:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary: #64748b;
    --dark: #0f172a;
    --light: #f8fafc;
    --accent: #38bdf8;
    --card-bg: rgba(255, 255, 255, 0.8);
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.1);
    --shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

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

body {
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    color: var(--dark);
    background-color: var(--light);
    overflow-x: hidden;
}

h1, h2, h3 {
    font-family: 'Outfit', sans-serif;
    font-weight: 700;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Header & Nav */
header {
    background: rgba(248, 250, 252, 0.8);
    backdrop-filter: blur(10px);
    position: sticky;
    top: 0;
    z-index: 1000;
    border-bottom: 1px solid rgba(0,0,0,0.05);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.8rem;
    font-weight: 900;
    font-family: 'Outfit', sans-serif;
    color: var(--dark);
}

.logo-icon {
    width: 40px;
    height: 40px;
    background: var(--primary);
    color: white;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.4rem;
    font-weight: 800;
}

.logo span {
    color: var(--primary);
}

nav ul {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
}

nav a {
    text-decoration: none;
    color: var(--secondary);
    font-weight: 600;
    transition: color 0.3s;
}

nav a:hover {
    color: var(--primary);
}

/* Hero Section */
.hero {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 6rem 10% 8rem;
    background: radial-gradient(circle at top right, #e0f2fe, transparent),
                radial-gradient(circle at bottom left, #dbeafe, transparent);
    min-height: 80vh;
}

.hero-content {
    max-width: 600px;
}

.hero h1 {
    font-size: 4rem;
    line-height: 1.1;
    margin-bottom: 1.5rem;
    color: var(--dark);
}

.hero h1 span {
    background: linear-gradient(90deg, var(--primary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero p {
    font-size: 1.25rem;
    color: var(--secondary);
    margin-bottom: 2.5rem;
}

.hero-btns {
    display: flex;
    gap: 1.5rem;
}

.btn-primary {
    background: var(--primary);
    color: white;
    padding: 0.8rem 1.8rem;
    border-radius: 99px;
    text-decoration: none;
    font-weight: 600;
    transition: transform 0.3s, box-shadow 0.3s;
    display: inline-block;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(37, 99, 235, 0.2);
}

.btn-secondary {
    background: white;
    color: var(--dark);
    padding: 0.8rem 1.8rem;
    border-radius: 99px;
    text-decoration: none;
    font-weight: 600;
    border: 1px solid #e2e8f0;
    transition: all 0.3s;
}

.btn-secondary:hover {
    background: #f1f5f9;
}

.large {
    padding: 1.2rem 2.5rem;
    font-size: 1.1rem;
}

/* Features Section */
.features {
    padding: 8rem 0;
}

.section-header {
    text-align: center;
    max-width: 700px;
    margin: 0 auto 5rem;
}

.section-header h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.card {
    background: white;
    padding: 3rem 2rem;
    border-radius: 24px;
    border: 1px solid #e2e8f0;
    transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover {
    transform: translateY(-10px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.05);
}

.icon {
    font-size: 3rem;
    margin-bottom: 1.5rem;
}

/* Socratic Section */
.socratic {
    padding: 8rem 0;
    background: var(--dark);
    color: white;
    overflow: hidden;
}

.flex-row {
    display: flex;
    align-items: center;
    gap: 4rem;
}

.socratic-visual {
    flex: 1;
}

.chat-example {
    background: rgba(255, 255, 255, 0.05);
    padding: 2rem;
    border-radius: 24px;
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 30px 60px rgba(0,0,0,0.5);
}

.msg {
    padding: 1rem 1.5rem;
    border-radius: 18px;
    margin-bottom: 1.5rem;
    max-width: 85%;
    font-size: 0.95rem;
}

.msg.bot {
    background: var(--primary);
    color: white;
    border-bottom-left-radius: 4px;
}

.msg.user {
    background: rgba(255, 255, 255, 0.1);
    margin-left: auto;
    border-bottom-right-radius: 4px;
    text-align: right;
}

.socratic-content {
    flex: 1;
}

.socratic-content h2 {
    font-size: 3rem;
    margin-bottom: 1.5rem;
}

.socratic-content ul {
    list-style: none;
    margin-top: 2rem;
}

.socratic-content li {
    margin-bottom: 1rem;
    font-size: 1.1rem;
}

/* Subject Grid */
.subjects {
    padding: 8rem 0;
}

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

.subject-card {
    background: white;
    padding: 3rem;
    border-radius: 24px;
    border: 1px solid #e2e8f0;
}

.subject-card h3 {
    font-size: 1.8rem;
    margin-bottom: 1.5rem;
    color: var(--primary);
}

.subject-card ul {
    list-style: none;
}

.subject-card li {
    padding: 0.8rem 0;
    border-bottom: 1px solid #f1f5f9;
}

.subject-card li:last-child {
    border-bottom: none;
}

/* Footer */
footer {
    background: #f8fafc;
    padding: 5rem 0 2rem;
    border-top: 1px solid #e2e8f0;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 4rem;
    margin-bottom: 4rem;
}

.footer-brand p {
    color: var(--secondary);
    margin-top: 1rem;
    max-width: 300px;
}

.footer-links h4 {
    margin-bottom: 1.5rem;
}

.footer-links ul {
    list-style: none;
}

.footer-links li {
    margin-bottom: 0.8rem;
}

.footer-links a {
    text-decoration: none;
    color: var(--secondary);
    transition: color 0.3s;
}

.footer-links a:hover {
    color: var(--primary);
}

.footer-bottom {
    text-align: center;
    border-top: 1px solid #e2e8f0;
    padding-top: 2rem;
    color: var(--secondary);
    font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 968px) {
    .hero {
        flex-direction: column;
        text-align: center;
        padding-top: 4rem;
    }
    .hero h1 { font-size: 3rem; }
    .hero-btns { justify-content: center; }
    .grid, .grid-2 { grid-template-columns: 1fr; }
    .flex-row { flex-direction: column; }
    .footer-grid { grid-template-columns: 1fr; text-align: center; }
    .footer-brand p { margin: 1rem auto; }
}