/* ============================================================
   WhereIWas — design system
   Field instrument. Navy ink on cold paper, pin green from the app icon.
   ============================================================ */

/* Fonts are served from this repo, not from Google: a page that promises
   nothing leaves your device should not hand a visitor's IP to a third
   party to render itself. Latin and Latin-Extended subsets only — the site
   is English. */
/* Archivo · latin-ext · self-hosted, no third-party request */
@font-face {
  font-family: 'Archivo';
  font-style: normal;
  font-weight: 400 700;
  font-stretch: 62% 125%;
  font-display: swap;
  src: url('fonts/archivo-400-700-latin-ext.woff2') format('woff2');
  unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C0, U+2113, U+2C60-2C7F, U+A720-A7FF;
}
/* Archivo · latin · self-hosted, no third-party request */
@font-face {
  font-family: 'Archivo';
  font-style: normal;
  font-weight: 400 700;
  font-stretch: 62% 125%;
  font-display: swap;
  src: url('fonts/archivo-400-700-latin.woff2') format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
/* IBM Plex Mono · latin-ext · self-hosted, no third-party request */
@font-face {
  font-family: 'IBM Plex Mono';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url('fonts/ibm-plex-mono-400-latin-ext.woff2') format('woff2');
  unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C0, U+2113, U+2C60-2C7F, U+A720-A7FF;
}
/* IBM Plex Mono · latin · self-hosted, no third-party request */
@font-face {
  font-family: 'IBM Plex Mono';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url('fonts/ibm-plex-mono-400-latin.woff2') format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
/* IBM Plex Mono · latin-ext · self-hosted, no third-party request */
@font-face {
  font-family: 'IBM Plex Mono';
  font-style: normal;
  font-weight: 500;
  font-display: swap;
  src: url('fonts/ibm-plex-mono-500-latin-ext.woff2') format('woff2');
  unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C0, U+2113, U+2C60-2C7F, U+A720-A7FF;
}
/* IBM Plex Mono · latin · self-hosted, no third-party request */
@font-face {
  font-family: 'IBM Plex Mono';
  font-style: normal;
  font-weight: 500;
  font-display: swap;
  src: url('fonts/ibm-plex-mono-500-latin.woff2') format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}

:root {
  /* Sampled from the app icon: navy ground, green-to-cyan pin. */
  --paper:      #EDEFF6;
  --paper-lift: #F7F8FC;
  --paper-sink: #DBDFEC;
  --ink:        #0D1B38;
  --ink-mid:    #4B5578;
  --ink-faint:  #868EA8;
  --accent:     #3DF089;
  --accent-2:   #35CDEC;
  --signal:     #B93A1C;

  --rule:        rgba(13, 27, 56, 0.14);
  --rule-strong: rgba(13, 27, 56, 0.30);

  --font-sans: 'Archivo', 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'IBM Plex Mono', ui-monospace, 'SF Mono', Menlo, monospace;

  --fs-display: clamp(2.6rem, 7vw, 5.25rem);
  --fs-h1:      clamp(1.9rem, 3.6vw, 2.75rem);
  --fs-h2:      clamp(1.35rem, 2.2vw, 1.75rem);
  --fs-h3:      1.125rem;
  --fs-body:    1.0625rem;
  --fs-small:   0.9375rem;
  --fs-tiny:    0.8125rem;

  --col-label: 11rem;
  --gap-col:   3.25rem;
  --measure:   40rem;
  --wide:      64rem;

  color-scheme: light;
}

*, *::before, *::after { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
img, svg { display: block; max-width: 100%; }

html {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.6;
  font-variation-settings: 'wdth' 100;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

body {
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
}

a { color: inherit; text-decoration-color: var(--rule-strong); text-underline-offset: 0.2em; }
a:hover { text-decoration-color: currentColor; }

:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 3px;
}

.container {
  width: 100%;
  max-width: var(--wide);
  margin-inline: auto;
  padding-inline: clamp(1.25rem, 5vw, 3rem);
}

/* ---------- header ---------- */

.masthead {
  border-bottom: 1px solid var(--rule-strong);
  position: sticky;
  top: 0;
  background: var(--paper);
  z-index: 10;
}

.masthead__inner {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1.5rem;
  padding-block: 0.9rem;
  flex-wrap: wrap;
}

.wordmark {
  font-variation-settings: 'wdth' 78, 'wght' 700;
  font-size: 1.05rem;
  letter-spacing: 0.01em;
  text-decoration: none;
}

.wordmark b { font-weight: inherit; color: var(--ink); }
.wordmark span { color: var(--ink-mid); }

.nav {
  display: flex;
  gap: 1.5rem;
  font-size: var(--fs-small);
  color: var(--ink-mid);
}

.nav a { text-decoration: none; }
.nav a:hover { text-decoration: underline; }
.nav a[aria-current='page'] {
  color: var(--ink);
  box-shadow: inset 0 -0.42em 0 var(--accent);
}

/* ---------- hero ---------- */

.hero { padding-block: clamp(2.5rem, 6vw, 4.5rem) clamp(2rem, 4vw, 3rem); }

.hero__icon {
  width: clamp(72px, 9vw, 104px);
  height: auto;
  border-radius: 22.37%;   /* the iOS squircle, near enough */
  margin-bottom: 1.75rem;
}

.hero h1 {
  font-size: var(--fs-display);
  font-variation-settings: 'wdth' 74, 'wght' 700;
  line-height: 0.95;
  letter-spacing: -0.015em;
  margin: 0 0 1.5rem;
  max-width: 16ch;
}

.hero p {
  font-size: clamp(1.0625rem, 1.6vw, 1.25rem);
  color: var(--ink-mid);
  max-width: 46ch;
  margin: 0;
}

.hero .hero__cta {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem 1.25rem;
  max-width: none;
  margin-top: 2rem;
}

/* The site's own button, not Apple's badge artwork. */
.store-button {
  display: inline-block;
  padding: 0.7rem 1.35rem;
  background: var(--ink);
  color: var(--paper-lift);
  font-size: var(--fs-body);
  font-variation-settings: 'wdth' 88, 'wght' 600;
  text-decoration: none;
  border-radius: 0.6rem;
  box-shadow: inset 0 -3px 0 var(--accent);
}
.store-button:hover { background: #1A2A4E; }
.store-button:focus-visible { outline: 2px solid var(--accent-2); outline-offset: 3px; }

.hero__req {
  font-family: var(--font-mono);
  font-size: var(--fs-tiny);
  color: var(--ink-mid);
}

/* ---------- shift diagram ---------- */

.shift {
  margin-block: clamp(2.5rem, 6vw, 4.5rem);
  border-top: 1px solid var(--rule-strong);
  padding-block: 1.75rem 0;
}

.shift__head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
  flex-wrap: wrap;
  margin-bottom: 1.25rem;
}

.shift__title {
  font-size: var(--fs-h3);
  font-variation-settings: 'wdth' 88, 'wght' 600;
  margin: 0;
}

.shift__stat {
  font-family: var(--font-mono);
  font-size: var(--fs-small);
  color: var(--ink-mid);
}

.shift__stat b {
  font-weight: 500;
  color: var(--ink);
  box-shadow: inset 0 -0.4em 0 var(--accent);
}

.shift__legend {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
  margin-top: 1.25rem;
  font-size: var(--fs-tiny);
  color: var(--ink-mid);
}

.shift__legend span {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.shift__chart { width: 100%; height: auto; }

.shift__band {
  font-family: var(--font-sans);
  font-size: 11px;
  font-variation-settings: 'wdth' 92, 'wght' 500;
  fill: var(--ink-mid);
}

.shift__tick {
  font-family: var(--font-mono);
  font-size: 11px;
  fill: var(--ink-faint);
}

.swatch {
  display: inline-block;
  width: 1.1rem;
  height: 0.7rem;
  flex: none;
  border: 1px solid var(--rule-strong);
}

.swatch--gps  { background: var(--accent); }
.swatch--idle { background: var(--paper-sink); }
.swatch--move { background: var(--ink-mid); }

/* ---------- sheet: label column + content ---------- */

.sheet {
  border-top: 1px solid var(--rule);
  padding-block: clamp(2.25rem, 5vw, 3.5rem);
}

.sheet__grid {
  display: grid;
  grid-template-columns: var(--col-label) minmax(0, 1fr);
  gap: 0 var(--gap-col);
  align-items: start;
}

.sheet__label {
  font-size: var(--fs-small);
  font-variation-settings: 'wdth' 88, 'wght' 500;
  color: var(--ink-mid);
  margin: 0;
  padding-top: 0.35rem;
}

.sheet__body { max-width: var(--measure); min-width: 0; }

.sheet__body > :first-child { margin-top: 0; }
.sheet__body > :last-child { margin-bottom: 0; }

.sheet h2 {
  font-size: var(--fs-h2);
  font-variation-settings: 'wdth' 84, 'wght' 600;
  line-height: 1.15;
  margin: 0 0 1rem;
  max-width: 22ch;
}

.sheet h3 {
  font-size: var(--fs-h3);
  font-variation-settings: 'wdth' 92, 'wght' 600;
  margin: 2rem 0 0.5rem;
}

.sheet p { margin: 0 0 1rem; }

.sheet ul, .sheet ol { margin: 0 0 1rem; padding-left: 1.2rem; }
.sheet li { margin-bottom: 0.5rem; }
.sheet li::marker { color: var(--ink-faint); }

/* ---------- state sequence (a real sequence, hence numbered) ---------- */

.states { list-style: none; margin: 0; padding: 0; counter-reset: state; }

.states li {
  counter-increment: state;
  display: grid;
  grid-template-columns: 2.25rem minmax(0, 1fr);
  gap: 0 1rem;
  padding-block: 0.9rem;
  border-top: 1px solid var(--rule);
  margin: 0;
}

.states li:first-child { border-top: 0; padding-top: 0; }

.states li::before {
  content: counter(state);
  font-family: var(--font-mono);
  font-size: var(--fs-small);
  color: var(--ink-faint);
  padding-top: 0.15rem;
}

.states__name {
  grid-column: 2;
  font-variation-settings: 'wdth' 92, 'wght' 600;
  font-weight: 400;
  margin-bottom: 0.15rem;
}

.states__note {
  grid-column: 2;
  color: var(--ink-mid);
  font-size: var(--fs-small);
}

/* ---------- spec table ---------- */

.scroll-x {
  overflow-x: auto;
  margin-bottom: 1rem;
  -webkit-overflow-scrolling: touch;
}

.scroll-x .spec { margin-bottom: 0; min-width: 26rem; }

.spec {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--fs-small);
  margin-bottom: 1rem;
}

.spec caption {
  text-align: left;
  color: var(--ink-mid);
  padding-bottom: 0.6rem;
}

.spec th, .spec td {
  text-align: left;
  padding: 0.55rem 1rem 0.55rem 0;
  border-bottom: 1px solid var(--rule);
  vertical-align: top;
}

.spec th {
  font-variation-settings: 'wdth' 92, 'wght' 600;
  white-space: nowrap;
}

.spec td:last-child { padding-right: 0; }

.spec .num {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  white-space: nowrap;
}

/* ---------- limits ---------- */

.limits { list-style: none; margin: 0; padding: 0; }

.limits li {
  padding: 0.85rem 0 0.85rem 1.5rem;
  border-top: 1px solid var(--rule);
  position: relative;
  margin: 0;
}

.limits li:first-child { border-top: 0; }

.limits li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 1.35rem;
  width: 0.6rem;
  height: 2px;
  background: var(--signal);
}

.limits b {
  font-variation-settings: 'wdth' 92, 'wght' 600;
  font-weight: 400;
}

/* ---------- contact list ---------- */

.contact { margin: 0; }
.contact dt {
  font-size: var(--fs-tiny);
  color: var(--ink-mid);
  margin-bottom: 0.15rem;
}
.contact dd {
  margin: 0 0 1rem;
  font-family: var(--font-mono);
  font-size: var(--fs-small);
  word-break: break-word;
}

/* ---------- document header for support / privacy ---------- */

.doc-head { padding-block: clamp(2.5rem, 6vw, 4rem) clamp(1.5rem, 3vw, 2.25rem); }

.doc-head h1 {
  font-size: var(--fs-h1);
  font-variation-settings: 'wdth' 76, 'wght' 700;
  line-height: 1.02;
  margin: 0 0 0.75rem;
  max-width: 18ch;
}

.doc-head p {
  margin: 0;
  color: var(--ink-mid);
  max-width: 52ch;
}

.doc-meta {
  font-family: var(--font-mono);
  font-size: var(--fs-tiny);
  color: var(--ink-faint);
  margin: 0 0 1.25rem;
}

/* ---------- callout ---------- */

.note {
  background: var(--paper-lift);
  border-left: 3px solid var(--accent);
  padding: 1rem 1.25rem;
  margin: 0 0 1rem;
  font-size: var(--fs-small);
}

.note p { margin: 0; }
.note p + p { margin-top: 0.6rem; }

/* ---------- footer ---------- */

.footer {
  margin-top: auto;
  border-top: 1px solid var(--rule-strong);
  padding-block: 2rem 3rem;
  font-size: var(--fs-tiny);
  color: var(--ink-mid);
}

.footer__inner {
  display: flex;
  justify-content: space-between;
  gap: 1.5rem;
  flex-wrap: wrap;
}

.footer nav { display: flex; gap: 0.5rem 1.25rem; flex-wrap: wrap; }

.footer__apps { flex-basis: 100%; margin: 0; }

/* ---------- diagrams ---------- */

.diagram { margin: 0 0 1.25rem; padding: 0; }

.diagram__frame {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.diagram__frame svg {
  width: 100%;
  min-width: 32rem;
  height: auto;
}

.diagram figcaption {
  margin-top: 0.75rem;
  font-size: var(--fs-tiny);
  color: var(--ink-mid);
}

.chart__inband {
  font-family: var(--font-sans);
  font-size: 11px;
  font-variation-settings: 'wdth' 92, 'wght' 500;
  fill: var(--ink);
}

.swatch--probe  { background: var(--accent-2); }
.swatch--settle {
  background: #9AF6C4;
  background: color-mix(in srgb, var(--accent) 45%, var(--paper));
}

.fsm__name {
  font-family: var(--font-sans);
  font-size: 13px;
  font-variation-settings: 'wdth' 88, 'wght' 600;
  fill: var(--ink);
}

.fsm__sub {
  font-family: var(--font-mono);
  font-size: 10px;
  fill: var(--ink-mid);
}

.fsm__edge {
  font-family: var(--font-sans);
  font-size: 11px;
  fill: var(--ink-mid);
}

code { font-family: var(--font-mono); font-size: 0.875em; }

/* ---------- on this page ---------- */

.toc {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 1.1rem;
  margin: 1.75rem 0 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: var(--fs-tiny);
  color: var(--ink-mid);
}

.toc li { margin: 0; }

/* ---------- responsive ---------- */

@media (max-width: 46rem) {
  .sheet__grid { grid-template-columns: minmax(0, 1fr); gap: 0; }
  .sheet__label {
    padding-top: 0;
    margin-bottom: 0.75rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--rule);
  }
  .hero h1 { max-width: none; }
}

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

@media print {
  .masthead, .footer nav, .footer__apps, .hero__cta { display: none; }
  html { background: #fff; font-size: 11pt; }
}