/* ============================================================
   Testbook247.com — Modern EdTech Design System Engine
   Bootstrap 5.3 + Custom Tokens | Light & Dark Mode | WCAG Compliant
   ============================================================ */

/* ── 1. CSS CUSTOM PROPERTIES (DESIGN TOKENS) ─────────────── */
:root {
    /* Brand Colors (Preserved Visual Identity) */
    --primary: #2563EB;
    --primary-hover: #1D4ED8;
    --primary-light: #3B82F6;
    --primary-dark: #1E40AF;
    --primary-bg: #EFF6FF;
    --primary-border: #BFDBFE;
    --primary-ring: rgba(37, 99, 235, 0.25);

    --secondary: #4F46E5;
    --secondary-hover: #4338CA;
    --secondary-light: #6366F1;
    --secondary-bg: #EEF2FF;
    --secondary-border: #C7D2FE;

    /* Semantic Accent Colors */
    --success: #16A34A;
    --success-hover: #15803D;
    --success-bg: #F0FDF4;
    --success-border: #BBF7D0;
    --success-text: #166534;

    --warning: #D97706;
    --warning-hover: #B45309;
    --warning-bg: #FFFBEB;
    --warning-border: #FDE68A;
    --warning-text: #92400E;

    --danger: #DC2626;
    --danger-hover: #B91C1C;
    --danger-bg: #FEF2F2;
    --danger-border: #FECACA;
    --danger-text: #991B1B;

    --info: #0EA5E9;
    --info-hover: #0369A1;
    --info-bg: #F0F9FF;
    --info-border: #BAE6FD;
    --info-text: #075985;

    /* Neutral & Background Tokens (Light Theme) */
    --bg-main: #F8FAFC;
    --bg-card: #FFFFFF;
    --bg-subtle: #F1F5F9;
    --bg-input: #FFFFFF;
    --border-color: #E2E8F0;
    --border-subtle: #F1F5F9;

    --text-main: #0F172A;
    --text-muted: #475569;
    --text-subtle: #64748B;
    --text-inverse: #FFFFFF;

    /* Elevation & Shadows */
    --shadow-xs: 0 1px 2px 0 rgba(15, 23, 42, 0.05);
    --shadow-sm: 0 1px 3px 0 rgba(15, 23, 42, 0.08), 0 1px 2px -1px rgba(15, 23, 42, 0.04);
    --shadow-md: 0 4px 12px -2px rgba(15, 23, 42, 0.08), 0 2px 6px -1px rgba(15, 23, 42, 0.04);
    --shadow-lg: 0 10px 25px -3px rgba(15, 23, 42, 0.1), 0 4px 10px -2px rgba(15, 23, 42, 0.04);
    --shadow-xl: 0 20px 30px -5px rgba(15, 23, 42, 0.15), 0 8px 12px -4px rgba(15, 23, 42, 0.06);
    --shadow-primary: 0 4px 14px 0 rgba(37, 99, 235, 0.3);

    /* Border Radii */
    --radius-xs: 4px;
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --radius-full: 9999px;

    /* Typography Scale */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    --font-xs: 0.75rem;     /* 12px */
    --font-sm: 0.84rem;     /* 13.5px */
    --font-base: 0.92rem;   /* 14.7px */
    --font-md: 1rem;        /* 16px */
    --font-lg: 1.125rem;    /* 18px */
    --font-xl: 1.25rem;     /* 20px */
    --font-2xl: 1.5rem;     /* 24px */
    --font-3xl: clamp(1.6rem, 4vw, 2.25rem); /* Fluid Heading */

    /* Spacing Scale */
    --space-1: 4px;
    --space-2: 8px;
    --space-3: 12px;
    --space-4: 16px;
    --space-5: 20px;
    --space-6: 24px;
    --space-8: 32px;
    --space-10: 40px;
    --space-12: 48px;

    /* Transitions & Timings */
    --transition-fast: 0.15s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 0.22s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-spring: 0.35s cubic-bezier(0.34, 1.56, 0.64, 1);

    /* Z-Index Architecture */
    --z-dropdown: 1000;
    --z-sticky: 1020;
    --z-fixed: 1030;
    --z-backdrop: 1040;
    --z-modal: 1050;
    --z-toast: 9999;
}

/* ── Dark Mode Tokens ──────────────────────────────────────── */
html[data-theme="dark"] {
    --bg-main: #0B0F19;
    --bg-card: #151D2A;
    --bg-subtle: #1E293B;
    --bg-input: #151D2A;
    --border-color: #2D3748;
    --border-subtle: #1E293B;

    --text-main: #F8FAFC;
    --text-muted: #CBD5E1;
    --text-subtle: #94A3B8;

    --primary-bg: rgba(37, 99, 235, 0.15);
    --primary-border: rgba(37, 99, 235, 0.35);

    --success-bg: rgba(22, 163, 74, 0.15);
    --success-border: rgba(22, 163, 74, 0.35);
    --success-text: #4ADE80;

    --warning-bg: rgba(217, 119, 6, 0.15);
    --warning-border: rgba(217, 119, 6, 0.35);
    --warning-text: #FBBF24;

    --danger-bg: rgba(220, 38, 38, 0.15);
    --danger-border: rgba(220, 38, 38, 0.35);
    --danger-text: #F87171;

    --info-bg: rgba(14, 165, 233, 0.15);
    --info-border: rgba(14, 165, 233, 0.35);
    --info-text: #38BDF8;

    --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.4);
    --shadow-sm: 0 2px 4px 0 rgba(0, 0, 0, 0.4);
    --shadow-md: 0 4px 16px 0 rgba(0, 0, 0, 0.45);
    --shadow-lg: 0 8px 30px 0 rgba(0, 0, 0, 0.55);
}

/* ── 2. BASE TYPOGRAPHY & RESET ────────────────────────────── */
body {
    font-family: var(--font-sans);
    background-color: var(--bg-main);
    color: var(--text-main);
    font-size: var(--font-base);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4, h5, h6 {
    color: var(--text-main);
    font-weight: 700;
    line-height: 1.25;
    letter-spacing: -0.015em;
}

h1 { font-size: var(--font-3xl); }
h2 { font-size: var(--font-2xl); }
h3 { font-size: var(--font-xl); }
h4 { font-size: var(--font-lg); }
h5 { font-size: var(--font-md); }
h6 { font-size: var(--font-sm); text-transform: uppercase; letter-spacing: 0.05em; }

p { margin-bottom: 1rem; color: var(--text-muted); }

/* Focus Visible WCAG AA Outline */
:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

/* ── 3. BUTTON SYSTEM ──────────────────────────────────────── */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    padding: 0.6rem 1.35rem;
    font-size: var(--font-base);
    font-weight: 600;
    border-radius: var(--radius-md);
    border: 1px solid transparent;
    cursor: pointer;
    white-space: nowrap;
    user-select: none;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.btn:active {
    transform: scale(0.98);
}

/* Primary Button */
.btn-primary {
    background-color: var(--primary);
    color: var(--text-inverse) !important;
    border-color: var(--primary);
}

.btn-primary:hover {
    background-color: var(--primary-hover);
    border-color: var(--primary-hover);
    box-shadow: var(--shadow-primary);
    transform: translateY(-1px);
}

/* Secondary Button */
.btn-secondary {
    background-color: var(--secondary);
    color: var(--text-inverse) !important;
    border-color: var(--secondary);
}

.btn-secondary:hover {
    background-color: var(--secondary-hover);
    border-color: var(--secondary-hover);
    transform: translateY(-1px);
}

/* Outline Button */
.btn-outline {
    background-color: transparent;
    color: var(--text-main);
    border-color: var(--border-color);
}

.btn-outline:hover {
    background-color: var(--primary-bg);
    border-color: var(--primary);
    color: var(--primary);
    transform: translateY(-1px);
}

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

.btn-ghost:hover {
    background-color: var(--bg-subtle);
    color: var(--primary);
}

/* Status Buttons */
.btn-success { background-color: var(--success); color: white !important; }
.btn-success:hover { background-color: var(--success-hover); transform: translateY(-1px); }

.btn-warning { background-color: var(--warning); color: white !important; }
.btn-warning:hover { background-color: var(--warning-hover); transform: translateY(-1px); }

.btn-danger { background-color: var(--danger); color: white !important; }
.btn-danger:hover { background-color: var(--danger-hover); transform: translateY(-1px); }

/* Sizes */
.btn-sm {
    padding: 0.35rem 0.85rem;
    font-size: var(--font-sm);
    border-radius: var(--radius-sm);
}

.btn-lg {
    padding: 0.85rem 1.8rem;
    font-size: var(--font-md);
    border-radius: var(--radius-lg);
}

.btn-pill {
    border-radius: var(--radius-full);
}

/* Disabled & Loading States */
.btn:disabled, .btn.disabled {
    opacity: 0.6;
    cursor: not-allowed;
    pointer-events: none;
    transform: none !important;
    box-shadow: none !important;
}

.btn-loading {
    color: transparent !important;
    pointer-events: none;
}

.btn-loading::after {
    content: '';
    position: absolute;
    width: 18px;
    height: 18px;
    top: 50%;
    left: 50%;
    margin-top: -9px;
    margin-left: -9px;
    border: 2px solid rgba(255, 255, 255, 0.4);
    border-top-color: #ffffff;
    border-radius: 50%;
    animation: btn-spin 0.6s linear infinite;
}

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

/* ── 4. CARD SYSTEM ────────────────────────────────────────── */
.app-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-base);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.app-card-interactive:hover {
    border-color: var(--primary-border);
    box-shadow: var(--shadow-md);
    transform: translateY(-3px);
}

.app-card-header {
    padding: var(--space-4) var(--space-5);
    border-bottom: 1px solid var(--border-subtle);
    display: flex;
    align-items: center;
    justify-content: space-between;
    background-color: transparent;
}

.app-card-body {
    padding: var(--space-5);
    flex: 1;
}

.app-card-footer {
    padding: var(--space-3) var(--space-5);
    border-top: 1px solid var(--border-subtle);
    background-color: var(--bg-subtle);
}

/* Accent Card Variants */
.app-card-accent-primary { border-top: 4px solid var(--primary); }
.app-card-accent-success { border-top: 4px solid var(--success); }
.app-card-accent-warning { border-top: 4px solid var(--warning); }
.app-card-accent-danger { border-top: 4px solid var(--danger); }

/* ── 5. BADGES & TAGS ──────────────────────────────────────── */
.app-badge {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 0.25rem 0.65rem;
    font-size: var(--font-xs);
    font-weight: 600;
    border-radius: var(--radius-full);
    line-height: 1;
    white-space: nowrap;
}

.app-badge-primary { background-color: var(--primary-bg); color: var(--primary); border: 1px solid var(--primary-border); }
.app-badge-secondary { background-color: var(--secondary-bg); color: var(--secondary); border: 1px solid var(--secondary-border); }
.app-badge-success { background-color: var(--success-bg); color: var(--success-text); border: 1px solid var(--success-border); }
.app-badge-warning { background-color: var(--warning-bg); color: var(--warning-text); border: 1px solid var(--warning-border); }
.app-badge-danger { background-color: var(--danger-bg); color: var(--danger-text); border: 1px solid var(--danger-border); }
.app-badge-info { background-color: var(--info-bg); color: var(--info-text); border: 1px solid var(--info-border); }

/* Pulsing Live Badge */
.app-badge-live {
    background-color: var(--success-bg);
    color: var(--dark-text);
    border: 1px solid var(--success-border);
}
.app-badge-live::before {
    content: '';
    display: inline-block;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background-color: var(--danger);
    animation: pulse-live 1.5s infinite;
}

@keyframes pulse-live {
    0% { transform: scale(0.95); box-shadow: 0 0 0 0 rgba(220, 38, 38, 0.7); }
    70% { transform: scale(1); box-shadow: 0 0 0 6px rgba(220, 38, 38, 0); }
    100% { transform: scale(0.95); box-shadow: 0 0 0 0 rgba(220, 38, 38, 0); }
}

/* ── 6. FORM CONTROLS & INPUTS ─────────────────────────────── */
.form-label {
    font-size: var(--font-sm);
    font-weight: 600;
    color: var(--text-main);
    margin-bottom: var(--space-2);
}

.form-control, .form-select {
    width: 100%;
    padding: 0.65rem 1rem;
    font-family: var(--font-sans);
    font-size: var(--font-base);
    color: var(--text-main);
    background-color: var(--bg-input);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.form-control:focus, .form-select:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-ring);
    outline: none;
}

/* Floating Label Groups */
.form-floating-custom {
    position: relative;
}

.form-floating-custom .form-control {
    padding-top: 1.25rem;
    padding-bottom: 0.35rem;
}

.form-floating-custom label {
    position: absolute;
    top: 50%;
    left: 1rem;
    transform: translateY(-50%);
    font-size: var(--font-base);
    color: var(--text-subtle);
    pointer-events: none;
    transition: all var(--transition-fast);
}

.form-floating-custom .form-control:focus ~ label,
.form-floating-custom .form-control:not(:placeholder-shown) ~ label {
    top: 0.65rem;
    font-size: var(--font-xs);
    font-weight: 600;
    color: var(--primary);
}

/* Input Icon Group */
.input-icon-group {
    position: relative;
}
.input-icon-group i {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-subtle);
    font-size: 1.1rem;
}
.input-icon-group.icon-left i { left: 1rem; }
.input-icon-group.icon-left .form-control { padding-left: 2.75rem; }
.input-icon-group.icon-right i { right: 1rem; cursor: pointer; }
.input-icon-group.icon-right .form-control { padding-right: 2.75rem; }

/* ── 7. TABLE SYSTEM ───────────────────────────────────────── */
.app-table-wrapper {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    overflow: hidden;
}

.app-table {
    width: 100%;
    margin-bottom: 0;
    border-collapse: collapse;
}

.app-table th {
    background-color: var(--bg-subtle);
    color: var(--text-main);
    font-size: var(--font-xs);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 0.85rem 1.25rem;
    border-bottom: 1px solid var(--border-color);
    white-space: nowrap;
}

.app-table td {
    padding: 0.95rem 1.25rem;
    color: var(--text-muted);
    font-size: var(--font-base);
    border-bottom: 1px solid var(--border-subtle);
    vertical-align: middle;
}

.app-table tbody tr:last-child td {
    border-bottom: none;
}

.app-table tbody tr {
    transition: background-color var(--transition-fast);
}

.app-table tbody tr:hover {
    background-color: var(--primary-bg);
}

.app-table.sticky-header th {
    position: sticky;
    top: 0;
    z-index: 10;
}

/* ── 8. TOAST NOTIFICATIONS ────────────────────────────────── */
.toast-container {
    position: fixed;
    bottom: 24px;
    right: 24px;
    z-index: var(--z-toast);
    display: flex;
    flex-direction: column;
    gap: 12px;
    max-width: 380px;
    width: 100%;
    pointer-events: none;
}

.toast-item {
    pointer-events: auto;
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--primary);
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-lg);
    padding: 14px 16px;
    display: flex;
    align-items: flex-start;
    gap: 12px;
    animation: toast-slide-in 0.35s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.toast-item.toast-success { border-left-color: var(--success); }
.toast-item.toast-warning { border-left-color: var(--warning); }
.toast-item.toast-danger { border-left-color: var(--danger); }
.toast-item.toast-info { border-left-color: var(--info); }

.toast-icon {
    font-size: 1.25rem;
    line-height: 1;
    margin-top: 2px;
}
.toast-success .toast-icon { color: var(--success); }
.toast-warning .toast-icon { color: var(--warning); }
.toast-danger .toast-icon { color: var(--danger); }
.toast-info .toast-icon { color: var(--info); }

.toast-content {
    flex: 1;
}

.toast-title {
    font-weight: 700;
    font-size: var(--font-sm);
    color: var(--text-main);
}

.toast-message {
    font-size: var(--font-xs);
    color: var(--text-muted);
}

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

/* ── 9. SKELETON SHIMMER LOADERS ────────────────────────────── */
.skeleton {
    background: linear-gradient(90deg, var(--bg-subtle) 25%, var(--border-subtle) 50%, var(--bg-subtle) 75%);
    background-size: 200% 100%;
    animation: shimmer 1.5s infinite;
    border-radius: var(--radius-xs);
}

.skeleton-text {
    height: 1rem;
    margin-bottom: 0.5rem;
    width: 100%;
}
.skeleton-text.short { width: 60%; }

.skeleton-avatar {
    width: 48px;
    height: 48px;
    border-radius: 50%;
}

.skeleton-card {
    height: 180px;
    border-radius: var(--radius-md);
}

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

/* ── 10. ILLUSTRATED EMPTY STATES ─────────────────────────── */
.empty-state {
    padding: var(--space-10) var(--space-5);
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.empty-state-icon {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background-color: var(--primary-bg);
    color: var(--primary);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    margin-bottom: var(--space-4);
}

.empty-state-title {
    font-size: var(--font-xl);
    font-weight: 700;
    color: var(--text-main);
    margin-bottom: var(--space-2);
}

.empty-state-description {
    font-size: var(--font-base);
    color: var(--text-subtle);
    max-width: 420px;
    margin-bottom: var(--space-6);
}

/* ── 11. ANIMATIONS & MICRO-INTERACTIONS ───────────────────── */
.fade-in {
    animation: fadeIn var(--transition-base) forwards;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(6px); }
    to { opacity: 1; transform: translateY(0); }
}

.hover-lift {
    transition: transform var(--transition-base), box-shadow var(--transition-base);
}
.hover-lift:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}