/* ============================================
   MOCK TESTS - PREMIUM MODERN DESIGN SYSTEM
   ============================================ */

:root {
    --primary: #6366f1;
    --primary-light: #818cf8;
    --primary-dark: #4338ca;
    --primary-glow: rgba(99, 102, 241, 0.15);
    
    --secondary: #14b8a6;
    --secondary-light: #2dd4bf;
    
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    
    --text-main: #0f172a;
    --text-secondary: #475569;
    --text-light: #64748b;
    
    --border: #e2e8f0;
    --border-light: #f1f5f9;
    --background: #f8fafc;
    --card-bg: #ffffff;
    
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 12px 32px rgba(0, 0, 0, 0.12);
    --shadow-xl: 0 20px 48px rgba(0, 0, 0, 0.15);
    
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 20px;
    --radius-full: 9999px;
}

* {
    box-sizing: border-box;
}

/* ============================================
   PAGE STRUCTURE
   ============================================ */

.page-content-header {
    text-align: center;
    margin-bottom: 4rem;
    position: relative;
    padding: 0 1rem;
    animation: fadeInDown 0.6s ease-out;
}

@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.page-title {
    font-size: clamp(2rem, 5vw, 3rem);
    margin-bottom: 1rem;
    font-weight: 800;
    letter-spacing: -1.5px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    position: relative;
    display: inline-block;
}

.page-title::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: var(--radius-full);
}

.page-subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
    max-width: 650px;
    margin: 1.5rem auto 0;
    line-height: 1.7;
    font-weight: 500;
}

/* ============================================
   FILTERS
   ============================================ */

.filters-container {
    display: flex;
    gap: 0.5rem;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 3rem;
    padding: 0.75rem;
    background: var(--card-bg);
    width: fit-content;
    margin-left: auto;
    margin-right: auto;
    border-radius: var(--radius-full);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border);
    animation: fadeInUp 0.6s ease-out 0.2s both;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.filter-btn {
    padding: 0.625rem 1.5rem;
    border-radius: var(--radius-full);
    border: 2px solid transparent;
    background: transparent;
    cursor: pointer;
    font-weight: 600;
    color: var(--text-secondary);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    font-size: 0.9375rem;
    position: relative;
    overflow: hidden;
}

.filter-btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: var(--primary-glow);
    transform: translate(-50%, -50%);
    transition: width 0.4s, height 0.4s;
}

.filter-btn:hover::before {
    width: 200px;
    height: 200px;
}

.filter-btn:hover {
    color: var(--primary);
    background: var(--primary-glow);
    transform: translateY(-2px);
}

.filter-btn.active {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    box-shadow: 0 4px 12px var(--primary-glow), 0 0 0 3px rgba(99, 102, 241, 0.1);
    border-color: transparent;
}

.filter-btn.active:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 16px var(--primary-glow), 0 0 0 3px rgba(99, 102, 241, 0.15);
}

/* ============================================
   TESTS GRID
   ============================================ */

.tests-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
    margin-bottom: 3rem;
    animation: fadeIn 0.6s ease-out 0.4s both;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@media (min-width: 640px) {
    .tests-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.75rem;
    }
}

@media (min-width: 1024px) {
    .tests-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 2rem;
    }
}

@media (min-width: 1280px) {
    .tests-grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

/* ============================================
   TEST CARD (Individual Tests)
   ============================================ */

.test-card {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    border: 2px solid var(--border);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    display: flex;
    flex-direction: column;
    box-shadow: var(--shadow-sm);
    position: relative;
    overflow: hidden;
}

.test-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    transform: scaleX(0);
    transition: transform 0.4s;
}

.test-card:hover::before {
    transform: scaleX(1);
}

@media (min-width: 1024px) {
    .test-card:hover {
        transform: translateY(-8px);
        box-shadow: var(--shadow-lg);
        border-color: var(--primary-light);
    }
}

.test-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 0.75rem;
    margin-bottom: 0.75rem;
}

.test-title {
    font-size: 1.0625rem;
    font-weight: 700;
    color: var(--text-main);
    line-height: 1.4;
    margin: 0;
    flex: 1;
}

.difficulty-badge {
    padding: 0.375rem 0.75rem;
    border-radius: var(--radius-full);
    font-size: 0.6875rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    white-space: nowrap;
    flex-shrink: 0;
    box-shadow: var(--shadow-sm);
}

.difficulty-badge.easy {
    background: linear-gradient(135deg, #d1fae5, #a7f3d0);
    color: #065f46;
}

.difficulty-badge.medium {
    background: linear-gradient(135deg, #fef3c7, #fde68a);
    color: #92400e;
}

.difficulty-badge.hard {
    background: linear-gradient(135deg, #fecaca, #fca5a5);
    color: #991b1b;
}

.test-subject {
    font-size: 0.875rem;
    color: var(--text-light);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 500;
}

.test-subject::before {
    content: '';
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    box-shadow: 0 0 8px var(--primary-glow);
}

.test-meta {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 0.75rem;
    padding: 1rem 0;
    margin-bottom: 1rem;
    border-top: 2px dashed var(--border-light);
    border-bottom: 2px dashed var(--border-light);
}

.meta-item {
    text-align: center;
}

.meta-item strong {
    display: block;
    font-size: 1.25rem;
    font-weight: 800;
    color: var(--primary);
    margin-bottom: 0.25rem;
}

.meta-item span {
    font-size: 0.6875rem;
    color: var(--text-light);
    text-transform: uppercase;
    font-weight: 700;
    letter-spacing: 0.5px;
}

.test-card .btn {
    width: 100%;
    padding: 1rem;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-weight: 700;
    font-size: 0.9375rem;
    cursor: pointer;
    transition: all 0.3s;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    box-shadow: 0 4px 12px var(--primary-glow);
    position: relative;
    overflow: hidden;
}

.test-card .btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
    transition: left 0.5s;
}

.test-card .btn:hover::before {
    left: 100%;
}

.test-card .btn:hover {
    transform: scale(1.02);
    box-shadow: 0 6px 16px var(--primary-glow);
}

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

.test-card .btn::after {
    content: '→';
    font-size: 1.25em;
    transition: transform 0.3s;
}

.test-card .btn:hover::after {
    transform: translateX(4px);
}

/* ============================================
   SERIES CARD (Bundle/Folder View)
   ============================================ */

.series-card {
    position: relative;
    background: linear-gradient(145deg, #ffffff, #fafbff);
    cursor: pointer;
    border: 2px solid var(--border);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    overflow: hidden;
}

.series-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.4s;
}

.series-card:hover::before {
    transform: scaleX(1);
}

@media (min-width: 1024px) {
    .series-card:hover {
        transform: translateY(-10px) scale(1.02);
        box-shadow: var(--shadow-xl);
        border-color: var(--primary);
    }
    
    .series-card:hover .bg-accent {
        opacity: 0.08;
    }
}

.bg-accent {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    opacity: 0;
    transition: opacity 0.4s;
    pointer-events: none;
}

.series-content {
    position: relative;
    z-index: 1;
    padding: 1.5rem;
}

.series-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1.25rem;
    gap: 1rem;
}

.series-icon-box {
    background: linear-gradient(135deg, #e0e7ff 0%, #c7d2fe 100%);
    width: 56px;
    height: 56px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    box-shadow: inset 0 2px 4px rgba(255, 255, 255, 0.8),
                0 4px 12px rgba(99, 102, 241, 0.15);
    border: 2px solid rgba(255, 255, 255, 0.8);
    transition: transform 0.3s;
}

.series-card:hover .series-icon-box {
    transform: rotate(-5deg) scale(1.05);
}

.series-free-badge {
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
    color: white;
    padding: 0.375rem 0.875rem;
    border-radius: var(--radius-full);
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.5px;
    text-transform: uppercase;
    box-shadow: 0 2px 8px rgba(16, 185, 129, 0.3);
    white-space: nowrap;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% {
        box-shadow: 0 2px 8px rgba(16, 185, 129, 0.3);
    }
    50% {
        box-shadow: 0 4px 12px rgba(16, 185, 129, 0.5);
    }
}

.series-title {
    color: var(--text-main);
    font-size: 1.375rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
    letter-spacing: -0.5px;
    line-height: 1.3;
}

.series-subtitle {
    margin: 0;
    font-size: 0.9375rem;
    color: var(--text-secondary);
    font-weight: 600;
}

.series-stats-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-top: 1.5rem;
    padding-top: 1.5rem;
    border-top: 2px dashed var(--border-light);
}

.series-stat-item {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    padding: 0.75rem;
    background: var(--background);
    border-radius: var(--radius-sm);
    transition: all 0.3s;
}

.series-card:hover .series-stat-item {
    background: white;
}

.series-stat-label {
    font-size: 0.75rem;
    text-transform: uppercase;
    color: var(--text-light);
    font-weight: 700;
    letter-spacing: 0.5px;
}

.series-stat-value {
    font-size: 1.5rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.series-launch-link {
    margin-top: 1.5rem;
    padding: 1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    color: white;
    font-weight: 700;
    font-size: 1rem;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    border-radius: var(--radius-md);
    transition: all 0.3s;
    box-shadow: 0 4px 12px var(--primary-glow);
}

.series-card:hover .series-launch-link {
    transform: scale(1.02);
    box-shadow: 0 6px 16px var(--primary-glow);
}

.series-launch-link svg {
    transition: transform 0.3s;
}

.series-card:hover .series-launch-link svg {
    transform: translateX(4px);
}

/* ============================================
   CONTENT SECTIONS
   ============================================ */

.content-section {
    margin-top: 5rem;
    padding: 4rem 2rem;
    background: white;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    position: relative;
    overflow: hidden;
}

.content-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 5px;
    background: linear-gradient(90deg, var(--primary), var(--secondary), var(--primary));
    background-size: 200% 100%;
    animation: gradientShift 3s ease infinite;
}

@keyframes gradientShift {
    0%, 100% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
}

.section-title {
    text-align: center;
    font-size: clamp(1.75rem, 4vw, 2.25rem);
    font-weight: 800;
    color: var(--text-main);
    margin-bottom: 3rem;
    letter-spacing: -1px;
    position: relative;
    display: inline-block;
    width: 100%;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -12px;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: var(--radius-full);
}

/* ============================================
   INFO CARDS
   ============================================ */

.info-card {
    padding: 2rem;
    background: var(--background);
    border-radius: var(--radius-lg);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    border: 2px solid transparent;
    position: relative;
    overflow: hidden;
}

.info-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, var(--primary-glow), transparent);
    opacity: 0;
    transition: opacity 0.4s;
}

@media (min-width: 1024px) {
    .info-card:hover {
        background: white;
        transform: translateY(-8px);
        box-shadow: var(--shadow-lg);
        border-color: var(--primary-light);
    }
    
    .info-card:hover::before {
        opacity: 1;
    }
}

.info-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    display: inline-block;
    filter: drop-shadow(0 4px 8px rgba(0,0,0,0.1));
    transition: transform 0.4s;
}

.info-card:hover .info-icon {
    transform: scale(1.1) rotate(-5deg);
}

.step-icon {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    display: inline-block;
    filter: drop-shadow(0 4px 8px rgba(0,0,0,0.1));
}

.steps-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
}

@media (min-width: 640px) {
    .steps-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

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

.step-item {
    text-align: center;
}

.step-item h3 {
    color: var(--primary);
    font-weight: 700;
    margin-bottom: 0.75rem;
    font-size: 1.125rem;
}

.step-item p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* ============================================
   SUBJECT GRADIENT CARDS
   ============================================ */

.subject-gradient-card {
    padding: 2rem;
    border-radius: var(--radius-lg);
    color: white;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-md);
}

.subject-gradient-card::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(0deg, rgba(0,0,0,0.2) 0%, transparent 100%);
    opacity: 0;
    transition: opacity 0.4s;
}

@media (min-width: 1024px) {
    .subject-gradient-card:hover {
        transform: translateY(-8px) scale(1.03);
        box-shadow: var(--shadow-xl);
    }
    
    .subject-gradient-card:hover::after {
        opacity: 1;
    }
}

.features-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
}

@media (min-width: 640px) {
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 768px) {
    .features-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (min-width: 1024px) {
    .features-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 2rem;
    }
}

/* ============================================
   FAQ / DETAILS
   ============================================ */

details {
    border: 2px solid var(--border);
    transition: all 0.3s;
    border-radius: var(--radius-md);
}

details[open] {
    background: var(--background);
    border-color: var(--primary);
    box-shadow: var(--shadow-sm);
}

summary {
    position: relative;
    padding-right: 40px;
    cursor: pointer;
}

summary::after {
    content: '+';
    position: absolute;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 1.75rem;
    color: var(--primary);
    font-weight: 300;
    transition: transform 0.3s;
}

details[open] summary::after {
    transform: translateY(-50%) rotate(45deg);
}

/* ============================================
   LOADING & EMPTY STATES
   ============================================ */

.empty-state {
    text-align: center;
    padding: 4rem 2rem;
    background: white;
    border-radius: var(--radius-lg);
    color: var(--text-light);
    grid-column: 1 / -1;
}

.skeleton {
    animation: skeleton-pulse 1.5s ease-in-out infinite;
}

@keyframes skeleton-pulse {
    0%, 100% {
        opacity: 0.4;
        background: var(--border-light);
    }
    50% {
        opacity: 1;
        background: var(--border);
    }
}

.skeleton-header {
    height: 32px;
    width: 60%;
    background: var(--border);
    border-radius: var(--radius-sm);
    margin-bottom: 1rem;
}

/* ============================================
   MODAL
   ============================================ */

.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.7);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 9999;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    padding: 1rem;
}

.modal-content {
    background: white;
    padding: 2rem;
    border-radius: var(--radius-xl);
    width: 100%;
    max-width: 500px;
    box-shadow: var(--shadow-xl);
    animation: modalPop 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

@keyframes modalPop {
    0% {
        transform: scale(0.9);
        opacity: 0;
    }
    100% {
        transform: scale(1);
        opacity: 1;
    }
}

.modal-header h2 {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--text-main);
    margin-bottom: 1rem;
    text-align: center;
}

.modal-footer {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-top: 1.5rem;
}

.modal-footer .btn {
    width: 100%;
    padding: 1rem;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.3s;
    border: 2px solid transparent;
}

.modal-footer .btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    box-shadow: 0 4px 12px var(--primary-glow);
}

.modal-footer .btn-primary:hover {
    transform: scale(1.02);
    box-shadow: 0 6px 16px var(--primary-glow);
}

.modal-footer .btn-outline {
    background: transparent;
    border: 2px solid var(--border);
    color: var(--text-secondary);
}

.modal-footer .btn-outline:hover {
    border-color: var(--primary);
    color: var(--primary);
    background: var(--primary-glow);
}

/* ============================================
   RESPONSIVE UTILITIES
   ============================================ */

@media (max-width: 640px) {
    .series-content {
        padding: 1.25rem;
    }
    
    .series-icon-box {
        width: 48px;
        height: 48px;
        font-size: 1.5rem;
    }
    
    .series-title {
        font-size: 1.125rem;
    }
    
    .series-stat-value {
        font-size: 1.25rem;
    }
}