/* ==========================================================================
   CSS Variables
   ========================================================================== */
   :root {
    /* Colors */
    --primary-color: #9333ea;      /* Purple 600 */
    --primary-hover: #7e22ce;      /* Purple 700 */
    --bg-color: #f8fafc;           /* Slate 50 */
    --surface-color: #ffffff;
    --text-main: #0f172a;          /* Slate 900 */
    --text-muted: #64748b;         /* Slate 500 */
    --border-color: #e2e8f0;       /* Slate 200 */
    --success-color: #10b981;      /* Emerald 500 */
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    
    /* Spacing & Layout */
    --container-max: 1200px;
    --section-padding: 5rem 0;
    
    /* Effects */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    --radius-full: 9999px;
    --transition: all 0.3s ease;
}

/* ==========================================================================
   Reset & Base Styles
   ========================================================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    color: var(--text-main);
    background-color: var(--bg-color);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

a {
    text-decoration: none;
    color: inherit;
}

.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 1.5rem;
}

h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    color: var(--text-main);
}

p {
    color: var(--text-muted);
}

/* ==========================================================================
   Buttons
   ========================================================================== */
.btn-primary, .btn-primary-sm, .btn-secondary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-weight: 500;
    border-radius: var(--radius-full);
    transition: var(--transition);
    cursor: pointer;
    border: none;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
    padding: 0.875rem 2rem;
    font-size: 1rem;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    background-color: var(--primary-hover);
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

.btn-primary-sm {
    background-color: var(--primary-color);
    color: white;
    padding: 0.5rem 1.25rem;
    font-size: 0.875rem;
}

.btn-primary-sm:hover {
    background-color: var(--primary-hover);
}

.btn-secondary {
    background-color: var(--surface-color);
    color: var(--text-main);
    padding: 0.875rem 2rem;
    font-size: 1rem;
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: var(--bg-color);
    border-color: #cbd5e1;
}

/* ==========================================================================
   Navigation
   ========================================================================== */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 4rem;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.25rem;
    font-weight: 800;
    color: var(--primary-color);
}

.logo i {
    font-size: 1.75rem;
}

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

.nav-links a:not(.btn-primary-sm) {
    font-weight: 500;
    color: var(--text-muted);
    transition: var(--transition);
}

.nav-links a:not(.btn-primary-sm):hover {
    color: var(--primary-color);
}

/* ==========================================================================
   Hero Section
   ========================================================================== */
.hero {
    padding: 8rem 0 5rem;
    background: linear-gradient(135deg, #f8fafc 0%, #faf5ff 100%);
    overflow: hidden;
}

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

.hero-content {
    flex: 1;
}

.hero-title {
    font-size: 3.5rem;
    margin-bottom: 1.5rem;
    letter-spacing: -0.02em;
}

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

.hero-subtitle {
    font-size: 1.25rem;
    margin-bottom: 2.5rem;
    max-width: 480px;
}

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

.hero-image {
    flex: 1;
    display: flex;
    justify-content: center;
    position: relative;
}

/* Hero Demo Image */
.hero-demo-img {
    width: 100%;
    max-width: 600px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
    display: block;
}

.ui-header {
    height: 3rem;
    background: #f1f5f9;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    padding: 0 1rem;
}

.ui-header::before {
    content: '';
    display: block;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: #ef4444;
    box-shadow: 20px 0 0 #f59e0b, 40px 0 0 #10b981;
}

.ui-body {
    display: flex;
    flex: 1;
}

.ui-sidebar {
    width: 25%;
    background: #f8fafc;
    border-right: 1px solid var(--border-color);
}

.ui-main {
    flex: 1;
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.ui-chat-bubble {
    padding: 0.75rem 1rem;
    border-radius: var(--radius-lg);
    font-size: 0.875rem;
    max-width: 85%;
}

.ui-chat-bubble.ai {
    background: #faf5ff;
    color: #6b21a8;
    align-self: flex-start;
    border-bottom-left-radius: 0;
}

.ui-chat-bubble.user {
    background: var(--primary-color);
    color: white;
    align-self: flex-end;
    border-bottom-right-radius: 0;
}

/* ==========================================================================
   Features Section
   ========================================================================== */
.features {
    padding: var(--section-padding);
    background-color: var(--surface-color);
    text-align: center;
}

.section-title {
    font-size: 2.25rem;
    margin-bottom: 1rem;
}

.section-subtitle {
    font-size: 1.125rem;
    max-width: 600px;
    margin: 0 auto 4rem;
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    text-align: left;
}

.feature-card {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 2rem;
    transition: var(--transition);
}

.feature-card:hover {
    box-shadow: var(--shadow-md);
    border-color: #cbd5e1;
    transform: translateY(-5px);
}

.feature-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 3.5rem;
    height: 3.5rem;
    border-radius: 1rem;
    background: #faf5ff;
    color: var(--primary-color);
    font-size: 1.75rem;
    margin-bottom: 1.5rem;
}

.feature-title {
    font-size: 1.25rem;
    margin-bottom: 0.75rem;
}

.feature-desc {
    font-size: 0.95rem;
}

/* ==========================================================================
   Registration Section
   ========================================================================== */
.registration {
    padding: var(--section-padding);
    background-color: var(--text-main);
    color: white;
    text-align: center;
}

.registration-content h2 {
    color: white;
    font-size: 2.25rem;
    margin-bottom: 1rem;
}

.registration-content p {
    color: #94a3b8;
    margin-bottom: 2.5rem;
    font-size: 1.125rem;
}

.registration-form {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    max-width: 500px;
    margin: 0 auto;
}

.input-group {
    position: relative;
    flex: 1;
}

.input-group i {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
    font-size: 1.25rem;
}

.input-group input {
    width: 100%;
    padding: 0.875rem 1rem 0.875rem 3rem;
    border: 1px solid transparent;
    border-radius: var(--radius-full);
    font-size: 1rem;
    font-family: var(--font-family);
    transition: var(--transition);
    outline: none;
}

.input-group input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(147, 51, 234, 0.3);
}

.form-message {
    margin-top: 1.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    color: var(--success-color);
    font-weight: 500;
}

.form-message.hidden {
    display: none;
}

/* ==========================================================================
   Footer
   ========================================================================== */
.footer {
    background-color: #020617; /* Slate 950 */
    color: #64748b;
    padding: 3rem 0;
}

.footer-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1.5rem;
}

.footer-brand .logo {
    color: white;
    margin-bottom: 0.5rem;
}

.footer-links {
    display: flex;
    gap: 1.5rem;
}

.footer-links a:hover {
    color: white;
}

/* ==========================================================================
   Responsive Design
   ========================================================================== */
@media (max-width: 768px) {
    .hero-container {
        flex-direction: column;
        text-align: center;
        gap: 2rem;
    }

    .hero-title {
        font-size: 2.5rem;
    }

    .hero-subtitle {
        margin: 0 auto 2rem;
    }

    .hero-actions {
        justify-content: center;
    }

    .registration-form {
        flex-direction: column;
    }

    .registration-form button {
        width: 100%;
    }

    .nav-links {
        display: none; /* simple mobile nav handling */
    }
}