/* ============================================================
   DT Street — Colours, type, and layout
   Minimal palette, hairline rules, Inter + IBM Plex Mono.
   British English in copy. No gradients. No decorative colour.
   ============================================================ */

@font-face {
  font-family: "Inter";
  src: url("./fonts/inter-400.woff2") format("woff2");
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "Inter";
  src: url("./fonts/inter-500.woff2") format("woff2");
  font-weight: 500;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "Inter";
  src: url("./fonts/inter-600.woff2") format("woff2");
  font-weight: 600;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "IBM Plex Mono";
  src: url("./fonts/plex-mono-400.woff2") format("woff2");
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "IBM Plex Mono";
  src: url("./fonts/plex-mono-500.woff2") format("woff2");
  font-weight: 500;
  font-style: normal;
  font-display: swap;
}

:root {
  --bg:               #FFFFFF;
  --fg-1:             #0E1219;
  --fg-2:             #3A4250;
  --fg-3:             #6B7280;
  --fg-4:             #9AA1AC;
  --accent:           #1B3A5C;
  --accent-hover:     #14304E;
  --rule:             #E5E7EB;
  --rule-strong:      #C9CDD3;
  --field-border:     #C9CDD3;
  --field-border-hover: #9AA1AC;
  --field-border-focus: var(--accent);
  --field-error:      #B0263A;
  --selection-bg:     #1B3A5C;
  --selection-fg:     #FFFFFF;

  --font-sans:        "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  --font-mono:        "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;

  --w-regular:        400;
  --w-medium:         500;
  --w-semibold:       600;

  --fs-display:       44px;
  --fs-h1:            32px;
  --fs-h2:            22px;
  --fs-h3:            17px;
  --fs-body:          16px;
  --fs-small:         14px;
  --fs-micro:         12px;

  --lh-tight:         1.15;
  --lh-snug:          1.3;
  --lh-normal:        1.55;

  --tr-tight:         -0.015em;
  --tr-eyebrow:       0.12em;

  --container-max:    1120px;
  --container-pad:    32px;
  --container-pad-sm: 20px;

  --section-y:        96px;

  --border-w:         1px;
  --radius-input:     2px;

  --ease:             cubic-bezier(0.22, 0.61, 0.36, 1);
  --dur-fast:         140ms;
  --dur-base:         260ms;
  --dur-slow:         600ms;
}

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

html {
  background: var(--bg);
  color: var(--fg-1);
  font-family: var(--font-sans);
  font-size: var(--fs-body);
  line-height: var(--lh-normal);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  font-feature-settings: "ss01", "cv11";
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg-2);
  font-weight: var(--w-regular);
}

::selection {
  background: var(--selection-bg);
  color: var(--selection-fg);
}

h1, h2, h3, h4, h5, h6 {
  margin: 0;
  color: var(--fg-1);
  font-weight: var(--w-semibold);
  line-height: var(--lh-tight);
  letter-spacing: var(--tr-tight);
}

h1 { font-size: var(--fs-display); }
h2 { font-size: var(--fs-h1); }
h3 { font-size: var(--fs-h2); font-weight: var(--w-medium); }
h4 { font-size: var(--fs-h3); font-weight: var(--w-medium); }

.eyebrow {
  font-size: var(--fs-micro);
  font-weight: var(--w-medium);
  letter-spacing: var(--tr-eyebrow);
  text-transform: uppercase;
  color: var(--fg-3);
}

p {
  margin: 0;
  color: var(--fg-2);
  font-size: var(--fs-body);
  line-height: var(--lh-normal);
  text-wrap: pretty;
}

small, .small {
  font-size: var(--fs-small);
  line-height: var(--lh-normal);
  color: var(--fg-3);
}

.fineprint {
  font-size: var(--fs-micro);
  line-height: var(--lh-normal);
  color: var(--fg-3);
}

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease);
}
a:hover {
  color: var(--accent-hover);
  border-bottom-color: currentColor;
}
a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

code, kbd, samp, .mono {
  font-family: var(--font-mono);
  font-size: 0.92em;
  font-weight: var(--w-regular);
  letter-spacing: 0;
}

hr, .rule {
  border: 0;
  border-top: var(--border-w) solid var(--rule);
  margin: 0;
}

.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding-inline: var(--container-pad);
}

.section {
  padding-block: var(--section-y);
  border-bottom: var(--border-w) solid var(--rule);
}
.section:last-of-type { border-bottom: 0; }

.fade-in {
  opacity: 0;
  transform: translateY(8px);
  transition: opacity var(--dur-slow) var(--ease), transform var(--dur-slow) var(--ease);
  will-change: opacity, transform;
}
.fade-in.is-visible {
  opacity: 1;
  transform: none;
}

@media (prefers-reduced-motion: reduce) {
  .fade-in { opacity: 1; transform: none; transition: none; }
  * { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
}

@media (max-width: 640px) {
  :root {
    --fs-display: 32px;
    --fs-h1:      24px;
    --fs-h2:      19px;
    --section-y:  64px;
    --container-pad: var(--container-pad-sm);
  }
}

/* ---------- Site shell ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: saturate(140%) blur(8px);
  -webkit-backdrop-filter: saturate(140%) blur(8px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--dur-base) var(--ease);
}
.site-header[data-scrolled] {
  border-bottom-color: var(--rule);
}
.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.site-header__brand {
  display: inline-flex;
  align-items: center;
  border-bottom: 0;
}
.site-header__brand:hover { border-bottom: 0; }
.site-header__nav {
  display: flex;
  align-items: center;
  gap: 32px;
}
.site-header__nav a {
  color: var(--fg-1);
  font-size: var(--fs-small);
  font-weight: 500;
  border-bottom: 1px solid transparent;
  transition: color var(--dur-fast) var(--ease), border-color var(--dur-fast) var(--ease);
}
.site-header__nav a:hover {
  color: var(--accent);
  border-bottom-color: currentColor;
}

/* ---------- Wordmark (Concept A — plain with accent pip) ---------- */
.wm {
  display: inline-flex;
  align-items: baseline;
  gap: 0;
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 16px;
  letter-spacing: -0.01em;
  color: var(--fg-1);
  line-height: 1;
  white-space: nowrap;
}
.wm__dt { letter-spacing: -0.02em; }
.wm__pip {
  display: inline-block;
  width: 5px; height: 5px;
  background: var(--accent);
  margin: 0 6px;
  position: relative;
  top: -1px;
  flex: none;
}
.wm__street { letter-spacing: 0.01em; }

.site-footer .wm { font-size: 18px; }
.site-footer .wm__pip { width: 6px; height: 6px; }

/* ---------- Hero ---------- */
.hero {
  padding-block: 128px 112px;
  border-bottom: 1px solid var(--rule);
  position: relative;
  overflow: hidden;
}
.hero__inner {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  gap: 32px;
}
.hero__headline {
  font-size: 64px;
  line-height: 1.06;
  letter-spacing: -0.025em;
  font-weight: 600;
  max-width: 18ch;
  position: relative;
  z-index: 2;
}
.hero__lead {
  font-size: 20px;
  line-height: 1.55;
  color: var(--fg-2);
  max-width: 56ch;
  font-weight: 400;
  position: relative;
  z-index: 2;
}
.hero__eyebrow { z-index: 2; position: relative; }

.hero__backdrop {
  position: absolute;
  top: 0;
  bottom: 0;
  right: -2%;
  width: 70%;
  max-width: 1000px;
  pointer-events: none;
  z-index: 0;
  -webkit-mask-image: linear-gradient(to right, transparent 0%, rgba(0,0,0,0.5) 18%, black 50%);
  mask-image: linear-gradient(to right, transparent 0%, rgba(0,0,0,0.5) 18%, black 50%);
}
.hero__backdrop img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  object-position: center center;
  display: block;
  opacity: 0.9;
}

.hero__cta {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--accent);
  font-size: 16px;
  font-weight: 500;
  border-bottom: 1px solid transparent;
  width: fit-content;
  padding-bottom: 2px;
  margin-top: 8px;
  z-index: 2;
  transition: color var(--dur-fast) var(--ease), border-color var(--dur-fast) var(--ease);
}
.hero__cta:hover {
  color: var(--accent-hover);
  border-bottom-color: currentColor;
}
.hero__cta-arrow {
  display: inline-block;
  width: 18px;
  height: 10px;
  flex: none;
  color: currentColor;
  transition: transform var(--dur-fast) var(--ease);
}
.hero__cta:hover .hero__cta-arrow { transform: translateX(2px); }

@media (max-width: 820px) {
  .hero { padding-block: 80px 64px; }
  .hero__headline { font-size: 36px; }
  .hero__lead { font-size: 18px; }
  .hero__backdrop {
    width: 100%;
    height: 70%;
    opacity: 0.45;
    -webkit-mask-image: linear-gradient(to bottom, transparent 0%, black 30%, black 70%, transparent 100%);
    mask-image: linear-gradient(to bottom, transparent 0%, black 30%, black 70%, transparent 100%);
  }
}

/* ---------- Section header ---------- */
.section-header {
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-width: 56ch;
  margin-bottom: 56px;
}
.section-header h2 {
  font-size: 32px;
  letter-spacing: -0.015em;
  line-height: 1.15;
}
.section-header__intro {
  font-size: 18px;
  line-height: 1.55;
  color: var(--fg-2);
  max-width: 64ch;
  margin-top: 4px;
}

/* ---------- What we do ---------- */
.what-we-do__grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0;
  border-top: 1px solid var(--rule);
}
.discipline {
  padding: 32px 32px 8px 0;
  border-right: 1px solid var(--rule);
  display: flex;
  flex-direction: column;
  gap: 14px;
}
.discipline:last-child { border-right: 0; padding-right: 0; }
.discipline:not(:first-child) { padding-left: 32px; }
.discipline__heading { font-size: 18px; font-weight: 500; line-height: 1.3; color: var(--fg-1); }
.discipline__body { color: var(--fg-2); font-size: 15px; line-height: 1.65; }
@media (max-width: 820px) {
  .what-we-do__grid { grid-template-columns: 1fr; }
  .discipline {
    border-right: 0;
    border-bottom: 1px solid var(--rule);
    padding: 28px 0;
  }
  .discipline:not(:first-child) { padding-left: 0; }
  .discipline:last-child { border-bottom: 0; }
}

/* ---------- About ---------- */
.about__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.6fr);
  gap: 48px 80px;
}
.about__header { display: flex; flex-direction: column; gap: 16px; }
.about__header h2 {
  font-size: 32px;
  letter-spacing: -0.015em;
  line-height: 1.15;
  max-width: 14ch;
}
.about__body { display: flex; flex-direction: column; gap: 24px; max-width: 64ch; }
.about__body p {
  font-size: 17px;
  line-height: 1.7;
  color: var(--fg-1);
}
.about__body p + p { color: var(--fg-2); }
@media (max-width: 820px) {
  .about__grid { grid-template-columns: 1fr; gap: 32px; }
}

/* ---------- Contact ---------- */
.contact__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.2fr);
  gap: 48px 80px;
}
.contact__header { display: flex; flex-direction: column; gap: 16px; max-width: 36ch; }
.contact__header h2 {
  font-size: 32px;
  letter-spacing: -0.015em;
  line-height: 1.15;
}
.contact__intro { color: var(--fg-2); font-size: 17px; line-height: 1.6; }
.contact__meta {
  margin-top: 24px;
  padding-top: 24px;
  border-top: 1px solid var(--rule);
  font-size: 14px;
  color: var(--fg-3);
  line-height: 1.6;
}

.contact-form { display: flex; flex-direction: column; gap: 18px; max-width: 520px; }
.field { display: flex; flex-direction: column; gap: 6px; }
.field__label {
  font-size: 14px;
  font-weight: 500;
  color: var(--fg-1);
}
.field__control {
  appearance: none;
  -webkit-appearance: none;
  font: inherit;
  font-size: 16px;
  color: var(--fg-1);
  background: var(--bg);
  border: 1px solid var(--field-border);
  border-radius: var(--radius-input);
  padding: 12px 14px;
  outline: none;
  transition: border-color var(--dur-fast) var(--ease);
  width: 100%;
  resize: vertical;
  font-family: var(--font-sans);
}
.field__control:hover { border-color: var(--field-border-hover); }
.field__control:focus { border-color: var(--field-border-focus); }
.field__control[aria-invalid="true"] { border-color: var(--field-error); }
.field__error {
  font-size: 12px;
  color: var(--field-error);
  min-height: 1em;
}

.field__honeypot {
  position: absolute;
  left: -9999px;
  width: 1px;
  height: 1px;
  overflow: hidden;
}

.contact-form__actions { padding-top: 4px; }
.contact-form__error {
  color: var(--field-error);
  font-size: 14px;
  line-height: 1.5;
  min-height: 1em;
}

.btn {
  appearance: none;
  font: inherit;
  font-size: 16px;
  font-weight: 500;
  color: #fff;
  background: var(--accent);
  border: 1px solid var(--accent);
  padding: 12px 22px;
  border-radius: var(--radius-input);
  cursor: pointer;
  transition: background var(--dur-fast) var(--ease), border-color var(--dur-fast) var(--ease);
}
.btn:hover { background: var(--accent-hover); border-color: var(--accent-hover); }
.btn:disabled { opacity: 0.55; cursor: default; }

.contact__success {
  font-size: 19px;
  color: var(--fg-1);
  padding: 12px 0;
  line-height: 1.5;
}

@media (max-width: 820px) {
  .contact__grid { grid-template-columns: 1fr; gap: 32px; }
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--rule);
  padding-top: 64px;
  padding-bottom: 32px;
  background: var(--bg);
}
.site-footer__inner {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr) minmax(0, 1fr);
  gap: 48px;
  padding-bottom: 56px;
}
.site-footer__col { display: flex; flex-direction: column; gap: 14px; }
.site-footer__wordmark { display: block; margin-bottom: 4px; }
.site-footer__tag {
  font-size: 14px;
  color: var(--fg-2);
  max-width: 32ch;
  line-height: 1.55;
}
.site-footer__eyebrow { color: var(--fg-3); margin-bottom: 4px; }
.site-footer__address {
  font-style: normal;
  font-size: 14px;
  color: var(--fg-2);
  line-height: 1.7;
}
.site-footer__list {
  list-style: none;
  margin: 0; padding: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
  font-size: 14px;
  color: var(--fg-2);
  line-height: 1.55;
}
.site-footer__rule { border-top: 1px solid var(--rule); }
.site-footer__base {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 24px;
}
.site-footer__base a { color: var(--fg-3); }
.site-footer__base a:hover { color: var(--accent); }
@media (max-width: 820px) {
  .site-footer__inner { grid-template-columns: 1fr; gap: 32px; }
  .site-footer__base { flex-direction: column; gap: 8px; align-items: flex-start; }
}

/* ---------- Privacy page ---------- */
.privacy { padding-block: 96px; }
.privacy__inner { max-width: 64ch; }
.privacy h1 { font-size: 32px; letter-spacing: -0.015em; line-height: 1.15; margin-bottom: 24px; }
.privacy h2 {
  font-size: 19px;
  font-weight: 500;
  letter-spacing: -0.005em;
  margin-top: 40px;
  margin-bottom: 12px;
  color: var(--fg-1);
}
.privacy p { font-size: 16px; line-height: 1.7; color: var(--fg-2); margin-bottom: 16px; }
.privacy .eyebrow { display: block; margin-bottom: 16px; }
.privacy__back {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  font-size: 14px;
  margin-bottom: 48px;
  color: var(--fg-3);
  border-bottom: 1px solid transparent;
}
.privacy__back:hover { color: var(--accent); }
.privacy__meta {
  font-size: 13px;
  color: var(--fg-3);
  margin-top: 56px;
  padding-top: 24px;
  border-top: 1px solid var(--rule);
}