```css
/* ===== Base Reset ===== */

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

/* ===== Body ===== */

body {
    background: #FFFFFF;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
    color: #2B2F33;
    line-height: 1.6;
    position: relative;
}

/* ===== Bottom Architectural Render ===== */

body::after {
    content: "";
    position: fixed;
    bottom: 0;
    right: 0;
    width: 60%;
    height: 60%;
    background: url('AIVA-background-bottom.webp') no-repeat bottom right;
    background-size: contain;
    opacity: 0.99;
    pointer-events: none;
    z-index: 0;
}

/* ===== Ensure Content Above Background ===== */

section,
.container {
    position: relative;
    z-index: 1;
}

/* ===== Container ===== */

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 40px;
}

/* ===== Header ===== */

header {
    width: 100%;
    background: #FFFFFF;
    border-bottom: 1px solid #E6EAEE;
    position: relative;
    z-index: 1000000;
}

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

/* ===== Navigation ===== */

.main-nav {
    display: flex;
    align-items: center;
    gap: 28px;
}

.main-nav a {
    text-decoration: none;
    color: #2B2F33;
    font-size: 16px;
}

.main-nav a:hover {
    text-decoration: underline;
}

/* ===== CTA Button ===== */

.cta-button {
    background: #C6A85A;
    color: #FFFFFF;
    text-decoration: none;
    padding: 12px 26px;
    font-size: 14px;
    letter-spacing: 1px;
    border-radius: 9px;
    transition: background 0.3s ease;
}

.cta-button:hover {
    background: #B39349;
}

/* ===== Mobile Toggle Hidden on Desktop ===== */

#menu-toggle {
    display: none;
}

.menu-icon {
    display: none;
    font-size: 28px;
    cursor: pointer;
}

/* ===== Hero Section ===== */

.hero {
    position: relative;
    padding: 100px 0 120px 0;
    overflow: hidden;
}

/* ===== Top Blueprint Overlay ===== */

.hero::before {
    content: "";
    position: absolute;
    top: 0;
    right: 0;
    width: 65%;
    height: 100%;
    background: url('AIVA-background-top.webp') no-repeat top right;
    background-size: contain;
    opacity: 0.81;
    pointer-events: none;
    z-index: 0;
}

.hero-grid {
    display: flex;
    justify-content: space-between;
    gap: 60px;
    position: relative;
    z-index: 1;
}

.hero-left {
    flex: 1;
}

.hero-left h1 {
    font-family: Georgia, "Times New Roman", serif;
    font-size: 52px;
    font-weight: normal;
    margin-bottom: 30px;
    line-height: 1.2;
}

.hero-left p {
    font-size: 18px;
    max-width: 500px;
}

/* ===== AI Card ===== */

.ai-card {
    flex: 1;
    background: #FFFFFF;
    padding: 30px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.05);
    border-radius: 6px;
    font-size: 14px;
}

/* ===== Section ===== */

.section {
    padding: 9px 0;
}

.section h2 {
    font-family: Georgia, "Times New Roman", serif;
    font-size: 34px;
    margin-bottom: 40px;
}

/* ===== LLM Boxes ===== */

.llm-grid {
    display: flex;
    gap: 30px;
}

.llm-box {
    flex: 1;
    background: #FFFFFF;
    padding: 30px;
    border: 1px solid #E2E6EA;
    border-radius: 6px;
    font-size: 15px;
}

/* ===== What We Do ===== */

.what-we-do {
    text-align: center;
    font-size: 20px;
}

.what-we-do span {
    display: block;
    margin-bottom: 12px;
}

/* ===== Footer ===== */

footer {
    background: #FFFFFF;
    padding: 60px 0;
    border-top: 1px solid #E2E6EA;
    font-size: 14px;
}

.footer-inner {
    max-width: 1200px;
    margin: 0 auto;
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 40px;
}

.footer-col strong {
    display: block;
    margin-bottom: 12px;
}

.footer-col a {
    display: block;
    color: #2B2F33;
    text-decoration: none;
    margin-bottom: 8px;
}

.footer-col a:hover {
    text-decoration: underline;
}

/* ===== Mobile Navigation ===== */

@media (max-width: 768px) {

    .menu-icon {
        display: block;
    }

    .main-nav {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 70px;
        right: 20px;
        width: 240px;
        background: #FFFFFF;
        padding: 20px;
        border: 1px solid #E6EAEE;
        box-shadow: 0 10px 25px rgba(0,0,0,0.08);
        z-index: 999999;
    }

    #menu-toggle:checked + .menu-icon + .main-nav {
        display: flex;
    }

    .main-nav a {
        display: block;
        padding: 16px 0;
        font-size: 19px;
        color: #000000;
        font-weight: 500;
    }

}
```