:root {
  --er-bg: #030817;
  --er-surface: #0a1424;
  --er-surface-2: #0e1b2d;
  --er-surface-3: #122238;
  --er-line: #21354b;
  --er-line-soft: rgba(137, 164, 191, 0.18);
  --er-text: #f7f9fc;
  --er-muted: #9aa9bd;
  --er-green: #53e393;
  --er-green-dark: #1ca663;
  --er-gold: #f2c35e;
  --er-red: #ff8b96;
  --er-blue: #82b7ff;
  --er-radius: 22px;
  --er-shadow: 0 24px 70px rgba(0, 0, 0, 0.28);
}

html,
body.er-page {
  overflow-x: hidden;
}

body.er-page {
  margin: 0;
  background: var(--er-bg);
  color: var(--er-text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.7;
}

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

.er-page a {
  color: inherit;
}

.er-skip {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 1000;
  padding: 0.8rem 1rem;
  border-radius: 0.55rem;
  background: #fff;
  color: #071426 !important;
  font-weight: 850;
  text-decoration: none;
  transform: translateY(-180%);
  transition: transform 160ms ease;
}

.er-skip:focus {
  transform: translateY(0);
}

.er-page .site-header {
  position: relative;
  z-index: 20;
  border-bottom: 1px solid rgba(123, 151, 181, 0.18);
  background: #0c1527;
}

.er-page .header-inner {
  min-height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
}

.er-page .logo a {
  color: var(--er-green);
  font-weight: 850;
  text-decoration: none;
  letter-spacing: -0.02em;
}

.er-page .main-nav ul {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  flex-wrap: wrap;
  gap: 8px 24px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.er-page .main-nav a {
  color: #b0bbca;
  font-size: 0.92rem;
  text-decoration: none;
  transition: color 160ms ease;
}

.er-page .main-nav a:hover,
.er-page .main-nav a[aria-current="page"] {
  color: #fff;
}

.er-main {
  position: relative;
  overflow: hidden;
  background:
    radial-gradient(circle at 84% 4%, rgba(47, 218, 127, 0.08), transparent 28rem),
    radial-gradient(circle at 8% 24%, rgba(242, 195, 94, 0.05), transparent 25rem),
    var(--er-bg);
}

.er-shell {
  width: min(1160px, calc(100% - 40px));
  margin: 0 auto;
}

.er-hero {
  min-height: 760px;
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(420px, 0.95fr);
  align-items: center;
  gap: 68px;
  padding: 108px 0 88px;
}

.er-kicker {
  margin: 0 0 14px;
  color: var(--er-green);
  font-size: 0.76rem;
  font-weight: 900;
  letter-spacing: 0.17em;
  line-height: 1.4;
  text-transform: uppercase;
}

.er-hero h1,
.er-section h2,
.er-sources h2,
.er-related h2 {
  margin: 0;
  color: var(--er-text);
  font-weight: 900;
  letter-spacing: -0.048em;
  line-height: 0.98;
}

.er-hero h1 {
  max-width: 720px;
  font-size: clamp(3.2rem, 6.5vw, 6.15rem);
}

.er-byline {
  margin: 24px 0 0;
  color: #aeb9c9;
  font-size: 0.94rem;
  font-weight: 650;
}

.er-byline a {
  color: #fff;
  text-decoration-color: rgba(83, 227, 147, 0.6);
  text-underline-offset: 4px;
}

.er-hero-lede {
  max-width: 690px;
  margin: 30px 0 0;
  color: #b7c2d2;
  font-size: clamp(1.08rem, 1.8vw, 1.32rem);
  line-height: 1.7;
}

.er-hero-lede strong {
  color: #fff;
}

.er-hero-actions,
.er-form-actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
  margin-top: 32px;
}

.er-button,
.er-reset {
  min-height: 48px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 22px;
  border: 0;
  border-radius: 12px;
  font: inherit;
  font-size: 0.92rem;
  font-weight: 850;
  text-decoration: none;
  cursor: pointer;
}

.er-button {
  background: linear-gradient(135deg, #70efa9, #34cd7d);
  color: #04160d;
  box-shadow: 0 14px 34px rgba(35, 204, 116, 0.18);
}

.er-button:hover {
  color: #03140b;
  transform: translateY(-1px);
}

.er-reset {
  border: 1px solid var(--er-line);
  background: #101e31;
  color: #cbd5e1;
}

.er-text-link {
  color: #d5dde8;
  font-weight: 760;
  text-decoration: none;
}

.er-text-link::after {
  content: "  →";
  color: var(--er-green);
}

.er-hero-facts {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin: 38px 0 0;
}

.er-hero-facts div {
  padding: 16px;
  border: 1px solid var(--er-line-soft);
  border-radius: 15px;
  background: rgba(13, 27, 45, 0.78);
}

.er-hero-facts dt {
  color: #fff;
  font-size: 0.83rem;
  font-weight: 850;
}

.er-hero-facts dd {
  margin: 5px 0 0;
  color: #8f9eb2;
  font-size: 0.76rem;
  line-height: 1.5;
}

.er-hero-figure {
  position: relative;
  margin: 0;
  padding: 14px;
  border: 1px solid rgba(107, 147, 129, 0.38);
  border-radius: 26px;
  background: rgba(11, 23, 39, 0.72);
  box-shadow: var(--er-shadow);
}

.er-hero-figure::before {
  content: "";
  position: absolute;
  inset: 9% 9% auto;
  height: 46%;
  border-radius: 50%;
  background: rgba(45, 219, 128, 0.12);
  filter: blur(56px);
  pointer-events: none;
}

.er-hero-figure img {
  position: relative;
  width: 100%;
  height: auto;
  display: block;
  border-radius: 18px;
}

.er-hero-figure figcaption {
  position: relative;
  padding: 14px 8px 2px;
  color: #8291a5;
  font-size: 0.8rem;
  line-height: 1.55;
}

.er-on-page {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 10px;
  padding: 18px 0 22px;
  border-top: 1px solid var(--er-line-soft);
  border-bottom: 1px solid var(--er-line-soft);
}

.er-on-page a {
  padding: 8px 13px;
  border: 1px solid rgba(124, 151, 179, 0.18);
  border-radius: 999px;
  background: rgba(13, 27, 45, 0.66);
  color: #aebac9;
  font-size: 0.78rem;
  font-weight: 750;
  text-decoration: none;
}

.er-on-page a:hover {
  border-color: rgba(83, 227, 147, 0.48);
  color: #fff;
}

.er-section,
.er-sources,
.er-related {
  position: relative;
  padding: 104px 0;
}

.er-section::before,
.er-sources::before,
.er-related::before {
  content: "";
  position: absolute;
  z-index: -1;
  top: 0;
  bottom: 0;
  left: 50%;
  width: 100vw;
  transform: translateX(-50%);
  border-top: 1px solid rgba(109, 137, 168, 0.1);
}

.er-section:nth-of-type(even)::before {
  background: rgba(8, 17, 31, 0.7);
}

.er-section-heading {
  max-width: 820px;
  margin-bottom: 46px;
}

.er-section h2,
.er-sources h2,
.er-related h2 {
  max-width: 930px;
  font-size: clamp(2.35rem, 4.8vw, 4.6rem);
}

.er-section-heading > p:last-child,
.er-principle-copy > p,
.er-sources > p,
.er-related > div > p:last-child {
  max-width: 790px;
  margin: 24px 0 0;
  color: var(--er-muted);
  font-size: 1.05rem;
}

.er-definition-grid,
.er-signal-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.er-definition-grid article,
.er-signal-grid article {
  min-height: 220px;
  padding: 25px;
  border: 1px solid var(--er-line-soft);
  border-radius: var(--er-radius);
  background: linear-gradient(145deg, rgba(16, 31, 51, 0.92), rgba(9, 20, 35, 0.9));
}

.er-definition-grid article > span,
.er-signal-grid article > span,
.er-mistake-grid article > span {
  color: var(--er-green);
  font-size: 0.7rem;
  font-weight: 900;
  letter-spacing: 0.14em;
}

.er-definition-grid h3,
.er-signal-grid h3 {
  margin: 26px 0 10px;
  color: #fff;
  font-size: 1.3rem;
  line-height: 1.15;
}

.er-definition-grid p,
.er-signal-grid p {
  margin: 0;
  color: #93a3b7;
  font-size: 0.92rem;
}

.er-source-note,
.er-callout,
.er-warning {
  display: grid;
  grid-template-columns: 190px minmax(0, 1fr);
  gap: 28px;
  align-items: start;
  margin-top: 24px;
  padding: 24px 26px;
  border: 1px solid rgba(83, 227, 147, 0.28);
  border-radius: 18px;
  background: rgba(12, 39, 30, 0.52);
}

.er-source-note strong,
.er-callout strong,
.er-warning strong {
  color: var(--er-green);
  font-size: 0.86rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.er-source-note p,
.er-callout p,
.er-warning p {
  margin: 0;
  color: #aab8c8;
}

.er-principle {
  display: grid;
  grid-template-columns: minmax(0, 0.86fr) minmax(520px, 1.14fr);
  gap: 70px;
  align-items: start;
}

.er-principle-copy p strong {
  color: #fff;
}

.er-clock-grid {
  display: grid;
  gap: 14px;
}

.er-clock-grid article {
  display: grid;
  grid-template-columns: 112px minmax(0, 1fr);
  gap: 4px 24px;
  padding: 22px 24px;
  border: 1px solid var(--er-line-soft);
  border-radius: 18px;
  background: var(--er-surface-2);
}

.er-clock-grid span {
  grid-row: span 2;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 68px;
  border-radius: 12px;
  background: #142943;
  color: var(--er-green);
  font-size: 0.78rem;
  font-weight: 900;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.er-clock-grid article:nth-child(2) span {
  background: #2a2316;
  color: var(--er-gold);
}

.er-clock-grid article:nth-child(3) span {
  background: #301922;
  color: var(--er-red);
}

.er-clock-grid strong {
  color: #fff;
  font-size: 1rem;
}

.er-clock-grid p {
  margin: 4px 0 0;
  color: #8f9fb4;
  font-size: 0.86rem;
}

.er-decision {
  border-top: 1px solid var(--er-line-soft);
  border-bottom: 1px solid var(--er-line-soft);
}

.er-decision-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}

.er-decision-grid article {
  position: relative;
  overflow: hidden;
  padding: 28px;
  border: 1px solid var(--er-line-soft);
  border-radius: 20px;
  background: linear-gradient(145deg, rgba(18, 34, 56, 0.96), rgba(10, 20, 36, 0.96));
}

.er-decision-grid article::before {
  position: absolute;
  inset: 0 auto 0 0;
  width: 4px;
  background: var(--er-green);
  content: "";
}

.er-decision-grid article[data-state="migrate"]::before {
  background: var(--er-blue);
}

.er-decision-grid article[data-state="cutoff"]::before,
.er-decision-grid article[data-state="stop"]::before {
  background: var(--er-red);
}

.er-decision-grid article > div {
  display: grid;
  gap: 8px;
  margin-bottom: 18px;
}

.er-decision-grid span {
  color: var(--er-green);
  font-size: 0.72rem;
  font-weight: 900;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.er-decision-grid article[data-state="migrate"] span {
  color: var(--er-blue);
}

.er-decision-grid article[data-state="cutoff"] span,
.er-decision-grid article[data-state="stop"] span {
  color: var(--er-red);
}

.er-decision-grid strong {
  color: #fff;
  font-size: clamp(1.12rem, 2vw, 1.38rem);
  line-height: 1.25;
}

.er-decision-grid p {
  margin: 9px 0;
  color: #aab6c8;
  font-size: 0.91rem;
}

.er-decision-grid p b {
  color: #fff;
}

.er-decision-grid em {
  display: block;
  margin-top: 18px;
  padding-top: 16px;
  border-top: 1px solid var(--er-line-soft);
  color: #d8e1ec;
  font-size: 0.88rem;
  font-style: normal;
  font-weight: 750;
}

.er-month-grid {
  display: grid;
  grid-template-columns: repeat(6, minmax(0, 1fr));
  gap: 12px;
}

.er-month-grid div {
  display: grid;
  grid-template-columns: 46px minmax(0, 1fr);
  align-items: center;
  gap: 12px;
  padding: 14px;
  border: 1px solid var(--er-line-soft);
  border-radius: 14px;
  background: var(--er-surface-2);
}

.er-month-grid b {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  border-radius: 10px;
  background: #153228;
  color: var(--er-green);
  font-size: 1.18rem;
}

.er-month-grid span {
  color: #c4cedb;
  font-size: 0.82rem;
  font-weight: 720;
}

.er-symbol-example {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 10px 14px;
  margin-top: 28px;
  padding: 26px;
  border: 1px solid rgba(83, 227, 147, 0.26);
  border-radius: 18px;
  background: rgba(12, 37, 30, 0.42);
}

.er-symbol-example span {
  color: #8191a6;
  font-size: 0.76rem;
  font-weight: 740;
  text-transform: uppercase;
}

.er-symbol-example strong,
.er-symbol-example b {
  color: #fff;
  font-size: 1.3rem;
}

.er-symbol-example b {
  padding: 8px 14px;
  border-radius: 10px;
  background: var(--er-green);
  color: #04160d;
}

.er-symbol-example i {
  color: var(--er-green);
  font-style: normal;
  font-weight: 900;
}

.er-boundary {
  margin: 18px 0 0;
  color: #7f90a5;
  font-size: 0.82rem;
}

.er-roll-cards {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}

.er-roll-cards article {
  padding: 28px;
  border: 1px solid var(--er-line);
  border-radius: var(--er-radius);
  background: var(--er-surface-2);
}

.er-roll-cards article > p:last-child {
  margin: 22px 0 0;
  color: #96a5b8;
}

.er-equation {
  display: flex;
  align-items: stretch;
  gap: 10px;
}

.er-equation span {
  flex: 1;
  padding: 18px;
  border-radius: 13px;
  background: #13263d;
  color: #fff;
  font-weight: 820;
  text-align: center;
}

.er-equation i {
  display: grid;
  place-items: center;
  color: var(--er-green);
  font-style: normal;
  font-weight: 900;
}

.er-table-wrap {
  width: 100%;
  margin-top: 24px;
  overflow-x: auto;
  border: 1px solid var(--er-line);
  border-radius: 18px;
  background: var(--er-surface);
  box-shadow: var(--er-shadow);
}

.er-table-wrap table {
  width: 100%;
  min-width: 760px;
  border-collapse: collapse;
}

.er-table-wrap caption {
  padding: 18px 20px;
  border-bottom: 1px solid var(--er-line);
  color: #c8d3df;
  font-size: 0.88rem;
  font-weight: 780;
  text-align: left;
}

.er-table-wrap th,
.er-table-wrap td {
  padding: 18px 20px;
  border-bottom: 1px solid var(--er-line-soft);
  color: #a6b3c3;
  font-size: 0.9rem;
  line-height: 1.55;
  text-align: left;
  vertical-align: top;
}

.er-table-wrap thead th {
  background: #102034;
  color: #fff;
  font-size: 0.76rem;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}

.er-table-wrap tbody th {
  color: #fff;
  font-weight: 800;
}

.er-table-wrap tbody tr:last-child th,
.er-table-wrap tbody tr:last-child td {
  border-bottom: 0;
}

.er-callout {
  border-color: rgba(242, 195, 94, 0.32);
  background: rgba(51, 39, 17, 0.48);
}

.er-callout strong {
  color: var(--er-gold);
}

.er-tool-section::before {
  background:
    radial-gradient(circle at 86% 28%, rgba(83, 227, 147, 0.08), transparent 23rem),
    #07111f;
}

.er-planner {
  display: grid;
  grid-template-columns: minmax(0, 1.08fr) minmax(400px, 0.92fr);
  gap: 20px;
  padding: 20px;
  border: 1px solid var(--er-line);
  border-radius: 26px;
  background: rgba(8, 17, 31, 0.86);
  box-shadow: var(--er-shadow);
}

.er-form,
.er-results {
  border: 1px solid var(--er-line-soft);
  border-radius: 20px;
  background: var(--er-surface-2);
}

.er-form {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
  padding: 26px;
}

.er-form fieldset {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 130px;
  gap: 12px;
  margin: 0;
  padding: 16px;
  border: 1px solid var(--er-line-soft);
  border-radius: 15px;
}

.er-form legend {
  padding: 0 8px;
  color: var(--er-green);
  font-size: 0.76rem;
  font-weight: 850;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.er-field {
  min-width: 0;
}

.er-field-wide,
.er-error,
.er-form-actions {
  grid-column: 1 / -1;
}

.er-field label {
  display: block;
  margin-bottom: 7px;
  color: #d2dbe6;
  font-size: 0.8rem;
  font-weight: 760;
}

.er-field small {
  display: block;
  margin-top: 6px;
  color: #788ba0;
  font-size: 0.72rem;
}

.er-field input,
.er-field select {
  width: 100%;
  min-height: 48px;
  padding: 11px 13px;
  border: 1px solid #2a4058;
  border-radius: 10px;
  outline: 0;
  background: #071425;
  color: #fff;
  font: inherit;
  font-size: 0.92rem;
}

.er-field input:focus,
.er-field select:focus {
  border-color: var(--er-green);
  box-shadow: 0 0 0 3px rgba(83, 227, 147, 0.13);
}

.er-field input[aria-invalid="true"],
.er-field select[aria-invalid="true"] {
  border-color: var(--er-red);
  box-shadow: 0 0 0 3px rgba(255, 139, 150, 0.1);
}

.er-error {
  margin: 0;
  padding: 12px 14px;
  border: 1px solid rgba(255, 139, 150, 0.42);
  border-radius: 10px;
  background: rgba(76, 28, 39, 0.52);
  color: #ffc3ca;
  font-size: 0.82rem;
}

.er-form-actions {
  margin-top: 2px;
}

.er-results {
  align-self: stretch;
  padding: 28px;
}

.er-results h3 {
  margin: 0;
  color: #fff;
  font-size: 2rem;
  letter-spacing: -0.035em;
}

.er-results dl {
  display: grid;
  gap: 1px;
  margin: 26px 0 0;
  overflow: hidden;
  border: 1px solid var(--er-line-soft);
  border-radius: 14px;
  background: var(--er-line-soft);
}

.er-results dl > div {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 15px 16px;
  background: #0c192a;
}

.er-results dt {
  color: #8fa0b5;
  font-size: 0.82rem;
}

.er-results dd {
  margin: 0;
  color: #fff;
  font-size: 1rem;
  font-weight: 850;
  text-align: right;
}

.er-results .er-result-primary {
  background: #102b23;
}

.er-results .er-result-primary dd {
  color: var(--er-green);
  font-size: 1.2rem;
}

.er-status {
  margin-top: 18px;
  padding: 18px;
  border: 1px solid;
  border-radius: 14px;
}

.er-status strong,
.er-status span {
  display: block;
}

.er-status strong {
  color: #fff;
  font-size: 0.95rem;
}

.er-status span {
  margin-top: 7px;
  color: #a6b4c3;
  font-size: 0.8rem;
  line-height: 1.55;
}

.er-status-transition,
.er-status-current {
  border-color: rgba(83, 227, 147, 0.35);
  background: rgba(15, 53, 38, 0.56);
}

.er-status-mixed {
  border-color: rgba(242, 195, 94, 0.4);
  background: rgba(61, 45, 18, 0.52);
}

.er-status-danger {
  border-color: rgba(255, 139, 150, 0.42);
  background: rgba(76, 28, 39, 0.52);
}

.er-tool-notes {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  margin-top: 18px;
}

.er-tool-notes p {
  margin: 0;
  padding: 16px;
  border: 1px solid var(--er-line-soft);
  border-radius: 13px;
  color: #8294a9;
  font-size: 0.78rem;
}

.er-tool-notes strong {
  color: #cdd7e2;
}

.er-warning {
  border-color: rgba(255, 139, 150, 0.35);
  background: rgba(62, 25, 35, 0.48);
}

.er-warning strong {
  color: var(--er-red);
}

.er-example-stack {
  display: grid;
  gap: 18px;
}

.er-example-stack article {
  display: grid;
  grid-template-columns: 240px minmax(0, 1fr);
  gap: 12px 34px;
  padding: 28px;
  border: 1px solid var(--er-line-soft);
  border-radius: var(--er-radius);
  background: var(--er-surface-2);
}

.er-example-label {
  grid-row: 1 / span 3;
  padding-right: 28px;
  border-right: 1px solid var(--er-line-soft);
}

.er-example-label span,
.er-example-label strong {
  display: block;
}

.er-example-label span {
  color: var(--er-green);
  font-size: 0.72rem;
  font-weight: 900;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.er-example-label strong {
  margin-top: 12px;
  color: #fff;
  font-size: 1.28rem;
  line-height: 1.2;
}

.er-example-stack article > p {
  margin: 0;
  color: #98a7b9;
}

.er-example-math {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 16px 18px;
  border-radius: 13px;
  background: #12253b;
}

.er-example-math span {
  color: #b5c1d0;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 0.86rem;
}

.er-example-math b {
  color: var(--er-green);
  white-space: nowrap;
}

.er-question-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
  margin-top: 24px;
}

.er-question-grid article {
  padding: 24px;
  border: 1px solid var(--er-line-soft);
  border-radius: 18px;
  background: var(--er-surface-2);
}

.er-question-grid span {
  color: var(--er-green);
  font-size: 0.7rem;
  font-weight: 900;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.er-question-grid strong {
  display: block;
  margin-top: 15px;
  color: #fff;
  font-size: 1.16rem;
}

.er-question-grid p {
  margin: 10px 0 0;
  color: #8fa0b4;
  font-size: 0.88rem;
}

.er-mistake-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.er-mistake-grid article {
  display: grid;
  grid-template-columns: 38px minmax(0, 1fr);
  gap: 14px;
  padding: 20px;
  border: 1px solid var(--er-line-soft);
  border-radius: 15px;
  background: var(--er-surface-2);
}

.er-mistake-grid p {
  margin: 0;
  color: #99a8ba;
  font-size: 0.9rem;
}

.er-mistake-grid strong {
  color: #fff;
}

.er-checklist {
  display: grid;
  grid-template-columns: minmax(320px, 0.8fr) minmax(0, 1.2fr);
  gap: 70px;
}

.er-checklist ol {
  display: grid;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.er-checklist li {
  display: grid;
  grid-template-columns: 48px minmax(0, 1fr);
  align-items: center;
  gap: 16px;
  padding: 14px 16px;
  border: 1px solid var(--er-line-soft);
  border-radius: 13px;
  background: var(--er-surface-2);
}

.er-checklist li span {
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: #123429;
  color: var(--er-green);
  font-size: 0.72rem;
  font-weight: 900;
}

.er-checklist li p {
  margin: 0;
  color: #a7b4c4;
  font-size: 0.9rem;
}

.er-faq-list {
  display: grid;
  gap: 10px;
}

.er-faq details {
  border: 1px solid var(--er-line-soft);
  border-radius: 15px;
  background: var(--er-surface-2);
}

.er-faq summary {
  position: relative;
  padding: 20px 54px 20px 22px;
  color: #fff;
  font-weight: 780;
  cursor: pointer;
  list-style: none;
}

.er-faq summary::-webkit-details-marker {
  display: none;
}

.er-faq summary::after {
  content: "+";
  position: absolute;
  top: 50%;
  right: 20px;
  transform: translateY(-50%);
  color: var(--er-green);
  font-size: 1.4rem;
}

.er-faq details[open] summary::after {
  content: "−";
}

.er-faq details p {
  margin: 0;
  padding: 0 22px 22px;
  color: #96a6b8;
}

.er-sources::before {
  background: #08111f;
}

.er-sources > p {
  max-width: 900px;
}

.er-sources ul {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin: 38px 0 0;
  padding: 0;
  list-style: none;
}

.er-sources li {
  padding: 18px;
  border: 1px solid var(--er-line-soft);
  border-radius: 14px;
  background: var(--er-surface-2);
}

.er-sources li a,
.er-sources li span {
  display: block;
}

.er-sources li a {
  color: #fff;
  font-size: 0.88rem;
  font-weight: 780;
  text-decoration-color: rgba(83, 227, 147, 0.45);
  text-underline-offset: 4px;
}

.er-sources li span {
  margin-top: 8px;
  color: #8294aa;
  font-size: 0.78rem;
  line-height: 1.55;
}

.er-related::before {
  background: linear-gradient(135deg, rgba(10, 24, 40, 0.88), rgba(6, 15, 28, 0.94));
}

.er-related-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
  margin-top: 38px;
}

.er-related-grid a {
  min-height: 210px;
  padding: 22px;
  border: 1px solid var(--er-line-soft);
  border-radius: 18px;
  background: var(--er-surface-2);
  text-decoration: none;
}

.er-related-grid a:hover {
  border-color: rgba(83, 227, 147, 0.42);
  transform: translateY(-2px);
}

.er-related-grid span,
.er-related-grid strong {
  display: block;
}

.er-related-grid span {
  color: var(--er-green);
  font-size: 0.7rem;
  font-weight: 900;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.er-related-grid strong {
  margin-top: 16px;
  color: #fff;
  font-size: 1.08rem;
  line-height: 1.25;
}

.er-related-grid p {
  margin: 12px 0 0;
  color: #8999ad;
  font-size: 0.82rem;
}

.er-disclaimer {
  margin: 22px 0 92px;
  padding: 22px 24px;
  border: 1px solid rgba(242, 195, 94, 0.3);
  border-radius: 16px;
  background: rgba(50, 38, 17, 0.42);
}

.er-disclaimer strong {
  color: var(--er-gold);
  font-size: 0.82rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.er-disclaimer p {
  margin: 8px 0 0;
  color: #a9a18f;
  font-size: 0.82rem;
}

.er-page .site-footer {
  border-top: 1px solid rgba(123, 151, 181, 0.18);
  background: #08111f;
}

.er-page .footer-inner {
  color: #98a6b8;
}

.er-page .footer-book h3,
.er-page .footer-links a,
.er-page .footer-book-link {
  color: #fff;
}

.er-page a:focus-visible,
.er-page button:focus-visible,
.er-page input:focus-visible,
.er-page select:focus-visible,
.er-page summary:focus-visible {
  outline: 3px solid rgba(83, 227, 147, 0.85);
  outline-offset: 3px;
}

@media (max-width: 1060px) {
  .er-hero {
    grid-template-columns: 1fr;
    gap: 50px;
  }

  .er-hero-copy {
    max-width: 860px;
  }

  .er-hero-figure {
    max-width: 820px;
  }

  .er-principle,
  .er-checklist {
    grid-template-columns: 1fr;
    gap: 44px;
  }

  .er-planner {
    grid-template-columns: 1fr;
  }

  .er-month-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .er-related-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 780px) {
  .er-page .header-inner {
    align-items: flex-start;
    flex-direction: column;
    padding-top: 16px;
    padding-bottom: 16px;
  }

  .er-page .main-nav ul {
    justify-content: flex-start;
    gap: 8px 18px;
  }

  .er-hero {
    min-height: 0;
    padding: 78px 0 64px;
  }

  .er-hero h1 {
    font-size: clamp(3rem, 13vw, 4.9rem);
  }

  .er-hero-facts,
  .er-definition-grid,
  .er-decision-grid,
  .er-signal-grid,
  .er-question-grid,
  .er-tool-notes {
    grid-template-columns: 1fr;
  }

  .er-section,
  .er-sources,
  .er-related {
    padding: 78px 0;
  }

  .er-definition-grid article,
  .er-signal-grid article {
    min-height: 0;
  }

  .er-month-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .er-roll-cards,
  .er-mistake-grid,
  .er-sources ul {
    grid-template-columns: 1fr;
  }

  .er-form {
    grid-template-columns: 1fr;
  }

  .er-form fieldset {
    grid-column: 1 / -1;
  }

  .er-example-stack article {
    grid-template-columns: 1fr;
  }

  .er-example-label {
    grid-row: auto;
    padding: 0 0 18px;
    border-right: 0;
    border-bottom: 1px solid var(--er-line-soft);
  }
}

@media (max-width: 560px) {
  .er-shell {
    width: min(100% - 32px, 1160px);
  }

  .er-page .main-nav a {
    font-size: 0.8rem;
  }

  .er-hero h1 {
    font-size: clamp(2.75rem, 13.8vw, 4.2rem);
  }

  .er-hero-actions,
  .er-form-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .er-button,
  .er-reset {
    width: 100%;
  }

  .er-hero-figure {
    padding: 8px;
    border-radius: 20px;
  }

  .er-on-page {
    gap: 8px;
  }

  .er-on-page a {
    font-size: 0.72rem;
  }

  .er-section h2,
  .er-sources h2,
  .er-related h2 {
    font-size: clamp(2.25rem, 11vw, 3.4rem);
  }

  .er-month-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .er-source-note,
  .er-callout,
  .er-warning {
    grid-template-columns: 1fr;
    gap: 10px;
  }

  .er-clock-grid article {
    grid-template-columns: 1fr;
  }

  .er-clock-grid span {
    grid-row: auto;
    justify-content: flex-start;
    min-height: 0;
    padding: 10px 12px;
  }

  .er-equation {
    flex-direction: column;
  }

  .er-planner {
    padding: 10px;
    border-radius: 20px;
  }

  .er-form,
  .er-results {
    padding: 20px;
  }

  .er-form fieldset {
    grid-template-columns: 1fr;
  }

  .er-results dl > div,
  .er-example-math {
    align-items: flex-start;
    flex-direction: column;
  }

  .er-results dd {
    text-align: left;
  }

  .er-example-math b {
    white-space: normal;
  }

  .er-related-grid {
    grid-template-columns: 1fr;
  }
}

@media (prefers-reduced-motion: reduce) {
  .er-page *,
  .er-page *::before,
  .er-page *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}