:root {
--ink: #eaf7ff;
--muted: #a8bfd1;
--bg: #051225;
--bg2: #071b31;
--card: rgba(255, 255, 255, 0.075);
--card2: rgba(255, 255, 255, 0.115);
--line: rgba(255, 255, 255, 0.16);
--teal: #19d5c2;
--green: #78f09c;
--blue: #1b78ff;
--paper: #f6fbff;
--paperink: #082034;
--paperfade: #4d6074;
--max: 1180px;
--calc-gap: 34px;

font-family: Inter, Instrument Sans, "Segoe UI", Roboto, Arial, sans-serif;
}

* {
  box-sizing: border-box;
  }

html {
scroll-behavior: smooth;
}

body {
margin: 0;
background:
radial-gradient(circle at 86% 0%, rgba(25, 213, 194, 0.24), transparent 38%),
linear-gradient(140deg, #02081a, #07182b 48%, #062336);
color: var(--ink);
line-height: 1.6;
}

a {
color: inherit;
}

/* Header */
.co-header {
position: sticky;
top: 0;
z-index: 20;
display: flex;
align-items: center;
justify-content: space-between;
gap: 20px;
padding: 16px max(22px, calc((100vw - var(--max)) / 2));
background: rgba(3, 12, 26, 0.78);
backdrop-filter: blur(18px);
border-bottom: 1px solid var(--line);
}

.co-brand {
display: flex;
align-items: center;
gap: 12px;
text-decoration: none;
font-weight: 900;
letter-spacing: 0.01em;
}

.co-brand img {
width: 42px;
height: 42px;
border-radius: 12px;
object-fit: cover;
}

.co-header nav {
display: flex;
gap: 16px;
flex-wrap: wrap;
}

.co-header nav a {
color: var(--muted);
text-decoration: none;
font-size: 14px;
}

.co-header nav a:hover {
color: #ffffff;
}

/* Shared Layout */
.hero,
.section,
.callout,
.related,
.video-section,
.calc-page,
.hub-section {
width: min(var(--max), calc(100% - 36px));
margin: 0 auto;
}

/* Hero */
.hero {
display: grid;
grid-template-columns: 1.05fr 0.8fr;
gap: 36px;
align-items: center;
padding: 86px 0 54px;
}

.hero h1 {
font-size: clamp(42px, 6.4vw, 78px);
line-height: 0.95;
margin: 10px 0 20px;
letter-spacing: -0.055em;
}

.lead {
font-size: clamp(18px, 2.4vw, 24px);
color: #d8eefb;
max-width: 780px;
}

.eyebrow {
margin: 0 0 10px;
text-transform: uppercase;
letter-spacing: 0.16em;
color: var(--green);
font-weight: 900;
font-size: 13px;
}

.cta-row {
display: flex;
gap: 14px;
flex-wrap: wrap;
margin-top: 28px;
}

.cta-row.stack {
flex-direction: column;
}

.btn {
display: inline-flex;
align-items: center;
justify-content: center;
padding: 13px 18px;
border-radius: 999px;
text-decoration: none;
font-weight: 900;
border: 1px solid var(--line);
}

.btn.primary {
background: linear-gradient(135deg, var(--teal), var(--green));
color: #021225;
}

.btn.ghost {
background: rgba(255, 255, 255, 0.06);
color: #ffffff;
}

/* Hero Panel */
.hero-panel {
background: linear-gradient(160deg, rgba(255, 255, 255, 0.1), rgba(255, 255, 255, 0.035));
border: 1px solid var(--line);
border-radius: 34px;
padding: 28px;
box-shadow: 0 28px 90px rgba(0, 0, 0, 0.28);
}

.hero-panel img {
width: 100%;
border-radius: 28px;
display: block;
}

.mini-grid {
display: grid;
grid-template-columns: repeat(3, 1fr);
gap: 10px;
margin-top: 16px;
}

.mini-grid span {
background: rgba(255, 255, 255, 0.08);
border: 1px solid var(--line);
border-radius: 16px;
padding: 10px;
text-align: center;
color: #ddffff;
font-weight: 800;
font-size: 13px;
}

/* Cards */
.cards {
width: min(var(--max), calc(100% - 36px));
margin: 28px auto;
display: grid;
gap: 18px;
}

.cards.four {
grid-template-columns: repeat(4, 1fr);
}

.cards.three {
grid-template-columns: repeat(3, 1fr);
}

.cards article,
.content-card,
.calc-card {
background: var(--card);
border: 1px solid var(--line);
border-radius: 26px;
padding: 24px;
}

.cards h3,
.content-card h3 {
margin: 0 0 8px;
font-size: 21px;
}

.cards p,
.content-card p {
color: var(--muted);
margin: 0;
}

/* Sections */
.section {
padding: 58px 0;
}

.section h2,
.callout h2,
.related h2,
.hub-section h2,
.video-section h2 {
font-size: clamp(30px, 4vw, 48px);
line-height: 1;
margin: 0 0 16px;
letter-spacing: -0.035em;
}

.section p {
color: #c2d5e8;
max-width: 870px;
}

/* Light Paper Section */
.paper {
background: var(--paper);
color: var(--paperink);
padding: 62px 0;
margin: 48px 0;
}

.paper .section {
padding: 0;
}

.paper p {
color: var(--paperfade);
}

/* Feature List */
.feature-list {
display: grid;
grid-template-columns: repeat(2, 1fr);
gap: 12px;
margin: 22px 0;
padding: 0;
list-style: none;
}

.feature-list li {
padding: 13px 14px;
border-radius: 16px;
background: rgba(8, 32, 52, 0.06);
border: 1px solid rgba(8, 32, 52, 0.12);
font-weight: 750;
}

/* Comparison Table */
.comparison-table {
width: 100%;
border-collapse: collapse;
overflow: hidden;
border-radius: 22px;
background: #ffffff;
margin-top: 20px;
}

.comparison-table th,
.comparison-table td {
padding: 16px;
border-bottom: 1px solid rgba(8, 32, 52, 0.12);
text-align: left;
vertical-align: top;
}

.comparison-table th {
background: #082034;
color: #ffffff;
}

.comparison-table tr:last-child td {
border-bottom: 0;
}

/* Callout */
.callout {
display: grid;
grid-template-columns: 1.1fr 0.45fr;
gap: 24px;
align-items: center;
margin-top: 44px;
margin-bottom: 44px;
padding: 34px;
border-radius: 30px;
border: 1px solid var(--line);
background: linear-gradient(135deg, rgba(25, 213, 194, 0.16), rgba(255, 255, 255, 0.06));
}

/* Related Links */
.related {
padding: 40px 0 64px;
}

.related-grid {
display: grid;
grid-template-columns: repeat(5, 1fr);
gap: 12px;
}

.related-grid a {
padding: 14px;
border-radius: 16px;
background: rgba(255, 255, 255, 0.07);
border: 1px solid var(--line);
text-decoration: none;
color: #ddffff;
font-weight: 800;
}

/* Footer */
.co-footer {
display: grid;
grid-template-columns: 1fr 0.8fr;
gap: 24px;
padding: 34px max(22px, calc((100vw - var(--max)) / 2));
border-top: 1px solid var(--line);
background: #020817;
color: var(--muted);
}

.co-footer strong {
color: #ffffff;
}

.co-footer-links {
display: flex;
gap: 12px;
flex-wrap: wrap;
justify-content: flex-end;
}

.co-footer-links a {
color: #ddffff;
}

/* Video Section */
.video-grid {
display: grid;
grid-template-columns: repeat(2, 1fr);
gap: 18px;
}

.video-card {
background: var(--card);
border: 1px solid var(--line);
border-radius: 26px;
overflow: hidden;
}

.video-card iframe {
width: 100%;
aspect-ratio: 16 / 9;
border: 0;
display: block;
}

.video-card div {
padding: 18px;
}

/* Calculator Hub */
.calc-grid {
display: grid;
grid-template-columns: repeat(3, 1fr);
gap: 18px;
margin-top: 24px;
}

.calc-card {
text-decoration: none;
color: #ffffff;
display: block;
}

.calc-card p {
color: var(--muted);
}

/* Calculator Pages */
.calc-page {
padding: 34px 0 72px;
}

.calc-page .content-card {
display: block;
overflow: hidden;
padding: 24px;
}

.calc-form {
display: grid;
grid-template-columns: repeat(2, 1fr);
gap: 16px;
}

.calc-form label {
display: flex;
flex-direction: column;
gap: 6px;
font-weight: 800;
color: #ddffff;
}

.calc-form input {
width: 100%;
border: 1px solid var(--line);
border-radius: 14px;
padding: 14px;
background: rgba(255, 255, 255, 0.08);
color: #ffffff;
font-size: 17px;
}

.calc-results {
display: grid;
grid-template-columns: repeat(3, 1fr);
gap: 14px;
margin: 24px 0 var(--calc-gap);
}

.metric {
padding: 18px;
border-radius: 20px;
background: linear-gradient(135deg, rgba(25, 213, 194, 0.18), rgba(120, 240, 156, 0.08));
border: 1px solid var(--line);
}

.metric b {
display: block;
font-size: 28px;
color: #ffffff;
}

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

.notice {
display: block;
width: 100%;
margin: 0;
padding: 18px;
border-radius: 22px;
background: rgba(120, 240, 156, 0.1);
border: 1px solid rgba(120, 240, 156, 0.32);
color: #eafff4;
line-height: 1.65;
}

/* Calculator notice separation: hard scoped */
.calc-page .content-card > .calc-results {
margin-bottom: var(--calc-gap) !important;
}

.calc-page .content-card > .calc-results + .notice {
margin-top: 0 !important;
}

.formula {
background: #020817;
border: 1px solid var(--line);
border-radius: 20px;
padding: 18px;
color: #ddffff;
overflow: auto;
}

/* FAQ */
.faq details {
background: rgba(255, 255, 255, 0.07);
border: 1px solid var(--line);
border-radius: 20px;
padding: 18px;
margin: 12px 0;
}

.faq summary {
font-weight: 900;
cursor: pointer;
}

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

/* Responsive */
@media (max-width: 900px) {
.hero,
.callout,
.co-footer,
.video-grid {
grid-template-columns: 1fr;
}

.cards.four,
.cards.three,
.related-grid,
.calc-grid,
.calc-results {
grid-template-columns: 1fr 1fr;
}

.co-header {
position: relative;
align-items: flex-start;
flex-direction: column;
}

.co-footer-links {
justify-content: flex-start;
}

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

@media (max-width: 620px) {
:root {
--calc-gap: 24px;
}

.cards.four,
.cards.three,
.related-grid,
.calc-grid,
.calc-results,
.feature-list {
grid-template-columns: 1fr;
}

.hero {
padding-top: 46px;
}

.hero h1 {
font-size: 42px;
}

.mini-grid {
grid-template-columns: 1fr 1fr;
}

.calc-page {
width: min(var(--max), calc(100% - 24px));
padding: 22px 0 56px;
}

.calc-page .content-card {
padding: 18px;
}

.calc-results {
margin: 22px 0 var(--calc-gap);
}

.metric b {
font-size: 26px;
}
}