/* Currency Exchange Board: the look of an old exchange-house rate board.
   Graphite panels, amber LED accents and a split-flap capsule for the result. */

:root {
  --bg: #121417;
  --panel: #1b1e23;
  --panel-edge: #2c3038;
  --tile-top: #1a1c20;
  --tile-bottom: #101114;
  --tile-edge: #33373f;
  --ink: #ece8df;
  --muted: #a4a9b1; /* 7:1 on --panel */
  --amber: #ffb22e; /* 10:1 on --bg */
  --amber-soft: rgba(255, 178, 46, 0.12);
  --danger: #ff7a6b; /* 6:1 on --panel */
  --radius: 14px;
  --font-sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
  --font-mono: ui-monospace, "Cascadia Mono", "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  color-scheme: dark;
}

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

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font-sans);
  color: var(--ink);
  background-color: var(--bg);
  /* Faint dot matrix, like an unlit LED board. */
  background-image: radial-gradient(circle at 1px 1px, rgba(255, 255, 255, 0.045) 1px, transparent 0);
  background-size: 18px 18px;
  line-height: 1.5;
}

a {
  color: var(--amber);
}

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

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

/* ---- Masthead ------------------------------------------------------------ */

.masthead,
.layout,
.footer {
  width: min(1040px, 100% - 2rem);
  margin-inline: auto;
}

.masthead {
  padding: 2.5rem 0 1.5rem;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  margin: 0 0 0.75rem;
  font: 600 0.8rem/1 var(--font-mono);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
}

.led {
  width: 0.55rem;
  height: 0.55rem;
  border-radius: 50%;
  background: var(--amber);
  box-shadow: 0 0 0.6rem var(--amber);
  animation: blink 2.4s ease-in-out infinite;
}

h1 {
  margin: 0;
  font-size: clamp(2.1rem, 6vw, 3.6rem);
  font-weight: 800;
  line-height: 1.02;
  letter-spacing: -0.02em;
  text-transform: uppercase;
}

h1 span {
  display: block;
  color: var(--amber);
}

.server-status {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  margin: 1.1rem 0 0;
  padding: 0.75rem 1rem;
  font-size: 0.95rem;
  color: var(--ink);
  background: var(--amber-soft);
  border: 1px solid rgba(255, 178, 46, 0.4);
  border-radius: 10px;
}

.server-status[hidden] {
  display: none;
}

.server-status .led {
  flex: none;
  animation-duration: 1s;
}

/* ---- Layout ---------------------------------------------------------------- */

.layout {
  display: grid;
  gap: 1.25rem;
  padding-bottom: 2rem;
}

@media (min-width: 860px) {
  .layout {
    grid-template-columns: minmax(0, 5fr) minmax(0, 6fr);
    align-items: start;
  }

  .layout > .wide {
    grid-column: 1 / -1;
  }
}

.panel,
.board {
  background: var(--panel);
  border: 1px solid var(--panel-edge);
  border-radius: var(--radius);
  padding: clamp(1.1rem, 3vw, 1.75rem);
  box-shadow: 0 18px 40px -24px rgba(0, 0, 0, 0.8);
}

.panel {
  container-type: inline-size;
}

.panel-title,
.board-title {
  margin: 0 0 1.1rem;
  font: 700 0.8rem/1 var(--font-mono);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--muted);
}

/* ---- Form ------------------------------------------------------------------ */

.field {
  display: grid;
  gap: 0.4rem;
  min-width: 0;
}

.field + .pair,
.pair + .convert {
  margin-top: 1.1rem;
}

label {
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--ink);
}

input,
select {
  width: 100%;
  min-height: 3rem;
  padding: 0.7rem 0.9rem;
  font: 500 1.15rem/1.2 var(--font-mono);
  color: var(--ink);
  background: var(--tile-bottom);
  border: 1px solid var(--tile-edge);
  border-radius: 10px;
}

input {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--amber);
}

select {
  appearance: none;
  padding-right: 2.4rem;
  font-size: 1rem;
  text-overflow: ellipsis;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 12 8'%3E%3Cpath d='M1 1l5 5 5-5' fill='none' stroke='%23ffb22e' stroke-width='2' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.9rem center;
  background-size: 0.75rem;
  cursor: pointer;
}

select option,
select optgroup {
  background: var(--panel);
  color: var(--ink);
}

input:hover,
select:hover:not(:disabled) {
  border-color: #4a4f59;
}

input[aria-invalid="true"] {
  border-color: var(--danger);
}

select:disabled {
  cursor: progress;
  opacity: 0.6;
}

.hint {
  margin: 0;
  font-size: 0.8rem;
  color: var(--muted);
}

.field-error {
  margin: 0;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--danger);
}

.pair {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
  align-items: end;
  gap: 0.6rem;
}

.swap {
  display: grid;
  place-items: center;
  width: 3rem;
  height: 3rem;
  padding: 0;
  color: var(--amber);
  background: transparent;
  border: 1px solid var(--tile-edge);
  border-radius: 50%;
  cursor: pointer;
  transition: background-color 0.15s, transform 0.3s;
}

.swap:hover:not(:disabled) {
  background: var(--amber-soft);
}

.swap.is-swapping svg {
  animation: spin 0.35s ease-out;
}

.swap:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* Stack From/To whenever the panel itself is narrow (phones, and the side
   column on desktop), so currency names are never cut off. */
@container (max-width: 34rem) {
  .pair {
    grid-template-columns: minmax(0, 1fr);
  }

  .swap {
    justify-self: center;
    transform: rotate(90deg);
  }
}

.convert {
  width: 100%;
  min-height: 3.25rem;
  font: 800 1rem/1 var(--font-sans);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--bg);
  background: var(--amber);
  border: 0;
  border-radius: 10px;
  cursor: pointer;
  transition: filter 0.15s, transform 0.1s;
}

.convert:hover:not(:disabled) {
  filter: brightness(1.08);
}

.convert:active:not(:disabled) {
  transform: translateY(1px);
}

.convert:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

/* ---- Alerts ------------------------------------------------------------------ */

.alert {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-top: 1.1rem;
  padding: 0.85rem 1rem;
  color: var(--ink);
  background: rgba(255, 122, 107, 0.08);
  border: 1px solid rgba(255, 122, 107, 0.35);
  border-left: 4px solid var(--danger);
  border-radius: 10px;
}

.alert[hidden],
.retry[hidden] {
  display: none;
}

.alert p {
  margin: 0;
  flex: 1 1 14rem;
}

.retry {
  min-height: 2.5rem;
  padding: 0 1rem;
  font: 700 0.85rem/1 var(--font-sans);
  color: var(--amber);
  background: transparent;
  border: 1px solid var(--amber);
  border-radius: 8px;
  cursor: pointer;
}

.retry:hover {
  background: var(--amber-soft);
}

/* ---- Result board --------------------------------------------------------------- */

.board {
  container-type: inline-size;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.025), transparent 40%),
    var(--panel);
}

.result-from {
  margin: 0 0 0.6rem;
  font: 600 clamp(1rem, 3.5cqi, 1.25rem) / 1.3 var(--font-mono);
  color: var(--muted);
  overflow-wrap: anywhere;
}

.capsule {
  /* --chars is set from JS so long values shrink to fit instead of overflowing.
     0.62em is roughly one monospace character, plus room for the padding. */
  --capsule-size: min(2.6rem, calc(100cqi / (var(--chars, 10) * 0.62 + 1.4)));
  position: relative;
  display: inline-block;
  max-width: 100%;
  margin: 0;
  padding: 0.3em 0.55em;
  font: 700 var(--capsule-size) / 1.15 var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
  white-space: nowrap;
  color: var(--amber);
  background: linear-gradient(var(--tile-top) 50%, var(--tile-bottom) 50%);
  border-radius: 0.3em;
  box-shadow: inset 0 0 0 1px var(--tile-edge), 0 0.08em 0 rgba(0, 0, 0, 0.6);
  text-shadow: 0 0 0.35em rgba(255, 178, 46, 0.35);
  animation: capsule-in 0.35s ease-out both;
}

/* The split-flap hinge line across the middle of the capsule. */
.capsule::after {
  content: "";
  position: absolute;
  inset: 50% 0 auto;
  height: 1px;
  background: rgba(0, 0, 0, 0.7);
}

.capsule-code {
  margin-left: 0.4em;
  color: var(--ink);
  text-shadow: none;
}

.capsule--empty {
  color: var(--tile-edge);
  text-shadow: none;
  animation: none;
}

/* Pulse only the empty placeholder: a value already on screen stays steady
   while it updates (the source line below says "updating…"). */
.result[aria-busy="true"] .capsule--empty {
  animation: pulse 0.9s ease-in-out infinite alternate;
}

.rates-source {
  min-height: 1.5em; /* reserved, so changing the text never moves the layout */
  margin: 0.6rem 0 0;
  font: 500 0.85rem/1.5 var(--font-mono);
  color: var(--muted);
}

.rates-source.is-warning {
  color: var(--amber);
}

.link-button {
  margin-left: 0.4rem;
  padding: 0;
  font: inherit;
  color: var(--amber);
  text-decoration: underline;
  background: none;
  border: 0;
  cursor: pointer;
}

.link-button[hidden] {
  display: none;
}

.result-meta {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(12rem, 1fr));
  gap: 0.75rem 1.5rem;
  margin: 1.4rem 0 0;
  padding-top: 1.1rem;
  border-top: 1px dashed var(--panel-edge);
}

.result-meta dt {
  font: 700 0.72rem/1 var(--font-mono);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
}

.result-meta dd {
  margin: 0.35rem 0 0;
  font: 500 1rem/1.35 var(--font-mono);
}

/* ---- History ------------------------------------------------------------------- */

.history-pair {
  color: var(--amber);
}

.history-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.75rem;
  margin: 0 0 1.1rem;
}

.history-stats div {
  min-width: 0;
  padding: 0.75rem 0.9rem;
  background: var(--tile-bottom);
  border: 1px solid var(--tile-edge);
  border-radius: 10px;
}

.history-stats dt {
  font: 700 0.72rem/1 var(--font-mono);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
}

.history-stats dd {
  margin: 0.4rem 0 0;
  font: 700 clamp(0.95rem, 2.5vw, 1.2rem) / 1.25 var(--font-mono);
  overflow-wrap: anywhere;
}

.history-stats small {
  display: block;
  margin-top: 0.15rem;
  font-size: 0.78rem;
  font-weight: 500;
  color: var(--muted);
}

/* Up/down are also spelled out with a sign and an arrow, never color alone. */
.trend-up {
  color: #7ddc8b;
}

.trend-down {
  color: var(--danger);
}

.chart-wrap {
  position: relative;
  height: clamp(220px, 38vw, 320px);
  transition: opacity 0.2s;
}

.chart-wrap[aria-busy="true"] {
  opacity: 0.4;
}

.chart-wrap[hidden] {
  display: none;
}

@media (max-width: 520px) {
  .history-stats {
    grid-template-columns: minmax(0, 1fr);
  }
}

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

.footer {
  padding: 0 0 2.5rem;
  font-size: 0.85rem;
  color: var(--muted);
}

/* ---- Motion ------------------------------------------------------------------ */

@keyframes capsule-in {
  from {
    opacity: 0;
    transform: translateY(0.25em) scale(0.97);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

@keyframes pulse {
  from {
    opacity: 0.35;
  }
  to {
    opacity: 0.8;
  }
}

@keyframes blink {
  0%,
  100% {
    opacity: 1;
  }
  50% {
    opacity: 0.35;
  }
}

@keyframes spin {
  from {
    rotate: 0deg;
  }
  to {
    rotate: 180deg;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    animation-delay: 0ms !important;
    transition-duration: 0.01ms !important;
  }
}