/* ─────────────────────────────────────────────────────────────────────────────
   Design tokens — the only place raw colour, type and spacing values live.
   Everything else references these. Change the brand here, once.

   Palette derived from assets/brand/logo/. The logo uses exactly three colours:
     #47abff  azure   — the mark
     #041635  navy    — the logo's own background variant
     #ffffff  white

   Measured contrast (WCAG 2.2, sRGB relative luminance):
     azure  on white ... 2.46:1  ← FAILS AA for text. Large display / graphics only.
     azure  on navy .... 7.29:1  ✓ AAA for large text, AA for body
     navy   on white ... 17.93:1 ✓
     white  on navy .... 17.93:1 ✓
   So the brand azure is kept untouched for the mark and for accents on dark
   ground, and a same-hue darker variant carries links and text on light ground.
   --azure-600 is the lightest 207° azure that still clears 4.5:1 on white.
   ──────────────────────────────────────────────────────────────────────────── */

:root {
    color-scheme: light dark;

    /* ── brand, exactly as the logo defines them ── */
    --brand-azure: #47abff;
    --brand-navy: #041635;

    /* ── azure ramp, same hue (207°) and saturation, varying lightness ── */
    --azure-800: #0059a3;   /* 7.10:1 on white — small text, high emphasis   */
    --azure-600: #0077db;   /* 4.50:1 on white — links, buttons, body accent */
    --azure-400: #1a96ff;   /* 3.07:1 on white — large text, icons, borders  */
    --azure-300: #47abff;   /* the brand azure — on dark only, or as graphic */
    --azure-200: #a7d5ff;   /* dark-theme accent text                        */

    /* ── navy surfaces, for the dark hero and dark theme ── */
    --navy-900: #041635;    /* the brand navy */
    --navy-800: #0a1f45;
    --navy-700: #0e2a5c;
    --navy-600: #143a7d;

    /* ── neutrals, tinted toward the navy hue so greys never look muddy ── */
    --ink:       #121721;
    --slate-700: #3c4453;
    --slate-500: #656f81;   /* 4.94:1 on paper — the lightest usable muted text */
    --slate-300: #b8bec8;
    --slate-200: #dee0e3;
    --slate-100: #f0f1f3;
    --paper:     #fbfcfe;

    /* ── semantic tokens: LIGHT theme (the default) ── */
    --color-bg: var(--paper);
    --color-surface: #ffffff;
    --color-surface-2: var(--slate-100);
    --color-text: var(--ink);
    --color-muted: var(--slate-500);
    --color-border: var(--slate-200);
    --color-accent: var(--azure-600);
    --color-accent-hover: var(--azure-800);
    --color-on-accent: #ffffff;
    --color-inverse-bg: var(--navy-900);
    --color-inverse-text: #ffffff;
    --color-inverse-muted: #a9b6cd;
    --color-inverse-border: rgba(255, 255, 255, 0.14);
    --color-inverse-accent: var(--azure-300);

    /* ── type ──
       System stack for now. The brief asks for self-hosted brand faces; no licensed
       font files were supplied, so this is the honest placeholder. Swapping in a real
       face is a two-line change here and a @font-face block in base.css.            */
    --font-display: ui-sans-serif, -apple-system, "Segoe UI", Inter, Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-body: ui-sans-serif, -apple-system, "Segoe UI", Inter, Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;

    /* fluid scale, 320px → 1400px viewport */
    --step--1: clamp(0.83rem, 0.80rem + 0.15vw, 0.92rem);
    --step-0:  clamp(1.00rem, 0.95rem + 0.24vw, 1.13rem);
    --step-1:  clamp(1.20rem, 1.11rem + 0.44vw, 1.44rem);
    --step-2:  clamp(1.44rem, 1.29rem + 0.75vw, 1.83rem);
    --step-3:  clamp(1.73rem, 1.48rem + 1.22vw, 2.33rem);
    --step-4:  clamp(2.07rem, 1.69rem + 1.90vw, 2.96rem);
    --step-5:  clamp(2.49rem, 1.91rem + 2.88vw, 3.76rem);
    --step-6:  clamp(2.99rem, 2.13rem + 4.28vw, 4.78rem);

    --leading-tight: 1.12;
    --leading-snug: 1.28;
    --leading-body: 1.65;
    --tracking-tight: -0.022em;
    --tracking-wide: 0.08em;

    /* ── space ── */
    --space-3xs: 0.25rem;
    --space-2xs: 0.5rem;
    --space-xs:  0.75rem;
    --space-s:   1rem;
    --space-m:   1.5rem;
    --space-l:   2.5rem;
    --space-xl:  4rem;
    --space-2xl: 6rem;
    --space-3xl: 9rem;

    /* ── shape ── */
    --radius-s: 4px;
    --radius-m: 10px;
    --radius-l: 18px;
    --shadow-s: 0 1px 2px rgba(4, 22, 53, 0.06), 0 1px 3px rgba(4, 22, 53, 0.05);
    --shadow-m: 0 4px 12px rgba(4, 22, 53, 0.07), 0 2px 4px rgba(4, 22, 53, 0.05);
    --shadow-l: 0 18px 40px rgba(4, 22, 53, 0.12), 0 4px 10px rgba(4, 22, 53, 0.06);

    --wrap: 76rem;
    --wrap-narrow: 48rem;
    --border-hairline: 1px solid var(--color-border);
}

/* ── semantic tokens: DARK theme ──
   Only the semantic layer is redefined; the ramps above stay put. Guarded so an
   explicit [data-theme="light"] still wins if a theme toggle is ever added.      */
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        --color-bg: #05112a;
        --color-surface: var(--navy-900);
        --color-surface-2: var(--navy-800);
        --color-text: #eaf1fb;
        --color-muted: #a9b6cd;
        --color-border: rgba(255, 255, 255, 0.13);
        --color-accent: var(--azure-300);
        --color-accent-hover: var(--azure-200);
        --color-on-accent: var(--navy-900);
        --color-inverse-bg: #020c1e;
        --shadow-s: 0 1px 2px rgba(0, 0, 0, 0.4);
        --shadow-m: 0 4px 14px rgba(0, 0, 0, 0.45);
        --shadow-l: 0 18px 44px rgba(0, 0, 0, 0.55);
    }
}

:root[data-theme="dark"] {
    --color-bg: #05112a;
    --color-surface: var(--navy-900);
    --color-surface-2: var(--navy-800);
    --color-text: #eaf1fb;
    --color-muted: #a9b6cd;
    --color-border: rgba(255, 255, 255, 0.13);
    --color-accent: var(--azure-300);
    --color-accent-hover: var(--azure-200);
    --color-on-accent: var(--navy-900);
    --color-inverse-bg: #020c1e;
}

/* ─── reset ─────────────────────────────────────────────────────────────── */

*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; }

html {
    -webkit-text-size-adjust: 100%;
    scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

body {
    background: var(--color-bg);
    color: var(--color-text);
    font-family: var(--font-body);
    font-size: var(--step-0);
    line-height: var(--leading-body);
    -webkit-font-smoothing: antialiased;
    text-rendering: optimizeLegibility;
    overflow-x: hidden;
}

img, picture, svg, video { display: block; max-width: 100%; height: auto; }
input, button, textarea, select { font: inherit; color: inherit; }
p, li { text-wrap: pretty; }

/* ─── typography ────────────────────────────────────────────────────────── */

h1, h2, h3, h4 {
    font-family: var(--font-display);
    line-height: var(--leading-tight);
    letter-spacing: var(--tracking-tight);
    font-weight: 640;
    text-wrap: balance;
}

h1 { font-size: var(--step-6); }
h2 { font-size: var(--step-4); }
h3 { font-size: var(--step-2); }
h4 { font-size: var(--step-1); }

a { color: var(--color-accent); text-decoration-thickness: 1px; text-underline-offset: 0.2em; }
a:hover { color: var(--color-accent-hover); }

:focus-visible {
    outline: 3px solid var(--color-accent);
    outline-offset: 3px;
    border-radius: 2px;
}

::selection { background: var(--brand-azure); color: var(--brand-navy); }

.lede {
    font-size: var(--step-1);
    line-height: var(--leading-snug);
    color: var(--color-muted);
    max-width: 46ch;
}

.eyebrow {
    font-size: var(--step--1);
    text-transform: uppercase;
    letter-spacing: var(--tracking-wide);
    font-weight: 620;
    color: var(--color-accent);
    margin-bottom: var(--space-xs);
}

/* ─── layout ────────────────────────────────────────────────────────────── */

.wrap {
    width: min(100% - 2.5rem, var(--wrap));
    margin-inline: auto;
}

.wrap--narrow { width: min(100% - 2.5rem, var(--wrap-narrow)); }

.section { padding-block: var(--space-2xl); }
.section--tight { padding-block: var(--space-xl); }

.section--inverse {
    background: var(--color-inverse-bg);
    color: var(--color-inverse-text);
}
.section--inverse h2, .section--inverse h3 { color: var(--color-inverse-text); }
.section--inverse .lede { color: var(--color-inverse-muted); }
.section--inverse .eyebrow { color: var(--color-inverse-accent); }
.section--inverse a { color: var(--color-inverse-accent); }

.section__head { max-width: 54ch; margin-bottom: var(--space-l); }
.section__head p { margin-top: var(--space-s); }

.stack > * + * { margin-top: var(--space-s); }

/* ─── skip link ─────────────────────────────────────────────────────────── */

.skip-link {
    position: absolute;
    left: var(--space-s);
    top: -100%;
    z-index: 100;
    background: var(--color-accent);
    color: var(--color-on-accent);
    padding: var(--space-2xs) var(--space-s);
    border-radius: var(--radius-s);
    text-decoration: none;
    transition: top 120ms ease;
}
.skip-link:focus { top: var(--space-s); }

main:focus { outline: none; }

/* Used for text that only assistive technology needs. */
.visually-hidden {
    position: absolute;
    width: 1px; height: 1px;
    padding: 0; margin: -1px;
    overflow: hidden;
    clip-path: inset(50%);
    white-space: nowrap;
}

/* ─── utilities ─────────────────────────────────────────────────────────── */
/* Kept deliberately few. Inline style attributes are avoided entirely so the
   Content-Security-Policy never needs style-src 'unsafe-inline'. */

.mt-xl { margin-top: var(--space-xl); }

/* ─── Markdown articles (news posts, case studies) and their listings ────── */

.article__meta { margin-top: var(--space-s); font-size: var(--step--1); color: var(--color-muted); }

.prose > * + * { margin-top: var(--space-s); }
.prose h2 { font-size: var(--step-2); margin-top: var(--space-l); }
.prose h3 { font-size: var(--step-1); margin-top: var(--space-m); }
.prose ul, .prose ol { padding-left: 1.4em; }
.prose li + li { margin-top: var(--space-3xs); }
.prose blockquote { border-left: 3px solid var(--color-accent); padding-left: var(--space-m); color: var(--color-muted); font-style: italic; }
.prose table { width: 100%; border-collapse: collapse; font-size: var(--step--1); }
.prose th, .prose td { text-align: left; padding: var(--space-2xs) var(--space-xs); border-bottom: var(--border-hairline); vertical-align: top; }
.prose th { color: var(--color-muted); font-weight: 620; }
.prose__source { font-size: var(--step--1); color: var(--color-muted); }

.post-list { list-style: none; padding: 0; display: grid; gap: var(--space-m); }
.post {
    display: grid;
    gap: var(--space-3xs) var(--space-m);
    padding: var(--space-m);
    border: var(--border-hairline);
    border-radius: var(--radius-m);
    background: var(--color-surface);
}
@media (min-width: 44rem) { .post { grid-template-columns: 9rem 1fr; } }
.post__date { font-size: var(--step--1); color: var(--color-muted); font-variant-numeric: tabular-nums; }
.post__title { font-size: var(--step-1); }
.post__title a { color: inherit; text-decoration: none; }
.post__title a:hover { color: var(--color-accent); }
.post__summary { color: var(--color-muted); margin-top: var(--space-3xs); }
@media (min-width: 44rem) { .post__summary { grid-column: 2; } }

/* the calculator placeholder shown while no validated refrigerant data exists */
.calc-teaser {
    display: grid;
    gap: var(--space-m);
    align-items: center;
    padding: var(--space-l);
    border: var(--border-hairline);
    border-radius: var(--radius-l);
    background: var(--color-surface);
}
@media (min-width: 52rem) { .calc-teaser { grid-template-columns: 1fr auto; } }
.calc-teaser .button-row { margin-top: 0; }

/* ─── stat row ──────────────────────────────────────────────────────────── */

.stats {
    display: grid;
    gap: var(--space-m);
    grid-template-columns: repeat(auto-fit, minmax(13rem, 1fr));
    margin-top: var(--space-l);
    padding: 0;
    list-style: none;
}

.stat {
    padding: var(--space-m);
    border: var(--border-hairline);
    border-radius: var(--radius-m);
    background: var(--color-surface);
}

.section--inverse .stat {
    background: rgba(255, 255, 255, 0.035);
    border-color: var(--color-inverse-border);
}

.stat__value {
    font-family: var(--font-display);
    font-size: var(--step-4);
    font-weight: 660;
    line-height: 1;
    letter-spacing: var(--tracking-tight);
    color: var(--color-accent);
}
.section--inverse .stat__value { color: var(--brand-azure); }

.stat__label {
    margin-top: var(--space-2xs);
    font-size: var(--step--1);
    color: var(--color-muted);
}
.section--inverse .stat__label { color: var(--color-inverse-muted); }

/* ─── feature cards ─────────────────────────────────────────────────────── */

.cards {
    display: grid;
    gap: var(--space-m);
    grid-template-columns: repeat(auto-fit, minmax(17rem, 1fr));
    padding: 0;
    list-style: none;
}

.card {
    display: flex;
    flex-direction: column;
    gap: var(--space-2xs);
    padding: var(--space-l) var(--space-m);
    background: var(--color-surface);
    border: var(--border-hairline);
    border-radius: var(--radius-m);
    box-shadow: var(--shadow-s);
}

.card__icon {
    width: 2rem; height: 2rem;
    margin-bottom: var(--space-2xs);
    color: var(--color-accent);
}

.card h3 { font-size: var(--step-1); }
.card p { color: var(--color-muted); font-size: var(--step-0); }

/* ─── problem list ──────────────────────────────────────────────────────── */

.problems {
    display: grid;
    gap: var(--space-l);
    grid-template-columns: repeat(auto-fit, minmax(16rem, 1fr));
    margin-top: var(--space-l);
    padding: 0;
    list-style: none;
}

.problem { border-top: 2px solid var(--color-inverse-border); padding-top: var(--space-s); }
.problem h3 { font-size: var(--step-1); margin-bottom: var(--space-2xs); }
.problem p { color: var(--color-inverse-muted); font-size: var(--step-0); }

/* ─── logo wall ─────────────────────────────────────────────────────────── */

.logo-wall {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: var(--space-l);
    margin-top: var(--space-l);
    padding: 0;
    list-style: none;
}

.logo-wall li {
    font-size: var(--step-0);
    font-weight: 600;
    color: var(--color-muted);
    padding: var(--space-2xs) var(--space-s);
    border: var(--border-hairline);
    border-radius: var(--radius-s);
}

/* ─── timeline ──────────────────────────────────────────────────────────── */

.timeline { list-style: none; padding: 0; margin-top: var(--space-l); display: grid; gap: var(--space-m); }

.timeline li {
    display: grid;
    gap: var(--space-3xs) var(--space-m);
    grid-template-columns: 1fr;
    padding-left: var(--space-m);
    border-left: 2px solid var(--color-border);
}

@media (min-width: 44rem) {
    .timeline li { grid-template-columns: 9rem 1fr; align-items: baseline; }
}

.timeline__when {
    font-size: var(--step--1);
    font-weight: 620;
    color: var(--color-accent);
    font-variant-numeric: tabular-nums;
}

/* ─── CTA band ──────────────────────────────────────────────────────────── */

.cta-band {
    background: var(--color-inverse-bg);
    color: var(--color-inverse-text);
    border-radius: var(--radius-l);
    padding: var(--space-xl) var(--space-l);
    text-align: center;
}
.cta-band h2 { color: #ffffff; }
.cta-band p { color: var(--color-inverse-muted); margin: var(--space-s) auto 0; max-width: 48ch; }
.cta-band .button-row { justify-content: center; }

/* ─── breadcrumbs ───────────────────────────────────────────────────────── */

.breadcrumbs { font-size: var(--step--1); color: var(--color-muted); padding-block: var(--space-xs); border-bottom: var(--border-hairline); }
.breadcrumbs ol { display: flex; flex-wrap: wrap; gap: var(--space-2xs); list-style: none; padding: 0; margin: 0; }
.breadcrumbs li + li::before { content: "›"; margin-right: var(--space-2xs); color: var(--slate-300); }
.breadcrumbs a { color: inherit; text-decoration: none; }
.breadcrumbs a:hover { color: var(--color-accent); text-decoration: underline; }
.breadcrumbs [aria-current="page"] { color: var(--color-text); }

/* the interior page head follows straight after; drop its top border */
.breadcrumbs + main .page-head { border-top: 0; }

/* ─── buttons ───────────────────────────────────────────────────────────── */

.button {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2xs);
    padding: 0.8em 1.5em;
    border: 1px solid transparent;
    border-radius: var(--radius-s);
    font-size: var(--step-0);
    font-weight: 600;
    line-height: 1.1;
    text-decoration: none;
    cursor: pointer;
    transition: background-color 140ms ease, border-color 140ms ease, transform 140ms ease;
}

.button:hover { transform: translateY(-1px); }
.button:active { transform: translateY(0); }

.button--primary {
    background: var(--color-accent);
    color: var(--color-on-accent);
}
.button--primary:hover {
    background: var(--color-accent-hover);
    color: var(--color-on-accent);
}

.button--ghost {
    background: transparent;
    border-color: var(--color-border);
    color: var(--color-text);
}
.button--ghost:hover { border-color: var(--color-accent); color: var(--color-accent); }

/* On the navy hero, where --color-accent would be the light-theme blue. */
.section--inverse .button--primary,
.hero .button--primary {
    background: var(--brand-azure);
    color: var(--brand-navy);
}
.section--inverse .button--primary:hover,
.hero .button--primary:hover { background: #7cc3ff; color: var(--brand-navy); }

.section--inverse .button--ghost,
.hero .button--ghost {
    color: #ffffff;
    border-color: var(--color-inverse-border);
}
.section--inverse .button--ghost:hover,
.hero .button--ghost:hover { border-color: var(--brand-azure); color: var(--brand-azure); }

.button-row {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-s);
    margin-top: var(--space-l);
}

/* ─── savings calculator ────────────────────────────────────────────────────
   Progressive enhancement: the static example table is what exists in the DOM
   for everyone; calculator.js flips data-ready on the root, which hides the
   static block and reveals the form + live results.                          */

.calculator {
    padding: var(--space-l);
    border: var(--border-hairline);
    border-radius: var(--radius-l);
    background: var(--color-surface);
    box-shadow: var(--shadow-s);
    --calc-ice: var(--azure-400);
    --calc-flame: #d64520;   /* 4.4:1 on white — used as a graphic accent */
}
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) .calculator { --calc-ice: var(--azure-300); --calc-flame: #ff7a52; }
}
:root[data-theme="dark"] .calculator { --calc-ice: var(--azure-300); --calc-flame: #ff7a52; }

/* ── heating / cooling toggle ── */
.calc-mode-row { grid-column: 1 / -1; display: flex; justify-content: center; }
.calc-mode {
    display: inline-flex;
    gap: 2px;
    padding: 4px;
    border: var(--border-hairline);
    border-radius: 999px;
    background: var(--color-bg);
}
.calc-mode__btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5em;
    padding: 0.5em 1.2em;
    border: 1px solid transparent;
    border-radius: 999px;
    background: transparent;
    cursor: pointer;
    font: inherit;
    font-weight: 620;
    font-size: var(--step--1);
    color: var(--color-muted);
    transition: background-color 120ms ease, color 120ms ease;
}
.calc-mode__btn svg { width: 1.2em; height: 1.2em; flex: none; }
.calc-mode__btn--cool svg { color: var(--calc-ice); }
.calc-mode__btn--heat svg { color: var(--calc-flame); }
.calc-mode__btn[aria-pressed="true"] {
    color: var(--color-text);
    background: var(--color-surface);
    border-color: var(--color-border);
    box-shadow: var(--shadow-s);
}
.calc-mode__btn:focus-visible { outline: 3px solid var(--color-accent); outline-offset: 2px; }

.calculator .section__head { margin-bottom: var(--space-m); }

.calculator__app { display: none; }
.calculator[data-ready] .calculator__app { display: grid; gap: var(--space-l); }
.calculator[data-ready] .calculator__static { display: none; }

@media (min-width: 60rem) {
    .calculator[data-ready] .calculator__app { grid-template-columns: minmax(0, 1fr) minmax(0, 1.1fr); gap: var(--space-xl); }
}

/* ── static fallback table ── */
.calculator__static h3 { font-size: var(--step-1); }
.calculator__static p { margin-top: var(--space-2xs); color: var(--color-muted); }

.calc-table { width: 100%; margin-top: var(--space-m); border-collapse: collapse; font-size: var(--step--1); }
.calc-table th, .calc-table td { padding: var(--space-2xs) var(--space-xs); text-align: left; border-bottom: var(--border-hairline); vertical-align: top; }
.calc-table th { color: var(--color-muted); font-weight: 620; }
.calc-table td:not(:first-child) { font-variant-numeric: tabular-nums; }
.calc-table-wrap { overflow-x: auto; }

/* ── inputs ── */
.calc-form { display: grid; gap: var(--space-m); }

.calc-field label { font-weight: 600; font-size: var(--step--1); }

.calc-field--select { display: grid; gap: var(--space-2xs); }
.calc-field--select select {
    width: 100%;
    padding: 0.6em 0.8em;
    border: var(--border-hairline);
    border-radius: var(--radius-s);
    background: var(--color-bg);
}

.calc-field__head {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    gap: var(--space-s);
    margin-bottom: var(--space-3xs);
}

.calc-field__value { display: inline-flex; align-items: baseline; gap: 0.3em; white-space: nowrap; }

.calc-field__num {
    width: 5.5em;
    padding: 0.2em 0.4em;
    border: 1px solid transparent;
    border-bottom-color: var(--color-border);
    border-radius: var(--radius-s);
    background: transparent;
    text-align: right;
    font-weight: 640;
    font-variant-numeric: tabular-nums;
    font-size: var(--step-0);
    color: var(--color-accent);
    -moz-appearance: textfield;
    appearance: textfield;
}
.calc-field__num::-webkit-outer-spin-button, .calc-field__num::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.calc-field__num:focus { border-color: var(--color-accent); outline: none; }
.calc-field__num--wide { width: 8em; text-align: left; }

.calc-field__unit { font-size: var(--step--1); color: var(--color-muted); }

.calc-field__hint { font-size: var(--step--1); color: var(--color-muted); margin-top: var(--space-2xs); }

/* the slider itself */
.calc-field input[type="range"] {
    width: 100%;
    height: 28px;
    margin: 0;
    background: transparent;
    cursor: pointer;
    -webkit-appearance: none;
    appearance: none;
}
.calc-field input[type="range"]::-webkit-slider-runnable-track {
    height: 4px; border-radius: 2px;
    background: linear-gradient(var(--color-accent), var(--color-accent)) 0 / var(--fill, 0%) 100% no-repeat, var(--color-border);
}
.calc-field input[type="range"]::-moz-range-track { height: 4px; border-radius: 2px; background: var(--color-border); }
.calc-field input[type="range"]::-moz-range-progress { height: 4px; border-radius: 2px; background: var(--color-accent); }
.calc-field input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 20px; height: 20px; margin-top: -8px;
    border-radius: 50%;
    background: var(--color-surface);
    border: 2px solid var(--color-accent);
    box-shadow: var(--shadow-s);
    transition: transform 120ms ease;
}
.calc-field input[type="range"]::-moz-range-thumb {
    width: 16px; height: 16px;
    border-radius: 50%;
    background: var(--color-surface);
    border: 2px solid var(--color-accent);
    box-shadow: var(--shadow-s);
}
.calc-field input[type="range"]:active::-webkit-slider-thumb, .calc-field input[type="range"]:hover::-webkit-slider-thumb { transform: scale(1.12); }
.calc-field input[type="range"]:focus-visible { outline: none; }
.calc-field input[type="range"]:focus-visible::-webkit-slider-thumb { outline: 3px solid var(--color-accent); outline-offset: 2px; }
.calc-field input[type="range"]:focus-visible::-moz-range-thumb { outline: 3px solid var(--color-accent); outline-offset: 2px; }

.calc-field--capex summary { cursor: pointer; font-size: var(--step--1); font-weight: 600; color: var(--color-accent); }
.calc-field--capex .calc-field__head { margin-top: var(--space-xs); }

/* ── results ── */
.calc-results { display: grid; gap: var(--space-m); align-content: start; }

.calc-results__invalid {
    padding: var(--space-s) var(--space-m);
    border: 1px solid var(--color-accent);
    border-left-width: 4px;
    border-radius: var(--radius-s);
    font-size: var(--step--1);
}
.calc-results[data-invalid] [data-calc-valid] { display: none; }

.calc-copchart { margin: 0; text-align: center; }
.calc-copchart svg { width: 100%; max-width: 320px; height: auto; font-family: var(--font-body); }
.calc-copchart__bar rect { fill: var(--slate-300); }
.calc-copchart__bar--ours rect { fill: var(--color-accent); }
.calc-copchart__bar text[data-bar-val] {
    font-family: var(--font-display);
    font-size: 26px;
    font-weight: 660;
    fill: var(--color-text);
    font-variant-numeric: tabular-nums;
}
.calc-copchart__bar--ours text[data-bar-val] { fill: var(--color-accent); }
.calc-copchart__label { font-size: 13px; fill: var(--color-muted); }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .calc-copchart__bar rect { fill: var(--navy-600); } }
:root[data-theme="dark"] .calc-copchart__bar rect { fill: var(--navy-600); }

.calc-copchart__uplift {
    margin-top: var(--space-s);
    font-size: var(--step-0);
    color: var(--color-muted);
}
.calc-copchart__uplift span {
    font-family: var(--font-display);
    font-size: var(--step-3);
    font-weight: 660;
    color: var(--color-accent);
    font-variant-numeric: tabular-nums;
}

.calc-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(9rem, 1fr));
    gap: var(--space-s);
    padding: 0;
    list-style: none;
}
.calc-stat { padding: var(--space-s); border: var(--border-hairline); border-radius: var(--radius-m); background: var(--color-bg); }
.calc-stat--wide { grid-column: 1 / -1; }
.calc-stat__value {
    display: block;
    font-family: var(--font-display);
    font-size: var(--step-3);
    font-weight: 660;
    line-height: 1.05;
    letter-spacing: var(--tracking-tight);
    color: var(--color-accent);
    font-variant-numeric: tabular-nums;
}
.calc-stat__label { display: block; margin-top: var(--space-3xs); font-size: var(--step--1); color: var(--color-muted); }
.calc-stat__label small { display: block; font-size: 0.85em; }

.calc-actions { display: flex; flex-wrap: wrap; gap: var(--space-s); align-items: center; }
.calc-actions__hint { flex-basis: 100%; font-size: var(--step--1); color: var(--color-muted); }

.calculator__how { margin-top: var(--space-l); font-size: var(--step--1); color: var(--color-muted); }
.calculator__how summary { cursor: pointer; font-weight: 620; color: var(--color-accent); }
.calculator__how p { margin-top: var(--space-xs); max-width: 70ch; }
.calculator__disclaimer { font-style: italic; }

/* ─── technical diagrams (inline SVG) ───────────────────────────────────────
   Both diagrams share one vocabulary: pipes, boxes, glyphs, labels, and an
   "ours" accent for the expander. Every colour is a custom property, set once
   for light ground here and once for the navy hero below, so the same partial
   reads identically wherever it is placed.                                    */

.cycle, .ph {
    --d-line: var(--slate-300);
    --d-box-fill: var(--color-surface);
    --d-box-stroke: var(--slate-300);
    --d-glyph: var(--slate-500);
    --d-text: var(--color-text);
    --d-muted: var(--color-muted);
    --d-ours: var(--azure-600);
    --d-ours-fill: color-mix(in srgb, var(--azure-600) 10%, transparent);
    width: 100%;
    height: auto;
    font-family: var(--font-body);
}

.hero .cycle, .section--inverse .cycle, .section--inverse .ph {
    --d-line: rgba(255, 255, 255, 0.32);
    --d-box-fill: rgba(255, 255, 255, 0.05);
    --d-box-stroke: rgba(255, 255, 255, 0.34);
    --d-glyph: rgba(255, 255, 255, 0.55);
    --d-text: #ffffff;
    --d-muted: #8fa3c2;
    --d-ours: var(--brand-azure);
    --d-ours-fill: rgba(71, 171, 255, 0.16);
}

@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) .cycle,
    :root:not([data-theme="light"]) .ph {
        --d-line: rgba(255, 255, 255, 0.28);
        --d-box-stroke: rgba(255, 255, 255, 0.30);
        --d-glyph: rgba(255, 255, 255, 0.5);
        --d-ours: var(--brand-azure);
        --d-ours-fill: rgba(71, 171, 255, 0.16);
    }
}
:root[data-theme="dark"] .cycle,
:root[data-theme="dark"] .ph {
    --d-line: rgba(255, 255, 255, 0.28);
    --d-box-stroke: rgba(255, 255, 255, 0.30);
    --d-glyph: rgba(255, 255, 255, 0.5);
    --d-ours: var(--brand-azure);
    --d-ours-fill: rgba(71, 171, 255, 0.16);
}

.cycle__pipe { fill: none; stroke: var(--d-line); stroke-width: 2; stroke-linecap: round; }
.cycle__heat { fill: none; stroke: var(--d-line); stroke-width: 2; stroke-linecap: round; }
.cycle__dashed { stroke-dasharray: 6 6; }
.cycle__arrowhead { fill: var(--d-line); }
.cycle__arrowhead--ours { fill: var(--d-ours); }

.cycle__box { fill: var(--d-box-fill); stroke: var(--d-box-stroke); stroke-width: 2; }
.cycle__box--ours { fill: var(--d-ours-fill); stroke: var(--d-ours); }
.cycle__glyph { fill: none; stroke: var(--d-glyph); stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
.cycle__glyph--fill { fill: var(--d-glyph); }
.cycle__glyph--ours { stroke: var(--d-ours); fill: var(--d-ours); }

.cycle__work { fill: none; stroke: var(--d-ours); stroke-width: 2; stroke-dasharray: 7 6; stroke-linecap: round; }

.cycle__label { fill: var(--d-text); font-size: 14px; font-weight: 600; text-anchor: middle; }
.cycle__label--ours { fill: var(--d-ours); }
.cycle__note { fill: var(--d-muted); font-size: 12px; text-anchor: middle; }
.cycle__side { fill: var(--d-muted); font-size: 11px; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; text-anchor: middle; }

/* P–h specifics */
.ph__dome { fill: none; stroke: var(--d-line); stroke-width: 1.5; stroke-dasharray: 2 5; stroke-linecap: round; }
.ph__points circle { fill: var(--d-text); }
.ph__point--ours { fill: var(--d-ours) !important; }
.ph__axis { text-anchor: start; }
.ph__axis--x { text-anchor: end; }
.ph__rot { text-anchor: start; }
.ph__left { text-anchor: start; }
.ph__right { text-anchor: end; }
.ph__gain { font-size: 12px; }

/* figure wrapper used on the technology page */
.diagram {
    padding: var(--space-m);
    border: var(--border-hairline);
    border-radius: var(--radius-m);
    background: var(--color-surface);
}
.diagram figcaption { margin-top: var(--space-s); font-size: var(--step--1); color: var(--color-muted); }

/* ─── FAQ accordion ─────────────────────────────────────────────────────────
   Native <details>, so it works without JS and every answer is in the DOM
   for search engines. build.mjs reads these pairs into FAQPage structured data. */

.faq { display: grid; gap: 0; margin-top: var(--space-m); border-top: var(--border-hairline); }
.faq__item { border-bottom: var(--border-hairline); }
.faq__item summary {
    cursor: pointer;
    padding: var(--space-s) 0;
    font-weight: 620;
    font-size: var(--step-0);
    list-style: none;
    display: flex;
    justify-content: space-between;
    gap: var(--space-s);
}
.faq__item summary::-webkit-details-marker { display: none; }
.faq__item summary::after { content: "+"; color: var(--color-accent); font-weight: 400; flex: none; }
.faq__item[open] summary::after { content: "–"; }
.faq__item summary:hover { color: var(--color-accent); }
.faq__a { padding-bottom: var(--space-m); color: var(--color-muted); max-width: 70ch; }
.faq__a p + p { margin-top: var(--space-xs); }

/* ─── site footer ───────────────────────────────────────────────────────── */

.site-footer {
    background: var(--color-inverse-bg);
    color: var(--color-inverse-text);
    padding-block: var(--space-xl) var(--space-l);
    margin-top: var(--space-2xl);
}

.site-footer__grid {
    display: grid;
    gap: var(--space-l);
    grid-template-columns: repeat(auto-fit, minmax(14rem, 1fr));
}

.site-footer__brand img { height: 2rem; width: auto; }

.site-footer__note {
    margin-top: var(--space-s);
    font-size: var(--step--1);
    color: var(--color-inverse-muted);
    max-width: 28ch;
}

.site-footer__heading {
    font-size: var(--step--1);
    text-transform: uppercase;
    letter-spacing: var(--tracking-wide);
    color: var(--color-inverse-muted);
    margin-bottom: var(--space-s);
    font-weight: 620;
}

.site-footer__list { list-style: none; padding: 0; display: grid; gap: var(--space-2xs); }

.site-footer a { color: #ffffff; text-decoration: none; }
.site-footer a:hover { color: var(--brand-azure); text-decoration: underline; }

.site-footer__address { font-style: normal; font-size: var(--step-0); color: var(--color-inverse-muted); }
.site-footer__address a { color: #ffffff; }

.site-footer__kvk {
    margin-top: var(--space-s);
    font-size: var(--step--1);
    color: var(--color-inverse-muted);
}

.site-footer .is-pending { color: var(--color-inverse-muted); }

/* ─── site header ───────────────────────────────────────────────────────── */

.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: var(--color-bg);                                  /* fallback first */
    background: color-mix(in srgb, var(--color-bg) 88%, transparent);
    backdrop-filter: blur(10px);
    border-bottom: var(--border-hairline);
}

.site-header__inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-m);
    min-height: 4.5rem;
}

.site-header__brand { display: flex; align-items: center; }
.site-header__logo { width: auto; height: 2rem; }

/* ─── nav ───────────────────────────────────────────────────────────────── */

.nav { display: flex; align-items: center; gap: var(--space-m); }

.nav__list {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
    list-style: none;
    padding: 0;
    margin: 0;
}

.nav__link {
    display: inline-block;
    padding: var(--space-2xs) var(--space-xs);
    border-radius: var(--radius-s);
    color: var(--color-text);
    text-decoration: none;
    font-size: var(--step--1);
    font-weight: 560;
    white-space: nowrap;
}

.nav__link:hover { color: var(--color-accent); background: var(--color-surface-2); }
.nav__link[aria-current="page"] { color: var(--color-accent); }

/* Pages that do not exist yet render as muted, non-interactive text rather than
   as links to a 404. Flip `built` to true in src/data/nav.json when each ships. */
.nav__link--pending,
.is-pending {
    color: var(--color-muted);
    cursor: default;
    opacity: 0.55;
}

.lang-switch {
    font-size: var(--step--1);
    font-weight: 620;
    text-decoration: none;
    padding: var(--space-3xs) var(--space-2xs);
    border: var(--border-hairline);
    border-radius: var(--radius-s);
    color: var(--color-muted);
    white-space: nowrap;
}
.lang-switch:hover { color: var(--color-accent); border-color: var(--color-accent); }

/* ─── mobile ────────────────────────────────────────────────────────────── */

.nav-toggle {
    display: none;
    align-items: center;
    gap: var(--space-2xs);
    background: none;
    border: var(--border-hairline);
    border-radius: var(--radius-s);
    padding: var(--space-2xs) var(--space-xs);
    cursor: pointer;
    font-size: var(--step--1);
}

.nav-toggle__bars { display: grid; gap: 3px; }
.nav-toggle__bars span {
    display: block;
    width: 16px;
    height: 2px;
    background: currentColor;
}

@media (max-width: 60rem) {
    .nav-toggle { display: inline-flex; }

    .nav {
        position: absolute;
        inset: 100% 0 auto 0;
        flex-direction: column;
        align-items: stretch;
        gap: var(--space-s);
        padding: var(--space-m) 1.25rem var(--space-l);
        background: var(--color-surface);
        border-bottom: var(--border-hairline);
        box-shadow: var(--shadow-m);
        display: none;
    }

    .nav[data-open="true"] { display: flex; }

    .nav__list { flex-direction: column; align-items: stretch; gap: 0; }
    .nav__link, .is-pending { display: block; padding: var(--space-xs) var(--space-2xs); font-size: var(--step-0); }
    .lang-switch { align-self: flex-start; }
}

/* ─── hero ──────────────────────────────────────────────────────────────── */

.hero {
    position: relative;
    background: var(--brand-navy);
    color: #ffffff;
    overflow: hidden;
    padding-block: var(--space-2xl) var(--space-2xl);
}

/* Engineered ground: a faint technical grid plus one azure glow behind the
   diagram. Both are CSS, so they cost nothing to download. */
.hero::before {
    content: "";
    position: absolute;
    inset: 0;
    background-image:
        linear-gradient(rgba(71, 171, 255, 0.055) 1px, transparent 1px),
        linear-gradient(90deg, rgba(71, 171, 255, 0.055) 1px, transparent 1px);
    background-size: 64px 64px;
    -webkit-mask-image: radial-gradient(ellipse 90% 70% at 50% 30%, #000 40%, transparent 100%);
    mask-image: radial-gradient(ellipse 90% 70% at 50% 30%, #000 40%, transparent 100%);
    pointer-events: none;
}

.hero::after {
    content: "";
    position: absolute;
    right: -10%;
    top: -20%;
    width: 60vw;
    aspect-ratio: 1;
    background: radial-gradient(circle, rgba(71, 171, 255, 0.20), transparent 62%);
    pointer-events: none;
}

.hero__inner {
    position: relative;
    z-index: 1;
    display: grid;
    gap: var(--space-xl);
    align-items: center;
    grid-template-columns: 1fr;
}

@media (min-width: 62rem) {
    .hero__inner { grid-template-columns: 1.05fr 1fr; gap: var(--space-2xl); }
}

.hero h1 { color: #ffffff; }

.hero__lede {
    margin-top: var(--space-m);
    font-size: var(--step-1);
    line-height: var(--leading-snug);
    color: #b9c8e0;
    max-width: 46ch;
}

.hero__claim {
    display: inline-flex;
    align-items: baseline;
    gap: 0.4em;
    margin-top: var(--space-l);
    padding: var(--space-2xs) var(--space-s);
    border: 1px solid var(--color-inverse-border);
    border-radius: 999px;
    font-size: var(--step--1);
    color: #cfe0f7;
}
.hero__claim strong { color: var(--brand-azure); font-size: var(--step-0); }

.hero__figure { position: relative; }
.hero__figure svg { width: 100%; height: auto; }

.hero__caption {
    margin-top: var(--space-s);
    font-size: var(--step--1);
    color: #8fa3c2;
    max-width: 42ch;
}

/* ─── photography ───────────────────────────────────────────────────────────
   Photos are always <picture> elements produced by the build from data-photo
   tags. These classes only decide where they sit and how they are framed.    */

.photo { border-radius: var(--radius-m); overflow: hidden; background: var(--color-surface-2); }
.photo img { width: 100%; height: auto; display: block; }

/* text beside one large photo and one tall one */
.photo-band { display: grid; gap: var(--space-l); align-items: center; }
@media (min-width: 60rem) { .photo-band { grid-template-columns: minmax(0, 1fr) minmax(0, 1.35fr); gap: var(--space-xl); } }
.photo-band__text .lede { margin-top: var(--space-s); }
.photo-band__text p + p { margin-top: var(--space-s); }

/* two photos side by side, sharing one row height. The <picture> wrapper the build emits
   is made a block so the image can fill the cell; landscape + portrait pairs use 2:1,
   two portraits use --equal so neither is cropped. */
.photo-duo { display: grid; grid-template-columns: minmax(0, 2fr) minmax(0, 1fr); gap: var(--space-s); align-items: stretch; }
.photo-duo--equal { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); }
.photo-duo .photo, .photo-duo .photo picture { height: 100%; display: block; }
.photo-duo .photo img { height: 100%; object-fit: cover; }

/* one edge-to-edge (within the wrap) photo with a caption */
.figure { margin: 0; }
.figure img { width: 100%; height: auto; border-radius: var(--radius-m); background: var(--color-surface-2); }
.figure figcaption { margin-top: var(--space-xs); font-size: var(--step--1); color: var(--color-muted); }

/* prose next to a figure on interior pages */
.prose-figure { display: grid; gap: var(--space-l); align-items: start; }
@media (min-width: 60rem) { .prose-figure { grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr); gap: var(--space-xl); } }
.prose-figure--flip > :first-child { order: 2; }
@media (min-width: 60rem) { .prose-figure--flip > :first-child { order: 0; } }

/* ─── team grid ─────────────────────────────────────────────────────────── */

.team {
    display: grid;
    gap: var(--space-l) var(--space-m);
    grid-template-columns: repeat(auto-fit, minmax(14rem, 1fr));
    padding: 0;
    list-style: none;
    margin-top: var(--space-l);
}
.team__member { scroll-margin-top: 6rem; }
.team__photo { border-radius: var(--radius-m); width: 100%; height: auto; }
.team__name { font-size: var(--step-1); margin-top: var(--space-s); }
.team__role { color: var(--color-accent); font-size: var(--step--1); font-weight: 620; margin-top: var(--space-3xs); }
.team__bio { color: var(--color-muted); font-size: var(--step--1); margin-top: var(--space-2xs); }
.team__link { display: inline-block; margin-top: var(--space-2xs); font-size: var(--step--1); }

/* the team teaser on the home page */
.team-teaser { display: grid; gap: var(--space-l); align-items: center; }
@media (min-width: 60rem) { .team-teaser { grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr); gap: var(--space-xl); } }

/* ─── interior page head ────────────────────────────────────────────────── */

.page-head {
    padding-block: var(--space-xl) var(--space-l);
    border-bottom: var(--border-hairline);
    background: var(--color-surface-2);
}

.page-head h1 { font-size: var(--step-5); }
.page-head .lede { margin-top: var(--space-m); max-width: 58ch; }

/* ─── prose bits used inside scaffolded sections ────────────────────────── */

.empty-state {
    padding: var(--space-l);
    border: 1px dashed var(--color-border);
    border-radius: var(--radius-m);
    color: var(--color-muted);
    text-align: center;
}

.contact-details {
    font-style: normal;
    font-size: var(--step-1);
    line-height: var(--leading-snug);
}

code {
    font-family: var(--font-mono);
    font-size: 0.9em;
    background: var(--color-surface-2);
    padding: 0.1em 0.35em;
    border-radius: var(--radius-s);
}

/* ─── TODO block ────────────────────────────────────────────────────────────
   Deliberately loud. These mark sections that are scaffolded but not written,
   and the build refuses to produce a production bundle while any remain — so
   this can never be the thing a visitor sees.                                */

.todo-block {
    border: 1px dashed var(--color-accent);
    border-left-width: 4px;
    border-left-style: solid;
    border-radius: var(--radius-s);
    background: color-mix(in srgb, var(--color-accent) 7%, transparent);
    padding: var(--space-s) var(--space-m);
    color: var(--color-text);
    font-size: var(--step--1);
}

.todo-block p { margin: 0; }

.todo-block__tag {
    display: inline-block;
    margin-right: var(--space-2xs);
    padding: 0.1em 0.5em;
    border-radius: var(--radius-s);
    background: var(--color-accent);
    color: var(--color-on-accent);
    font-family: var(--font-mono);
    font-size: 0.8em;
    font-weight: 700;
    letter-spacing: 0.06em;
    vertical-align: 0.08em;
}