi-label {
        color: var(--nli-gray-900);
    }

    body .wifi-action {
        color: var(--nli-primary);
    }

    body .divider-line {
        background: var(--nli-gray-300);
    }

    /* ServiceView location list for dark mode */
    body .location-search {
        background: var(--nli-gray-200);
        border-color: var(--nli-gray-300);
        color: var(--nli-gray-900);
    }

    body .location-search:focus {
        background: var(--nli-gray-100);
    }

    body .location-item {
        border-color: var(--nli-gray-300);
    }

    body .location-item:hover {
        border-color: var(--nli-primary);
        background: var(--nli-gray-200);
    }

    body .location-details {
        background: var(--nli-gray-200);
        border-top-color: var(--nli-gray-300);
    }

    body .location-name {
        color: var(--nli-gray-900);
    }

    body .location-speeds {
        color: var(--nli-gray-700);
    }

    body .detail-label {
        color: var(--nli-gray-700);
    }

    body .detail-value {
        color: var(--nli-gray-900);
    }

    body .expand-arrow {
        color: var(--nli-gray-500);
    }

    body .view-locations-btn {
        background: var(--nli-gray-200);
        border-color: var(--nli-gray-300);
    }

    body .view-locations-btn:hover {
        background: var(--nli-gray-300);
    }

    /* Issue cards and healthy units cards for dark mode */
    body .issue-card {
        background: var(--nli-gray-200);
        border-color: var(--nli-gray-300);
    }

    body .issue-card:hover {
        background: var(--nli-gray-300);
        border-color: var(--nli-primary);
    }

    body .healthy-units-card {
        background: var(--nli-gray-200);
        border-color: var(--nli-gray-300);
    }
}

/* Responsive */
@media (min-width: 768px) {
    .login-form,
    .status-card,
    .quick-actions,
    .bill-summary,
    .bill-details,
    .payment-method,
    .support-options {
        max-width: 600px;
        margin-left: auto;
        margin-right: auto;
    }
}

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

.form-label {
    display: block;
    font-size: 14px;
    font-weight: 500;
    margin-bottom: 8px;
    color: var(--nli-gray-800);
}

.form-input {
    width: 100%;
    padding: 12px 16px;
    font-size: 16px;
    border: 1px solid var(--nli-gray-300);
    border-radius: 8px;
    transition: border-color 0.2s;
    -webkit-appearance: none;
}

.form-input:focus {
    outline: 2px solid var(--nli-primary);
    outline-offset: 2px;
    border-color: var(--nli-primary);
}

/* Skip link for keyboard navigation */
.skip-link {
    position: absolute;
    top: -40px;
    left: 6px;
    background: var(--nli-primary);
    color: white;
    padding: 8px;
    text-decoration: none;
    z-index: 1000;
    border-radius: 4px;
}

.skip-link:focus {
    top: 6px;
}

.btn {
    display: block;
    width: 100%;
    padding: 14px 24px;
    font-size: 16px;
    font-weight: 500;
    text-align: center;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
    -webkit-tap-highlight-color: transparent;
}

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

.btn-primary:active {
    background: var(--nli-primary-dark);
    transform: scale(0.98);
}

.divider {
    position: relative;
    text-align: center;
    margin: 32px 0;
}

.divider::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 0;
    right: 0;
    height: 1px;
    background: var(--nli-gray-300);
}

.divider span {
    position: relative;
    background: white;
    padding: 0 16px;
    color: var(--nli-gray-700);
    font-size: 14px;
}

/* Header */
.header {
    background: white;
    border-bottom: 1px solid var(--nli-gray-200);
    position: sticky;
    top: 0;
    z-index: 100;
    padding-top: var(--safe-area-inset-top);
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 16px 20px;
}

.header-logo {
    height: 32px;
    width: auto;
    max-width: 150px;
    object-fit: contain;
}

.header-actions {
    display: flex;
    gap: 12px;
}

.icon-btn {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: none;
    background: none;
    cursor: pointer;
    border-radius: 50%;
    transition: background 0.2s;
}

.icon-btn:active {
    background: var(--nli-gray-100);
}

.icon-btn:focus {
    outline: 2px solid var(--nli-primary);
    outline-offset: 2px;
}

/* Bottom Navigation */

.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: white;
    border-top: 1px solid var(--nli-gray-200);
    padding-bottom: var(--safe-area-inset-bottom);
    z-index: 100;
}

.nav-content {
    display: flex;
    justify-content: space-around;
    padding: 8px 0;
}

.nav-item {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 8px;
    cursor: pointer;
    text-decoration: none;
    color: var(--nli-gray-700);
    transition: color 0.2s;
}

.nav-item.active {
    color: var(--nli-primary);
}

.nav-item:focus {
    outline: 2px solid var(--nli-primary);
    outline-offset: 2px;
    background: none;
    border: none;
}

.nav-item {
    background: none;
    border: none;
    font-family: inherit;
}

.nav-item svg {
    width: 24px;
    height: 24px;
    margin-bottom: 4px;
}

.nav-label {
    font-size: 12px;
    font-weight: 500;
}

/* Main Content */
.main {
    flex: 1;
    padding-bottom: calc(80px + var(--safe-area-inset-bottom));
    background: var(--nli-gray-100);
}

/* Screens */
.screen {
    display: flex;
    min-height: 100%;
    flex: 1;
    padding-bottom: calc(90px + var(--safe-area-inset-bottom));
    background: var(--nli-gray-100);
    overflow-y: auto;
}

.screen.active {
    display: block;
}

/* Main App */
.app {
    display: flex;
    min-height: 100vh;
    flex-direction: column;
}

.app.active {
    display: flex;
}

.app-layout {
    display: flex;
    min-height: 100vh;
    flex-direction: column;
}

/* Utility classes for hardened CSP compliance */
.hidden {
    display: none;
}

.install-button {
    margin-top: 16px;
}

.bill-total {
    font-weight: 600;
}

.usage-bar-24 {
    width: 24%;
}

.usage-bar-87 {
    width: 87%;
}

.usage-bar-71 {
    width: 71%;
}