/**
 * Courses Platform Design System
 * Modern UK-style design with flat UI elements
 * Max border-radius: 5px
 */

/* ============================================
   TAILWIND COMPATIBILITY LAYER
   Prevents conflicts when Tailwind CDN is also loaded
   ============================================ */

/* Reset Tailwind's aggressive resets on our components */
.design-system-scope button,
.design-system-scope [type="button"],
.design-system-scope [type="reset"],
.design-system-scope [type="submit"] {
    -webkit-appearance: button;
    background-color: initial;
    background-image: initial;
}

/* Ensure our design tokens take precedence */
@layer base {
    :root {
        /* This layer ensures our variables load first */
    }
}

/* ============================================
   CSS VARIABLES / DESIGN TOKENS
   ============================================ */
:root {
    /* Primary Colors - Monochrome */
    --color-black: #000000;
    --color-white: #ffffff;
    --color-gray-50: #fafafa;
    --color-gray-100: #f5f5f5;
    --color-gray-200: #e5e5e5;
    --color-gray-300: #d4d4d4;
    --color-gray-400: #a3a3a3;
    --color-gray-500: #737373;
    --color-gray-600: #525252;
    --color-gray-700: #404040;
    --color-gray-800: #262626;
    --color-gray-900: #171717;

    /* Accent Color - Blue */
    --color-accent: #2563eb;
    --color-accent-hover: #1d4ed8;
    --color-accent-light: #dbeafe;
    --color-accent-dark: #1e40af;

    /* Semantic Colors */
    --color-success: #16a34a;
    --color-success-light: #dcfce7;
    --color-warning: #ca8a04;
    --color-warning-light: #fef9c3;
    --color-error: #dc2626;
    --color-error-light: #fee2e2;
    --color-info: #0284c7;
    --color-info-light: #e0f2fe;

    /* Typography */
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, monospace;

    /* Font Sizes */
    --text-xs: 0.75rem;
    --text-sm: 0.875rem;
    --text-base: 1rem;
    --text-lg: 1.125rem;
    --text-xl: 1.25rem;
    --text-2xl: 1.5rem;
    --text-3xl: 1.875rem;
    --text-4xl: 2.25rem;

    /* Font Weights */
    --font-normal: 400;
    --font-medium: 500;
    --font-semibold: 600;
    --font-bold: 700;

    /* Line Heights */
    --leading-tight: 1.25;
    --leading-normal: 1.5;
    --leading-relaxed: 1.625;

    /* Spacing */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;
    --space-12: 3rem;
    --space-16: 4rem;

    /* Border Radius - MAX 5px */
    --radius-sm: 2px;
    --radius-md: 4px;
    --radius-lg: 5px;
    --radius-full: 9999px;

    /* Shadows - Subtle */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 2px 4px rgba(0, 0, 0, 0.06), 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-lg: 0 4px 6px rgba(0, 0, 0, 0.05), 0 2px 4px rgba(0, 0, 0, 0.03);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 200ms ease;
    --transition-slow: 300ms ease;

    /* Z-Index Scale */
    --z-dropdown: 100;
    --z-sticky: 200;
    --z-modal-backdrop: 300;
    --z-modal: 400;
    --z-tooltip: 500;
    --z-onboarding: 600;
}

/* ============================================
   CSS RESET & BASE STYLES
   ============================================ */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-sans);
    font-size: var(--text-base);
    line-height: var(--leading-normal);
    color: var(--color-gray-900);
    background-color: var(--color-gray-50);
}

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* ============================================
   TYPOGRAPHY
   ============================================ */
h1, h2, h3, h4, h5, h6 {
    font-weight: var(--font-semibold);
    line-height: var(--leading-tight);
    color: var(--color-gray-900);
}

h1 { font-size: var(--text-4xl); }
h2 { font-size: var(--text-3xl); }
h3 { font-size: var(--text-2xl); }
h4 { font-size: var(--text-xl); }
h5 { font-size: var(--text-lg); }
h6 { font-size: var(--text-base); }

p {
    color: var(--color-gray-600);
    line-height: var(--leading-relaxed);
}

a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

small {
    font-size: var(--text-sm);
    color: var(--color-gray-500);
}

/* ============================================
   BUTTONS - FLAT DESIGN
   ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-5);
    font-family: var(--font-sans);
    font-size: var(--text-sm);
    font-weight: var(--font-medium);
    line-height: 1;
    text-decoration: none;
    border: 1px solid transparent;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* Primary Button */
.btn-primary {
    background-color: var(--color-accent);
    color: var(--color-white);
    border-color: var(--color-accent);
}

.btn-primary:hover:not(:disabled) {
    background-color: var(--color-accent-hover);
    border-color: var(--color-accent-hover);
}

/* Secondary Button */
.btn-secondary {
    background-color: var(--color-white);
    color: var(--color-gray-700);
    border-color: var(--color-gray-300);
}

.btn-secondary:hover:not(:disabled) {
    background-color: var(--color-gray-50);
    border-color: var(--color-gray-400);
}

/* Ghost Button */
.btn-ghost {
    background-color: transparent;
    color: var(--color-gray-600);
    border-color: transparent;
}

.btn-ghost:hover:not(:disabled) {
    background-color: var(--color-gray-100);
    color: var(--color-gray-900);
}

/* Danger Button */
.btn-danger {
    background-color: var(--color-error);
    color: var(--color-white);
    border-color: var(--color-error);
}

.btn-danger:hover:not(:disabled) {
    background-color: #b91c1c;
    border-color: #b91c1c;
}

/* Button Sizes */
.btn-sm {
    padding: var(--space-2) var(--space-3);
    font-size: var(--text-xs);
}

.btn-lg {
    padding: var(--space-4) var(--space-6);
    font-size: var(--text-base);
}

.btn-full {
    width: 100%;
}

/* ============================================
   FORM ELEMENTS
   ============================================ */
.form-group {
    margin-bottom: var(--space-5);
}

.form-label {
    display: block;
    margin-bottom: var(--space-2);
    font-size: var(--text-sm);
    font-weight: var(--font-medium);
    color: var(--color-gray-700);
}

.form-input,
.form-select,
.form-textarea {
    width: 100%;
    padding: var(--space-3) var(--space-4);
    font-family: var(--font-sans);
    font-size: var(--text-base);
    color: var(--color-gray-900);
    background-color: var(--color-white);
    border: 1px solid var(--color-gray-300);
    border-radius: var(--radius-md);
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px var(--color-accent-light);
}

.form-input::placeholder {
    color: var(--color-gray-400);
}

.form-input.error {
    border-color: var(--color-error);
}

.form-input.error:focus {
    box-shadow: 0 0 0 3px var(--color-error-light);
}

.form-hint {
    margin-top: var(--space-1);
    font-size: var(--text-sm);
    color: var(--color-gray-500);
}

.form-error {
    margin-top: var(--space-1);
    font-size: var(--text-sm);
    color: var(--color-error);
}

/* Checkbox & Radio */
.form-checkbox,
.form-radio {
    width: 1rem;
    height: 1rem;
    border: 1px solid var(--color-gray-300);
    border-radius: var(--radius-sm);
    cursor: pointer;
}

.form-radio {
    border-radius: var(--radius-full);
}

/* ============================================
   CARDS
   ============================================ */
.card {
    background-color: var(--color-white);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-lg);
}

.card-header {
    padding: var(--space-5) var(--space-6);
    border-bottom: 1px solid var(--color-gray-200);
}

.card-body {
    padding: var(--space-6);
}

.card-footer {
    padding: var(--space-4) var(--space-6);
    border-top: 1px solid var(--color-gray-200);
    background-color: var(--color-gray-50);
}

/* ============================================
   NAVIGATION
   ============================================ */
.nav {
    display: flex;
    align-items: center;
    gap: var(--space-1);
}

.nav-link {
    padding: var(--space-2) var(--space-4);
    font-size: var(--text-sm);
    font-weight: var(--font-medium);
    color: var(--color-gray-600);
    text-decoration: none;
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.nav-link:hover {
    color: var(--color-gray-900);
    background-color: var(--color-gray-100);
}

.nav-link.active {
    color: var(--color-accent);
    background-color: var(--color-accent-light);
}

/* ============================================
   HEADER / TOP BAR
   ============================================ */
.header {
    position: sticky;
    top: 0;
    z-index: var(--z-sticky);
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
    padding: 0 var(--space-6);
    background-color: var(--color-white);
    border-bottom: 1px solid var(--color-gray-200);
}

.header-logo {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    font-size: var(--text-lg);
    font-weight: var(--font-semibold);
    color: var(--color-gray-900);
    text-decoration: none;
}

.header-logo-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    background-color: var(--color-accent);
    color: var(--color-white);
    font-weight: var(--font-bold);
    font-size: var(--text-sm);
    border-radius: var(--radius-md);
}

.header-actions {
    display: flex;
    align-items: center;
    gap: var(--space-3);
}

/* ============================================
   SIDEBAR
   ============================================ */
.sidebar {
    position: fixed;
    top: 64px;
    left: 0;
    width: 256px;
    height: calc(100vh - 64px);
    padding: var(--space-4);
    background-color: var(--color-white);
    border-right: 1px solid var(--color-gray-200);
    overflow-y: auto;
}

.sidebar-nav {
    display: flex;
    flex-direction: column;
    gap: var(--space-1);
}

.sidebar-link {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-3) var(--space-4);
    font-size: var(--text-sm);
    font-weight: var(--font-medium);
    color: var(--color-gray-600);
    text-decoration: none;
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.sidebar-link:hover {
    color: var(--color-gray-900);
    background-color: var(--color-gray-100);
}

.sidebar-link.active {
    color: var(--color-accent);
    background-color: var(--color-accent-light);
}

.sidebar-link-icon {
    width: 20px;
    height: 20px;
    opacity: 0.7;
}

.sidebar-section {
    margin-top: var(--space-6);
    padding-top: var(--space-4);
    border-top: 1px solid var(--color-gray-200);
}

.sidebar-section-title {
    padding: var(--space-2) var(--space-4);
    font-size: var(--text-xs);
    font-weight: var(--font-semibold);
    color: var(--color-gray-400);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* ============================================
   MAIN CONTENT AREA
   ============================================ */
.main-content {
    margin-left: 256px;
    padding: var(--space-8);
    min-height: calc(100vh - 64px);
}

.main-content.no-sidebar {
    margin-left: 0;
}

.page-header {
    margin-bottom: var(--space-8);
}

.page-title {
    font-size: var(--text-2xl);
    font-weight: var(--font-semibold);
    color: var(--color-gray-900);
}

.page-description {
    margin-top: var(--space-2);
    color: var(--color-gray-500);
}

/* ============================================
   TABLES
   ============================================ */
.table {
    width: 100%;
    border-collapse: collapse;
}

.table th,
.table td {
    padding: var(--space-4);
    text-align: left;
    border-bottom: 1px solid var(--color-gray-200);
}

.table th {
    font-size: var(--text-xs);
    font-weight: var(--font-semibold);
    color: var(--color-gray-500);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    background-color: var(--color-gray-50);
}

.table tbody tr:hover {
    background-color: var(--color-gray-50);
}

/* ============================================
   BADGES / TAGS
   ============================================ */
.badge {
    display: inline-flex;
    align-items: center;
    padding: var(--space-1) var(--space-2);
    font-size: var(--text-xs);
    font-weight: var(--font-medium);
    border-radius: var(--radius-sm);
}

.badge-default {
    background-color: var(--color-gray-100);
    color: var(--color-gray-700);
}

.badge-primary {
    background-color: var(--color-accent-light);
    color: var(--color-accent-dark);
}

.badge-success {
    background-color: var(--color-success-light);
    color: var(--color-success);
}

.badge-warning {
    background-color: var(--color-warning-light);
    color: var(--color-warning);
}

.badge-error {
    background-color: var(--color-error-light);
    color: var(--color-error);
}

/* ============================================
   ALERTS
   ============================================ */
.alert {
    display: flex;
    align-items: flex-start;
    gap: var(--space-3);
    padding: var(--space-4);
    border-radius: var(--radius-md);
    font-size: var(--text-sm);
}

.alert-icon {
    flex-shrink: 0;
    width: 20px;
    height: 20px;
}

.alert-info {
    background-color: var(--color-info-light);
    color: var(--color-info);
}

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

.alert-warning {
    background-color: var(--color-warning-light);
    color: var(--color-warning);
}

.alert-error {
    background-color: var(--color-error-light);
    color: var(--color-error);
}

/* ============================================
   MODAL
   ============================================ */
.modal-backdrop {
    position: fixed;
    inset: 0;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: var(--z-modal-backdrop);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
}

.modal-backdrop.active {
    opacity: 1;
    visibility: visible;
}

.modal {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%) scale(0.95);
    width: 100%;
    max-width: 500px;
    max-height: 90vh;
    background-color: var(--color-white);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    z-index: var(--z-modal);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
    overflow: hidden;
}

.modal.active {
    opacity: 1;
    visibility: visible;
    transform: translate(-50%, -50%) scale(1);
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-5) var(--space-6);
    border-bottom: 1px solid var(--color-gray-200);
}

.modal-title {
    font-size: var(--text-lg);
    font-weight: var(--font-semibold);
}

.modal-close {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    background: none;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    color: var(--color-gray-400);
    transition: all var(--transition-fast);
}

.modal-close:hover {
    background-color: var(--color-gray-100);
    color: var(--color-gray-600);
}

.modal-body {
    padding: var(--space-6);
    overflow-y: auto;
}

.modal-footer {
    display: flex;
    align-items: center;
    justify-content: flex-end;
    gap: var(--space-3);
    padding: var(--space-4) var(--space-6);
    border-top: 1px solid var(--color-gray-200);
    background-color: var(--color-gray-50);
}

/* ============================================
   DROPDOWN
   ============================================ */
.dropdown {
    position: relative;
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    right: 0;
    min-width: 200px;
    margin-top: var(--space-2);
    padding: var(--space-2);
    background-color: var(--color-white);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    z-index: var(--z-dropdown);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px);
    transition: all var(--transition-fast);
}

.dropdown.active .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-item {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    width: 100%;
    padding: var(--space-2) var(--space-3);
    font-size: var(--text-sm);
    color: var(--color-gray-700);
    text-decoration: none;
    background: none;
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.dropdown-item:hover {
    background-color: var(--color-gray-100);
    color: var(--color-gray-900);
}

.dropdown-divider {
    height: 1px;
    margin: var(--space-2) 0;
    background-color: var(--color-gray-200);
}

/* ============================================
   PROGRESS BAR
   ============================================ */
.progress {
    height: 6px;
    background-color: var(--color-gray-200);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    background-color: var(--color-accent);
    transition: width var(--transition-slow);
}

.progress-bar.success {
    background-color: var(--color-success);
}

/* ============================================
   AVATAR
   ============================================ */
.avatar {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background-color: var(--color-gray-200);
    color: var(--color-gray-600);
    font-weight: var(--font-medium);
    font-size: var(--text-sm);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.avatar img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.avatar-sm {
    width: 32px;
    height: 32px;
    font-size: var(--text-xs);
}

.avatar-lg {
    width: 56px;
    height: 56px;
    font-size: var(--text-lg);
}

/* ============================================
   EMPTY STATE
   ============================================ */
.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--space-16);
    text-align: center;
}

.empty-state-icon {
    width: 64px;
    height: 64px;
    margin-bottom: var(--space-4);
    color: var(--color-gray-300);
}

.empty-state-title {
    font-size: var(--text-lg);
    font-weight: var(--font-medium);
    color: var(--color-gray-900);
    margin-bottom: var(--space-2);
}

.empty-state-description {
    font-size: var(--text-sm);
    color: var(--color-gray-500);
    max-width: 320px;
    margin-bottom: var(--space-6);
}

/* ============================================
   COURSE CARD
   ============================================ */
.course-card {
    display: flex;
    flex-direction: column;
    background-color: var(--color-white);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: box-shadow var(--transition-fast);
}

.course-card:hover {
    box-shadow: var(--shadow-md);
}

.course-card-image {
    position: relative;
    aspect-ratio: 16/9;
    background-color: var(--color-gray-100);
    overflow: hidden;
}

.course-card-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.course-card-body {
    flex: 1;
    display: flex;
    flex-direction: column;
    padding: var(--space-5);
}

.course-card-category {
    font-size: var(--text-xs);
    font-weight: var(--font-medium);
    color: var(--color-accent);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--space-2);
}

.course-card-title {
    font-size: var(--text-base);
    font-weight: var(--font-semibold);
    color: var(--color-gray-900);
    margin-bottom: var(--space-2);
    line-height: var(--leading-tight);
}

.course-card-instructor {
    font-size: var(--text-sm);
    color: var(--color-gray-500);
    margin-bottom: var(--space-3);
}

.course-card-meta {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    margin-top: auto;
    padding-top: var(--space-4);
    border-top: 1px solid var(--color-gray-100);
    font-size: var(--text-sm);
    color: var(--color-gray-500);
}

.course-card-price {
    font-weight: var(--font-semibold);
    color: var(--color-gray-900);
}

.course-card-price.free {
    color: var(--color-success);
}

/* ============================================
   STAT CARD
   ============================================ */
.stat-card {
    padding: var(--space-6);
    background-color: var(--color-white);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-lg);
}

.stat-card-label {
    font-size: var(--text-sm);
    font-weight: var(--font-medium);
    color: var(--color-gray-500);
    margin-bottom: var(--space-2);
}

.stat-card-value {
    font-size: var(--text-3xl);
    font-weight: var(--font-bold);
    color: var(--color-gray-900);
}

.stat-card-change {
    display: inline-flex;
    align-items: center;
    gap: var(--space-1);
    margin-top: var(--space-2);
    font-size: var(--text-sm);
    font-weight: var(--font-medium);
}

.stat-card-change.positive {
    color: var(--color-success);
}

.stat-card-change.negative {
    color: var(--color-error);
}

/* ============================================
   GRID LAYOUTS
   ============================================ */
.grid {
    display: grid;
    gap: var(--space-6);
}

.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); }

@media (max-width: 1024px) {
    .grid-cols-4 { grid-template-columns: repeat(3, 1fr); }
}

@media (max-width: 768px) {
    .grid-cols-3,
    .grid-cols-4 { grid-template-columns: repeat(2, 1fr); }

    .sidebar {
        display: none;
    }

    .main-content {
        margin-left: 0;
        padding: var(--space-4);
    }
}

@media (max-width: 640px) {
    .grid-cols-2,
    .grid-cols-3,
    .grid-cols-4 { grid-template-columns: 1fr; }
}

/* ============================================
   UTILITIES
   ============================================ */
.text-center { text-align: center; }
.text-right { text-align: right; }
.text-left { text-align: left; }

.text-sm { font-size: var(--text-sm); }
.text-lg { font-size: var(--text-lg); }

.text-gray { color: var(--color-gray-500); }
.text-dark { color: var(--color-gray-900); }
.text-accent { color: var(--color-accent); }

.font-medium { font-weight: var(--font-medium); }
.font-semibold { font-weight: var(--font-semibold); }
.font-bold { font-weight: var(--font-bold); }

.mt-2 { margin-top: var(--space-2); }
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mt-8 { margin-top: var(--space-8); }

.mb-2 { margin-bottom: var(--space-2); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }
.mb-8 { margin-bottom: var(--space-8); }

.p-4 { padding: var(--space-4); }
.p-6 { padding: var(--space-6); }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: var(--space-2); }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }

.hidden { display: none; }
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    border: 0;
}

/* ============================================
   LOADING STATES
   ============================================ */
.loading-spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 2px solid var(--color-gray-200);
    border-top-color: var(--color-accent);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

.loading-spinner.lg {
    width: 32px;
    height: 32px;
    border-width: 3px;
}

.loading-spinner.xl {
    width: 48px;
    height: 48px;
    border-width: 4px;
}

.loading-spinner.white {
    border-color: rgba(255, 255, 255, 0.3);
    border-top-color: white;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

.btn.loading {
    position: relative;
    color: transparent;
    pointer-events: none;
}

.btn.loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 18px;
    height: 18px;
    margin: -9px 0 0 -9px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-top-color: white;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

.btn-secondary.loading::after {
    border-color: var(--color-gray-300);
    border-top-color: var(--color-gray-700);
}

/* Skeleton loading */
.skeleton {
    background: linear-gradient(90deg, var(--color-gray-200) 25%, var(--color-gray-100) 50%, var(--color-gray-200) 75%);
    background-size: 200% 100%;
    animation: skeleton-loading 1.5s ease-in-out infinite;
    border-radius: var(--radius-md);
}

.skeleton-text {
    height: 1em;
    margin-bottom: var(--space-2);
}

.skeleton-text:last-child {
    width: 70%;
}

.skeleton-circle {
    border-radius: 50%;
}

@keyframes skeleton-loading {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

/* Loading overlay */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: var(--z-modal);
}

.loading-overlay-content {
    text-align: center;
}

.loading-overlay-text {
    margin-top: var(--space-4);
    font-size: var(--text-sm);
    color: var(--color-gray-600);
}

/* ============================================
   IMPROVED ERROR MESSAGES
   ============================================ */
.error-page {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--space-4);
    background: var(--color-gray-50);
}

.error-content {
    text-align: center;
    max-width: 400px;
}

.error-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto var(--space-6);
    background: var(--color-error-light);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.error-icon i {
    font-size: 32px;
    color: var(--color-error);
}

.error-icon.warning {
    background: var(--color-warning-light);
}

.error-icon.warning i {
    color: var(--color-warning);
}

.error-title {
    font-size: var(--text-2xl);
    font-weight: var(--font-semibold);
    color: var(--color-gray-900);
    margin-bottom: var(--space-3);
}

.error-message {
    font-size: var(--text-base);
    color: var(--color-gray-600);
    line-height: var(--leading-relaxed);
    margin-bottom: var(--space-6);
}

.error-details {
    background: var(--color-gray-100);
    border-radius: var(--radius-md);
    padding: var(--space-3);
    font-size: var(--text-sm);
    color: var(--color-gray-700);
    font-family: var(--font-mono);
    margin-bottom: var(--space-6);
    text-align: left;
    overflow-x: auto;
}

/* Inline error messages */
.inline-error {
    display: flex;
    align-items: flex-start;
    gap: var(--space-2);
    padding: var(--space-3);
    background: var(--color-error-light);
    border: 1px solid var(--color-error);
    border-radius: var(--radius-md);
    font-size: var(--text-sm);
    color: var(--color-error);
}

.inline-error i {
    flex-shrink: 0;
    margin-top: 2px;
}

/* Toast notifications */
.toast-container {
    position: fixed;
    bottom: var(--space-6);
    right: var(--space-6);
    z-index: var(--z-tooltip);
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
}

.toast {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-3) var(--space-4);
    background: var(--color-gray-900);
    color: var(--color-white);
    border-radius: var(--radius-md);
    font-size: var(--text-sm);
    box-shadow: var(--shadow-lg);
    animation: toast-in 0.3s ease;
}

.toast.success {
    background: var(--color-success);
}

.toast.error {
    background: var(--color-error);
}

.toast.warning {
    background: var(--color-warning);
    color: var(--color-gray-900);
}

.toast-close {
    background: none;
    border: none;
    color: inherit;
    opacity: 0.7;
    cursor: pointer;
    padding: var(--space-1);
}

.toast-close:hover {
    opacity: 1;
}

@keyframes toast-in {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* ============================================
   RESPONSIVE UTILITIES
   ============================================ */
@media (max-width: 640px) {
    .hide-mobile { display: none !important; }
}

@media (min-width: 641px) {
    .show-mobile { display: none !important; }
}

@media (max-width: 768px) {
    .hide-tablet { display: none !important; }
}

@media (min-width: 769px) {
    .show-tablet { display: none !important; }
}

/* Mobile-first responsive padding */
@media (max-width: 640px) {
    .main {
        padding: var(--space-4);
    }

    .section {
        padding: var(--space-4);
    }

    .card-body {
        padding: var(--space-4);
    }

    .modal {
        margin: var(--space-4);
        max-height: calc(100vh - var(--space-8));
    }
}

/* Stack buttons on mobile */
@media (max-width: 480px) {
    .btn-group {
        flex-direction: column;
    }

    .btn-group .btn {
        width: 100%;
    }

    .modal-footer {
        flex-direction: column-reverse;
    }

    .modal-footer .btn {
        width: 100%;
    }
}

/* ============================================
   MOBILE TOUCH TARGETS (48x48px minimum)
   ============================================ */
@media (max-width: 768px) {
    /* Buttons minimum touch target */
    .btn,
    button,
    [type="button"],
    [type="submit"],
    [type="reset"] {
        min-height: 48px;
        min-width: 48px;
    }

    .btn-sm {
        min-height: 44px;
        padding: var(--space-3) var(--space-4);
    }

    /* Links that act as buttons */
    a.btn,
    .nav-link,
    .dropdown-item {
        min-height: 48px;
        display: inline-flex;
        align-items: center;
    }

    /* Form inputs minimum height */
    input[type="text"],
    input[type="email"],
    input[type="password"],
    input[type="number"],
    input[type="tel"],
    input[type="url"],
    input[type="search"],
    input[type="date"],
    input[type="time"],
    select,
    textarea {
        min-height: 48px;
        font-size: 16px; /* Prevents iOS zoom on focus */
    }

    /* Checkboxes and radios - larger touch area */
    input[type="checkbox"],
    input[type="radio"] {
        width: 24px;
        height: 24px;
        cursor: pointer;
    }

    /* Checkbox/radio labels as touch targets */
    label:has(input[type="checkbox"]),
    label:has(input[type="radio"]) {
        display: flex;
        align-items: center;
        min-height: 48px;
        padding: var(--space-2) 0;
        gap: var(--space-3);
        cursor: pointer;
    }

    /* Clickable table rows */
    tr.clickable,
    .list-item-clickable {
        min-height: 48px;
    }

    /* Icon buttons */
    .btn-icon,
    .icon-btn,
    [class*="icon-button"] {
        min-width: 48px;
        min-height: 48px;
        padding: var(--space-3);
    }

    /* Navigation items */
    .nav-item a,
    .menu-item,
    .sidebar-link {
        min-height: 48px;
        padding: var(--space-3) var(--space-4);
    }

    /* Tab items */
    .tab,
    .tab-item,
    [role="tab"] {
        min-height: 48px;
        padding: var(--space-3) var(--space-4);
    }

    /* Dropdown toggles */
    .dropdown-toggle {
        min-height: 48px;
    }

    /* Pagination links */
    .pagination-link {
        min-width: 44px;
        min-height: 44px;
    }

    /* Close buttons */
    .close-btn,
    .btn-close,
    [aria-label="Close"] {
        min-width: 44px;
        min-height: 44px;
    }

    /* Card actions */
    .card-action,
    .card-link {
        min-height: 48px;
        padding: var(--space-3);
    }

    /* Ensure adequate spacing between touch targets */
    .btn + .btn,
    button + button {
        margin-left: var(--space-2);
    }

    .btn-group {
        gap: var(--space-2);
    }
}

/* ============================================
   ACCESSIBILITY ENHANCEMENTS
   WCAG 2.1 AA Compliance
   ============================================ */

/* Focus visible styles for keyboard navigation */
:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

/* Remove default focus outline, use focus-visible instead */
:focus:not(:focus-visible) {
    outline: none;
}

/* High contrast focus for buttons */
.btn:focus-visible,
button:focus-visible,
[role="button"]:focus-visible {
    outline: 3px solid var(--color-accent);
    outline-offset: 2px;
    box-shadow: 0 0 0 4px var(--color-accent-light);
}

/* Skip to main content link */
.skip-link {
    position: absolute;
    top: -100px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--color-accent);
    color: var(--color-white);
    padding: var(--space-3) var(--space-5);
    border-radius: var(--radius-md);
    z-index: 10000;
    text-decoration: none;
    font-weight: var(--font-semibold);
}

.skip-link:focus {
    top: var(--space-4);
}

/* Screen reader only content */
.sr-only,
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Show on focus for skip links */
.sr-only-focusable:focus,
.sr-only-focusable:active {
    position: static;
    width: auto;
    height: auto;
    overflow: visible;
    clip: auto;
    white-space: normal;
}

/* Ensure minimum color contrast (4.5:1 for normal text) */
/* Override gray text that might not meet contrast */
.text-muted,
.text-gray-400,
.text-gray-500 {
    color: var(--color-gray-600); /* Darker for better contrast */
}

/* Links - no underline */
a {
    text-decoration: none;
}

/* Error states with icons for colorblind users */
.form-error,
.has-error .form-input,
.is-invalid {
    border-color: var(--color-error);
    border-width: 2px;
}

.form-error::before,
.error-message::before {
    content: "⚠ ";
}

/* Success states */
.form-success,
.has-success .form-input,
.is-valid {
    border-color: var(--color-success);
    border-width: 2px;
}

.success-message::before {
    content: "✓ ";
}

/* Required field indicator */
.required::after,
label.required::after {
    content: " *";
    color: var(--color-error);
    font-weight: var(--font-bold);
}

/* Reduced motion preference */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    .btn {
        border-width: 2px;
    }

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

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

    a:not(.btn) {
        text-decoration-thickness: 2px;
    }

    input,
    select,
    textarea {
        border-width: 2px;
        border-color: var(--color-black);
    }
}

/* Dark mode text contrast fixes */
@media (prefers-color-scheme: dark) {
    .text-gray-500,
    .text-gray-400 {
        color: var(--color-gray-300);
    }
}

/* Ensure interactive elements have visible focus */
[tabindex]:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible,
[contenteditable]:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

/* Loading states - provide text alternative */
.loading::after,
.spinner::after {
    content: "Loading...";
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Ensure disabled states are clear */
[disabled],
.disabled,
[aria-disabled="true"] {
    opacity: 0.5;
    cursor: not-allowed;
    pointer-events: none;
}

/* Live region for dynamic content */
[aria-live] {
    /* Ensure screen readers announce changes */
}

/* Landmark role styling */
[role="main"] {
    display: block;
}

[role="navigation"] {
    display: block;
}

[role="complementary"] {
    display: block;
}

/* Dialog/Modal accessibility */
[role="dialog"],
[role="alertdialog"] {
    position: fixed;
}

[role="dialog"][aria-hidden="true"],
[role="alertdialog"][aria-hidden="true"] {
    display: none;
}

/* Button states for screen readers */
[aria-pressed="true"] {
    background-color: var(--color-accent);
    color: var(--color-white);
}

[aria-expanded="true"] {
    /* Visual indicator for expanded state */
}

[aria-selected="true"] {
    background-color: var(--color-accent-light);
    font-weight: var(--font-semibold);
}

/* Current page indicator */
[aria-current="page"] {
    font-weight: var(--font-bold);
    color: var(--color-accent);
}

/* Tab panel visibility */
[role="tabpanel"][hidden] {
    display: none;
}

/* Tooltip accessibility */
[role="tooltip"] {
    position: absolute;
    z-index: var(--z-tooltip);
}

/* Alert styling with appropriate colors */
[role="alert"] {
    padding: var(--space-4);
    border-radius: var(--radius-md);
    border-left: 4px solid var(--color-error);
    background-color: var(--color-error-light);
}

[role="status"] {
    padding: var(--space-4);
    border-radius: var(--radius-md);
    border-left: 4px solid var(--color-info);
    background-color: var(--color-info-light);
}