:root {
  --bg: #0f1218;
  --card: #161b24;
  --card-2: #1c2230;
  --border: #283042;
  --text: #e7eaf1;
  --muted: #8a93a8;
  --code-text: #d6dbe6;

  --flow: #f5b544;
  --call: #b794ff;
  --out: #4ade80;
  --err: #f87171;
  --assign: #60a5fa;
  --loop: #2dd4bf;

  --tk-kw: #c792ea;
  --tk-str: #a5d6a7;
  --tk-var: #ffb86c;
  --tk-cmd: #82aaff;
  --tk-fn: #f78fb3;
  --tk-num: #f78c6c;
  --tk-op: #89ddff;
  --tk-cmt: #6b7489;

  --label-ink: #141821;
  --shadow: 0 6px 20px rgba(0, 0, 0, 0.35);
  --mono: 'JetBrains Mono', 'Fira Code', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --sans: Inter, ui-sans-serif, system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  color-scheme: dark;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg: #f4f5f8;
    --card: #ffffff;
    --card-2: #f0f2f7;
    --border: #dde1ea;
    --text: #1b2130;
    --muted: #667085;
    --code-text: #273046;
    --flow: #d98a00;
    --call: #8b5cf6;
    --out: #16a34a;
    --err: #dc2626;
    --assign: #2563eb;
    --loop: #0d9488;
    --tk-kw: #8b3fd1;
    --tk-str: #2f7d32;
    --tk-var: #c15c00;
    --tk-cmd: #2b5cd6;
    --tk-fn: #c2185b;
    --tk-num: #c2410c;
    --tk-op: #0f7c99;
    --tk-cmt: #8a93a8;
    --label-ink: #ffffff;
    --shadow: 0 6px 18px rgba(20, 30, 60, 0.15);
    color-scheme: light;
  }
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

html,
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 15px/1.5 var(--sans);
}

code,
kbd {
  font-family: var(--mono);
  font-size: 0.9em;
}

kbd {
  border: 1px solid var(--border);
  border-bottom-width: 2px;
  border-radius: 4px;
  padding: 0 4px;
}

.muted {
  color: var(--muted);
}

button,
select,
input,
textarea {
  font: inherit;
  color: inherit;
}

button {
  background: var(--card-2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 7px 13px;
  cursor: pointer;
  white-space: nowrap;
}

button:hover:not(:disabled) {
  border-color: var(--muted);
}

button:disabled {
  opacity: 0.4;
  cursor: default;
}

button.primary {
  background: var(--flow);
  border-color: var(--flow);
  color: #141821;
  font-weight: 600;
}

select {
  background: var(--card-2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 5px 8px;
}

/* ---------- top bar ---------- */

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  padding: 12px 24px;
  border-bottom: 1px solid var(--border);
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 18px;
}

.logo {
  display: inline-grid;
  place-items: center;
  width: 30px;
  height: 30px;
  border-radius: 8px;
  background: var(--flow);
  color: #141821;
  font: 700 14px var(--mono);
}

.pickers {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  color: var(--muted);
  font-size: 14px;
}

.pickers label {
  display: flex;
  align-items: center;
  gap: 8px;
}

main {
  padding: 20px 24px 40px;
  max-width: 1500px;
  margin: 0 auto;
}

/* ---------- editor ---------- */

.editor {
  max-width: 900px;
  margin: 0 auto;
  display: grid;
  gap: 18px;
}

.field > label,
.field > summary {
  display: block;
  font-weight: 600;
  margin-bottom: 6px;
}

.field > summary {
  cursor: pointer;
}

.hint {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: 13px;
}

.cmdline {
  display: flex;
  align-items: center;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding-left: 12px;
}

.cmdline input {
  flex: 1;
  border: 0;
  background: transparent;
  padding: 10px 12px 10px 8px;
  font-family: var(--mono);
  outline: none;
}

.prompt {
  color: var(--out);
  font-family: var(--mono);
  font-weight: 700;
}

textarea {
  width: 100%;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px 14px;
  font-family: var(--mono);
  font-size: 14px;
  line-height: 1.6;
  resize: vertical;
  tab-size: 2;
  outline: none;
}

textarea:focus,
.cmdline:focus-within {
  border-color: var(--flow);
}

.files-list {
  display: grid;
  gap: 10px;
  margin-bottom: 10px;
}

.file-item {
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--card);
  overflow: hidden;
}

.file-head {
  display: flex;
  border-bottom: 1px solid var(--border);
  background: var(--card-2);
}

.file-name {
  flex: 1;
  min-width: 0;
  border: 0;
  background: transparent;
  padding: 8px 12px;
  font: 600 14px var(--mono);
  color: var(--tk-cmd);
  outline: none;
}

.file-remove {
  border: 0;
  border-radius: 0;
  background: transparent;
  color: var(--muted);
}

.file-item textarea {
  border: 0;
  border-radius: 0;
  background: transparent;
}

.file-item:focus-within {
  border-color: var(--flow);
}

.actions {
  display: flex;
  align-items: center;
  gap: 14px;
  flex-wrap: wrap;
}

.actions .primary {
  padding: 10px 22px;
  font-size: 16px;
}

.error {
  border: 1px solid var(--err);
  background: color-mix(in srgb, var(--err) 12%, transparent);
  border-radius: 10px;
  padding: 10px 14px;
  font-family: var(--mono);
  font-size: 14px;
  white-space: pre-wrap;
}

/* ---------- viewer ---------- */

.sticky {
  position: sticky;
  top: 0;
  z-index: 20;
  background: var(--bg);
  padding: 4px 0 12px;
}

.controls {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.nav {
  display: flex;
  gap: 6px;
}

#slider {
  flex: 1;
  min-width: 120px;
  accent-color: var(--flow);
}

.counter {
  color: var(--muted);
  font-variant-numeric: tabular-nums;
  min-width: 90px;
  text-align: right;
}

.desc-row {
  display: flex;
  gap: 10px;
  align-items: stretch;
  margin-top: 12px;
}

.desc-row .desc {
  flex: 1;
  margin-top: 0;
}

.more {
  flex: none;
  border-color: color-mix(in srgb, var(--flow) 50%, var(--border));
  color: var(--flow);
  font-weight: 600;
}

@media (max-width: 600px) {
  .desc-row {
    flex-direction: column;
  }
}

.desc {
  margin-top: 12px;
  background: var(--card);
  border: 1px solid var(--border);
  border-left: 4px solid var(--flow);
  border-radius: 10px;
  padding: 12px 16px;
  font-size: 17px;
  min-height: 52px;
}

.desc.is-error {
  border-left-color: var(--err);
}

.desc code {
  background: var(--card-2);
  border: 1px solid var(--border);
  border-radius: 5px;
  padding: 0 5px;
  white-space: pre-wrap;
}

.desc .step-no {
  color: var(--muted);
  font-size: 13px;
  font-weight: 600;
  margin-right: 8px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.stage {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1.7fr) minmax(260px, 1fr);
  gap: 40px;
  align-items: start;
  margin-top: 8px;
}

@media (max-width: 900px) {
  .stage {
    grid-template-columns: minmax(0, 1fr);
  }
}

.code-col,
.side-col {
  display: grid;
  gap: 18px;
  min-width: 0;
}

/* Variables, files and the terminal stay in view while the code scrolls. */
.side-col {
  position: sticky;
  top: calc(var(--sticky-h, 140px) + 8px);
  max-height: calc(100vh - var(--sticky-h, 140px) - 16px);
  overflow-y: auto;
  overscroll-behavior: contain;
  align-content: start;
}

@media (max-width: 900px) {
  .side-col {
    position: static;
    max-height: none;
    overflow: visible;
  }
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  min-width: 0;
}

.card-title {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  padding: 10px 16px 0;
}

.inv-row {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 0 16px 6px;
  font-size: 15px;
}

.code-wrap {
  display: flex;
  padding: 0 16px 10px 0;
  overflow-x: auto;
}

.code-block {
  position: relative;
  flex: 1;
  min-width: 0;
}

.hl-layer {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

pre.code,
pre.gutter {
  margin: 0;
  padding: 30px 0 26px;
  font: 15px/2.8 var(--mono);
  white-space: pre;
  tab-size: 4;
}

pre.code {
  position: relative;
  color: var(--code-text);
}

pre.gutter {
  color: var(--muted);
  opacity: 0.6;
  text-align: right;
  padding-left: 14px;
  padding-right: 16px;
  user-select: none;
}

.tk-kw { color: var(--tk-kw); }
.tk-str { color: var(--tk-str); }
.tk-var { color: var(--tk-var); }
.tk-cmd { color: var(--tk-cmd); }
.tk-fn { color: var(--tk-fn); }
.tk-num { color: var(--tk-num); }
.tk-op { color: var(--tk-op); }
.tk-cmt { color: var(--tk-cmt); font-style: italic; }

/* highlights */

.hl {
  position: absolute;
  border-radius: 6px;
  scroll-margin: 200px 0 120px;
}

.hl-stmt {
  background: color-mix(in srgb, var(--text) 6%, transparent);
}

.hl-active {
  background: color-mix(in srgb, var(--flow) 22%, transparent);
  box-shadow: 0 0 0 1.5px color-mix(in srgb, var(--flow) 75%, transparent);
  animation: hl-in 0.35s ease-out;
}

.hl-focus {
  box-shadow: 0 0 0 2px var(--flow);
  background: color-mix(in srgb, var(--flow) 14%, transparent);
}

.hl-call {
  background: color-mix(in srgb, var(--call) 24%, transparent);
  box-shadow: 0 0 0 1.5px var(--call);
}

.hl-def {
  box-shadow: 0 0 0 1.5px var(--call);
  background: color-mix(in srgb, var(--call) 10%, transparent);
}

.hl-loop {
  background: color-mix(in srgb, var(--loop) 14%, transparent);
  box-shadow: inset 0 -2px 0 color-mix(in srgb, var(--loop) 70%, transparent);
}

.hl-cond-true {
  background: color-mix(in srgb, var(--out) 13%, transparent);
}

.hl-cond-false {
  background: color-mix(in srgb, var(--err) 13%, transparent);
}

@keyframes hl-in {
  from {
    opacity: 0;
    transform: scale(0.97);
  }
}

/* value labels */

.label-layer {
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 6;
}

.vlabel {
  position: absolute;
  display: grid;
  max-width: 340px;
  padding: 1px 8px;
  border-radius: 7px;
  font: 600 12px/1.45 var(--mono);
  white-space: pre;
  background: var(--flow);
  color: var(--label-ink);
  box-shadow: var(--shadow);
}

.vlabel > span {
  grid-area: 1 / 1;
  text-align: left;
  overflow: hidden;
  text-overflow: ellipsis;
}

.vlabel::after {
  content: '';
  position: absolute;
  left: var(--tip, 50%);
  bottom: -4px;
  width: 8px;
  height: 8px;
  background: inherit;
  transform: translateX(-50%) rotate(45deg);
  border-radius: 1px;
  z-index: -1;
}

.vlabel.vl-below::after {
  bottom: auto;
  top: -4px;
}

.vl-assign { background: var(--assign); }
.vl-out { background: var(--out); }
.vl-true { background: var(--out); }
.vl-false { background: var(--err); }
.vl-empty {
  background: var(--card-2);
  color: var(--muted);
  font-style: italic;
  box-shadow: 0 0 0 1px var(--border), var(--shadow);
}

/* arrows */

.arrow-layer {
  position: absolute;
  left: 0;
  top: 0;
  overflow: visible;
  pointer-events: none;
  z-index: 5;
}

.arrow path:first-child {
  fill: none;
  stroke-width: 2.2;
  stroke-linecap: round;
}

.arrow path:last-child {
  stroke: none;
}

.arrow-flow { color: var(--flow); }
.arrow-call { color: var(--call); }
.arrow-out { color: var(--out); }
.arrow-err { color: var(--err); }

.arrow path:first-child { stroke: currentColor; }
.arrow path:last-child { fill: currentColor; }

.arrow.is-old {
  opacity: 0.32;
}

.arrow-call path:first-child {
  stroke-width: 2.6;
}

/* variables panel */

.vars {
  display: grid;
  gap: 10px;
  padding: 10px 12px 12px;
}

.frame {
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
  animation: frame-in 0.35s ease-out;
}

.frame.call {
  border-color: color-mix(in srgb, var(--call) 60%, var(--border));
}

.frame-head {
  display: flex;
  justify-content: space-between;
  gap: 8px;
  padding: 5px 10px;
  background: var(--card-2);
  font-size: 13px;
}

.frame.call .frame-head {
  background: color-mix(in srgb, var(--call) 16%, var(--card-2));
}

.frame-title {
  font-family: var(--mono);
  font-weight: 700;
}

.frame-sub {
  color: var(--muted);
}

.frame-empty {
  padding: 6px 10px;
  color: var(--muted);
  font-size: 13px;
  font-style: italic;
}

.var-row {
  display: grid;
  grid-template-columns: minmax(60px, auto) 1fr;
  gap: 12px;
  padding: 4px 10px;
  font: 13.5px/1.5 var(--mono);
  border-top: 1px solid color-mix(in srgb, var(--border) 60%, transparent);
}

.var-row:first-of-type {
  border-top: 0;
}

.var-name {
  color: var(--tk-var);
  font-weight: 600;
}

.kind-arg .var-name {
  color: var(--call);
}

.kind-file .var-name {
  color: var(--tk-cmd);
}

.var-value {
  word-break: break-all;
  white-space: pre-wrap;
}

.var-value .empty {
  color: var(--muted);
  font-style: italic;
}

.var-value s {
  color: var(--muted);
}

.var-value .to {
  color: var(--muted);
  margin: 0 6px;
}

.kind-element {
  padding-left: 26px;
}

.kind-element .var-name {
  color: var(--muted);
}

.var-type {
  margin-left: 8px;
  color: var(--muted);
  font: italic 11px var(--sans);
}

.arr-type {
  color: var(--muted);
  font-style: italic;
}

.vis-table {
  border-collapse: collapse;
  font: 14px var(--mono);
}

.vis-table th,
.vis-table td {
  border: 1px solid var(--border);
  padding: 4px 12px;
  text-align: left;
  white-space: pre-wrap;
}

.vis-table th {
  color: var(--tk-var);
  background: var(--card-2);
}

.var-value .block {
  display: block;
}

.var-value .to.block {
  margin: 0;
  line-height: 1.2;
}

.var-row.changed {
  background: color-mix(in srgb, var(--assign) 14%, transparent);
}

.var-row.flash {
  animation: flash 1.2s ease-out;
}

.badge {
  font: 700 10px var(--sans);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--assign);
  margin-left: 8px;
}

@keyframes flash {
  0% {
    background: color-mix(in srgb, var(--assign) 45%, transparent);
  }
}

@keyframes frame-in {
  from {
    opacity: 0;
    transform: translateY(-4px);
  }
}

/* console */

.console {
  margin: 10px 12px 12px;
  background: #0a0d12;
  color: #e5e7eb;
  border-radius: 8px;
  padding: 10px 12px;
  font: 14px/1.6 var(--mono);
  min-height: 90px;
  max-height: 320px;
  overflow: auto;
}

.con-line {
  white-space: pre-wrap;
  word-break: break-all;
}

.con-cmd {
  color: #8a93a8;
}

.con-cmd::before {
  content: '$ ';
  color: #4ade80;
}

.con-err {
  color: #f87171;
}

.con-in {
  color: #93c5fd;
  font-style: italic;
}

.con-line.new {
  animation: con-in 0.5s ease-out 0.35s both;
}

@keyframes con-in {
  from {
    opacity: 0;
    transform: translateX(-6px);
    background: rgba(74, 222, 128, 0.25);
  }
}

/* detail dialog */

.detail {
  width: min(760px, calc(100vw - 32px));
  max-height: calc(100vh - 48px);
  padding: 0;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--card);
  color: var(--text);
  box-shadow: 0 24px 80px rgba(0, 0, 0, 0.5);
}

.detail::backdrop {
  background: rgba(5, 8, 12, 0.6);
  backdrop-filter: blur(2px);
}

.detail-head {
  position: sticky;
  top: 0;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  padding: 14px 20px;
  background: var(--card);
  border-bottom: 1px solid var(--border);
}

.detail-head h2 {
  margin: 0;
  font-size: 19px;
}

.detail-head h2 code,
.detail-body p code,
.detail-parts span code,
.vis-caption code {
  background: var(--card-2);
  border: 1px solid var(--border);
  border-radius: 5px;
  padding: 0 5px;
}

.detail-body {
  padding: 6px 20px 20px;
}

.detail-body h3 {
  margin: 20px 0 8px;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
}

.detail-body p {
  margin: 8px 0;
  line-height: 1.6;
}

.detail-code {
  margin: 14px 0 0;
  padding: 16px 18px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  font: 600 22px/1.5 var(--mono);
  white-space: pre-wrap;
  word-break: break-all;
}

.dp {
  border-radius: 5px;
  padding: 0 3px;
  transition: box-shadow 0.15s, background 0.15s;
}

.dp-0 { color: #f5b544; }
.dp-1 { color: #60a5fa; }
.dp-2 { color: #f472b6; }
.dp-3 { color: #4ade80; }
.dp-4 { color: #c084fc; }
.dp-5 { color: #2dd4bf; }

@media (prefers-color-scheme: light) {
  .dp-0 { color: #b45309; }
  .dp-1 { color: #1d4ed8; }
  .dp-2 { color: #be185d; }
  .dp-3 { color: #15803d; }
  .dp-4 { color: #7e22ce; }
  .dp-5 { color: #0f766e; }
}

.dp.lit {
  background: color-mix(in srgb, currentColor 18%, transparent);
  box-shadow: 0 0 0 1.5px currentColor;
}

.detail-parts {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.detail-parts li {
  display: grid;
  grid-template-columns: minmax(70px, auto) 1fr;
  gap: 14px;
  align-items: baseline;
  padding: 7px 10px;
  border-radius: 8px;
}

.detail-parts li.lit {
  background: var(--card-2);
}

.detail-parts li > code {
  font: 700 15px var(--mono);
  justify-self: start;
  background: var(--card-2);
}

.detail-tip {
  border-left: 3px solid var(--assign);
  background: color-mix(in srgb, var(--assign) 10%, transparent);
  border-radius: 6px;
  padding: 8px 12px;
}

.detail-tip strong {
  color: var(--assign);
  margin-right: 6px;
}

.vis-chars {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
}

.vc {
  display: grid;
  justify-items: center;
  min-width: 30px;
  padding: 5px 4px 3px;
  border: 1px solid var(--border);
  border-radius: 7px;
  background: var(--card-2);
}

.vc b {
  font: 700 17px var(--mono);
}

.vc small {
  color: var(--muted);
  font-size: 11px;
}

.vc.space b {
  color: var(--muted);
}

.vc.marked {
  border-color: var(--flow);
  background: color-mix(in srgb, var(--flow) 20%, var(--card-2));
}

.vis-caption {
  color: var(--muted);
  font-size: 14px;
}

.vis-trim {
  font: 600 20px var(--mono);
}

.vis-trim del {
  color: var(--err);
  background: color-mix(in srgb, var(--err) 12%, transparent);
  border-radius: 4px;
}

.vis-trim ins {
  color: var(--out);
  text-decoration: none;
}

.vis-flow {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.vf {
  display: grid;
  gap: 3px;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--card-2);
}

.vf small {
  color: var(--muted);
  font-size: 12px;
}

.vf code {
  font: 600 15px var(--mono);
  white-space: pre-wrap;
}

.vf-arrow {
  color: var(--flow);
  font-size: 20px;
}

/* legend */

.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 20px;
  margin-top: 20px;
  color: var(--muted);
  font-size: 13px;
}

.legend span {
  display: inline-flex;
  align-items: center;
  gap: 7px;
}

.sw {
  width: 22px;
  height: 14px;
  border-radius: 4px;
}

.sw-active {
  background: color-mix(in srgb, var(--flow) 30%, transparent);
  box-shadow: 0 0 0 1.5px var(--flow);
}

.sw-call {
  background: color-mix(in srgb, var(--call) 30%, transparent);
  box-shadow: 0 0 0 1.5px var(--call);
}

.sw-loop {
  background: color-mix(in srgb, var(--loop) 25%, transparent);
}

.ln {
  width: 24px;
  height: 0;
  border-top: 2.5px solid;
  position: relative;
}

.ln::after {
  content: '';
  position: absolute;
  right: -2px;
  top: -6px;
  border: 5px solid transparent;
  border-left: 7px solid;
  border-left-color: inherit;
  border-right: 0;
}

.ln-flow { border-color: var(--flow); }
.ln-call { border-color: var(--call); }
.ln-out { border-color: var(--out); }

@media (max-width: 600px) {
  .topbar,
  main {
    padding-left: 16px;
    padding-right: 16px;
  }
  .nav button {
    padding: 7px 10px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
  }
}