:root {
  --bg: #0c0f14;
  --bg-elevated: #141a24;
  --bg-input: #0e131c;
  --border: rgba(94, 234, 212, 0.12);
  --accent: #5eead4;
  --accent-dim: rgba(94, 234, 212, 0.55);
  --text: #e8edf5;
  --text-muted: #8b98ab;
  --danger: #f87171;
  --font-sans: "DM Sans", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", "Fira Code", ui-monospace, monospace;
  --radius: 12px;
  --shadow: 0 24px 48px rgba(0, 0, 0, 0.45);
  --plot-min-height: 520px;
}

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

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.5;
  color: var(--text);
  background:
    radial-gradient(ellipse 120% 80% at 50% -20%, rgba(94, 234, 212, 0.08), transparent),
    radial-gradient(ellipse 80% 50% at 100% 50%, rgba(56, 189, 248, 0.06), transparent),
    var(--bg);
}

.graphit-app {
  max-width: 1480px;
  margin: 0 auto;
  padding: 2rem 1.25rem 4rem;
}

main {
  max-width: 1320px;
  margin: 0 auto;
  padding: 2rem 1.25rem 4rem;
}

.graphit-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, 320px);
  gap: 1.25rem;
  align-items: start;
}

.graphit-main {
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

@media (max-width: 1100px) {
  .graphit-layout {
    grid-template-columns: 1fr;
  }

  .graphit-rail--scroll {
    max-height: min(70vh, 640px);
  }

  .plot-panel--pinned {
    position: static;
  }
}

/* Collapsible data spreadsheet */
.data-panel {
  flex-shrink: 0;
}

.data-panel__summary {
  list-style: none;
  cursor: pointer;
  user-select: none;
  margin: 0 0 0.85rem;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent-dim);
  display: flex;
  align-items: center;
  gap: 0.45rem;
}

.data-panel__summary::-webkit-details-marker {
  display: none;
}

.data-panel__summary::before {
  content: "";
  width: 0.45rem;
  height: 0.45rem;
  border-right: 2px solid var(--accent);
  border-bottom: 2px solid var(--accent);
  transform: rotate(-45deg);
  transition: transform 0.15s ease;
  flex-shrink: 0;
}

.data-panel:not([open]) .data-panel__summary {
  margin-bottom: 0;
}

.data-panel:not([open]) .data-panel__summary::before {
  transform: rotate(45deg);
}

.data-panel__body {
  margin-top: 0;
}

.data-panel:not([open]) .data-panel__body {
  display: none;
}

/* Graph stays in view; options rail scrolls */
.plot-panel--pinned {
  position: sticky;
  top: max(0.75rem, env(safe-area-inset-top, 0px));
  z-index: 2;
  flex-shrink: 0;
}

.graphit-rail--scroll {
  position: sticky;
  top: max(0.75rem, env(safe-area-inset-top, 0px));
  z-index: 1;
  max-height: calc(100vh - 1.5rem - env(safe-area-inset-top, 0px) - env(safe-area-inset-bottom, 0px));
  overflow-y: auto;
  overflow-x: hidden;
  overscroll-behavior: contain;
  padding-right: 0.15rem;
  scrollbar-gutter: stable;
}

.graphit-rail--scroll::-webkit-scrollbar {
  width: 8px;
}

.graphit-rail--scroll::-webkit-scrollbar-thumb {
  background: rgba(94, 234, 212, 0.25);
  border-radius: 4px;
}

.graphit-rail .panel + .panel {
  margin-top: 0.85rem;
}

.toolbar-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 0.75rem;
}

.btn--file {
  cursor: pointer;
  margin: 0;
}

.btn--tiny {
  padding: 0.2rem 0.45rem;
  font-size: 0.78rem;
  min-width: auto;
}

.data-grid-wrap {
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: 8px;
  max-height: 280px;
  overflow-y: auto;
}

.data-grid {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.82rem;
}

.data-grid th,
.data-grid td {
  border: 1px solid var(--border);
  padding: 0;
}

.data-grid th {
  background: rgba(94, 234, 212, 0.1);
  color: var(--accent-dim);
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 0.35rem 0.4rem;
  position: sticky;
  top: 0;
  z-index: 1;
}

.data-grid input {
  width: 100%;
  min-width: 4.5rem;
  border: none;
  background: var(--bg-input);
  color: var(--text);
  padding: 0.35rem 0.4rem;
  font: inherit;
  font-size: 0.82rem;
}

.data-grid input:focus {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
}

.data-grid__actions {
  width: 2.2rem;
  text-align: center;
}

.plot-toolbar {
  margin-bottom: 0.65rem;
}

.sig-list {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  margin-bottom: 0.65rem;
  max-height: 120px;
  overflow-y: auto;
}

.sig-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  padding: 0.35rem 0.5rem;
  background: var(--bg-input);
  border-radius: 6px;
}

.sig-custom {
  width: 100%;
}

.graphit-app header.hero,
header.hero {
  text-align: center;
  margin-bottom: 1rem;
}

header.hero h1 {
  margin: 0 0 0.35rem;
  font-weight: 700;
  font-size: clamp(1.55rem, 4vw, 2.05rem);
  letter-spacing: -0.03em;
  background: linear-gradient(135deg, #f0fdfa 0%, var(--accent) 55%, #38bdf8 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

header.hero .hero-tagline {
  max-width: 42rem;
  margin: 0.65rem auto 0;
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.55;
}

.page-guide {
  margin-bottom: 1.5rem;
}

.page-guide > h2 {
  margin: 0 0 1rem;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent-dim);
}

.page-guide-body {
  text-align: left;
}

.page-guide-body p {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.58;
}

.page-guide-body .guide-lead {
  font-size: 1rem;
  color: var(--text);
  line-height: 1.62;
}

.page-guide-body .guide-section {
  margin-top: 1.35rem;
  padding-top: 1.15rem;
  border-top: 1px solid var(--border);
}

.page-guide-body .guide-section h2 {
  margin: 0 0 0.55rem;
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--accent);
}

.page-guide-body ul,
.page-guide-body ol {
  margin: 0.5rem 0 0;
  padding-left: 1.25rem;
  color: var(--text-muted);
  font-size: 0.93rem;
  line-height: 1.55;
}

.page-guide-body li + li {
  margin-top: 0.4rem;
}

.page-guide-body code {
  font-family: var(--font-mono);
  font-size: 0.86em;
  color: var(--accent);
  background: rgba(94, 234, 212, 0.08);
  padding: 0.1em 0.35em;
  border-radius: 4px;
}

.workspace {
  display: grid;
  grid-template-columns: minmax(280px, 340px) 1fr;
  gap: 1.25rem;
  align-items: start;
}

@media (max-width: 960px) {
  .workspace {
    grid-template-columns: 1fr;
  }
}

.panel {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.15rem 1.2rem;
  box-shadow: var(--shadow);
}

.panel + .panel {
  margin-top: 1rem;
}

.panel h2 {
  margin: 0 0 0.85rem;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent-dim);
}

.field-label {
  display: block;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-dim);
  margin-bottom: 0.35rem;
}

.field-label-spaced {
  margin-top: 0.85rem;
}

select,
input[type="text"],
input[type="number"],
input[type="color"] {
  width: 100%;
  font: inherit;
  color: var(--text);
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.45rem 0.55rem;
}

input[type="color"] {
  height: 2.25rem;
  padding: 0.2rem;
  cursor: pointer;
}

input[type="file"] {
  width: 100%;
  font-size: 0.85rem;
  color: var(--text-muted);
}

input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
}

.control-row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 0.5rem;
  align-items: center;
  margin-top: 0.35rem;
}

.control-row .range-value {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-muted);
  min-width: 2.5rem;
  text-align: right;
}

.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.65rem;
}

.hint,
.status {
  margin: 0.5rem 0 0;
  font-size: 0.82rem;
  color: var(--text-muted);
  line-height: 1.45;
}

.status--error {
  color: var(--danger);
}

.status--ok {
  color: var(--accent);
}

.checkbox-row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-top: 0.5rem;
  font-size: 0.88rem;
  color: var(--text-muted);
}

.checkbox-row input {
  width: auto;
  accent-color: var(--accent);
}

.export-row,
.demo-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 0.75rem;
}

.demo-row {
  margin-top: 0.55rem;
}

.demo-row .btn {
  text-decoration: none;
  text-align: center;
}

.btn {
  font: inherit;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: rgba(94, 234, 212, 0.12);
  color: var(--accent);
  padding: 0.45rem 0.75rem;
  transition: background 0.15s, border-color 0.15s;
}

.btn:hover {
  background: rgba(94, 234, 212, 0.22);
  border-color: var(--accent-dim);
}

.btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.btn--primary {
  background: var(--accent);
  color: #0c0f14;
  border-color: transparent;
}

.btn--primary:hover {
  background: #7df0de;
}

.btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.plot-panel {
  min-height: var(--plot-min-height);
  padding: 0.75rem;
}

.graphit-main .plot-panel {
  margin-top: 0;
}

.plot-stage {
  position: relative;
  min-height: var(--plot-min-height);
  border-radius: 8px;
  overflow: hidden;
}

.plot-stage.has-plot .plot-placeholder {
  display: none;
}

.plot-placeholder {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: var(--plot-min-height);
  padding: 2rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.5;
}

.plot-canvas {
  width: 100%;
  min-height: var(--plot-min-height);
}

.hub-about-author {
  margin-top: 2rem;
  font-size: 0.88rem;
  color: var(--text-muted);
  line-height: 1.55;
}

.hub-about-author a {
  color: var(--accent);
}