:root {
  --page: #f3f8fc;
  --surface: #ffffff;
  --surface-2: #f7fafd;
  --surface-3: #edf5fa;
  --border: #dce8f0;
  --border-strong: #c9dbe7;
  --primary: #2f8fdb;
  --primary-hover: #237cc2;
  --primary-soft: #e2f2fd;
  --ink: #17364d;
  --muted: #667d8d;
  --faint: #8ea1af;
  --success: #3cbf83;
  --warning: #f3a638;
  --danger: #e36b6b;
  --shadow: 0 10px 30px rgba(50, 91, 119, .07), 0 2px 8px rgba(50, 91, 119, .04);
  --shadow-raised: 0 15px 40px rgba(34, 74, 103, .16), 0 3px 10px rgba(34, 74, 103, .08);
  --sidebar-w: 76px;
  color-scheme: light;
}

html[data-theme="dark"] {
  --page: #0d161d;
  --surface: #14212a;
  --surface-2: #1b2a34;
  --surface-3: #20313c;
  --border: #2e414e;
  --border-strong: #3a5261;
  --primary: #55b7f2;
  --primary-hover: #79c8f5;
  --primary-soft: #17384b;
  --ink: #eaf4fa;
  --muted: #91a7b5;
  --faint: #718896;
  --success: #3cbf83;
  --warning: #f3a638;
  --danger: #e36b6b;
  --shadow: 0 12px 32px rgba(0, 0, 0, .18), 0 2px 8px rgba(0, 0, 0, .12);
  --shadow-raised: 0 18px 48px rgba(0, 0, 0, .35), 0 3px 12px rgba(0, 0, 0, .22);
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { background: var(--page); }
body {
  margin: 0;
  min-width: 1024px;
  min-height: 100vh;
  overflow-x: hidden;
  background:
    radial-gradient(circle at 16% 0%, color-mix(in srgb, var(--primary) 7%, transparent) 0, transparent 28rem),
    var(--page);
  color: var(--ink);
  font-family: Inter, "Segoe UI", "Microsoft JhengHei", system-ui, sans-serif;
  font-size: 15px;
  line-height: 1.5;
  font-variant-numeric: tabular-nums;
}

button, input, select, textarea { font: inherit; }
button { color: inherit; }
button:focus-visible, input:focus-visible, select:focus-visible, textarea:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--primary) 22%, transparent);
  outline-offset: 2px;
}
button:disabled { cursor: not-allowed; opacity: .45; }
.svg-sprite { position: fixed; width: 0; height: 0; overflow: hidden; }
svg { width: 20px; height: 20px; fill: none; stroke: currentColor; stroke-width: 1.7; stroke-linecap: round; stroke-linejoin: round; }

.sidebar {
  position: fixed;
  z-index: 30;
  inset: 0 auto 0 0;
  width: var(--sidebar-w);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  background: color-mix(in srgb, var(--surface) 96%, transparent);
  border-right: 1px solid var(--border);
  box-shadow: 8px 0 30px rgba(36, 76, 105, .04);
  transition: width .24s cubic-bezier(.2,.7,.2,1), box-shadow .2s ease;
}
.sidebar:hover { width: 228px; box-shadow: var(--shadow-raised); }
body.sidebar-pinned { --sidebar-w: 228px; }
.brand-row {
  height: 60px;
  min-height: 60px;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 0 16px;
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}
.brand-mark {
  width: 42px;
  min-width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border-radius: 12px;
  background: var(--primary-soft);
  border: 1px solid color-mix(in srgb, var(--primary) 28%, var(--border));
}
.brand-mark::before, .brand-mark::after, .brand-mark span {
  content: "";
  position: absolute;
  width: 20px;
  height: 20px;
  border: 2px solid var(--primary);
  border-radius: 50%;
}
.brand-mark::after { width: 12px; height: 12px; opacity: .75; }
.brand-mark span { width: 4px; height: 4px; border: 0; background: var(--primary); }
.brand-copy { min-width: 102px; display: grid; line-height: 1.1; }
.brand-copy strong { font-size: 14px; letter-spacing: .08em; }
.brand-copy small { color: var(--muted); font-size: 10px; letter-spacing: .2em; margin-top: 4px; }
.icon-button {
  display: inline-grid;
  place-items: center;
  width: 34px;
  height: 34px;
  padding: 0;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--surface-2);
  cursor: pointer;
}
.sidebar-toggle { margin-left: auto; min-width: 34px; opacity: 0; transform: translateX(6px); transition: opacity .15s ease, transform .15s ease; }
.sidebar:hover .sidebar-toggle, body.sidebar-pinned .sidebar-toggle { opacity: 1; transform: none; }

.nav-list { display: flex; flex-direction: column; gap: 4px; padding: 14px 10px; overflow: auto; scrollbar-width: none; }
.nav-item {
  width: 100%;
  min-height: 42px;
  display: grid;
  grid-template-columns: 42px minmax(112px, 1fr) 26px;
  align-items: center;
  gap: 10px;
  padding: 0;
  border: 0;
  border-radius: 10px;
  background: transparent;
  color: var(--muted);
  text-align: left;
  white-space: nowrap;
  cursor: default;
}
.nav-item > svg { justify-self: center; width: 19px; height: 19px; }
.nav-item span { font-size: 13.5px; font-weight: 650; letter-spacing: .01em; }
.nav-item kbd { color: var(--faint); font: 11px/1 Inter, sans-serif; text-align: center; }
button.nav-item { cursor: pointer; }
button.nav-item:hover { color: var(--primary); background: var(--primary-soft); }
.nav-item.is-active { color: var(--primary); background: var(--primary-soft); box-shadow: inset 3px 0 0 var(--primary); }
.nav-item.is-active span { color: var(--ink); }
.nav-item.is-muted { opacity: .72; }
.sidebar-foot {
  margin-top: auto;
  min-height: 66px;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 24px;
  border-top: 1px solid var(--border);
  white-space: nowrap;
}
.sidebar-foot .status-dot { width: 9px; min-width: 9px; height: 9px; border-radius: 50%; background: var(--success); box-shadow: 0 0 0 4px color-mix(in srgb, var(--success) 14%, transparent); }
.sidebar-foot div { display: grid; }
.sidebar-foot strong { font-size: 12px; }
.sidebar-foot small { color: var(--muted); font-size: 11px; }

.workspace { margin-left: var(--sidebar-w); min-height: 100vh; transition: margin-left .24s cubic-bezier(.2,.7,.2,1); }
.topbar {
  position: sticky;
  z-index: 20;
  top: 0;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 0 24px;
  background: color-mix(in srgb, var(--surface) 88%, transparent);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border);
}
.page-identity { min-width: 0; display: flex; align-items: center; gap: 16px; }
.page-identity p { margin: 0; color: var(--muted); font-size: 12px; white-space: nowrap; }
.page-identity p span { margin: 0 6px; color: var(--border-strong); }
.page-identity p b { color: var(--muted); font-weight: 600; }
.page-identity h1 { display: none; margin: 0; font-size: 18px; }
.top-actions { display: flex; align-items: center; justify-content: flex-end; gap: 8px; }
.preview-chip {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  min-height: 30px;
  padding: 0 10px;
  border: 1px solid color-mix(in srgb, var(--warning) 45%, var(--border));
  border-radius: 999px;
  background: color-mix(in srgb, var(--warning) 9%, var(--surface));
  color: color-mix(in srgb, var(--warning) 72%, var(--ink));
  font-size: 12px;
  font-weight: 700;
}
.preview-chip span { width: 7px; height: 7px; border-radius: 50%; background: var(--warning); }
.quiet-button, .mini-button, .secondary-button, .primary-button, .text-button {
  min-height: 38px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 0 13px;
  border-radius: 9px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--ink);
  font-size: 13px;
  font-weight: 650;
  cursor: pointer;
  transition: border-color .15s ease, background .15s ease, color .15s ease, transform .15s ease;
}
.quiet-button svg, .mini-button svg, .secondary-button svg, .primary-button svg { width: 17px; height: 17px; }
.quiet-button:hover, .mini-button:hover, .secondary-button:hover { border-color: var(--border-strong); background: var(--surface-2); }
.primary-button { border-color: var(--primary); background: var(--primary); color: #fff; box-shadow: 0 5px 14px color-mix(in srgb, var(--primary) 22%, transparent); }
html[data-theme="dark"] .primary-button { color: #082031; }
.primary-button:hover { border-color: var(--primary-hover); background: var(--primary-hover); transform: translateY(-1px); }
.mini-button { min-height: 32px; padding: 0 10px; background: var(--surface-2); font-size: 12px; }
.text-button { min-height: 30px; padding: 0 4px; border-color: transparent; background: transparent; color: var(--primary); }
.theme-switch { display: flex; gap: 2px; padding: 3px; border: 1px solid var(--border); border-radius: 10px; background: var(--surface-2); }
.theme-switch button { width: 30px; height: 30px; padding: 0; display: grid; place-items: center; border: 0; border-radius: 7px; background: transparent; color: var(--muted); cursor: pointer; }
.theme-switch button svg { width: 17px; height: 17px; }
.theme-switch button.is-on { background: var(--surface); color: var(--primary); box-shadow: 0 1px 5px rgba(30, 67, 92, .12); }
.account { display: flex; align-items: center; gap: 9px; padding-left: 8px; }
.account > span { width: 34px; height: 34px; display: grid; place-items: center; border-radius: 50%; background: var(--primary-soft); color: var(--primary); }
.account > span svg { width: 18px; height: 18px; }
.account div { display: grid; line-height: 1.2; }
.account strong { font-size: 12px; }
.account small { color: var(--muted); font-size: 10px; }

main { width: 100%; max-width: 3600px; margin: 0 auto; padding: 24px; }
.page { min-width: 0; }
.page[hidden] { display: none !important; }
.context-row { display: flex; align-items: flex-end; justify-content: space-between; gap: 28px; margin-bottom: 18px; }
.context-row h2 { margin: 3px 0 2px; font-size: clamp(21px, 1.35vw, 28px); letter-spacing: -.025em; line-height: 1.25; }
.context-row p { margin: 0; color: var(--muted); font-size: 14px; }
.eyebrow { color: var(--primary); font-size: 11px; font-weight: 800; letter-spacing: .15em; }
.context-note { max-width: 460px; display: flex; align-items: center; gap: 10px; color: var(--muted); font-size: 12px; text-align: right; }
.context-note span { padding: 3px 8px; border-radius: 6px; background: color-mix(in srgb, var(--warning) 12%, var(--surface)); color: color-mix(in srgb, var(--warning) 72%, var(--ink)); font-weight: 750; }

.layout-grid { display: grid; grid-template-columns: repeat(12, minmax(0, 1fr)); gap: 16px; align-items: start; }
.panel {
  min-width: 0;
  padding: 18px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface);
  box-shadow: var(--shadow);
}
.panel-head { min-height: 32px; display: flex; align-items: center; justify-content: space-between; gap: 16px; margin-bottom: 16px; }
.panel-head > div:first-child { min-width: 0; display: flex; align-items: center; gap: 9px; }
.panel-head h3 { margin: 0; font-size: 15px; letter-spacing: .01em; }
.panel-head h4 { margin: 0; }
.section-no { width: 24px; height: 24px; display: inline-grid; place-items: center; border: 1px solid color-mix(in srgb, var(--primary) 35%, var(--border)); border-radius: 7px; background: var(--primary-soft); color: var(--primary); font-size: 11px; font-weight: 800; }
.head-meta { overflow: hidden; color: var(--muted); font-size: 12px; text-overflow: ellipsis; white-space: nowrap; }
.field-label, label > span { display: block; margin-bottom: 6px; color: var(--muted); font-size: 12px; font-weight: 650; }
.field-label em { margin-left: 5px; color: var(--faint); font-size: 11px; font-style: normal; font-weight: 500; }
input, select, textarea {
  width: 100%;
  min-height: 38px;
  padding: 8px 11px;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--surface-2);
  color: var(--ink);
  transition: border-color .15s ease, box-shadow .15s ease;
}
input:hover, select:hover, textarea:hover { border-color: var(--border-strong); }
input:focus, select:focus, textarea:focus { border-color: var(--primary); box-shadow: 0 0 0 3px color-mix(in srgb, var(--primary) 12%, transparent); outline: 0; }
textarea { min-height: 82px; resize: vertical; font-family: "Cascadia Mono", Consolas, monospace; font-size: 12px; line-height: 1.55; }
.select-shell { position: relative; }
.select-shell > svg { position: absolute; z-index: 1; left: 11px; top: 9px; width: 18px; height: 18px; color: var(--primary); pointer-events: none; }
.select-shell select { padding-left: 38px; }
.drop-zone { width: 100%; min-height: 64px; display: flex; align-items: center; justify-content: flex-start; gap: 12px; margin-top: 10px; padding: 10px 12px; border: 1px dashed var(--border-strong); border-radius: 10px; background: var(--surface-2); color: var(--muted); text-align: left; cursor: pointer; }
.drop-zone:hover { border-color: var(--primary); background: var(--primary-soft); color: var(--primary); }
.drop-zone > svg { width: 21px; height: 21px; }
.drop-zone span { display: grid; }
.drop-zone strong { color: var(--ink); font-size: 12px; }
.drop-zone small { font-size: 11px; }
.divider { height: 1px; margin: 16px 0; background: var(--border); }
.panel-subhead { display: flex; align-items: center; justify-content: space-between; margin-bottom: 8px; }
.panel-subhead h4 { margin: 0; font-size: 12px; }
.panel-subhead > span { color: var(--muted); font-size: 11px; }
.site-list { display: grid; gap: 5px; }
.site-row { width: 100%; display: grid; grid-template-columns: 34px 1fr 18px; align-items: center; gap: 10px; padding: 9px; border: 1px solid transparent; border-radius: 10px; background: transparent; color: var(--ink); text-align: left; cursor: pointer; }
.site-row:hover { background: var(--surface-2); }
.site-row.is-selected { border-color: color-mix(in srgb, var(--primary) 32%, var(--border)); background: var(--primary-soft); }
.site-code { width: 34px; height: 34px; display: grid; place-items: center; border-radius: 9px; background: var(--surface); color: var(--primary); font-size: 11px; font-weight: 800; box-shadow: inset 0 0 0 1px var(--border); }
.site-row > span:nth-child(2) { min-width: 0; display: grid; }
.site-row strong { overflow: hidden; font-size: 12px; text-overflow: ellipsis; white-space: nowrap; }
.site-row small { color: var(--muted); font-size: 10.5px; }
.site-row > svg { width: 15px; height: 15px; color: var(--faint); }

.source-panel { grid-column: span 4; }
.points-panel { grid-column: span 8; }
.export-panel { grid-column: span 7; }
.output-panel { grid-column: span 5; }
.segmented { display: flex; gap: 2px; padding: 3px; border-radius: 9px; background: var(--surface-2); }
.segmented button { min-height: 29px; padding: 0 10px; border: 0; border-radius: 7px; background: transparent; color: var(--muted); font-size: 11px; font-weight: 650; cursor: pointer; }
.segmented button b { margin-left: 4px; color: var(--faint); font-size: 10px; }
.segmented button.is-on { background: var(--surface); color: var(--ink); box-shadow: 0 1px 4px rgba(31, 69, 94, .09); }
.table-scroll, .result-table-wrap { overflow: auto; border: 1px solid var(--border); border-radius: 10px; }
table { width: 100%; border-collapse: collapse; font-size: 12.5px; }
th, td { padding: 10px 12px; border-bottom: 1px solid var(--border); text-align: right; white-space: nowrap; }
th { background: var(--surface-2); color: var(--muted); font-size: 10.5px; font-weight: 750; letter-spacing: .03em; }
th:first-child, td:first-child, th:nth-child(5), td:nth-child(5), th:nth-child(6), td:nth-child(6) { text-align: left; }
tbody tr:last-child td { border-bottom: 0; }
tbody tr:hover td { background: color-mix(in srgb, var(--primary-soft) 38%, transparent); }
td strong { color: var(--ink); }
.state { display: inline-flex; align-items: center; gap: 6px; font-size: 11px; font-weight: 650; }
.state i { width: 7px; height: 7px; border-radius: 50%; background: currentColor; }
.state.ok { color: var(--success); }
.state.warn { color: var(--warning); }
.table-foot { display: flex; justify-content: space-between; margin-top: 9px; color: var(--muted); font-size: 10.5px; }
.subtle-status { display: inline-flex; align-items: center; gap: 6px; color: var(--success); font-size: 11px; }
.subtle-status i { width: 7px; height: 7px; border-radius: 50%; background: var(--success); }
.form-grid { display: grid; gap: 12px; }
.form-grid.three { grid-template-columns: repeat(3, minmax(0, 1fr)); margin-bottom: 13px; }
.action-row { display: flex; align-items: center; gap: 8px; margin-top: 13px; flex-wrap: wrap; }
.action-row.align-end { justify-content: flex-end; padding-top: 13px; border-top: 1px solid var(--border); }
.code-preview { min-height: 136px; overflow: hidden; padding: 10px 12px; border: 1px solid var(--border); border-radius: 10px; background: var(--surface-2); color: var(--muted); font: 11px/1.65 "Cascadia Mono", Consolas, monospace; }
.code-preview div { display: grid; grid-template-columns: 54px repeat(3, 1fr); gap: 10px; }
.code-preview span:not(:first-child) { text-align: right; }
.code-preview span:first-child { color: var(--primary); font-weight: 700; }
.filename { display: flex; align-items: center; gap: 8px; margin-top: 10px; color: var(--muted); font-size: 11px; }
.filename svg { width: 16px; height: 16px; color: var(--primary); }

.files-panel { grid-column: span 4; grid-row: span 2; }
.traverse-main { grid-column: span 8; display: grid; grid-template-columns: repeat(8, minmax(0, 1fr)); gap: 16px; }
.known-panel, .params-panel { grid-column: 1 / -1; }
.result-panel { grid-column: 1 / -1; }
.form-stack { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.round-summary { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin: 14px 0; padding: 12px; border-radius: 10px; background: var(--primary-soft); }
.round-summary > div { display: grid; }
.round-summary > div > span { color: var(--muted); font-size: 10px; font-weight: 650; }
.round-summary strong { color: var(--primary); font-size: 23px; line-height: 1.15; }
.round-summary strong small { font-size: 10px; font-weight: 650; }
.station-files { display: grid; gap: 6px; margin: 0 0 13px; padding: 0; list-style: none; }
.station-files li { display: grid; grid-template-columns: 32px 1fr auto; align-items: center; gap: 9px; padding: 9px 8px; border: 1px solid var(--border); border-radius: 9px; background: var(--surface-2); }
.station-files li > span:nth-child(2) { min-width: 0; display: grid; }
.station-files strong { font-size: 11.5px; }
.station-files small { color: var(--muted); font-size: 10px; }
.file-order { width: 28px; height: 28px; display: grid; place-items: center; border-radius: 8px; background: var(--surface); color: var(--muted); font-size: 10px; font-weight: 700; }
.full { width: 100%; }
.route-pill { max-width: 58%; overflow: hidden; padding: 5px 9px; border-radius: 7px; background: var(--surface-2); color: var(--primary); font: 10.5px/1.3 "Cascadia Mono", Consolas, monospace; text-overflow: ellipsis; white-space: nowrap; }
.known-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 10px; }
.known-grid article { min-width: 0; padding: 11px; border: 1px solid var(--border); border-radius: 10px; background: var(--surface-2); }
.known-grid article > strong { display: block; margin: 2px 0 7px; color: var(--primary); font-size: 17px; }
.point-role { color: var(--muted); font-size: 10px; font-weight: 650; }
.known-grid dl { display: grid; gap: 3px; margin: 0; }
.known-grid dl div { display: flex; justify-content: space-between; gap: 8px; }
.known-grid dt { color: var(--faint); font-size: 9px; font-weight: 700; }
.known-grid dd { overflow: hidden; margin: 0; color: var(--muted); font: 10px/1.4 "Cascadia Mono", Consolas, monospace; text-overflow: ellipsis; }
.form-grid.params { grid-template-columns: repeat(6, minmax(0, 1fr)); }
.unit-input { position: relative; }
.unit-input input { padding-right: 34px; }
.unit-input span { position: absolute; right: 11px; top: 10px; color: var(--muted); font-size: 11px; }
.helper { display: inline-flex; align-items: center; gap: 7px; margin-right: auto; color: var(--muted); font-size: 11px; }
.helper svg { width: 16px; height: 16px; color: var(--success); }
.quality-strip { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 10px; margin-bottom: 14px; }
.quality-strip > div { min-width: 0; padding: 11px 12px; border: 1px solid var(--border); border-radius: 10px; background: var(--surface-2); }
.quality-strip span:not(.state) { display: block; color: var(--muted); font-size: 10px; font-weight: 650; }
.quality-strip strong { display: block; margin: 3px 0 1px; color: var(--ink); font-size: 16px; }
.quality-strip small { display: block; color: var(--faint); font-size: 9.5px; }
.quality-strip .quality-pass { border-color: color-mix(in srgb, var(--success) 32%, var(--border)); background: color-mix(in srgb, var(--success) 8%, var(--surface)); }
.quality-strip .quality-pass strong { color: var(--success); }
.result-table-wrap th:nth-child(n), .result-table-wrap td:nth-child(n) { text-align: right; }
.result-table-wrap th:first-child, .result-table-wrap td:first-child, .result-table-wrap th:nth-child(2), .result-table-wrap td:nth-child(2), .result-table-wrap th:last-child, .result-table-wrap td:last-child { text-align: left; }
.result-actions { justify-content: flex-end; }

.toast { position: fixed; z-index: 80; right: 24px; bottom: 24px; min-width: 260px; display: grid; padding: 12px 16px; border: 1px solid var(--border-strong); border-radius: 11px; background: var(--surface); box-shadow: var(--shadow-raised); opacity: 0; transform: translateY(12px); pointer-events: none; transition: opacity .2s ease, transform .2s ease; }
.toast.is-visible { opacity: 1; transform: none; }
.toast strong { font-size: 12px; }
.toast span { color: var(--muted); font-size: 11px; }

@media (min-width: 1900px) {
  main { padding: 32px; }
  .layout-grid, .traverse-main { gap: 20px; }
  .panel { padding: 20px; }
  .source-panel, .files-panel { grid-column: span 3; }
  .points-panel, .traverse-main { grid-column: span 9; }
  .export-panel { grid-column: span 7; }
  .output-panel { grid-column: span 5; }
}

@media (min-width: 2560px) {
  main { padding: 40px; }
  .layout-grid, .traverse-main { gap: 24px; }
  .panel { padding: 24px; }
  .topbar { padding: 0 40px; }
}

@media (max-width: 1366px) {
  main { padding: 16px; }
  .topbar { padding: 0 16px; }
  .quiet-button { padding: 0 10px; }
  .account div { display: none; }
  .panel { padding: 15px; }
  .form-grid.params { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .known-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  th, td { padding: 9px 10px; }
}

@media (max-height: 790px) {
  .nav-list { gap: 1px; padding-block: 8px; }
  .nav-item { min-height: 37px; }
  main { padding-top: 16px; }
  .context-row { margin-bottom: 12px; }
  .context-row h2 { font-size: 21px; }
  .panel { padding-top: 14px; padding-bottom: 14px; }
  .panel-head { margin-bottom: 11px; }
}

/* Preview revision 2: compact settings rail and concrete tunnel depth. */
body {
  background:
    radial-gradient(ellipse at 8% 8%, #ffffff 0%, transparent 48%),
    linear-gradient(125deg, #e1edf5 0%, #f1f5f8 48%, #d2e1ec 100%);
  background-attachment: fixed;
}
html[data-theme="dark"] {
  --page: #171b1e;
  --surface: #292f33;
  --surface-2: #20262a;
  --surface-3: #363e43;
  --border: #495158;
  --border-strong: #69757d;
  --ink: #f0f3f5;
  --muted: #b7c1c7;
  --faint: #98a7af;
  --primary-soft: #2a424f;
}
html[data-theme="dark"] body {
  background:
    repeating-radial-gradient(ellipse at 85% 42%, transparent 0 105px, #a3aaaf12 108px 112px, #080b0d24 115px 120px, transparent 124px 168px),
    radial-gradient(ellipse at 85% 42%, #101417 0%, #252b2f 28%, #51585d 65%, #959b9e 120%);
  background-attachment: fixed;
}
.context-row { padding: 12px 16px; border: 1px solid var(--border); border-radius: 12px; background: color-mix(in srgb, var(--surface) 94%, transparent); box-shadow: var(--shadow); }
.panel { box-shadow: 0 8px 22px #172a3c12, inset 0 1px 0 #ffffff26; }
html[data-theme="dark"] .panel { box-shadow: 0 12px 26px #00000035, inset 0 1px 0 #ffffff0d; }
.cp-layout, .traverse-layout { grid-template-columns: minmax(290px, 320px) minmax(0, 1fr); gap: 16px; }
.source-panel, .files-panel { grid-column: 1; grid-row: 1; }
.export-panel, .params-panel { grid-column: 1; grid-row: 2; }
.points-panel, .known-panel { grid-column: 2; grid-row: 1; }
.output-panel, .result-panel { grid-column: 2; grid-row: 2 / span 2; }
.traverse-main { display: contents; }
.source-panel, .files-panel, .export-panel, .params-panel { padding: 13px; }
.source-panel .panel-head, .files-panel .panel-head, .export-panel .panel-head, .params-panel .panel-head { gap: 6px; margin-bottom: 10px; }
.form-grid.params, .export-panel .form-grid.three { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 8px; }
.params-panel .helper { display: none; }
.params-panel .action-row { margin-top: 10px; padding-top: 10px; }
.files-panel .round-summary { margin: 8px 0; padding: 8px; }
.station-files { gap: 4px; }
.station-files li { padding: 5px 7px; }
.points-panel table, .result-panel table { font-size: 14px; }
.points-panel td, .result-panel td { padding: 14px 12px; }
.output-panel .code-preview { min-height: 240px; font-size: 13px; line-height: 2; }
.known-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.known-grid dd { font-size: 11px; }
@media (max-width: 1200px) {
  .cp-layout, .traverse-layout { grid-template-columns: 290px minmax(0, 1fr); }
  .known-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

/* Preview revision 3: permanent navigation and layered material surfaces. */
:root { --sidebar-w: 228px; }
.sidebar, .sidebar:hover { width: 228px; }
.sidebar-toggle { display: none; }
.workspace { margin-left: 228px; transition: none; }
body {
  background:
    repeating-linear-gradient(115deg, transparent 0 110px, #ffffff24 111px 112px, transparent 113px 220px),
    radial-gradient(ellipse at 28% 0%, #ffffff 0%, transparent 52%),
    radial-gradient(ellipse at 100% 85%, #b4cbdc 0%, transparent 65%),
    linear-gradient(135deg, #d8e6ef, #edf3f7 48%, #cbdce9);
  background-attachment: fixed;
}
.sidebar {
  background: linear-gradient(155deg, #ffffff, #eaf1f6 65%, #dbe7ef);
  border-right-color: #b8cddc;
  box-shadow: 6px 0 24px #183a5014, inset -1px 0 0 #ffffff;
}
.topbar { background: linear-gradient(100deg, #fffffff5, #e9f2f9f5); box-shadow: 0 3px 15px #2c4c6010; }
.panel {
  background: linear-gradient(150deg, #ffffff 0%, #ffffff 50%, #f0f5f9 100%);
  border-color: #c8d9e5;
  box-shadow: 0 12px 28px #254b6617, 0 2px 4px #254b660a, inset 0 1px 0 #ffffff;
}
.panel-head { border-bottom: 1px solid var(--border); padding-bottom: 10px; }
input, select, textarea, .code-preview, .known-grid article {
  box-shadow: inset 0 2px 4px #142a3c0b, 0 1px 0 #ffffff70;
}
.context-row { background: linear-gradient(110deg, #ffffff, #e8f2f9); border-top: 2px solid #ffffff; }
.result-panel, .points-panel { border-top: 3px solid #80b5d8; }
html[data-theme="dark"] body {
  background:
    repeating-radial-gradient(ellipse at 88% 38%, transparent 0 88px, #c9ced321 90px 93px, #090b0d55 95px 104px, transparent 108px 165px),
    conic-gradient(from 20deg at 88% 38%, transparent 0deg 39deg, #bfc6ca09 40deg 41deg, transparent 42deg 139deg, #00000018 140deg 142deg, transparent 143deg),
    radial-gradient(ellipse at 88% 38%, #080c0f 0%, #1c2327 22%, #434a4e 52%, #858b8e 95%, #b1b6b8 140%);
  background-attachment: fixed;
}
html[data-theme="dark"] .sidebar {
  background: linear-gradient(155deg, #555d62 0%, #323a40 35%, #20272c 100%);
  border-right-color: #758088;
  box-shadow: 8px 0 26px #00000040, inset -1px 0 0 #ffffff12;
}
html[data-theme="dark"] .topbar { background: linear-gradient(100deg, #454d53f5, #242b30f5); border-bottom-color: #64717a; box-shadow: 0 5px 18px #00000030; }
html[data-theme="dark"] .panel {
  background: linear-gradient(145deg, #3f474d 0%, #30383e 38%, #252d32 100%);
  border-color: #58656e;
  box-shadow: 0 15px 32px #00000048, 0 3px 7px #00000028, inset 0 1px 0 #ffffff20;
}
html[data-theme="dark"] .context-row { background: linear-gradient(110deg, #50585e, #2c343a 65%, #232a30); border-top-color: #939b9f; }
html[data-theme="dark"] input, html[data-theme="dark"] select, html[data-theme="dark"] textarea,
html[data-theme="dark"] .code-preview, html[data-theme="dark"] .known-grid article {
  background: #1e262c;
  box-shadow: inset 0 2px 5px #00000035, 0 1px 0 #ffffff0c;
}
html[data-theme="dark"] .result-panel, html[data-theme="dark"] .points-panel { border-top-color: #8eacbe; }
html[data-theme="dark"] th { background: #39444c; color: #d2dce3; }
html[data-theme="dark"] tbody tr:nth-child(even) { background: #ffffff04; }

/* Revision 4: photographic backgrounds, opaque reading surfaces. */
body {
  background: linear-gradient(110deg, #b9c9d8a8, #adbcc983), url('./urban-construction-background.png') center / cover fixed;
  background-attachment: fixed;
}
.panel { background: linear-gradient(145deg, #eaf0f4, #dfe8ef); }
.sidebar { background: linear-gradient(155deg, #e2eaf0, #ccd9e3); }
.topbar, .context-row { background: linear-gradient(110deg, #e1e9ef, #d2dee7); }
html[data-theme="dark"] body {
  background: linear-gradient(110deg, #03080caa, #05090eb3), url('./tunnel-background.png') center / cover fixed;
  background-attachment: fixed;
}
html[data-theme="dark"] .panel { background: linear-gradient(145deg, #272e34, #1c2329); border-color: #3e4b55; }
html[data-theme="dark"] .sidebar { background: linear-gradient(155deg, #242c33, #131a20); border-right-color: #3e4b55; }
html[data-theme="dark"] .topbar, html[data-theme="dark"] .context-row { background: linear-gradient(110deg, #252e35, #161e25); border-color: #46545e; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; }
}