/* Custom resets & Design variables matching Vercel/Linear design languages */
:root {
    --bg-main: #030712;
    --bg-surface: rgba(17, 24, 39, 0.7);
    --bg-surface-solid: #0b0f19;
    --border-color: rgba(255, 255, 255, 0.08);
    --border-hover: rgba(99, 102, 241, 0.4);
    
    --color-primary: #4f46e5;
    --color-primary-glow: rgba(79, 70, 229, 0.15);
    --color-text-main: #f3f4f6;
    --color-text-muted: #9ca3af;
    --gradient-brand: linear-gradient(135deg, #6366f1 0%, #3b82f6 100%);
    
    --font-stack: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, sans-serif;
    --transition-smooth: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

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

html {
    scroll-behavior: smooth;
    background-color: var(--bg-main);
    color: var(--color-text-main);
    font-family: var(--font-stack);
    -webkit-font-smoothing: antialiased;
}

body {
    overflow-x: hidden;
    position: relative;
}

/* Ambient glow accents behind cards */
.bg-glow {
    position: absolute;
    width: 600px;
    height: 600px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.12) 0%, rgba(0,0,0,0) 70%);
    z-index: -1;
    pointer-events: none;
    filter: blur(40px);
}
.glow-1 { top: -100px; right: -100px; }
.glow-2 { top: 1200px; left: -200px; }

/* Layout Grid Mechanics */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.section {
    padding: 8rem 0;
}

.section-header {
    text-align: center;
    max-width: 700px;
    margin: 0 auto 4rem auto;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    letter-spacing: -0.04em;
    margin-bottom: 1rem;
    background: linear-gradient(180deg, #ffffff 0%, #cbd5e1 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.section-description {
    color: var(--color-text-muted);
    font-size: 1.125rem;
    line-height: 1.6;
}

.gradient-text {
    background: var(--gradient-brand);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    display: inline-block;
}

/* Premium Buttons Architecture */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-stack);
    font-size: 0.95rem;
    font-weight: 600;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition-smooth);
    text-decoration: none;
}

.btn-primary {
    background: var(--gradient-brand);
    color: #ffffff;
    border: none;
    box-shadow: 0 4px 20px rgba(99, 102, 241, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 24px rgba(99, 102, 241, 0.45);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.04);
    color: var(--color-text-main);
    border: 1px solid var(--border-color);
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.08);
    border-color: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

.btn-lg {
    padding: 1rem 2.25rem;
    font-size: 1.05rem;
}

.btn-block {
    width: 100%;
}

/* Sticky Premium Navigation Bar */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    border-bottom: 1px solid var(--border-color);
    transition: var(--transition-smooth);
}

.header.scrolled {
    background: rgba(3, 7, 18, 0.75);
    backdrop-filter: blur(16px);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    height: 4.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 2rem;
}

.logo-area {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    text-decoration: none;
}

.brand-logo {
    height: 32px;
    width: auto;
}

.brand-name {
    font-size: 1.25rem;
    font-weight: 700;
    color: #ffffff;
    letter-spacing: -0.02em;
}

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-links a {
    color: var(--color-text-muted);
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 500;
    transition: var(--transition-smooth);
}

.nav-links a:hover {
    color: #ffffff;
}

.nav-actions {
    display: flex;
    gap: 1rem;
}

.mobile-toggle {
    display: none;
    flex-direction: column;
    gap: 6px;
    background: none;
    border: none;
    cursor: pointer;
    width: 24px;
}

.mobile-toggle span {
    display: block;
    height: 2px;
    width: 100%;
    background: #ffffff;
    transition: var(--transition-smooth);
}

/* Hero Section */
.hero-section {
    padding: 12rem 0 6rem 0;
    text-align: center;
    position: relative;
}

.badge-container {
    margin-bottom: 1.5rem;
    display: inline-block;
}

.hero-badge {
    background: rgba(99, 102, 241, 0.1);
    border: 1px solid rgba(99, 102, 241, 0.2);
    padding: 0.5rem 1.25rem;
    border-radius: 100px;
    font-size: 0.85rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    color: #818cf8;
    text-transform: uppercase;
}

.hero-title {
    font-size: 4.5rem;
    font-weight: 800;
    letter-spacing: -0.05em;
    line-height: 1.1;
    margin-bottom: 1.5rem;
    background: linear-gradient(180deg, #ffffff 0%, #94a3b8 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-subtitle {
    font-size: 1.35rem;
    color: var(--color-text-muted);
    max-width: 650px;
    margin: 0 auto 3rem auto;
    line-height: 1.6;
}

.hero-cta {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
}

/* Premium Stats Infrastructure */
.stats-section {
    padding: 3rem 0;
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
    background: rgba(255, 255, 255, 0.01);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 2rem;
    text-align: center;
}

.stat-card {
    padding: 1.5rem;
}

.stat-number {
    font-size: 3rem;
    font-weight: 800;
    background: var(--gradient-brand);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -0.02em;
    margin-bottom: 0.25rem;
}

.stat-label {
    color: var(--color-text-muted);
    font-size: 0.95rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* Product Overview Grid styling */
.overview-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.25rem;
}

.overview-item {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    backdrop-filter: blur(12px);
    border-radius: 12px;
    padding: 2rem 1.5rem;
    text-align: center;
    font-weight: 600;
    font-size: 1.1rem;
    transition: var(--transition-smooth);
    display: flex;
    align-items: center;
    justify-content: center;
}

.overview-item:hover {
    border-color: var(--border-hover);
    transform: scale(1.03);
    background: rgba(17, 24, 39, 0.9);
}

/* Glassmorphism Feature Cards Section */
.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.feature-card {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    backdrop-filter: blur(12px);
    border-radius: 16px;
    padding: 2.5rem;
    transition: var(--transition-smooth);
    position: relative;
    overflow: hidden;
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; width: 100%; height: 100%;
    background: radial-gradient(800px circle at var(--x, 0px) var(--y, 0px), rgba(255,255,255,0.06), transparent 40%);
    pointer-events: none;
}

.feature-card:hover {
    transform: translateY(-5px);
    border-color: var(--border-hover);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
}

.feature-icon-wrapper {
    width: 48px;
    height: 48px;
    border-radius: 10px;
    background: rgba(99, 102, 241, 0.1);
    border: 1px solid rgba(99, 102, 241, 0.2);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
}

/* Custom CSS Geometric Icons (Self-contained, no network assets required) */
.feature-icon {
    width: 20px;
    height: 20px;
    border: 2px solid #818cf8;
    position: relative;
}
.icon-course { border-radius: 4px; }
.icon-live { border-radius: 50%; background: #818cf8; transform: scale(0.6); }
.icon-bank { width: 16px; border-radius: 2px; }
.icon-bank::after { content:''; position:absolute; top:4px; left:2px; width:8px; height:2px; background:#818cf8;}
.icon-test { transform: rotate(45deg); }
.icon-student { border: none; background: radial-gradient(circle, #818cf8 40%, transparent 50%); }
.icon-teacher { border-width: 2px 2px 0 2px; height: 14px; margin-top: 4px;}
.icon-doubt { border-radius: 4px 4px 4px 0; }
.icon-resources { border-radius: 0 6px 0 0; }
.icon-analytics { border: none; display: flex; align-items: flex-end; gap: 2px; }
.icon-analytics::before, .icon-analytics::after { content:''; display:block; width:4px; background:#818cf8; }
.icon-analytics::before { height:10px; }
.icon-analytics::after { height:18px; }

.feature-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: #ffffff;
}

.feature-card p {
    color: var(--color-text-muted);
    font-size: 0.95rem;
    line-height: 1.6;
}

/* Premium App Screenshots Slider Carousel */
.carousel-viewport {
    overflow: hidden;
    width: 100%;
    cursor: grab;
    padding: 2rem 0;
}

.carousel-viewport:active {
    cursor: grabbing;
}

.carousel-track {
    display: flex;
    gap: 3rem;
    transition: transform 0.5s cubic-bezier(0.25, 1, 0.5, 1);
    will-change: transform;
}

.carousel-slide {
    flex: 0 0 320px;
    text-align: center;
    user-select: none;
}

.mockup-frame {
    background: #000000;
    border: 12px solid #1e293b;
    border-radius: 36px;
    box-shadow: 0 25px 60px -15px rgba(0, 0, 0, 0.7);
    overflow: hidden;
    aspect-ratio: 9 / 19;
    margin-bottom: 1.5rem;
    border-bottom-width: 14px;
    border-top-width: 14px;
    position: relative;
}

.mockup-frame img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
    background: #0f172a; /* Fallback rendering block container */
}

.slide-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: #ffffff;
}

.carousel-controls {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 2rem;
    margin-top: 3rem;
}

.carousel-btn {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    color: #ffffff;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 1.2rem;
    transition: var(--transition-smooth);
}

.carousel-btn:hover {
    border-color: var(--border-hover);
    background: rgba(255, 255, 255, 0.05);
}

.carousel-indicators {
    display: flex;
    gap: 0.5rem;
}

.indicator {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    cursor: pointer;
    transition: var(--transition-smooth);
}

.indicator.active {
    background: #6366f1;
    width: 24px;
    border-radius: 4px;
}

/* Premium Continuous Timeline (Evaluation Flow) */
.flow-timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}

.flow-timeline::before {
    content: '';
    position: absolute;
    left: 31px;
    top: 0;
    height: 100%;
    width: 2px;
    background: linear-gradient(180deg, var(--color-primary) 0%, rgba(255,255,255,0.05) 100%);
}

.flow-step {
    display: flex;
    gap: 2.5rem;
    margin-bottom: 3rem;
    position: relative;
}

.step-number {
    width: 64px;
    height: 64px;
    border-radius: 50%;
    background: var(--bg-surface-solid);
    border: 2px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    font-weight: 700;
    color: #818cf8;
    z-index: 2;
    flex-shrink: 0;
    transition: var(--transition-smooth);
}

.flow-step:hover .step-number {
    border-color: #6366f1;
    box-shadow: 0 0 20px rgba(99, 102, 241, 0.3);
}

.step-content {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    backdrop-filter: blur(10px);
    padding: 1.75rem 2rem;
    border-radius: 14px;
    width: 100%;
}

.step-content h4 {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #ffffff;
}

.step-content p {
    color: var(--color-text-muted);
    font-size: 0.95rem;
    line-height: 1.5;
}

/* Demo Credentials Premium Context Cards */
.credentials-badge {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    background: rgba(16, 185, 129, 0.06);
    border: 1px solid rgba(16, 185, 129, 0.2);
    max-width: 420px;
    margin: -1rem auto 3rem auto;
    padding: 0.6rem 1.25rem;
    border-radius: 100px;
    font-size: 0.9rem;
    color: #34d399;
    font-weight: 500;
}

.pulse-indicator {
    width: 8px;
    height: 8px;
    background: #10b981;
    border-radius: 50%;
    animation: indicatorPulse 2s infinite ease-in-out;
}

@keyframes indicatorPulse {
    0% { transform: scale(0.9); opacity: 0.6; }
    50% { transform: scale(1.2); opacity: 1; box-shadow: 0 0 10px #10b981; }
    100% { transform: scale(0.9); opacity: 0.6; }
}

.credentials-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
}

.cred-card {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    backdrop-filter: blur(10px);
    border-radius: 14px;
    padding: 1.5rem;
    position: relative;
    transition: var(--transition-smooth);
}

.cred-card:hover {
    border-color: rgba(255, 255, 255, 0.15);
    transform: translateY(-2px);
}

.cred-badge {
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 0.25rem 0.6rem;
    border-radius: 4px;
    display: inline-block;
    margin-bottom: 1.25rem;
}

.card-admin .cred-badge { background: rgba(239, 68, 68, 0.1); color: #f87171; }
.card-teacher .cred-badge { background: rgba(59, 130, 246, 0.1); color: #60a5fa; }
.card-student .cred-badge { background: rgba(163, 230, 53, 0.1); color: #a3e635; }

.cred-info {
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
}

.cred-label {
    font-size: 0.8rem;
    color: var(--color-text-muted);
}

.cred-value {
    font-size: 1.15rem;
    font-weight: 700;
    color: #ffffff;
    display: flex;
    align-items: center;
    justify-content: space-between;
    cursor: pointer;
}

.copy-icon::after {
    content: '📋';
    font-size: 0.9rem;
    opacity: 0.4;
    transition: var(--transition-smooth);
}

.cred-value:hover .copy-icon::after {
    opacity: 1;
}

/* Download Premium Banner Container */
.download-banner {
    background: radial-gradient(circle at top right, rgba(99, 102, 241, 0.15), transparent 50%), var(--bg-surface-solid);
    border: 1px solid var(--border-color);
    border-radius: 24px;
    padding: 5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    overflow: hidden;
    position: relative;
}

.download-content {
    max-width: 550px;
    z-index: 2;
}

.download-content h2 {
    font-size: 2.5rem;
    font-weight: 700;
    letter-spacing: -0.03em;
    margin-bottom: 1rem;
}

.download-content p {
    color: var(--color-text-muted);
    font-size: 1.1rem;
    margin-bottom: 2.5rem;
    line-height: 1.6;
}

.download-graphics {
    position: relative;
    width: 200px;
    height: 200px;
}

/* 3D Wireframe Cube Vector Drawing Graphic inside CSS */
.cube-element {
    width: 100px;
    height: 100px;
    position: absolute;
    top: 25%; left: 25%;
    border: 2px solid var(--color-primary);
    transform: rotateX(45deg) rotateY(45deg);
    animation: cubeRotate 12s infinite linear;
}
.cube-element::before {
    content:''; position:absolute; top:20px; left:20px; width:100%; height:100%;
    border: 2px dashed rgba(255, 255, 255, 0.2);
}

@keyframes cubeRotate {
    0% { transform: rotateX(0deg) rotateY(0deg); }
    100% { transform: rotateX(360deg) rotateY(360deg); }
}

/* Infrastructure Tech Badges Section */
.tech-section {
    padding: 4rem 0;
    border-top: 1px solid var(--border-color);
    background: rgba(0,0,0,0.2);
}

.tech-header-title {
    text-align: center;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--color-text-muted);
    margin-bottom: 2.5rem;
}

.tech-badges-container {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 1rem;
}

.tech-badge {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--border-color);
    color: var(--color-text-main);
    padding: 0.6rem 1.25rem;
    border-radius: 8px;
    font-size: 0.9rem;
    font-weight: 600;
    transition: var(--transition-smooth);
}

.tech-badge:hover {
    background: rgba(255, 255, 255, 0.06);
    border-color: rgba(255,255,255,0.15);
}

/* Feedback Section & Custom Form Inputs */
.feedback-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.feedback-info h2 {
    font-size: 2.5rem;
    font-weight: 700;
    letter-spacing: -0.04em;
    margin-bottom: 1rem;
}

.feedback-info p {
    color: var(--color-text-muted);
    font-size: 1.1rem;
    line-height: 1.6;
    margin-bottom: 2rem;
}

.dev-tag {
    font-size: 0.95rem;
    color: #818cf8;
}

.feedback-card {
    background: var(--bg-surface-solid);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    padding: 3rem;
    box-shadow: 0 30px 60px rgba(0,0,0,0.4);
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.form-group input, .form-group textarea {
    width: 100%;
    background: rgba(0,0,0,0.3);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 0.85rem 1.1rem;
    color: #ffffff;
    font-family: var(--font-stack);
    font-size: 0.95rem;
    transition: var(--transition-smooth);
}

.form-group input:focus, .form-group textarea:focus {
    outline: none;
    border-color: #6366f1;
    box-shadow: 0 0 0 4px var(--color-primary-glow);
}

/* Async Submission Spinner */
.spinner {
    display: none;
    width: 20px;
    height: 20px;
    border: 2px solid rgba(255,255,255,0.3);
    border-top-color: #ffffff;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin-left: 0.5rem;
}

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

form.loading .btn-text { display: none; }
form.loading .spinner { display: block; }
form.loading button { pointer-events: none; opacity: 0.8; }

/* Global System Notification Toast Architecture */
.toast-container {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    z-index: 2000;
}

.toast {
    background: #0f172a;
    border: 1px solid var(--border-color);
    padding: 1rem 1.5rem;
    border-radius: 10px;
    color: #ffffff;
    font-size: 0.95rem;
    font-weight: 500;
    box-shadow: 0 20px 40px rgba(0,0,0,0.5);
    display: flex;
    align-items: center;
    gap: 0.75rem;
    transform: translateY(20px);
    opacity: 0;
    animation: toastPresent 0.4s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

@keyframes toastPresent { to { transform: translateY(0); opacity: 1; } }

.toast-success { border-left: 4px solid #10b981; }
.toast-error { border-left: 4px solid #ef4444; }

/* Clean Production Footer Minimalist Design */
.footer {
    border-top: 1px solid var(--border-color);
    padding: 3rem 0;
    background: #020613;
}

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

.footer-tech {
    color: var(--color-text-muted);
    font-size: 0.9rem;
}

.footer-tech strong { color: #ffffff; }
.footer-copyright {
    color: rgba(255,255,255,0.3);
    font-size: 0.85rem;
}

/* Fully Responsive Breakpoint Adjustments Matrix */
@media (max-width: 1024px) {
    .features-grid { grid-template-columns: repeat(2, 1fr); }
    .overview-grid { grid-template-columns: repeat(2, 1fr); }
    .credentials-grid { grid-template-columns: repeat(2, 1fr); }
    .hero-title { font-size: 3.5rem; }
}

@media (max-width: 768px) {
    .nav-links, .nav-actions { display: none; }
    .mobile-toggle { display: flex; }
    
    /* Interactive Mobile Overlay Menu Drawer */
    .header.mobile-open { background: #030712; height: 100vh; }
    .header.mobile-open .nav-container { flex-direction: column; justify-content: flex-start; gap: 3rem; padding-top: 2rem;}
    .header.mobile-open .nav-links { display: flex; flex-direction: column; align-items: center; gap: 2rem; }
    .header.mobile-open .nav-links a { font-size: 1.5rem; }
    
    .hero-title { font-size: 2.75rem; }
    .stats-grid { grid-template-columns: repeat(2, 1fr); }
    .features-grid, .overview-grid, .credentials-grid, .feedback-container { grid-template-columns: 1fr; }
    .download-banner { flex-direction: column; text-align: center; padding: 3rem 1.5rem; gap: 2rem;}
    .footer-content { flex-direction: column; gap: 1rem; text-align: center; }
}