/* ============================================================
   TDD — clean engineering-notebook design system
   Paper canvas, white cards, blue marker accent, mono eyebrows.
   Prefix: .tdd- (avoid Tailwind-utility collisions).
   ============================================================ */

@import url("https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800;900&family=JetBrains+Mono:wght@400;500;600&display=swap");

:root {
  /* Canvas & surfaces */
  --tdd-bg: #f7f7f8;
  --tdd-surface: #ffffff;
  --tdd-surface-hover: #fafafa;

  /* Ink */
  --tdd-ink: #1a1a2e;
  --tdd-ink-2: #4b5160;
  --tdd-ink-3: #6b7280;
  --tdd-ink-4: #9ca3af;
  --tdd-ink-ghost: #d1d5db;

  /* Marker accents (subdued, professional) */
  --tdd-blue: #2563eb;
  --tdd-blue-700: #1d4ed8;
  --tdd-blue-100: #dbeafe;
  --tdd-blue-50: #eff6ff;

  --tdd-red: #dc2626;
  --tdd-red-100: #fee2e2;

  --tdd-green: #16a34a;
  --tdd-green-100: #dcfce7;

  --tdd-orange: #ea580c;
  --tdd-orange-100: #fff7ed;

  --tdd-violet: #7c3aed;
  --tdd-violet-100: #ede9fe;

  /* Borders & grid */
  --tdd-border: #eceef2;
  --tdd-border-strong: #e5e7eb;
  --tdd-dot: #e5e7eb;

  /* Radii */
  --tdd-r-sm: 6px;
  --tdd-r: 10px;
  --tdd-r-lg: 14px;
  --tdd-r-xl: 20px;

  /* Shadows */
  --tdd-shadow-1: 0 1px 2px rgba(15, 23, 42, 0.04);
  --tdd-shadow-2: 0 2px 8px rgba(15, 23, 42, 0.05);
  --tdd-shadow-3: 0 8px 28px rgba(15, 23, 42, 0.08);

  /* Type */
  --tdd-sans: "Inter", ui-sans-serif, system-ui, -apple-system,
    "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --tdd-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas,
    monospace;
}

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

html {
  -webkit-text-size-adjust: 100%;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body.tdd {
  margin: 0;
  min-height: 100vh;
  font-family: var(--tdd-sans);
  font-size: 16px;
  line-height: 1.55;
  color: var(--tdd-ink);
  background-color: var(--tdd-bg);
  background-image: radial-gradient(var(--tdd-dot) 1px, transparent 1px);
  background-size: 24px 24px;
  background-position: 0 0;
  letter-spacing: -0.002em;
}

body.tdd a:where(:not(.tdd-btn):not(.tdd-pill):not(.sp-email-btn):not(.tdd-brand):not(.nl__button)) {
  color: var(--tdd-blue);
  text-decoration: none;
}

body.tdd a:where(:not(.tdd-btn):not(.tdd-pill):not(.sp-email-btn):not(.tdd-brand):not(.nl__button)):hover {
  color: var(--tdd-blue-700);
}

body.tdd img,
body.tdd svg {
  display: block;
  max-width: 100%;
}

body.tdd ::selection {
  background: var(--tdd-blue-100);
  color: var(--tdd-ink);
}

/* ----------------------------- layout */
.tdd-container {
  width: 100%;
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 clamp(20px, 4vw, 32px);
  position: relative;
}

.tdd-section {
  padding: clamp(56px, 9vw, 112px) 0;
  position: relative;
}

/* ----------------------------- typography */
.tdd-eyebrow {
  font-family: var(--tdd-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--tdd-ink-3);
}

.tdd-eyebrow--blue {
  color: var(--tdd-blue);
}

.tdd-display {
  font-family: var(--tdd-sans);
  font-weight: 800;
  font-size: clamp(44px, 7.5vw, 96px);
  line-height: 0.96;
  letter-spacing: -0.028em;
  color: var(--tdd-ink);
  margin: 0;
}

.tdd-h1 {
  font-family: var(--tdd-sans);
  font-weight: 800;
  font-size: clamp(34px, 4.4vw, 56px);
  line-height: 1.02;
  letter-spacing: -0.022em;
  color: var(--tdd-ink);
  margin: 0;
}

.tdd-h2 {
  font-family: var(--tdd-sans);
  font-weight: 700;
  font-size: clamp(22px, 2vw, 28px);
  line-height: 1.2;
  letter-spacing: -0.015em;
  color: var(--tdd-ink);
  margin: 0;
}

.tdd-h3 {
  font-family: var(--tdd-sans);
  font-weight: 700;
  font-size: 18px;
  line-height: 1.3;
  letter-spacing: -0.01em;
  color: var(--tdd-ink);
  margin: 0;
}

.tdd-lede {
  font-size: clamp(17px, 1.4vw, 20px);
  line-height: 1.55;
  color: var(--tdd-ink-2);
  max-width: 52ch;
  margin: 0;
}

.tdd-body {
  font-size: 15px;
  line-height: 1.6;
  color: var(--tdd-ink-2);
  margin: 0;
}

.tdd-accent {
  color: var(--tdd-blue);
}

.tdd-muted {
  color: var(--tdd-ink-3);
}

/* ----------------------------- buttons */
.tdd-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-family: var(--tdd-sans);
  font-weight: 600;
  font-size: 15px;
  line-height: 1;
  padding: 13px 18px;
  border-radius: var(--tdd-r);
  border: 1.5px solid transparent;
  cursor: pointer;
  transition: background 0.15s ease, border-color 0.15s ease,
    color 0.15s ease, transform 0.08s ease, box-shadow 0.15s ease;
  white-space: nowrap;
  text-decoration: none;
}

.tdd-btn:active {
  transform: translateY(1px);
}

.tdd-btn--primary {
  background: var(--tdd-blue);
  color: #fff;
  border-color: var(--tdd-blue);
  box-shadow: 0 1px 0 rgba(37, 99, 235, 0.2),
    0 1px 3px rgba(37, 99, 235, 0.24);
}

.tdd-btn--primary:hover {
  background: var(--tdd-blue-700);
  border-color: var(--tdd-blue-700);
  color: #fff;
}

.tdd-btn--secondary {
  background: var(--tdd-surface);
  color: var(--tdd-ink);
  border-color: var(--tdd-border-strong);
}

.tdd-btn--secondary:hover {
  background: var(--tdd-surface-hover);
  border-color: var(--tdd-ink-4);
  color: var(--tdd-ink);
}

.tdd-btn--ghost {
  background: transparent;
  color: var(--tdd-ink-2);
  border-color: transparent;
  padding: 8px 10px;
}

.tdd-btn--ghost:hover {
  color: var(--tdd-ink);
  background: rgba(15, 23, 42, 0.04);
}

.tdd-btn--sm {
  font-size: 13.5px;
  padding: 9px 14px;
}

.tdd-btn__arrow {
  transition: transform 0.2s ease;
}

.tdd-btn:hover .tdd-btn__arrow {
  transform: translateX(3px);
}

/* ----------------------------- pills / tags */
.tdd-pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--tdd-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 4px 10px;
  border-radius: var(--tdd-r-sm);
  background: var(--tdd-blue-100);
  color: var(--tdd-blue);
  line-height: 1.4;
}

.tdd-pill--blue {
  background: var(--tdd-blue-100);
  color: var(--tdd-blue);
}

.tdd-pill--red {
  background: var(--tdd-red-100);
  color: var(--tdd-red);
}

.tdd-pill--green {
  background: var(--tdd-green-100);
  color: var(--tdd-green);
}

.tdd-pill--orange {
  background: var(--tdd-orange-100);
  color: var(--tdd-orange);
}

.tdd-pill--violet {
  background: var(--tdd-violet-100);
  color: var(--tdd-violet);
}

.tdd-pill--ghost {
  background: transparent;
  color: var(--tdd-ink-3);
  border: 1px solid var(--tdd-border-strong);
}

.tdd-dot {
  width: 6px;
  height: 6px;
  border-radius: 999px;
  background: currentColor;
  display: inline-block;
}

/* ----------------------------- card */
.tdd-card {
  background: var(--tdd-surface);
  border: 1px solid var(--tdd-border);
  border-radius: var(--tdd-r-lg);
  box-shadow: var(--tdd-shadow-1);
  padding: clamp(20px, 2.4vw, 28px);
  position: relative;
  transition: border-color 0.15s ease, box-shadow 0.2s ease,
    transform 0.2s ease;
}

.tdd-card--link {
  display: flex;
  flex-direction: column;
  text-decoration: none;
  color: inherit;
}

.tdd-card--link:hover {
  border-color: var(--tdd-border-strong);
  box-shadow: var(--tdd-shadow-3);
  transform: translateY(-2px);
  color: inherit;
}

.tdd-card--muted {
  background: var(--tdd-surface-hover);
  border-style: dashed;
}

.tdd-card__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 14px;
}

.tdd-card__eyebrow {
  font-family: var(--tdd-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--tdd-ink-3);
}

.tdd-card__title {
  font-size: 22px;
  font-weight: 700;
  line-height: 1.18;
  letter-spacing: -0.015em;
  color: var(--tdd-ink);
  margin: 0 0 10px;
}

.tdd-card__body {
  font-size: 14.5px;
  line-height: 1.6;
  color: var(--tdd-ink-2);
  margin: 0;
  flex: 1;
}

.tdd-card__footer {
  margin-top: 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  font-family: var(--tdd-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--tdd-ink);
  font-weight: 600;
}

.tdd-card--link .tdd-card__arrow {
  transition: transform 0.2s ease;
  font-size: 16px;
  color: var(--tdd-blue);
}

.tdd-card--link:hover .tdd-card__arrow {
  transform: translateX(4px);
}

/* ----------------------------- grids */
.tdd-grid-3 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
}

.tdd-grid-2 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 20px;
}

.tdd-stack {
  display: grid;
  gap: 12px;
}

.tdd-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
}

/* ----------------------------- nav */
.tdd-nav {
  position: sticky;
  top: 0;
  z-index: 30;
  backdrop-filter: saturate(140%) blur(10px);
  -webkit-backdrop-filter: saturate(140%) blur(10px);
  background: rgba(247, 247, 248, 0.75);
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s ease, background 0.2s ease;
}

.tdd-nav.is-scrolled {
  border-bottom-color: var(--tdd-border);
  background: rgba(247, 247, 248, 0.9);
}

.tdd-nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 14px 0;
}

.tdd-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--tdd-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--tdd-ink);
  text-decoration: none;
}

.tdd-brand__mark {
  width: 26px;
  height: 26px;
  display: inline-grid;
  place-items: center;
  background: var(--tdd-ink);
  color: #fff;
  border-radius: 7px;
  font-family: var(--tdd-sans);
  font-weight: 800;
  font-size: 14px;
  letter-spacing: 0;
}

.tdd-nav__links {
  display: flex;
  align-items: center;
  gap: 6px;
}

.tdd-nav__links a:where(:not(.tdd-btn)) {
  color: var(--tdd-ink-2);
  font-size: 14px;
  font-weight: 500;
  padding: 8px 12px;
  border-radius: 8px;
  text-decoration: none;
  transition: color 0.15s ease, background 0.15s ease;
}

.tdd-nav__links a:where(:not(.tdd-btn)):hover {
  color: var(--tdd-ink);
  background: rgba(15, 23, 42, 0.04);
}

.tdd-nav__links a.tdd-btn {
  padding: 9px 14px;
}

@media (max-width: 640px) {
  .tdd-nav__links a:not(.tdd-btn) {
    display: none;
  }
}

/* ----------------------------- section head */
.tdd-section-head {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
  margin-bottom: clamp(28px, 4vw, 44px);
  max-width: 820px;
}

.tdd-section-head__meta {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--tdd-ink-3);
}

.tdd-section-head__meta::before {
  content: "";
  width: 22px;
  height: 1.5px;
  background: var(--tdd-ink-4);
}

.tdd-section-head__sub {
  font-size: 16px;
  line-height: 1.55;
  color: var(--tdd-ink-3);
  max-width: 62ch;
  margin: 0;
}

/* ----------------------------- stat block */
.tdd-stat {
  display: grid;
  gap: 4px;
  padding: 14px 16px;
  background: var(--tdd-surface);
  border: 1px solid var(--tdd-border);
  border-radius: var(--tdd-r);
}

.tdd-stat__label {
  font-family: var(--tdd-mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--tdd-ink-3);
}

.tdd-stat__value {
  font-weight: 700;
  font-size: 20px;
  letter-spacing: -0.02em;
  color: var(--tdd-ink);
}

/* ----------------------------- footer */
.tdd-footer {
  border-top: 1px solid var(--tdd-border);
  padding: 40px 0 56px;
  background: transparent;
}

.tdd-footer__inner {
  display: flex;
  justify-content: flex-end;
  align-items: center;
  gap: 20px;
  flex-wrap: wrap;
}

.tdd-footer__inner:has(.tdd-footer__brand) {
  justify-content: space-between;
}

.tdd-footer__brand {
  color: var(--tdd-ink-3);
  font-size: 13px;
}

.tdd-footer__links {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
}

.tdd-footer__links a {
  color: var(--tdd-ink-3);
  font-size: 13px;
  text-decoration: none;
}

.tdd-footer__links a:hover {
  color: var(--tdd-ink);
}

/* ----------------------------- ghost diagram (right rail residue) */
.tdd-ghost {
  position: absolute;
  inset: 0;
  pointer-events: none;
  opacity: 0.85;
  overflow: hidden;
  mask-image: linear-gradient(
    to bottom,
    black 0%,
    black 65%,
    transparent 100%
  );
  -webkit-mask-image: linear-gradient(
    to bottom,
    black 0%,
    black 65%,
    transparent 100%
  );
}

.tdd-ghost svg {
  position: absolute;
  right: -40px;
  top: 20px;
  width: clamp(320px, 40vw, 560px);
  height: auto;
  opacity: 0.11;
}

@media (max-width: 900px) {
  .tdd-ghost {
    display: none;
  }
}

/* ----------------------------- fades / reveal */
@keyframes tdd-fade-up {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

.tdd-reveal {
  animation: tdd-fade-up 0.6s cubic-bezier(0.2, 0.7, 0.2, 1) both;
}

.tdd-stagger-1 {
  animation-delay: 0.02s;
}
.tdd-stagger-2 {
  animation-delay: 0.1s;
}
.tdd-stagger-3 {
  animation-delay: 0.2s;
}
.tdd-stagger-4 {
  animation-delay: 0.3s;
}
.tdd-stagger-5 {
  animation-delay: 0.4s;
}

/* ----------------------------- Beehiiv widget override (.nl-)
   Newsletter.js renders hardcoded `.nl / .nl__*` classes.
   Override whiteboard's rough style to match this clean system. */
body.tdd .nl {
  font-family: var(--tdd-sans);
  color: var(--tdd-ink);
}

body.tdd .nl__eyebrow {
  font-family: var(--tdd-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--tdd-ink-3);
  margin-bottom: 10px;
}

body.tdd .nl__headline {
  font-family: var(--tdd-sans);
  font-weight: 800;
  letter-spacing: -0.022em;
  color: var(--tdd-ink);
  line-height: 1.05;
  margin: 0 0 10px;
}

body.tdd .nl__sub {
  color: var(--tdd-ink-3);
  font-size: 16px;
  line-height: 1.55;
  margin: 0 0 20px;
  max-width: 54ch;
}

body.tdd .nl__form {
  display: flex;
  gap: 10px;
  align-items: stretch;
  flex-wrap: wrap;
  max-width: 520px;
}

body.tdd .nl__input {
  flex: 1 1 240px;
  min-width: 0;
  background: var(--tdd-surface);
  border: 1.5px solid var(--tdd-border-strong);
  border-radius: var(--tdd-r);
  padding: 12px 14px;
  font-family: var(--tdd-sans);
  font-size: 15px;
  color: var(--tdd-ink);
  outline: none;
  transition: border-color 0.12s ease, box-shadow 0.12s ease;
  box-shadow: none;
}

body.tdd .nl__input::placeholder {
  color: var(--tdd-ink-4);
  font-family: var(--tdd-sans);
  font-size: 15px;
}

body.tdd .nl__input:focus {
  border-color: var(--tdd-blue);
  box-shadow: 0 0 0 4px var(--tdd-blue-50);
}

body.tdd .nl__button {
  cursor: pointer;
  background: var(--tdd-blue);
  color: #fff;
  border: 1.5px solid var(--tdd-blue);
  border-radius: var(--tdd-r);
  padding: 12px 18px;
  font-family: var(--tdd-sans);
  font-weight: 600;
  font-size: 15px;
  box-shadow: 0 1px 3px rgba(37, 99, 235, 0.24);
  transition: background 0.15s ease, border-color 0.15s ease,
    transform 0.08s ease;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  white-space: nowrap;
}

body.tdd .nl__button:hover {
  background: var(--tdd-blue-700);
  border-color: var(--tdd-blue-700);
}

body.tdd .nl__button:active {
  transform: translateY(1px);
}

body.tdd .nl__button[disabled] {
  opacity: 0.7;
  cursor: wait;
}

body.tdd .nl__button .arrow {
  transition: transform 0.2s ease;
}

body.tdd .nl__button:hover .arrow {
  transform: translateX(3px);
}

body.tdd .nl__note {
  margin-top: 10px;
  font-family: var(--tdd-sans);
  font-size: 12.5px;
  letter-spacing: 0;
  color: var(--tdd-ink-3);
  text-transform: none;
}

body.tdd .nl__terms {
  margin-top: 6px;
  font-family: var(--tdd-sans);
  font-size: 11.5px;
  color: var(--tdd-ink-4);
  line-height: 1.55;
}

body.tdd .nl__terms a {
  color: var(--tdd-ink-3);
  text-decoration: underline;
  text-underline-offset: 2px;
}

body.tdd .nl__terms a:hover {
  color: var(--tdd-ink);
}

body.tdd .nl__msg {
  margin-top: 12px;
  font-family: var(--tdd-sans);
  font-size: 14px;
  color: var(--tdd-green);
  min-height: 20px;
}

body.tdd .nl__msg--error {
  color: var(--tdd-red);
}

body.tdd .nl--hero .nl__headline,
body.tdd .nl--inline .nl__headline {
  /* Hidden by landing page inline style (we render our own head above the widget) */
}

body.tdd .nl--inline {
  background: var(--tdd-surface);
  border: 1px solid var(--tdd-border);
  border-radius: var(--tdd-r-lg);
  padding: 28px;
  box-shadow: var(--tdd-shadow-1);
}

body.tdd .nl--inline::after {
  display: none;
}

body.tdd .nl--compact {
  background: var(--tdd-blue-50);
  border: 1px solid var(--tdd-blue-100);
  border-radius: var(--tdd-r-lg);
  padding: 20px 24px;
  box-shadow: none;
}

body.tdd .nl__success-mark {
  color: var(--tdd-green);
}

@media (max-width: 560px) {
  body.tdd .nl__form {
    flex-direction: column;
    flex-wrap: nowrap;
  }
  body.tdd .nl__input,
  body.tdd .nl__button {
    flex: 0 0 auto;
    width: 100%;
  }
}