/* ==========================================================================
   chain.css - the interactive proof-of-work chain demo
   ========================================================================== */

.chain {
  display: grid;
  gap: var(--space-l);
}

/* Toolbar ------------------------------------------------------------------ */

.chain__bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-s);
  padding: var(--space-s) var(--space-m);
  border: 1px solid var(--rule);
  border-radius: var(--radius-lg);
  background: var(--paper-raised);
}

.chain__status {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: var(--step--1);
  margin-inline-end: auto;
}

.chain__status[data-state="valid"]   { color: var(--verify); }
.chain__status[data-state="invalid"] { color: var(--signal); }
.chain__status[data-state="working"] { color: var(--accent); }

.chain__difficulty {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--ink-faint);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.chain__difficulty input {
  width: 6.5rem;
  accent-color: var(--accent);
  cursor: pointer;
}

/* Track -------------------------------------------------------------------- */

.chain__track {
  display: flex;
  gap: 0;
  align-items: stretch;
  overflow-x: auto;
  overscroll-behavior-x: contain;
  scroll-snap-type: x proximity;
  padding-block: var(--space-xs) var(--space-m);
  margin-inline: calc(var(--gutter) * -1);
  padding-inline: var(--gutter);
  scrollbar-width: thin;
}

.chain__track::-webkit-scrollbar { height: 6px; }
.chain__track::-webkit-scrollbar-thumb { background: var(--rule); border-radius: 100px; }

/* Block -------------------------------------------------------------------- */

.block {
  position: relative;
  flex: 0 0 min(21rem, 78vw);
  scroll-snap-align: center;
  display: grid;
  gap: var(--space-s);
  padding: var(--space-m);
  border: 1.5px solid var(--rule);
  border-radius: var(--radius-lg);
  background: var(--paper-raised);
  transition: border-color var(--dur-mid) var(--ease-out),
              background-color var(--dur-mid) var(--ease-out),
              box-shadow var(--dur-mid) var(--ease-out);
}

/* The link between two blocks: a hash tether drawn with a pseudo-element */
.block + .block { margin-inline-start: 2.75rem; }

.block + .block::before {
  content: "";
  position: absolute;
  top: 50%;
  left: -2.75rem;
  width: 2.75rem;
  height: 2px;
  background: repeating-linear-gradient(
    to right,
    var(--verify) 0 6px,
    transparent 6px 10px
  );
  transition: background var(--dur-mid) var(--ease-out);
}

.block + .block::after {
  content: "";
  position: absolute;
  top: 50%;
  left: -0.85rem;
  width: 0.5rem;
  height: 0.5rem;
  margin-top: -0.24rem;
  border: 2px solid var(--verify);
  border-top: 0;
  border-left: 0;
  transform: rotate(-45deg);
  transition: border-color var(--dur-mid) var(--ease-out);
}

.block[data-valid="false"] {
  border-color: var(--signal);
  background: var(--signal-soft);
  animation: nudge 420ms var(--ease-out);
}

.block[data-valid="false"] + .block::before,
.block[data-valid="false"]::before { background: repeating-linear-gradient(to right, var(--signal) 0 3px, transparent 3px 8px); }

.block[data-valid="false"] + .block::after,
.block[data-valid="false"]::after { border-color: var(--signal); }

.block[data-mining="true"] {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px var(--accent-soft);
}

@keyframes nudge {
  0%, 100% { transform: translateX(0); }
  25%      { transform: translateX(-4px); }
  75%      { transform: translateX(4px); }
}

.block__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-s);
  padding-bottom: var(--space-xs);
  border-bottom: 1px solid var(--rule);
}

.block__index {
  font-family: var(--font-display);
  font-size: var(--step-1);
  font-weight: 600;
  letter-spacing: -0.02em;
}

.block__index span { color: var(--ink-faint); font-weight: 400; }

.block__state {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  color: var(--verify);
}

.block[data-valid="false"] .block__state { color: var(--signal); }
.block[data-mining="true"] .block__state { color: var(--accent); }

/* Fields ------------------------------------------------------------------- */

.block__field { display: grid; gap: 0.3rem; }

.block__key {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-faint);
}

.block__data {
  width: 100%;
  min-height: 4.5rem;
  resize: vertical;
  padding: var(--space-xs) var(--space-s);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  background: var(--paper);
  font-family: var(--font-code);
  font-size: 0.78rem;
  line-height: 1.5;
  transition: border-color var(--dur-fast) var(--ease-out);
}

.block__data:focus-visible { border-color: var(--accent); }

.block__hash {
  font-family: var(--font-code);
  font-size: 0.72rem;
  line-height: 1.45;
  overflow-wrap: anywhere;   /* breaks the long hex run, but not "(genesis)" */
  word-break: normal;
  color: var(--ink-soft);
  padding: 0.35rem var(--space-xs);
  border-radius: var(--radius);
  background: var(--paper-sunken);
}

/* The leading zeros that make a hash "solved" are highlighted */
.block__hash b { color: var(--verify); font-weight: 600; }
.block[data-valid="false"] .block__hash b { color: var(--signal); }

.block__hash--prev { color: var(--ink-faint); }

.block__foot {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-s);
  padding-top: var(--space-xs);
  border-top: 1px dashed var(--rule);
}

.block__nonce {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--ink-faint);
}

.block__nonce b { color: var(--ink); font-weight: 500; font-variant-numeric: tabular-nums; }

/* Legend ------------------------------------------------------------------- */

.chain__legend {
  display: grid;
  gap: var(--space-s);
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 15rem), 1fr));
  font-size: var(--step--1);
  color: var(--ink-soft);
}

.chain__legend li {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: var(--space-xs);
  align-items: start;
}

.chain__legend .num {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--accent);
  padding-top: 0.2rem;
}

@media (max-width: 48rem) {
  .block { flex-basis: min(19rem, 82vw); }
  .block + .block { margin-inline-start: 2rem; }
  .block + .block::before { left: -2rem; width: 2rem; }
}

/* The status line changes between four messages of very different lengths.
   Reserving two lines of height keeps the toolbar from resizing underneath
   the reader when it does. */
.chain__status { min-height: 2.9em; align-items: flex-start; padding-top: 0.15em; }
.chain__status .dot { margin-top: 0.45em; }

@media (min-width: 60rem) {
  .chain__status { min-height: 1.5em; align-items: center; padding-top: 0; }
  .chain__status .dot { margin-top: 0; }
}