:root{
  --bg: #ffffff;
  --ink: #1a1a1a;
  --ink-soft: #5c5c5c;
  --ink-faint: #8f8f8f;
  --ink-fade: #bbbbbb;
  --line: #dcdcdc;
  --line-strong: #b4b4b4;
  --wash: rgba(255, 255, 255, .8);
  --serif-display: "Fraunces", "Iowan Old Style", serif;
  --serif-body: "Source Serif 4", "Iowan Old Style", Georgia, serif;
  --mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, monospace;
  --dur: 220ms;
  --zoom-dur: 420ms;
}

*{ box-sizing: border-box; }

html, body{
  height: 100%;
  margin: 0;
}

body{
  background: var(--bg);
  color: var(--ink);
  font-family: var(--serif-body);
  display: flex;
  flex-direction: column;
}

::selection{ background: rgba(0, 0, 0, .12); }

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

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

.chrome{
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  padding: 22px 32px;
  flex-wrap: wrap;
  gap: 12px;
}

.chrome-left{
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.mark{
  font-family: var(--serif-display);
  font-weight: 600;
  font-size: 1.15rem;
  letter-spacing: .01em;
}

.mark-sub{
  font-family: var(--mono);
  font-size: .68rem;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--ink-faint);
}

.lang-switcher{
  display: flex;
  align-items: center;
  gap: 6px;
  margin-top: 8px;
}

.lang-btn{
  appearance: none;
  border: 1px solid var(--line);
  background: transparent;
  color: var(--ink-soft);
  font-family: var(--mono);
  font-size: .66rem;
  letter-spacing: .06em;
  padding: 4px 10px;
  border-radius: 999px;
  cursor: pointer;
  transition: background var(--dur), color var(--dur), border-color var(--dur);
}

.lang-btn:hover{ background: rgba(0, 0, 0, .05); }

.lang-btn.is-active{
  background: var(--ink);
  border-color: var(--ink);
  color: var(--bg);
}

.pager{
  display: flex;
  align-items: center;
  gap: 14px;
  font-family: var(--mono);
}

.pager-divider{
  width: 1px;
  height: 20px;
  background: var(--line);
}

.page-label{
  font-size: .78rem;
  letter-spacing: .06em;
  color: var(--ink-soft);
  min-width: 6.5ch;
  text-align: center;
}

.pager-btn{
  appearance: none;
  border: 1px solid var(--line);
  background: transparent;
  color: var(--ink);
  width: 34px;
  height: 34px;
  border-radius: 50%;
  font-size: 1rem;
  line-height: 1;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: background var(--dur), border-color var(--dur), transform var(--dur), opacity var(--dur), color var(--dur);
}

.pager-btn:hover:not(:disabled){
  background: rgba(0, 0, 0, .06);
  border-color: var(--line-strong);
}

.pager-btn:active:not(:disabled){
  transform: scale(.94);
}

.pager-btn:disabled{
  opacity: .3;
  cursor: default;
}

.zoom-btn[aria-pressed="true"]{
  background: var(--ink);
  border-color: var(--ink);
  color: var(--bg);
}

/* ---------- layout ---------- */

.app{
  flex: 1;
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  min-height: 0;
}

.app.is-loading{
  opacity: .55;
  transition: opacity var(--dur);
  pointer-events: none;
}

.pane{
  min-height: 0;
  overflow-y: auto;
}

.pane-image{
  position: relative;
  background: var(--bg);
}

.viewport{
  position: absolute;
  inset: 0;
  overflow: hidden;
}

.viewport.can-zoom{ cursor: zoom-in; }
.viewport.can-pan{ cursor: grab; }
.viewport.is-panning{ cursor: grabbing; }

.svg-host{
  width: 100%;
  height: 100%;
  transform-origin: 0 0;
  will-change: transform;
}

.svg-host svg,
.svg-host .plain-image{
  display: block;
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.region{
  fill: transparent;
  stroke: transparent;
  cursor: pointer;
  vector-effect: non-scaling-stroke;
  transition: filter var(--dur), stroke var(--dur);
}

.region.is-active{
  stroke: rgba(20, 20, 20, .16);
  stroke-width: 1px;
  filter: drop-shadow(0 2px 6px rgba(0, 0, 0, .28));
}

.region.is-pinned{
  stroke: rgba(20, 20, 20, .22);
  stroke-width: 1px;
  filter: drop-shadow(0 3px 10px rgba(0, 0, 0, .35));
}

.dim-overlay{
  fill: var(--wash);
  opacity: 0;
  transition: opacity var(--dur);
}

.dim-overlay.is-visible{ opacity: 1; }

.pane-text{
  padding: 56px 48px;
}

.text-host{
  max-width: 62ch;
}

.passage{
  position: relative;
  padding: 4px 0;
  margin: 0 0 30px 0;
  cursor: pointer;
  color: var(--ink);
  transition: color var(--dur);
}

.passage p{
  margin: 0 0 .7em 0;
  font-size: 1.08rem;
  line-height: 1.65;
}

.passage > *:last-child{ margin-bottom: 0; }

.passage em{ font-style: italic; }
.passage strong{ font-weight: 700; }

.passage h1, .passage h2, .passage h3,
.passage h4, .passage h5, .passage h6{
  font-family: var(--serif-display);
  font-weight: 600;
  line-height: 1.3;
  margin: 0 0 .5em 0;
}
.passage h1{ font-size: 1.5rem; }
.passage h2{ font-size: 1.28rem; }
.passage h3{ font-size: 1.15rem; }
.passage h4, .passage h5, .passage h6{ font-size: 1.05rem; }

.passage blockquote{
  margin: 0 0 .9em 0;
  padding-left: 18px;
  border-left: 2px solid var(--line-strong);
  color: var(--ink-soft);
  font-style: italic;
}

.passage ul, .passage ol{
  margin: 0 0 .9em 0;
  padding-left: 1.3em;
}
.passage li{
  margin-bottom: .3em;
  line-height: 1.6;
}

.passage code{
  font-family: var(--mono);
  font-size: .9em;
  background: rgba(0, 0, 0, .05);
  padding: .1em .35em;
  border-radius: 3px;
}
.passage pre{
  margin: 0 0 .9em 0;
  padding: 12px 14px;
  background: rgba(0, 0, 0, .04);
  border-radius: 4px;
  overflow-x: auto;
}
.passage pre code{
  background: none;
  padding: 0;
}

.passage a{
  color: inherit;
  text-decoration: underline;
  text-decoration-color: var(--line-strong);
  text-underline-offset: 2px;
}
.passage a:hover{ text-decoration-color: var(--ink); }

.passage hr{
  border: none;
  border-top: 1px solid var(--line);
  margin: 1.2em 0;
}

.text-host.has-active .passage{
  color: var(--ink-fade);
}

.text-host.has-active .passage.is-active,
.text-host.has-active .passage.is-pinned,
.text-host.has-active .passage.intro{
  color: var(--ink);
}

.passage.intro{
  cursor: default;
  padding-bottom: 22px;
  margin-bottom: 8px;
  border-bottom: 1px solid var(--line);
}

.toast{
  position: absolute;
  left: 50%;
  bottom: 28px;
  transform: translate(-50%, 6px);
  background: var(--ink);
  color: var(--bg);
  font-family: var(--mono);
  font-size: .74rem;
  letter-spacing: .04em;
  padding: 9px 16px;
  border-radius: 3px;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--dur), transform var(--dur);
  z-index: 2;
}

.toast.is-shown{
  opacity: .94;
  transform: translate(-50%, 0);
}

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

@media (max-width: 860px){
  .app{
    grid-template-columns: 1fr;
    grid-auto-rows: min-content;
    overflow-y: auto;
  }
  .pane{ overflow-y: visible; }
  .pane-image{
    height: 62vh;
  }
  .pane-text{ padding: 36px 24px 64px; }
}

/* ---------- reduced motion ---------- */

@media (prefers-reduced-motion: reduce){
  *{
    transition-duration: 1ms !important;
    animation-duration: 1ms !important;
    scroll-behavior: auto !important;
  }
  .svg-host{ will-change: auto; }
}

/* ---------- auth gate ---------- */

.auth-gate{
  position: fixed;
  inset: 0;
  background: var(--bg);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 50;
}

.auth-gate[hidden]{ display: none; }

.auth-card{
  width: min(360px, 88vw);
  border: 1px solid var(--line);
  padding: 34px 30px;
  display: flex;
  flex-direction: column;
  gap: 14px;
  text-align: center;
}

.auth-title{
  font-family: var(--serif-display);
  font-weight: 600;
  font-size: 1.2rem;
  margin: 0;
}

.auth-sub{
  font-size: .86rem;
  color: var(--ink-soft);
  margin: 0 0 6px 0;
  line-height: 1.5;
}

#authInput{
  font-family: var(--mono);
  font-size: .9rem;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 3px;
  background: var(--bg);
  color: var(--ink);
}

#authInput:focus-visible{
  outline: 2px solid var(--ink);
  outline-offset: 1px;
}

.auth-card button{
  appearance: none;
  font-family: var(--mono);
  font-size: .8rem;
  letter-spacing: .04em;
  padding: 10px 14px;
  border: 1px solid var(--ink);
  background: var(--ink);
  color: var(--bg);
  border-radius: 3px;
  cursor: pointer;
  transition: opacity var(--dur);
}

.auth-card button:hover{ opacity: .85; }

.auth-error{
  font-family: var(--mono);
  font-size: .74rem;
  color: var(--ink-soft);
  margin: 0;
}