:root {
  --ink: #10151a;
  --panel: #1b232b;
  --panel-raised: #212b34;
  --line: #2a3540;
  --line-soft: #202a33;
  --amber: #e8a33d;
  --amber-dim: #6b5228;
  --mint: #6fe7c0;
  --mint-dim: #2d4a41;
  --text: #edeff2;
  --text-dim: #93a1ab;
  --text-faint: #5c6b76;
  --danger: #e8654b;

  --font-display: "Space Grotesk", "Avenir Next", ui-sans-serif, system-ui, sans-serif;
  --font-body: "Inter", ui-sans-serif, system-ui, -apple-system, sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  height: 100%;
  background: var(--ink);
  color: var(--text);
  font-family: var(--font-body);
  -webkit-tap-highlight-color: transparent;
}

body {
  background-image:
    radial-gradient(ellipse 900px 500px at 50% -10%, rgba(232, 163, 61, 0.06), transparent 60%);
}

::selection { background: var(--mint-dim); color: var(--text); }

button, input, select {
  font-family: inherit;
  color: inherit;
}

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

.app {
  max-width: 760px;
  margin: 0 auto;
  min-height: 100dvh;
  display: grid;
  grid-template-columns: 180px 1fr;
  grid-template-areas:
    "header header"
    "nav    panel"
    "footer footer";
  column-gap: 20px;
  align-content: start;
  padding: max(20px, env(safe-area-inset-top)) 18px max(18px, env(safe-area-inset-bottom));
}

@media (max-width: 640px) {
  .app {
    max-width: 480px;
    grid-template-columns: 1fr;
    grid-template-areas:
      "header"
      "nav"
      "panel"
      "footer";
  }

  .category-tabs {
    grid-template-columns: repeat(auto-fill, minmax(110px, 1fr));
  }

  .tab-btn {
    text-align: center;
  }
}

/* ---------- Header ---------- */

.app-header {
  grid-area: header;
  margin-bottom: 18px;
}

.header-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
}

h1 {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.5rem;
  letter-spacing: -0.01em;
  margin: 0;
}

.subtitle {
  margin: 4px 0 0;
  color: var(--text-dim);
  font-size: 0.85rem;
}

.install-btn {
  flex-shrink: 0;
  background: transparent;
  border: 1px solid var(--amber-dim);
  color: var(--amber);
  font-size: 0.78rem;
  font-weight: 500;
  padding: 6px 12px;
  border-radius: 999px;
  cursor: pointer;
  transition: background 0.15s ease, border-color 0.15s ease;
}
.install-btn:hover { background: rgba(232, 163, 61, 0.08); border-color: var(--amber); }

/* ---------- Category tabs ---------- */

.category-tabs {
  grid-area: nav;
  display: grid;
  grid-template-columns: 1fr;
  gap: 6px;
  align-content: start;
  padding-bottom: 10px;
  margin-bottom: 4px;
}

.tab-btn {
  background: var(--panel);
  border: 1px solid var(--line);
  color: var(--text-dim);
  font-family: var(--font-body);
  font-size: 0.82rem;
  font-weight: 500;
  padding: 9px 12px;
  border-radius: 8px;
  cursor: pointer;
  transition: border-color 0.15s ease, color 0.15s ease, background 0.15s ease;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  text-align: left;
}
.tab-btn:hover { color: var(--text); border-color: var(--text-faint); }
.tab-btn[aria-selected="true"] {
  color: var(--ink);
  background: var(--amber);
  border-color: var(--amber);
  font-weight: 600;
}

/* ---------- Panel ---------- */

.panel {
  grid-area: panel;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 18px;
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.load-error {
  background: rgba(232, 101, 75, 0.1);
  border: 1px solid rgba(232, 101, 75, 0.35);
  color: #f4b3a4;
  font-size: 0.8rem;
  padding: 10px 12px;
  border-radius: 8px;
  line-height: 1.4;
}

.field-label {
  display: block;
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-faint);
  margin-bottom: 7px;
}

/* ---------- Selected category label ---------- */

.category-label {
  display: inline-flex;
  align-self: flex-start;
  background: var(--amber);
  color: var(--ink);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 0.85rem;
  letter-spacing: -0.005em;
  padding: 6px 14px;
  border-radius: 999px;
  white-space: normal;
  word-break: break-word;
}
.category-label:empty { display: none; }

/* ---------- Input ---------- */

.input-group {
  display: flex;
  gap: 8px;
}

.value-input {
  flex: 1;
  min-width: 0;
  background: var(--ink);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 11px 12px;
  font-family: var(--font-mono);
  font-size: 1.15rem;
  font-variant-numeric: tabular-nums;
  color: var(--text);
}
.value-input:focus { border-color: var(--amber); }
.value-input.invalid { border-color: var(--danger); }

.ghost-btn {
  background: transparent;
  border: 1px solid var(--line);
  color: var(--text-dim);
  font-size: 0.82rem;
  padding: 0 14px;
  border-radius: 8px;
  cursor: pointer;
  transition: border-color 0.15s ease, color 0.15s ease;
}
.ghost-btn:hover { color: var(--text); border-color: var(--text-faint); }

.input-error {
  margin: 7px 0 0;
  font-size: 0.78rem;
  color: var(--danger);
}

/* ---------- From select ---------- */

.select-wrap {
  position: relative;
}
.select-wrap::after {
  content: "";
  position: absolute;
  right: 14px;
  top: 50%;
  width: 8px;
  height: 8px;
  border-right: 1.5px solid var(--text-faint);
  border-bottom: 1.5px solid var(--text-faint);
  transform: translateY(-70%) rotate(45deg);
  pointer-events: none;
}

#from-select,
#to-select {
  width: 100%;
  appearance: none;
  background: var(--ink);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 11px 36px 11px 12px;
  font-size: 0.92rem;
  cursor: pointer;
}
#from-select:focus,
#to-select:focus { border-color: var(--amber); }

/* ---------- Rate / destination calculator ---------- */

.rate-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: flex-end;
}

.rate-field {
  flex: 1 1 140px;
  min-width: 0;
}

.rate-row #rate-input {
  width: 100%;
}

.rate-row .input-error {
  flex-basis: 100%;
  margin: 0;
}

.rate-result-row {
  flex-basis: 100%;
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  padding: 11px 12px;
  border-radius: 8px;
  background: var(--panel-raised);
  border: 1px solid var(--line);
}

.rate-result-label {
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-faint);
}

.rate-result-value {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-weight: 600;
  font-size: 1.05rem;
  color: var(--mint);
}

.rate-result-value-group {
  display: flex;
  align-items: center;
  gap: 6px;
}
.rate-result-value-group .copy-btn {
  padding: 3px;
}

/* ---------- Results ledger ---------- */

.results-section {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
}

.ledger-head {
  display: flex;
  justify-content: space-between;
  padding: 0 4px 6px 34px;
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-faint);
  border-bottom: 1px solid var(--line-soft);
}

.ledger {
  list-style: none;
  margin: 0;
  padding: 0;
  overflow-y: auto;
}

.ledger-row {
  display: grid;
  grid-template-columns: 26px 1fr auto;
  align-items: center;
  gap: 10px;
  padding: 10px 4px 10px 8px;
  border-left: 2px solid var(--line);
  border-bottom: 1px solid var(--line-soft);
  transition: border-color 0.15s ease;
}

.ledger-row.is-source {
  border-left: 2px solid var(--amber);
  background: linear-gradient(90deg, rgba(232, 163, 61, 0.06), transparent 40%);
}

.copy-btn {
  background: transparent;
  border: none;
  color: var(--text-faint);
  padding: 4px;
  border-radius: 6px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: color 0.15s ease, background 0.15s ease;
}
.copy-btn:hover { color: var(--text); background: rgba(255,255,255,0.05); }
.copy-btn.copied { color: var(--mint); }

.ledger-unit {
  font-size: 0.87rem;
  color: var(--text-dim);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.is-source .ledger-unit { color: var(--amber); font-weight: 500; }

.ledger-value {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-variant-numeric: tabular-nums;
  text-align: right;
  color: var(--text);
}
.is-source .ledger-value { color: var(--mint); font-weight: 600; }

/* ---------- Footer ---------- */

.app-footer {
  grid-area: footer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding-top: 14px;
  min-height: 24px;
}

.developer-info {
  font-size: 0.72rem;
  color: var(--text-faint);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
}
.developer-info:hover {
  color: var(--text-dim);
  border-bottom-color: var(--text-faint);
}

.offline-pill {
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-faint);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 3px 10px;
}

/* ---------- Reduced motion ---------- */

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; }
}

/* ---------- Small screens ---------- */

@media (max-width: 360px) {
  h1 { font-size: 1.3rem; }
  .panel { padding: 14px; }
}