/* ==========================================================================
   Pred-D Systems — Design System & Shared Styles
   Based on UX/UI Specification v1
   ========================================================================== */

/* ---------- Design Tokens ---------- */
:root {
    --bg-main:            #0B1016;
    --bg-surface:         #101923;
    --bg-elevated:        #172330;
    --accent-blue:        #4392D0;
    --accent-blue-bright: #66B5F0;
    --text-primary:       #F0F0F0;
    --text-secondary:     #B1BCC9;
    --text-muted:         #96A6B7;
    --border-subtle:      #2D3B4B;
    --success:            #62C58A;
    --warning:            #F0B45B;
    --white:              #ffffff;

    --font-stack: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    --max-width: 1180px;
    --header-height: 80px;
    --header-height-compact: 64px;
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-pill: 100px;
}

/* ---------- Reset ---------- */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }

@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
}

body {
    font-family: var(--font-stack);
    font-size: 17px;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-main);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img { max-width: 100%; height: auto; display: block; }
a { color: var(--accent-blue); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--accent-blue-bright); }

/* Focus-visible for keyboard users */
:focus-visible {
    outline: 2px solid var(--accent-blue-bright);
    outline-offset: 3px;
}
:focus:not(:focus-visible) { outline: none; }

/* Scroll offset for anchors under sticky header */
[id] { scroll-margin-top: calc(var(--header-height) + 24px); }

/* ---------- Layout ---------- */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

.section {
    padding: 96px 0;
}
.section--surface { background-color: var(--bg-surface); }
.section--main    { background-color: var(--bg-main); }
.section--elevated { background-color: var(--bg-elevated); }

/* ---------- Typography ---------- */
.display {
    font-size: clamp(2.25rem, 5vw, 4rem);
    font-weight: 700;
    line-height: 1.08;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}
h1 { font-size: clamp(2rem, 4.5vw, 3.5rem); font-weight: 700; line-height: 1.1; letter-spacing: -0.01em; }
h2 { font-size: clamp(1.75rem, 3.5vw, 2.75rem); font-weight: 700; line-height: 1.15; color: var(--text-primary); }
h3 { font-size: clamp(1.25rem, 2vw, 1.625rem); font-weight: 600; line-height: 1.3; color: var(--text-primary); }
h4 { font-size: 1.125rem; font-weight: 600; line-height: 1.4; color: var(--text-primary); }

.eyebrow {
    display: inline-block;
    font-size: 0.85rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1.5px;
    color: var(--accent-blue);
    margin-bottom: 12px;
}

.section-heading {
    text-align: center;
    margin-bottom: 16px;
}

.section-intro {
    text-align: center;
    font-size: 1.125rem;
    color: var(--text-secondary);
    max-width: 720px;
    margin: 0 auto 56px;
    line-height: 1.7;
}

/* ---------- Header / Navigation ---------- */
.site-header {
    position: sticky;
    top: 0;
    z-index: 200;
    background-color: var(--bg-main);
    border-bottom: 1px solid var(--border-subtle);
    height: var(--header-height);
    display: flex;
    align-items: center;
}

.site-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
}

.site-header__logo img {
    height: 52px;
    width: auto;
}

.site-nav { display: flex; align-items: center; gap: 8px; }
.site-nav__links { list-style: none; display: flex; gap: 28px; align-items: center; }
.site-nav__links a {
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    transition: color 0.2s;
}
.site-nav__links a:hover,
.site-nav__links a[aria-current="page"] {
    color: var(--text-primary);
}
.site-nav__contact {
    color: var(--text-secondary) !important;
    font-weight: 500;
    font-size: 0.95rem;
    margin-left: 8px;
}
.site-nav__contact:hover { color: var(--text-primary) !important; }

/* ---------- Buttons ---------- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 28px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.95rem;
    font-family: var(--font-stack);
    cursor: pointer;
    transition: background-color 0.2s, color 0.2s, border-color 0.2s, box-shadow 0.2s;
    text-decoration: none;
    border: 2px solid transparent;
    line-height: 1.4;
    min-height: 44px;
    min-width: 44px;
}

.btn--primary {
    background-color: var(--accent-blue);
    color: var(--bg-main);
    border-color: var(--accent-blue);
}
.btn--primary:hover {
    background-color: var(--accent-blue-bright);
    border-color: var(--accent-blue-bright);
    color: var(--bg-main);
}
.btn--primary:active { opacity: 0.85; }

.btn--secondary {
    background-color: transparent;
    color: var(--accent-blue);
    border-color: var(--accent-blue);
}
.btn--secondary:hover {
    background-color: var(--accent-blue);
    color: var(--bg-main);
}

.btn--ghost {
    background-color: transparent;
    color: var(--text-secondary);
    border-color: var(--border-subtle);
}
.btn--ghost:hover {
    border-color: var(--text-secondary);
    color: var(--text-primary);
}

.btn-group { display: flex; flex-wrap: wrap; gap: 12px; }

/* ---------- Hero ---------- */
.hero {
    padding: 80px 0 96px;
    position: relative;
    overflow: hidden;
}
.hero::after {
    content: '';
    position: absolute;
    top: -40%;
    right: -15%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(67,146,208,0.06) 0%, transparent 70%);
    pointer-events: none;
}

.hero__inner {
    display: flex;
    align-items: center;
    gap: 56px;
    position: relative;
    z-index: 1;
}

.hero__text { flex: 1 1 55%; }
.hero__text h1 { margin-bottom: 20px; }
.hero__text p {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: 32px;
    max-width: 540px;
    line-height: 1.7;
}

.hero__visual {
    flex: 1 1 40%;
    text-align: center;
}
.hero__visual img {
    border-radius: var(--radius-md);
    border: 1px solid var(--border-subtle);
    box-shadow: 0 24px 48px rgba(0,0,0,0.4);
}

/* Page-level hero (inner pages) */
.page-hero {
    padding: 64px 0 48px;
    border-bottom: 1px solid var(--border-subtle);
}
.page-hero h1 { margin-bottom: 12px; }
.page-hero p {
    font-size: 1.15rem;
    color: var(--text-secondary);
    max-width: 640px;
    line-height: 1.7;
}

/* ---------- Proof Strip ---------- */
.proof-strip {
    padding: 56px 0;
    background-color: var(--bg-surface);
    border-top: 1px solid var(--border-subtle);
    border-bottom: 1px solid var(--border-subtle);
}
.proof-strip__grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 32px;
}
.proof-item {
    padding: 24px;
    border-left: 3px solid var(--accent-blue);
}
.proof-item__label {
    font-size: 0.78rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 8px;
}
.proof-item__label--published   { color: var(--accent-blue); }
.proof-item__label--tested      { color: var(--success); }
.proof-item__label--milestone   { color: var(--warning); }
.proof-item__label--inprogress  { color: var(--text-muted); }
.proof-item__title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 6px;
}
.proof-item__context {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

/* ---------- Problem / Consequence Cards ---------- */
.problem-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 24px;
}
.problem-card {
    padding: 32px 24px;
    background: var(--bg-surface);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
}
.problem-card h3 { margin-bottom: 12px; font-size: 1.15rem; }
.problem-card p  { color: var(--text-secondary); font-size: 0.95rem; }

/* ---------- Solution Flow ---------- */
.solution-flow {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    position: relative;
}
.solution-flow::before {
    content: '';
    position: absolute;
    top: 40px;
    left: 10%;
    right: 10%;
    height: 2px;
    background: var(--border-subtle);
    z-index: 0;
}
.flow-step {
    text-align: center;
    position: relative;
    z-index: 1;
}
.flow-step__number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: var(--bg-elevated);
    border: 2px solid var(--accent-blue);
    color: var(--accent-blue);
    font-weight: 700;
    font-size: 1.25rem;
    margin-bottom: 16px;
}
.flow-step h4 { margin-bottom: 8px; }
.flow-step p  { font-size: 0.9rem; color: var(--text-secondary); }

/* ---------- Cards (generic) ---------- */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 32px;
}

.card {
    background: var(--bg-surface);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    padding: 36px 28px;
    transition: border-color 0.2s, transform 0.2s;
}
.card:hover {
    border-color: var(--accent-blue);
}
@media (prefers-reduced-motion: no-preference) {
    .card:hover { transform: translateY(-3px); }
}

.card__img {
    width: 100%;
    aspect-ratio: 16 / 10;
    object-fit: cover;
    border-radius: var(--radius-sm);
    margin-bottom: 20px;
    border: 1px solid var(--border-subtle);
    opacity: 0.85;
}
.card h3 { margin-bottom: 10px; }
.card p  { color: var(--text-secondary); font-size: 0.95rem; line-height: 1.6; }
.card__link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    margin-top: 16px;
    font-weight: 600;
    font-size: 0.9rem;
}

/* ---------- Evidence Card ---------- */
.evidence-card {
    background: var(--bg-surface);
    border: 1px solid var(--border-subtle);
    border-left: 5px solid var(--accent-blue);
    border-radius: var(--radius-md);
    padding: 40px 36px;
}
.evidence-card h3 { margin-bottom: 12px; line-height: 1.35; }
.evidence-card p  { color: var(--text-secondary); margin-bottom: 10px; font-size: 1rem; line-height: 1.65; }

/* ---------- Status Labels / Badges ---------- */
.badge {
    display: inline-block;
    padding: 4px 14px;
    border-radius: var(--radius-pill);
    font-size: 0.78rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.8px;
    margin-bottom: 14px;
}
.badge--published  { background: rgba(67,146,208,0.12); color: var(--accent-blue); border: 1px solid rgba(67,146,208,0.25); }
.badge--reviewed   { background: rgba(67,146,208,0.12); color: var(--accent-blue); border: 1px solid rgba(67,146,208,0.25); }
.badge--tested     { background: rgba(98,197,138,0.12); color: var(--success); border: 1px solid rgba(98,197,138,0.25); }
.badge--milestone  { background: rgba(240,180,91,0.12); color: var(--warning); border: 1px solid rgba(240,180,91,0.25); }
.badge--inprogress { background: rgba(116,116,116,0.12); color: var(--text-muted); border: 1px solid rgba(116,116,116,0.25); }

/* ---------- Split Layout ---------- */
.split {
    display: flex;
    align-items: center;
    gap: 56px;
}
.split--reverse { flex-direction: row-reverse; }
.split__content { flex: 1 1 55%; }
.split__visual  { flex: 1 1 40%; }
.split__visual img {
    border-radius: var(--radius-md);
    border: 1px solid var(--border-subtle);
    box-shadow: 0 16px 32px rgba(0,0,0,0.3);
}

.split__content h3 { margin-bottom: 16px; }
.split__content p  { color: var(--text-secondary); margin-bottom: 20px; font-size: 1.05rem; line-height: 1.65; }

/* ---------- Feature List (checkmarks) ---------- */
.feature-list { list-style: none; }
.feature-list li {
    padding: 10px 0 10px 32px;
    position: relative;
    color: var(--text-secondary);
    font-size: 1rem;
    border-bottom: 1px solid var(--border-subtle);
}
.feature-list li:last-child { border-bottom: none; }
.feature-list li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--accent-blue);
    font-weight: 700;
}

/* ---------- Capability Modules ---------- */
.capability-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 28px;
}
.capability {
    padding: 32px 24px;
    background: var(--bg-elevated);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
}
.capability__label {
    font-size: 0.78rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--accent-blue);
    font-weight: 700;
    margin-bottom: 12px;
}
.capability h3 { margin-bottom: 10px; font-size: 1.15rem; }
.capability p  { font-size: 0.93rem; color: var(--text-secondary); line-height: 1.6; margin-bottom: 8px; }
.capability__constraint {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-style: italic;
    margin-top: 8px;
}

/* ---------- Workflow / Timeline ---------- */
.workflow {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
    gap: 12px;
    counter-reset: step;
}
.workflow__step {
    text-align: center;
    padding: 28px 16px;
    background: var(--bg-elevated);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    position: relative;
}
.workflow__step::before {
    counter-increment: step;
    content: counter(step);
    display: block;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-blue);
    margin-bottom: 10px;
}
.workflow__step h4 { font-size: 1rem; margin-bottom: 6px; }
.workflow__step p  { font-size: 0.85rem; color: var(--text-secondary); }

/* ---------- FAQ Accordion ---------- */
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item {
    border-bottom: 1px solid var(--border-subtle);
}
.faq-item summary {
    padding: 20px 0;
    cursor: pointer;
    font-weight: 600;
    font-size: 1.05rem;
    color: var(--text-primary);
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
    min-height: 44px;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
    content: "+";
    font-size: 1.4rem;
    color: var(--accent-blue);
    transition: transform 0.2s;
    flex-shrink: 0;
    margin-left: 16px;
}
.faq-item[open] summary::after {
    content: "−";
}
.faq-item__answer {
    padding: 0 0 24px;
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.7;
    max-width: 680px;
}

/* ---------- Conversion Band ---------- */
.conversion-band {
    padding: 72px 0;
    text-align: center;
    background: var(--bg-surface);
    border-top: 1px solid var(--border-subtle);
    border-bottom: 1px solid var(--border-subtle);
}
.conversion-band h2 { margin-bottom: 16px; }
.conversion-band p {
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: 32px;
    max-width: 560px;
    margin-left: auto;
    margin-right: auto;
}
.conversion-band .btn-group { justify-content: center; }

/* ---------- Application Module ---------- */
.application-module {
    padding: 48px 0;
    border-bottom: 1px solid var(--border-subtle);
}
.application-module:last-child { border-bottom: none; }
.application-module h3 { margin-bottom: 24px; color: var(--accent-blue); }

.app-detail-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 20px;
}
.app-detail {
    padding: 20px;
    background: var(--bg-elevated);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-sm);
}
.app-detail__label {
    font-size: 0.78rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--accent-blue);
    font-weight: 700;
    margin-bottom: 8px;
}
.app-detail p { font-size: 0.93rem; color: var(--text-secondary); }

/* ---------- Fit Checklist ---------- */
.fit-checklist {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 16px;
}
.fit-checklist__item {
    padding: 16px 20px;
    background: var(--bg-elevated);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-sm);
    display: flex;
    gap: 12px;
    align-items: flex-start;
}
.fit-checklist__icon {
    color: var(--accent-blue);
    font-size: 1.1rem;
    flex-shrink: 0;
    margin-top: 2px;
}
.fit-checklist__item h4 { font-size: 0.95rem; margin-bottom: 4px; }
.fit-checklist__item p  { font-size: 0.85rem; color: var(--text-secondary); }

/* ---------- Limitations / Honesty Panel ---------- */
.limitations-panel {
    background: var(--bg-elevated);
    border: 1px solid var(--border-subtle);
    border-left: 4px solid var(--warning);
    border-radius: var(--radius-md);
    padding: 36px 32px;
}
.limitations-panel h3 { margin-bottom: 16px; color: var(--warning); }
.limitations-panel ul {
    list-style: none;
    padding: 0;
}
.limitations-panel li {
    padding: 8px 0 8px 24px;
    position: relative;
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
}
.limitations-panel li::before {
    content: "—";
    position: absolute;
    left: 0;
    color: var(--warning);
}

/* ---------- Forms ---------- */
.form-section { max-width: 640px; margin: 0 auto; }

.form-group {
    margin-bottom: 24px;
}
.form-group label {
    display: block;
    font-weight: 600;
    font-size: 0.93rem;
    margin-bottom: 6px;
    color: var(--text-primary);
}
.form-group label .optional {
    font-weight: 400;
    color: var(--text-muted);
    font-size: 0.85rem;
}

.form-input,
.form-select,
.form-textarea {
    width: 100%;
    padding: 12px 16px;
    background: var(--bg-elevated);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-family: var(--font-stack);
    font-size: 1rem;
    transition: border-color 0.2s;
    min-height: 44px;
}
.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    border-color: var(--accent-blue);
    outline: none;
    box-shadow: 0 0 0 3px rgba(67,146,208,0.15);
}
.form-textarea { min-height: 120px; resize: vertical; }
.form-select { cursor: pointer; appearance: auto; }

.form-privacy {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 16px;
    line-height: 1.5;
}

/* ---------- Footer ---------- */
.site-footer {
    background: var(--bg-surface);
    border-top: 1px solid var(--border-subtle);
    padding: 64px 0 40px;
}
.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 40px;
}
.footer-col h4 {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-muted);
    margin-bottom: 16px;
}
.footer-col a {
    display: block;
    color: var(--text-secondary);
    font-size: 0.93rem;
    padding: 4px 0;
    transition: color 0.2s;
}
.footer-col a:hover { color: var(--text-primary); }

.footer-brand p {
    color: var(--text-secondary);
    font-size: 0.93rem;
    line-height: 1.6;
    margin-top: 16px;
    max-width: 320px;
}
.footer-brand img { height: 44px; margin-bottom: 8px; }

.footer-bottom {
    border-top: 1px solid var(--border-subtle);
    padding-top: 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.85rem;
    color: var(--text-muted);
}
.footer-bottom a { color: var(--text-muted); }
.footer-bottom a:hover { color: var(--text-secondary); }

/* ---------- Validation Status Legend ---------- */
.status-legend {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    padding: 24px;
    background: var(--bg-elevated);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    margin-bottom: 48px;
}
.status-legend__item {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.85rem;
    color: var(--text-secondary);
}
.status-legend__dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    flex-shrink: 0;
}
.status-legend__dot--reviewed  { background: var(--accent-blue); }
.status-legend__dot--tested    { background: var(--success); }
.status-legend__dot--milestone { background: var(--warning); }
.status-legend__dot--inprogress { background: var(--text-muted); }

/* ---------- Architecture Diagram (CSS) ---------- */
.arch-diagram {
    display: flex;
    align-items: stretch;
    gap: 0;
    overflow-x: auto;
    padding: 24px 0;
}
.arch-stage {
    flex: 1;
    text-align: center;
    padding: 28px 20px;
    background: var(--bg-elevated);
    border: 1px solid var(--border-subtle);
    position: relative;
    min-width: 180px;
}
.arch-stage:first-child { border-radius: var(--radius-md) 0 0 var(--radius-md); }
.arch-stage:last-child  { border-radius: 0 var(--radius-md) var(--radius-md) 0; }
.arch-stage + .arch-stage { border-left: none; }
.arch-stage::after {
    content: "→";
    position: absolute;
    right: -12px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 1.2rem;
    color: var(--accent-blue);
    z-index: 1;
    font-weight: 700;
}
.arch-stage:last-child::after { display: none; }
.arch-stage__icon {
    font-size: 1.8rem;
    margin-bottom: 10px;
}
.arch-stage h4 { font-size: 0.95rem; margin-bottom: 6px; }
.arch-stage p  { font-size: 0.82rem; color: var(--text-secondary); }

/* ---------- Responsive: Tablet ---------- */
@media (max-width: 900px) {
    .section { padding: 64px 0; }

    .hero__inner { flex-direction: column; text-align: center; gap: 40px; }
    .hero__text p { margin-left: auto; margin-right: auto; }
    .hero__text .btn-group { justify-content: center; }

    .split, .split--reverse { flex-direction: column; gap: 32px; }

    .solution-flow { grid-template-columns: repeat(2, 1fr); }
    .solution-flow::before { display: none; }

    .workflow { grid-template-columns: repeat(3, 1fr); }

    .footer-grid { grid-template-columns: 1fr 1fr; }

    .arch-diagram { flex-direction: column; }
    .arch-stage { border-radius: 0; }
    .arch-stage:first-child { border-radius: var(--radius-md) var(--radius-md) 0 0; }
    .arch-stage:last-child  { border-radius: 0 0 var(--radius-md) var(--radius-md); }
    .arch-stage + .arch-stage { border-left: 1px solid var(--border-subtle); border-top: none; }
    .arch-stage::after { content: "↓"; right: auto; left: 50%; bottom: -12px; top: auto; transform: translateX(-50%); }
}

/* ---------- Responsive: Mobile ---------- */
@media (max-width: 600px) {
    .section { padding: 48px 0; }
    .hero { padding: 48px 0 56px; }

    .solution-flow { grid-template-columns: 1fr 1fr; }
    .workflow { grid-template-columns: 1fr 1fr; }
    .card-grid { grid-template-columns: 1fr; }
    .problem-grid { grid-template-columns: 1fr; }
    .capability-grid { grid-template-columns: 1fr; }
    .fit-checklist { grid-template-columns: 1fr; }
    .proof-strip__grid { grid-template-columns: 1fr; }

    .footer-grid { grid-template-columns: 1fr; }
    .footer-bottom { flex-direction: column; gap: 8px; text-align: center; }

    .btn-group { flex-direction: column; }
    .btn-group .btn { width: 100%; }
}

/* ---------- Utility ---------- */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0,0,0,0);
    white-space: nowrap;
    border: 0;
}
.mt-0 { margin-top: 0; }
.mt-16 { margin-top: 16px; }
.mt-24 { margin-top: 24px; }
.mt-32 { margin-top: 32px; }
.mt-48 { margin-top: 48px; }
.mb-0 { margin-bottom: 0; }
.mb-16 { margin-bottom: 16px; }
.mb-24 { margin-bottom: 24px; }
.mb-32 { margin-bottom: 32px; }
.mb-48 { margin-bottom: 48px; }
.text-center { text-align: center; }

/* Shared layout and accessible navigation */
:root { color-scheme: dark; }
[hidden] { display: none !important; }
.skip-link { position: fixed; top: 8px; left: 16px; z-index: 1000; padding: 12px 20px; background: var(--text-primary); color: var(--bg-main); transform: translateY(-160%); }
.skip-link:focus { transform: translateY(0); }
.site-header__logo { flex-shrink: 0; }
.site-nav { gap: 20px; }
.site-nav__links { gap: 22px; }
.site-nav .btn { white-space: nowrap; padding-inline: 20px; }
.site-nav__contact[aria-current="page"] { color: var(--text-primary) !important; text-decoration: underline; text-underline-offset: 6px; }
.menu-button { display: none; min-width: 92px; min-height: 44px; padding: 8px 14px; border: 1px solid var(--border-subtle); border-radius: var(--radius-sm); background: var(--bg-elevated); color: var(--text-primary); font: inherit; cursor: pointer; }
.menu-button span { margin-left: 8px; }
.hero__text, .hero__visual, .split__content, .split__visual { min-width: 0; }
.hero__visual img { width: 100%; }
.hero__text h1 { font-size: clamp(2rem, 3.7vw, 3.25rem); }
.section h2 { margin-bottom: 24px; }
.section-intro { text-align: left; margin: 0 0 40px; }
.proof-item p { color: var(--text-secondary); font-size: 0.95rem; }
.proof-item__label { display: block; color: var(--accent-blue-bright); }
.flow-step h3 { font-size: 1.15rem; margin-bottom: 10px; }
.solution-flow::before { top: 28px; }
.content-illustration { width: 100%; height: auto; border-radius: var(--radius-md); }
.card > .content-illustration { margin-bottom: 24px; }
.application-module .content-illustration { margin-top: 32px; max-height: 380px; object-fit: contain; background: var(--bg-elevated); }
.application-module > .container > p { max-width: 850px; margin-bottom: 32px; color: var(--text-secondary); }
.app-detail h3 { font-size: 0.8rem; letter-spacing: 0.06em; color: var(--accent-blue-bright); margin-bottom: 12px; }
.arch-stage { min-width: 0; }
.arch-stage h3 { font-size: 1rem; margin-bottom: 12px; }
.workflow__step h3 { font-size: 1.05rem; margin-bottom: 8px; }
.timeline { display: grid; gap: 24px; }
.evidence-card__body h4 { margin: 24px 0 8px; }
.evidence-card ol { padding-left: 24px; color: var(--text-secondary); }
.evidence-card ol li { padding: 6px 0; }
.fit-checklist { list-style: none; }
.fit-checklist > li { padding: 24px; border: 1px solid var(--border-subtle); border-radius: var(--radius-md); color: var(--text-secondary); background: var(--bg-elevated); }
.fit-checklist strong { color: var(--text-primary); }
.status-legend { margin-bottom: 0; }
.status-dot { width: 10px; height: 10px; border-radius: 50%; flex-shrink: 0; }
.status-dot--accent { background: var(--accent-blue); }
.status-dot--success { background: var(--success); }
.status-dot--warning { background: var(--warning); }
.status-dot--muted { background: var(--text-muted); }
.form-help { color: var(--text-secondary); margin-bottom: 24px; }
.form-help::after { content: ' Fields marked optional may be left blank.'; }
.form-input, .form-select, .form-textarea { border-color: #777; }
.form-input::placeholder, .form-textarea::placeholder { color: var(--text-muted); opacity: 1; }
.form-input:focus-visible, .form-select:focus-visible, .form-textarea:focus-visible { outline: 2px solid var(--accent-blue-bright); outline-offset: 3px; }
.btn:disabled { cursor: not-allowed; opacity: 0.6; }
.inquiry-draft { margin-top: 24px; padding: 24px; border: 1px solid var(--accent-blue); border-radius: var(--radius-md); }
.inquiry-draft p, .inquiry-draft textarea, .inquiry-draft h3 { margin-bottom: 16px; }
#form-status:not(:empty) { margin-top: 24px; color: var(--accent-blue-bright); }
.card a, .inquiry-draft a { overflow-wrap: anywhere; }
.footer-col a { min-height: 44px; display: flex; align-items: center; }
.footer-bottom a { display: inline-block; padding: 10px 0; }

@media (max-width: 1100px) {
    .site-header { height: auto; min-height: var(--header-height); }
    .site-header .container { flex-wrap: wrap; padding-block: 12px; }
    .site-nav { width: 100%; flex-direction: column; align-items: stretch; gap: 12px; padding: 16px 0; }
    .site-nav__links { flex-direction: column; align-items: stretch; gap: 0; }
    .site-nav__links a, .site-nav__contact { display: block; padding: 12px; margin: 0; min-height: 44px; }
    .js .menu-button { display: inline-flex; align-items: center; justify-content: center; }
    .js .site-nav { display: none; }
    .js .site-nav.is-open { display: flex; max-height: calc(100dvh - 80px); overflow-y: auto; }
    .arch-diagram { flex-direction: column; }
    .arch-stage { border-radius: 0; }
    .arch-stage:first-child { border-radius: var(--radius-md) var(--radius-md) 0 0; }
    .arch-stage:last-child { border-radius: 0 0 var(--radius-md) var(--radius-md); }
    .arch-stage + .arch-stage { border-left: 1px solid var(--border-subtle); border-top: none; }
    .arch-stage::after { content: '↓'; right: auto; left: 50%; bottom: -12px; top: auto; transform: translateX(-50%); }
}
@media (max-width: 900px) {
    .hero__text { max-width: 680px; }
    .hero__visual { width: 100%; max-width: 580px; }
    .split__visual { width: 100%; max-width: 580px; }
}
@media (max-width: 600px) {
    .container { padding-inline: 20px; }
    .hero__inner { gap: 32px; }
    .hero__text p { font-size: 1.05rem; }
    .evidence-card, .limitations-panel { padding: 24px 20px; }
    .proof-strip__grid, .app-detail-grid { grid-template-columns: minmax(0, 1fr); }
    .btn-group { gap: 12px; }
    .inquiry-draft { padding: 20px 16px; }
}
@media (max-width: 380px) {
    .solution-flow, .workflow { grid-template-columns: 1fr; }
}