/* QR Crypt landing page.
 *
 * One idea drives the whole sheet: the page has two worlds. The online world is
 * dark and marked amber; the offline world is cool paper marked navy. Between
 * them is an air gap — a band of dissolving QR modules at the top of the page,
 * and a literal empty channel running down the middle of the six-step diagram
 * that the message crosses exactly twice.
 *
 * No external requests: system fonts only, and the two SVGs are same-origin.
 */

:root {
  /* Online world */
  --void: #0e0e12;
  --void-2: #17171e;
  --void-3: #2a2a35;
  --amber: #f0a11a;
  --dim: #9096a6;

  /* Offline world */
  --paper: #edf0f4;
  --white: #ffffff;
  --navy: #1e3a5f;
  --ink: #0f172a;
  --muted: #55606f;
  --rule: #d3dae3;

  --red: #c0362c;

  --sans:
    system-ui, -apple-system, "Segoe UI", Roboto, "Hiragino Sans", "Noto Sans JP",
    "Yu Gothic UI", sans-serif;
  --mono:
    ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;

  --display: clamp(2.3rem, 7.2vw, 5.75rem);
  --h2: clamp(1.6rem, 3.6vw, 2.6rem);

  --wrap: 68rem;
  --pad: clamp(1.25rem, 5vw, 3.5rem);
  --flow-channel: 6rem;
  --step-pad: 1.125rem;

  /* Shared by the wordmark and the fixed language switcher so both start on the
     same line, and by the switcher's inset so it sits on the content edge. */
  --head-top: clamp(2rem, 7vh, 4.5rem);
  --head-height: 2.25rem;
  --content-right: max(var(--pad), calc(50vw - var(--wrap) / 2 + var(--pad)));
}

/* Japanese leads with a Japanese face. Left to the Latin-first stack above, the
   OS fallback picks whatever CJK font it likes — on some systems a mincho — and
   the page reads as a different design in each language. */
:lang(ja) {
  --sans:
    "Hiragino Sans", "Noto Sans JP", "Noto Sans CJK JP", "Yu Gothic UI", "Yu Gothic",
    Meiryo, sans-serif;
}

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

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

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 1.0625rem;
  line-height: 1.7;
  overflow-wrap: break-word;
}

:lang(ja) body {
  line-height: 1.9;
  line-break: strict;
}

/* Break display type at phrase boundaries instead of mid-word, where supported. */
:lang(ja) .thesis,
:lang(ja) .h2,
:lang(ja) .seam__body,
:lang(ja) .step__title,
:lang(ja) .warn__title {
  word-break: auto-phrase;
}

a {
  color: inherit;
}

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

.wrap {
  /* width:100% matters inside .hero, a flex column: without it the auto inline
     margins shrink-wrap each child to its content instead of the shared measure. */
  width: 100%;
  max-width: var(--wrap);
  margin: 0 auto;
  padding-inline: var(--pad);
}

.skip {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 20;
  padding: 0.75rem 1rem;
  background: var(--white);
  color: var(--ink);
}

.skip:focus {
  left: 0;
}

/* --- shared type ------------------------------------------------------- */

.eyebrow {
  margin: 0 0 1.25rem;
  font-family: var(--mono);
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--muted);
}

:lang(ja) .eyebrow {
  /* 11px mono is legible for Latin caps and not for kanji. */
  font-size: 0.875rem;
  letter-spacing: 0.14em;
  text-transform: none;
}

:lang(ja) .route__tag,
:lang(ja) .lock__when,
:lang(ja) .flow__headName,
:lang(ja) .scroll-cue {
  font-size: 0.8125rem;
}

.eyebrow--amber {
  color: var(--amber);
}

.eyebrow--red {
  color: var(--red);
}

.h2 {
  margin: 0 0 1.25rem;
  max-width: 20ch;
  font-size: var(--h2);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.06;
  text-wrap: balance;
  color: var(--navy);
}

:lang(ja) .h2 {
  max-width: 24ch;
  letter-spacing: -0.01em;
  line-height: 1.35;
  /* Headings break at the 読点 and nowhere else, so a line never ends mid-phrase.
     Safe because every JA heading's longest punctuation-free run still fits. */
  word-break: keep-all;
}

.h2--void {
  color: var(--white);
}

.h3 {
  margin: 0 0 0.625rem;
  font-size: 1.1875rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1.35;
  color: var(--ink);
}

.prose {
  margin: 0 0 1.5rem;
  max-width: 60ch;
  /* Keeps a last line from ending on one orphaned word or 「す。」 */
  text-wrap: pretty;
  color: var(--muted);
}

.lock__body,
.step__note,
.warn__body,
.answer,
.seam__body {
  text-wrap: pretty;
}

/* Japanese copy carries its own sentence breaks so that, wherever the width
   allows, a line ends at a 句点 rather than mid-sentence. English has no
   newlines in its strings, so it is unaffected. */
:lang(ja) .answer {
  white-space: pre-line;
}

/* `ch` is the width of "0", so a ch-based measure is far too narrow once the
   glyphs are full-width — narrow enough that the sentence breaks above never
   get to land. `em` is one full-width character, which is how a Japanese
   measure is actually counted. */
:lang(ja) .prose {
  max-width: 40em;
}

:lang(ja) .answer {
  max-width: 32em;
}

:lang(ja) .seam__body {
  max-width: 27em;
}

/* --- language switcher ------------------------------------------------- */

.lang {
  position: fixed;
  z-index: 10;
  top: var(--head-top);
  right: var(--content-right);
  display: flex;
  gap: 1px;
  padding: 1px;
  border: 1px solid var(--void-3);
  border-radius: 999px;
  background: var(--void);
}

.lang__button {
  display: inline-flex;
  align-items: center;
  min-height: 2rem;
  padding: 0 0.875rem;
  border: 0;
  border-radius: 999px;
  background: transparent;
  color: var(--dim);
  font-family: var(--mono);
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  text-decoration: none;
  cursor: pointer;
}

.lang__button[aria-current="page"] {
  background: var(--paper);
  color: var(--void);
}

/* Narrow screens have no empty margin for it to float in, so it takes up as
   little of the line it overlaps as possible. */
@media (max-width: 52rem) {
  :root {
    --head-height: 1.875rem;
  }

  .lang__button {
    min-height: 1.625rem;
    padding: 0 0.625rem;
    font-size: 0.6875rem;
  }
}

/* --- hero: the premise, stated first and stated large ------------------ */

.hero {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: clamp(2rem, 6vh, 4rem);
  min-height: 100vh;
  min-height: 100svh;
  padding-block: var(--head-top) clamp(3rem, 9vh, 6rem);
  background: var(--void);
  color: var(--paper);
}

.mark {
  /* No `margin: 0` here: it would cancel .wrap's auto inline margins and drop
     the wordmark to the viewport edge instead of the content edge. */
  margin-block: 0;
  /* Same box height as the switcher pill, so their top edges line up. */
  min-height: var(--head-height);
  font-family: var(--mono);
  font-size: 0.8125rem;
  font-weight: 600;
  line-height: var(--head-height);
  letter-spacing: 0.34em;
  color: var(--paper);
}

.thesis {
  margin: 0 0 2.25rem;
  max-width: 18ch;
  font-size: var(--display);
  font-weight: 800;
  letter-spacing: -0.045em;
  line-height: 0.98;
  text-wrap: balance;
}

:lang(ja) .thesis {
  max-width: 22ch;
  letter-spacing: -0.015em;
  line-height: 1.28;
}

.thesis__line {
  display: block;
  color: var(--dim);
}

.thesis__line--turn {
  color: var(--white);
}

.answer {
  margin: 0;
  max-width: 46ch;
  padding-left: 1.125rem;
  border-left: 2px solid var(--amber);
  color: var(--paper);
}

.scroll-cue {
  margin-block: 0;
  font-family: var(--mono);
  font-size: 0.6875rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--dim);
}

:lang(ja) .scroll-cue {
  letter-spacing: 0.12em;
  text-transform: none;
}

.scroll-cue span::after {
  content: "";
  display: inline-block;
  width: 3.5rem;
  height: 1px;
  margin-left: 0.75rem;
  vertical-align: middle;
  background: var(--void-3);
}

/* --- the crossing: the page itself leaves the dark world --------------- */

.seam {
  background: var(--paper);
}

.seam__modules {
  height: clamp(3rem, 7vw, 5rem);
  background-image: url("./seam.svg");
  background-repeat: repeat-x;
  background-position: top center;
  background-size: auto 100%;
}

.seam__text {
  padding-block: clamp(2.5rem, 7vw, 5rem) 0;
}

.seam__body {
  margin: 0;
  /* Each line is its own block, so the measure only decides whether a line
     wraps further, never where the main break falls. */
  max-width: 46ch;
  font-size: clamp(1.25rem, 2.6vw, 1.75rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.25;
  color: var(--navy);
}

:lang(ja) .seam__body {
  letter-spacing: 0;
  line-height: 1.5;
}

/* Each half of the seam sentence is its own line by structure, so the break
   never depends on the measure or on which font `ch` was resolved against. */
.seam__line {
  display: block;
}

/* --- offline-world sections -------------------------------------------- */

.band {
  padding-block: clamp(3.5rem, 9vw, 7rem);
}

.facts {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 2rem;
  margin: 0;
  padding: 1.25rem 0 0;
  border-top: 1px solid var(--rule);
  list-style: none;
}

.facts__item {
  font-family: var(--mono);
  font-size: 0.8125rem;
  color: var(--navy);
}

/* --- ciphers ----------------------------------------------------------- */

.locks {
  display: grid;
  gap: 1px;
  background: var(--rule);
  border: 1px solid var(--rule);
}

@media (min-width: 48rem) {
  .locks {
    grid-template-columns: 1fr 1fr;
  }
}

.lock {
  padding: clamp(1.5rem, 3vw, 2.25rem);
  background: var(--white);
}

.lock--pq {
  background: var(--navy);
  color: var(--white);
}

.lock__name {
  margin: 0 0 0.25rem;
  font-family: var(--mono);
  font-size: 1.375rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--navy);
}

.lock--pq .lock__name {
  color: var(--white);
}

.lock__when {
  margin: 0 0 1.125rem;
  font-family: var(--mono);
  font-size: 0.6875rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
}

:lang(ja) .lock__when {
  letter-spacing: 0.12em;
  text-transform: none;
}

.lock--pq .lock__when {
  color: var(--amber);
}

.lock__body {
  margin: 0;
  color: var(--muted);
}

.lock--pq .lock__body {
  color: #cdd8e6;
}

/* --- install routes ---------------------------------------------------- */

.route {
  display: grid;
  gap: 0.75rem 2.5rem;
  padding-block: clamp(1.75rem, 4vw, 2.75rem);
  border-top: 1px solid var(--rule);
}

@media (min-width: 52rem) {
  .route {
    /* Fixed QR column so the code fills it and matches its own caption width. */
    grid-template-columns: 7rem minmax(0, 1fr) 15rem;
    align-items: start;
  }
}

.route__tag {
  margin: 0;
  font-family: var(--mono);
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--navy);
}

:lang(ja) .route__tag {
  letter-spacing: 0.12em;
  text-transform: none;
}

.route__link {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin: 0;
}

.cta {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 0.4375rem;
  /* Both routes get the same button, whatever their labels are. */
  width: 100%;
  max-width: 22rem;
  min-height: 3rem;
  padding: 0.625rem 1.25rem;
  background: var(--navy);
  color: var(--white);
  font-weight: 700;
  line-height: 1.3;
  text-decoration: none;
}

.cta:hover {
  background: var(--ink);
}

.cta__url {
  font-family: var(--mono);
  font-size: 0.6875rem;
  font-weight: 400;
  letter-spacing: 0.02em;
  color: #b9c6d8;
}

/* Narrow screens give the code the full column; the desktop grid caps it at the
   width of its own caption. */
.route__qr {
  margin: 0.5rem 0 0;
}

.route__qr img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 1;
  padding: 0.75rem;
  background: var(--white);
}

.route__qr figcaption {
  margin-top: 0.75rem;
  font-size: 0.8125rem;
  line-height: 1.5;
  color: var(--muted);
}

@media (min-width: 52rem) {
  .route__qr {
    margin: 0;
  }
}

/* --- the signature: six steps across the air gap ----------------------- */

.band--flow {
  border-top: 1px solid var(--rule);
}

.flow {
  position: relative;
  margin-top: 1.5rem;
}

.flow__heads,
.flow__list {
  display: grid;
  grid-template-columns: 1fr;
  /* Stacked, the cards need real separation to read as separate steps; the wide
     layout re-tightens this because the channel already separates them. */
  gap: 1rem;
}

.flow__heads {
  display: none;
}

.flow__head {
  margin: 0 0 1rem;
  padding-bottom: 0.625rem;
  border-bottom: 1px solid var(--rule);
}

.flow__headName {
  font-family: var(--mono);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.2em;
  text-transform: uppercase;
}

:lang(ja) .flow__headName {
  letter-spacing: 0.12em;
  text-transform: none;
}

.flow__head--online .flow__headName {
  color: var(--amber);
}

.flow__head--offline .flow__headName {
  color: var(--navy);
}

.flow__headSub {
  display: block;
  font-size: 0.8125rem;
  color: var(--muted);
}

.flow__list {
  counter-reset: step;
  margin: 0;
  padding: 0;
  list-style: none;
}

.channel {
  display: none;
}

.step {
  position: relative;
  counter-increment: step;
  padding: var(--step-pad);
  border-left: 3px solid var(--navy);
  background: var(--white);
}

.step--online {
  border-left-color: var(--amber);
  background: var(--void-2);
  color: var(--paper);
}

.step__n {
  margin: 0 0 0.25rem;
  font-family: var(--mono);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--muted);
}

.step__n::before {
  content: counter(step, decimal-leading-zero);
}

.step--online .step__n {
  color: var(--dim);
}

.step__title {
  margin: 0 0 0.375rem;
  font-size: 1.0625rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1.4;
}

.step__where {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin: 0;
  font-family: var(--mono);
  font-size: 0.75rem;
  line-height: 1.6;
  color: var(--navy);
}

/* The same lucide glyphs the app's own bottom navigation shows
   (LockKeyhole, LockKeyholeOpen, KeyRound, Settings), so the step points at
   the icon a reader will actually look for. */
.step__icon {
  width: 1.125rem;
  height: 1.125rem;
  flex-shrink: 0;
}

.step__sep {
  opacity: 0.45;
}

.step--online .step__where {
  color: var(--amber);
}

.step__note {
  margin: 0.5rem 0 0;
  font-size: 0.875rem;
  line-height: 1.6;
  color: var(--muted);
}

.step--online .step__note {
  color: var(--dim);
}

/* The two moments the message actually crosses the gap. */
.cross {
  position: relative;
  margin: 0 0 0.625rem;
  font-size: 0.8125rem;
  line-height: 1.5;
  color: var(--muted);
}

.step--online .cross {
  color: var(--dim);
}

@media (min-width: 60rem) {
  /* The wide layout has room to breathe; the stacked one does not. */
  .flow {
    --step-pad: 1.375rem;
  }

  .flow__heads {
    display: grid;
    grid-template-columns: 1fr var(--flow-channel) 1fr;
  }

  .flow__head--online {
    grid-column: 1;
  }

  .flow__head--offline {
    grid-column: 3;
  }

  .flow__list {
    grid-template-columns: 1fr var(--flow-channel) 1fr;
    gap: 1rem 0;
  }

  /* Explicit rows: auto-placement would let a left-column step share a row with
     the right-column step above it. */
  .step:nth-child(1) {
    grid-row: 1;
  }
  .step:nth-child(2) {
    grid-row: 2;
  }
  .step:nth-child(3) {
    grid-row: 3;
  }
  .step:nth-child(4) {
    grid-row: 4;
  }
  .step:nth-child(5) {
    grid-row: 5;
  }
  .step:nth-child(6) {
    grid-row: 6;
  }

  .step--online {
    grid-column: 1;
  }

  .step--offline {
    grid-column: 3;
  }

  /* The gap itself: nothing but light travels down it. */
  .channel {
    display: block;
    position: absolute;
    top: 0;
    bottom: 0;
    left: 50%;
    width: 1px;
    overflow: hidden;
    background: var(--rule);
  }

  .channel__light {
    position: absolute;
    left: 0;
    width: 100%;
    height: 22%;
    background: linear-gradient(
      to bottom,
      transparent,
      var(--navy) 35%,
      var(--navy) 65%,
      transparent
    );
    animation: channel-travel 7s linear infinite;
  }

  /* The hairline that reaches from a crossing note out to the channel. */
  .cross::after {
    content: "";
    position: absolute;
    top: 0.75em;
    width: calc(var(--flow-channel) / 2 + var(--step-pad));
    height: 1px;
    background: currentColor;
    opacity: 0.55;
  }

  .cross__left::after {
    left: 100%;
  }

  .cross__right::after {
    right: 100%;
  }
}

@keyframes channel-travel {
  from {
    top: -25%;
  }
  to {
    top: 100%;
  }
}

/* --- warnings: back into the dangerous world --------------------------- */

.warn {
  padding-block: clamp(3.5rem, 9vw, 7rem);
  background: var(--void);
  color: var(--paper);
}

.warn__items {
  display: grid;
  gap: 2rem;
  padding-top: 2rem;
  border-top: 1px solid var(--void-3);
}

@media (min-width: 52rem) {
  .warn__items {
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
  }
}

.warn__title {
  margin: 0 0 0.75rem;
  padding-left: 1rem;
  border-left: 3px solid var(--red);
  font-size: 1.125rem;
  font-weight: 700;
  line-height: 1.4;
  color: var(--white);
}

.warn__body {
  margin: 0;
  padding-left: 1rem;
  color: var(--dim);
}

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

.foot {
  padding-block: 2.5rem;
  background: var(--void);
  color: var(--dim);
  border-top: 1px solid var(--void-3);
}

.foot__row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem 2rem;
  font-family: var(--mono);
  font-size: 0.75rem;
}

.foot__link {
  min-height: 2.75rem;
  display: inline-flex;
  align-items: center;
  color: var(--paper);
}

.foot__note {
  margin: 0;
  flex: 1 1 20rem;
}

@media (prefers-reduced-motion: reduce) {
  .channel__light {
    animation: none;
    top: 39%;
  }
}