<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
    <title>Rich Core · CSS</title>

    <!-- ====== RICH CORE CSS ====== -->
    <style>
        /* ── Reset & Base ── */
        *,
        *::before,
        *::after {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }

        :root {
            --slate: #1E293B;
            --teal: #14B8A6;
            --grey: #E2E8F0;
            --white: #FFFFFF;
            --slate-light: #334155;
            --slate-dark: #0F172A;
            --teal-hover: #0D9488;
            --grey-dark: #CBD5E1;
            --shadow: 0 8px 24px rgba(30, 41, 59, 0.08);
            --radius: 12px;
            --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
            --font: 'Segoe UI', system-ui, -apple-system, sans-serif;
        }

        html {
            scroll-behavior: smooth;
        }

        body {
            font-family: var(--font);
            background: var(--white);
            color: var(--slate);
            line-height: 1.6;
            -webkit-font-smoothing: antialiased;
        }

        img {
            max-width: 100%;
            display: block;
        }

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

        ul {
            list-style: none;
        }

        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 24px;
        }

        /* ── Buttons ── */
        .btn {
            display: inline-flex;
            align-items: center;
            gap: 8px;
            padding: 12px 28px;
            border-radius: 100px;
            font-weight: 600;
            font-size: 0.95rem;
            border: none;
            cursor: pointer;
            transition: var(--transition);
            background: transparent;
        }

        .btn--primary {
            background: var(--teal);
            color: var(--white);
        }
        .btn--primary:hover {
            background: var(--teal-hover);
            transform: translateY(-2px);
            box-shadow: 0 12px 28px -8px rgba(20, 184, 166, 0.4);
        }

        .btn--outline {
            border: 2px solid var(--slate);
            color: var(--slate);
        }
        .btn--outline:hover {
            background: var(--slate);
            color: var(--white);
        }

        .btn--outline-light {
            border: 2px solid var(--white);
            color: var(--white);
        }
        .btn--outline-light:hover {
            background: var(--white);
            color: var(--slate);
        }

        /* ── Section Headings ── */
        .section__label {
            display: inline-block;
            font-size: 0.8rem;
            font-weight: 700;
            letter-spacing: 2px;
            text-transform: uppercase;
            color: var(--teal);
            margin-bottom: 12px;
        }

        .section__title {
            font-size: 2.4rem;
            font-weight: 800;
            letter-spacing: -0.02em;
            line-height: 1.2;
            color: var(--slate);
        }
        .section__title--light {
            color: var(--white);
        }

        .section__desc {
            font-size: 1.1rem;
            color: var(--slate-light);
            max-width: 560px;
            margin-top: 16px;
        }
        .section__desc--light {
            color: var(--grey);
        }

        @media (max-width: 768px) {
            .section__title {
                font-size: 1.8rem;
            }
            .section__desc {
                font-size: 1rem;
            }
        }

        /* ══════════════════════════════════════
                   NAVIGATION
                   ══════════════════════════════════════ */
        .nav {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            z-index: 1000;
            padding: 16px 0;
            transition: var(--transition);
            background: transparent;
        }

        .nav--scrolled {
            background: rgba(255, 255, 255, 0.92);
            backdrop-filter: blur(12px);
            -webkit-backdrop-filter: blur(12px);
            box-shadow: 0 4px 20px rgba(30, 41, 59, 0.06);
            padding: 10px 0;
        }

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

        /* logo */
        .nav__logo {
            font-size: 1.6rem;
            font-weight: 800;
            color: var(--white);
            letter-spacing: -0.03em;
            transition: var(--transition);
        }
        .nav__logo span {
            color: var(--teal);
        }
        .nav--scrolled .nav__logo {
            color: var(--slate);
        }

        /* desktop links */
        .nav__links {
            display: flex;
            align-items: center;
            gap: 32px;
        }

        .nav__links a {
            font-size: 0.9rem;
            font-weight: 600;
            color: rgba(255, 255, 255, 0.85);
            transition: var(--transition);
            position: relative;
            padding: 4px 0;
        }
        .nav__links a::after {
            content: '';
            position: absolute;
            bottom: -2px;
            left: 0;
            width: 0;
            height: 2px;
            background: var(--teal);
            transition: var(--transition);
        }
        .nav__links a:hover::after,
        .nav__links a.active::after {
            width: 100%;
        }
        .nav__links a:hover {
            color: var(--white);
        }

        .nav--scrolled .nav__links a {
            color: var(--slate-light);
        }
        .nav--scrolled .nav__links a:hover {
            color: var(--slate);
        }

        /* hamburger */
        .nav__hamburger {
            display: none;
            flex-direction: column;
            gap: 5px;
            cursor: pointer;
            background: none;
            border: none;
            padding: 4px;
            z-index: 1100;
        }
        .nav__hamburger span {
            display: block;
            width: 26px;
            height: 2.5px;
            background: var(--white);
            border-radius: 4px;
            transition: var(--transition);
            transform-origin: center;
        }
        .nav--scrolled .nav__hamburger span {
            background: var(--slate);
        }

        /* hamburger open state */
        .nav__hamburger.open span:nth-child(1) {
            transform: rotate(45deg) translate(5px, 5px);
        }
        .nav__hamburger.open span:nth-child(2) {
            opacity: 0;
            transform: scaleX(0);
        }
        .nav__hamburger.open span:nth-child(3) {
            transform: rotate(-45deg) translate(5px, -5px);
        }

        /* mobile menu overlay */
        .nav__mobile {
            position: fixed;
            top: 0;
            right: -100%;
            width: 300px;
            max-width: 80vw;
            height: 100vh;
            background: var(--slate);
            padding: 100px 40px 40px;
            display: flex;
            flex-direction: column;
            gap: 28px;
            transition: right 0.4s cubic-bezier(0.4, 0, 0.2, 1);
            box-shadow: -8px 0 30px rgba(0, 0, 0, 0.2);
            z-index: 1050;
        }
        .nav__mobile.open {
            right: 0;
        }

        .nav__mobile a {
            font-size: 1.3rem;
            font-weight: 700;
            color: var(--grey);
            transition: var(--transition);
            padding: 8px 0;
            border-bottom: 1px solid rgba(255, 255, 255, 0.06);
        }
        .nav__mobile a:hover {
            color: var(--teal);
            padding-left: 12px;
        }

        /* overlay backdrop */
        .nav__backdrop {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(15, 23, 42, 0.6);
            backdrop-filter: blur(4px);
            -webkit-backdrop-filter: blur(4px);
            opacity: 0;
            pointer-events: none;
            transition: var(--transition);
            z-index: 1040;
        }
        .nav__backdrop.open {
            opacity: 1;
            pointer-events: all;
        }

        /* ── responsive nav ── */
        @media (max-width: 768px) {
            .nav__links {
                display: none;
            }
            .nav__hamburger {
                display: flex;
            }
            .nav--scrolled .nav__logo {
                color: var(--slate);
            }
        }

        /* ══════════════════════════════════════
                   HERO
                   ══════════════════════════════════════ */
        .hero {
            min-height: 100vh;
            display: flex;
            align-items: center;
            background: var(--slate);
            position: relative;
            overflow: hidden;
            padding: 120px 0 80px;
        }

        .hero::before {
            content: '';
            position: absolute;
            top: -40%;
            right: -20%;
            width: 700px;
            height: 700px;
            border-radius: 50%;
            background: radial-gradient(circle, rgba(20, 184, 166, 0.15) 0%, transparent 70%);
            pointer-events: none;
        }

        .hero .container {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 60px;
            align-items: center;
            position: relative;
            z-index: 1;
        }

        .hero__content {
            max-width: 580px;
        }

        .hero__badge {
            display: inline-flex;
            align-items: center;
            gap: 8px;
            background: rgba(20, 184, 166, 0.15);
            color: var(--teal);
            padding: 6px 16px 6px 12px;
            border-radius: 100px;
            font-size: 0.8rem;
            font-weight: 600;
            margin-bottom: 24px;
            border: 1px solid rgba(20, 184, 166, 0.2);
        }
        .hero__badge::before {
            content: '';
            width: 8px;
            height: 8px;
            border-radius: 50%;
            background: var(--teal);
            display: inline-block;
            animation: pulse-dot 2s infinite;
        }

        @keyframes pulse-dot {
            0%,
            100% {
                opacity: 1;
                transform: scale(1);
            }
            50% {
                opacity: 0.5;
                transform: scale(0.8);
            }
        }

        .hero__title {
            font-size: 3.6rem;
            font-weight: 800;
            line-height: 1.1;
            letter-spacing: -0.03em;
            color: var(--white);
        }
        .hero__title span {
            color: var(--teal);
        }

        .hero__desc {
            font-size: 1.15rem;
            color: var(--grey);
            margin: 24px 0 36px;
            max-width: 480px;
            opacity: 0.85;
        }

        .hero__actions {
            display: flex;
            gap: 16px;
            flex-wrap: wrap;
        }

        .hero__visual {
            display: flex;
            justify-content: center;
            align-items: center;
        }

        .hero__card {
            background: rgba(255, 255, 255, 0.04);
            border: 1px solid rgba(255, 255, 255, 0.08);
            border-radius: 24px;
            padding: 40px 32px;
            width: 100%;
            max-width: 400px;
            backdrop-filter: blur(8px);
            box-shadow: 0 30px 60px rgba(0, 0, 0, 0.2);
        }

        .hero__card-stats {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 20px;
        }

        .hero__stat {
            text-align: center;
            padding: 16px 8px;
            border-radius: 16px;
            background: rgba(255, 255, 255, 0.04);
        }
        .hero__stat-number {
            font-size: 2rem;
            font-weight: 800;
            color: var(--teal);
        }
        .hero__stat-label {
            font-size: 0.75rem;
            color: var(--grey);
            text-transform: uppercase;
            letter-spacing: 1px;
            margin-top: 4px;
            opacity: 0.7;
        }
        .hero__card-divider {
            height: 1px;
            background: rgba(255, 255, 255, 0.06);
            margin: 20px 0;
        }
        .hero__card-footer {
            display: flex;
            align-items: center;
            gap: 12px;
            color: var(--grey);
            font-size: 0.85rem;
            opacity: 0.7;
        }
        .hero__card-footer .dot {
            width: 6px;
            height: 6px;
            border-radius: 50%;
            background: var(--teal);
        }

        @media (max-width: 900px) {
            .hero .container {
                grid-template-columns: 1fr;
                gap: 40px;
                text-align: center;
            }
            .hero__content {
                margin: 0 auto;
            }
            .hero__desc {
                margin-left: auto;
                margin-right: auto;
            }
            .hero__actions {
                justify-content: center;
            }
            .hero__title {
                font-size: 2.6rem;
            }
            .hero__card {
                max-width: 340px;
                margin: 0 auto;
            }
        }

        @media (max-width: 480px) {
            .hero__title {
                font-size: 2rem;
            }
            .hero__actions .btn {
                width: 100%;
                justify-content: center;
            }
        }

        /* ══════════════════════════════════════
                   SECTIONS (shared)
                   ══════════════════════════════════════ */
        .section {
            padding: 100px 0;
        }

        @media (max-width: 768px) {
            .section {
                padding: 60px 0;
            }
        }

        /* ── Features Section ── */
        .features {
            background: var(--white);
        }

        .features .section__title {
            text-align: center;
        }
        .features .section__desc {
            text-align: center;
            margin-left: auto;
            margin-right: auto;
        }

        .features__grid {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 32px;
            margin-top: 56px;
        }

        .feature-card {
            background: var(--white);
            border: 1px solid var(--grey);
            border-radius: var(--radius);
            padding: 36px 28px;
            transition: var(--transition);
        }
        .feature-card:hover {
            transform: translateY(-6px);
            box-shadow: var(--shadow);
            border-color: var(--teal);
        }

        .feature-card__icon {
            width: 52px;
            height: 52px;
            border-radius: 14px;
            background: rgba(20, 184, 166, 0.1);
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.6rem;
            color: var(--teal);
            margin-bottom: 20px;
        }

        .feature-card__title {
            font-size: 1.2rem;
            font-weight: 700;
            color: var(--slate);
            margin-bottom: 10px;
        }

        .feature-card__desc {
            font-size: 0.95rem;
            color: var(--slate-light);
            line-height: 1.7;
        }

        @media (max-width: 900px) {
            .features__grid {
                grid-template-columns: 1fr 1fr;
            }
        }
        @media (max-width: 560px) {
            .features__grid {
                grid-template-columns: 1fr;
            }
        }

        /* ── Stats / Showcase ── */
        .showcase {
            background: var(--grey);
        }

        .showcase__grid {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 40px;
            align-items: center;
            margin-top: 48px;
        }

        .showcase__image {
            background: var(--slate);
            border-radius: var(--radius);
            height: 340px;
            display: flex;
            align-items: center;
            justify-content: center;
            color: var(--grey);
            font-weight: 600;
            font-size: 1.1rem;
            background-image: radial-gradient(circle at 30% 40%, rgba(20, 184, 166, 0.2) 0%, transparent 60%);
            border: 1px solid var(--grey-dark);
        }

        .showcase__list {
            display: flex;
            flex-direction: column;
            gap: 24px;
        }

        .showcase__item {
            display: flex;
            gap: 16px;
            align-items: flex-start;
        }
        .showcase__item-icon {
            flex-shrink: 0;
            width: 28px;
            height: 28px;
            border-radius: 50%;
            background: var(--teal);
            color: var(--white);
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 0.8rem;
            font-weight: 700;
            margin-top: 2px;
        }
        .showcase__item-title {
            font-weight: 700;
            font-size: 1.05rem;
            color: var(--slate);
        }
        .showcase__item-desc {
            font-size: 0.9rem;
            color: var(--slate-light);
            margin-top: 4px;
        }

        @media (max-width: 768px) {
            .showcase__grid {
                grid-template-columns: 1fr;
            }
            .showcase__image {
                height: 220px;
            }
        }

        /* ── CTA Section ── */
        .cta {
            background: var(--slate);
            text-align: center;
        }

        .cta .container {
            max-width: 700px;
        }

        .cta .section__desc {
            margin-left: auto;
            margin-right: auto;
        }

        .cta__actions {
            display: flex;
            gap: 16px;
            justify-content: center;
            flex-wrap: wrap;
            margin-top: 36px;
        }

        /* ── Footer ── */
        .footer {
            background: var(--slate-dark);
            padding: 40px 0;
            border-top: 1px solid rgba(255, 255, 255, 0.04);
        }

        .footer .container {
            display: flex;
            align-items: center;
            justify-content: space-between;
            flex-wrap: wrap;
            gap: 16px;
        }

        .footer__copy {
            font-size: 0.85rem;
            color: var(--grey);
            opacity: 0.6;
        }

        .footer__links {
            display: flex;
            gap: 24px;
        }
        .footer__links a {
            font-size: 0.85rem;
            color: var(--grey);
            opacity: 0.6;
            transition: var(--transition);
        }
        .footer__links a:hover {
            opacity: 1;
            color: var(--teal);
        }

        @media (max-width: 480px) {
            .footer .container {
                flex-direction: column;
                text-align: center;
            }
        }

        /* ── Utility ── */
        .text-teal {
            color: var(--teal);
        }
        .text-slate {
            color: var(--slate);
        }
        .bg-grey {
            background: var(--grey);
        }
        .bg-slate {
            background: var(--slate);
        }
        .bg-white {
            background: var(--white);
        }
    </style>
</head>

<body>

    <!-- ═══════════ NAVIGATION ═══════════ -->
    <nav class="nav" id="navbar">
        <div class="container">
            <a href="#" class="nav__logo">rich<span>core</span></a>

            <ul class="nav__links">
                <li><a href="#hero" class="active">Home</a></li>
                <li><a href="#features">Features</a></li>
                <li><a href="#showcase">Showcase</a></li>
                <li><a href="#cta">Get Started</a></li>
            </ul>

            <button class="nav__hamburger" id="hamburger" aria-label="Menu">
                <span></span>
                <span></span>
                <span></span>
            </button>
        </div>
    </nav>

    <!-- mobile menu -->
    <div class="nav__mobile" id="mobileMenu">
        <a href="#hero">Home</a>
        <a href="#features">Features</a>
        <a href="#showcase">Showcase</a>
        <a href="#cta">Get Started</a>
    </div>
    <div class="nav__backdrop" id="backdrop"></div>

    <!-- ═══════════ HERO ═══════════ -->
    <section class="hero" id="hero">
        <div class="container">
            <div class="hero__content">
                <div class="hero__badge">Now in public beta</div>
                <h1 class="hero__title">
                    Build with<br /><span>Rich Core</span>
                </h1>
                <p class="hero__desc">
                    A modern design system anchored in slate, teal, and grey.
                    Purpose‑built for clarity, speed, and beautiful interfaces.
                </p>
                <div class="hero__actions">
                    <button class="btn btn--primary">Get started</button>
                    <button class="btn btn--outline-light">View demo</button>
                </div>
            </div>

            <div class="hero__visual">
                <div class="hero__card">
                    <div class="hero__card-stats">
                        <div class="hero__stat">
                            <div class="hero__stat-number">98%</div>
                            <div class="hero__stat-label">Uptime</div>
                        </div>
                        <div class="hero__stat">
                            <div class="hero__stat-number">12k</div>
                            <div class="hero__stat-label">Stars</div>
                        </div>
                        <div class="hero__stat">
                            <div class="hero__stat-number">4.9</div>
                            <div class="hero__stat-label">Rating</div>
                        </div>
                        <div class="hero__stat">
                            <div class="hero__stat-number">2s</div>
                            <div class="hero__stat-label">Deploy</div>
                        </div>
                    </div>
                    <div class="hero__card-divider"></div>
                    <div class="hero__card-footer">
                        <span class="dot"></span>
                        <span>Live on 3 continents</span>
                        <span style="margin-left:auto;">&rarr;</span>
                    </div>
                </div>
            </div>
        </div>
    </section>

    <!-- ═══════════ FEATURES ═══════════ -->
    <section class="section features" id="features">
        <div class="container">
            <span class="section__label">Features</span>
            <h2 class="section__title">Everything you need</h2>
            <p class="section__desc">
                From utility classes to full‑bleed sections — Rich Core gives you
                a cohesive, on‑brand foundation.
            </p>

            <div class="features__grid">
                <div class="feature-card">
                    <div class="feature-card__icon">⚡</div>
                    <h3 class="feature-card__title">Lightning fast</h3>
                    <p class="feature-card__desc">
                        Optimised for performance. Zero runtime overhead and
                        instant layout shifts are a thing of the past.
                    </p>
                </div>
                <div class="feature-card">
                    <div class="feature-card__icon">🎨</div>
                    <h3 class="feature-card__title">Teal · Slate · Grey</h3>
                    <p class="feature-card__desc">
                        A restrained, elegant palette that works across
                        marketing sites, dashboards, and beyond.
                    </p>
                </div>
                <div class="feature-card">
                    <div class="feature-card__icon">📱</div>
                    <h3 class="feature-card__title">Responsive by default</h3>
                    <p class="feature-card__desc">
                        Every component adapts from 360px to 2560px.
                        No breakpoint hassle — just one fluid system.
                    </p>
                </div>
            </div>
        </div>
    </section>

    <!-- ═══════════ SHOWCASE ═══════════ -->
    <section class="section showcase" id="showcase">
        <div class="container">
            <span class="section__label">Showcase</span>
            <h2 class="section__title">Designed for impact</h2>
            <p class="section__desc">
                Real‑world patterns that put your content first.
            </p>

            <div class="showcase__grid">
                <div class="showcase__image">
                    <span style="opacity:0.5;">▲ preview</span>
                </div>
                <div class="showcase__list">
                    <div class="showcase__item">
                        <div class="showcase__item-icon">✓</div>
                        <div>
                            <div class="showcase__item-title">Hero with live stats</div>
                            <div class="showcase__item-desc">Engage visitors with real‑time data cards.</div>
                        </div>
                    </div>
                    <div class="showcase__item">
                        <div class="showcase__item-icon">✓</div>
                        <div>
                            <div class="showcase__item-title">Hamburger + overlay nav</div>
                            <div class="showcase__item-desc">Smooth mobile menu with backdrop blur.</div>
                        </div>
                    </div>
                    <div class="showcase__item">
                        <div class="showcase__item-icon">✓</div>
                        <div>
                            <div class="showcase__item-title">3‑column feature grid</div>
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