/* Shared visual system for the learning website, lessons, and account pages. */
:root {
  --ink:#142238; --muted:#526174; --navy:#101d2d; --blue:#175bc8;
  --sky:#b7d8ff; --ice:#eef3f9; --paper:#f7f8fa; --line:#d4dce6;
  --radius:12px; --shadow:0 8px 30px #14223809; --ease:cubic-bezier(.2,.7,.2,1);
}
html {scroll-padding-top:7rem}
body {font-size:1rem;line-height:1.7}
h1,h2,h3 {letter-spacing:-.04em}
h2 {font-size:clamp(1.9rem,3.1vw,2.75rem);line-height:1.15}
a,button {touch-action:manipulation}
a:focus-visible,button:focus-visible,input:focus-visible,summary:focus-visible {outline:3px solid #bc6b00;outline-offset:5px}
.wrap {max-width:1280px;padding-inline:clamp(1.25rem,4vw,3rem)}
.eyebrow,.small-meta,.lab-caption,.card-code {font-size:.72rem;letter-spacing:.09em}
.site-header {max-width:none;min-height:88px;padding:1rem max(1.25rem,calc((100vw - 1184px)/2));position:sticky;top:0;z-index:10;background:#fff;border-bottom:1px solid var(--line);box-shadow:0 3px 20px #14223805}
.brand {font-size:1.1rem;letter-spacing:-.025em}
.brand-mark {border-radius:9px;background:var(--navy);color:#fff;box-shadow:inset 0 0 0 1px #ffffff1a;width:2.75rem;height:2.75rem}
.brand-caption {font-size:.63rem;letter-spacing:.12em;margin-top:.35rem}
.site-header nav {gap:1.4rem}
.site-header nav a {font-size:.82rem;font-weight:500;min-width:0}
.site-header nav a:hover {color:var(--blue);text-decoration:none}
.site-header .nav-lesson {border:0;background:var(--ice);border-radius:6px;padding:.6rem .9rem}
.site-header nav a[aria-current="page"] {color:var(--blue);box-shadow:inset 0 -2px var(--blue)}
.nav-account {padding:.6rem .9rem;border:1px solid var(--line);border-radius:6px}
.draft-strip {gap:.8rem;background:#f0f3f7;border-top:0;padding-block:.55rem;font-size:.75rem}
.draft-label {font-size:.66rem;letter-spacing:.08em}
.button {min-height:48px;gap:.9rem;border-radius:6px;padding:.85rem 1.2rem;box-shadow:0 3px 8px #175bc81a;transition:background 180ms var(--ease),box-shadow 180ms var(--ease),transform 180ms var(--ease)}
.button:hover {background:#12499e;box-shadow:0 6px 18px #175bc824}
.button:active {transform:translateY(1px)}
.button.secondary {background:#fff;box-shadow:none;border-color:var(--line)}
.text-link {gap:.8rem;text-decoration:none}
.text-link:hover {text-decoration:underline}
.hero-shell {background:radial-gradient(ellipse at 10% 10%,#213852 0,transparent 55%),var(--navy);color:#fff;position:relative}
.home-hero {padding-top:4.25rem;padding-bottom:3.5rem;gap:4rem;grid-template-columns:1.05fr 1fr}
.hero-copy .eyebrow {color:var(--sky);font-size:.72rem}
.small-rule {background:var(--sky);width:28px}
.home-hero h1 {font-size:clamp(3.5rem,5.4vw,5rem);letter-spacing:-.055em;line-height:1.04}
.home-hero h1 em {font-family:inherit;font-style:normal;font-weight:600;color:var(--sky)}
.home-hero h1>span {margin-top:1rem;font-size:.46em;font-weight:400;letter-spacing:-.035em}
.hero-intro {color:#ccd8e7;font-size:1.04rem;max-width:29rem}
.hero-actions {gap:1.25rem;margin-top:1.9rem}
.hero-actions .button {background:#c9e1ff;border-color:#c9e1ff;color:#102744}
.hero-actions .button:hover {background:#e5f0ff;border-color:#e5f0ff}
.hero-actions .text-link {color:#e7effa}
.hero-note {color:#b9c7d8;font-size:.75rem}
.hero-note span {margin-inline:.35rem;color:#b9c7d8}
.hero-visual {height:max(475px,28rem);border-radius:var(--radius);border:1px solid #6c80984d;box-shadow:0 18px 60px #0004}
.hero-visual img {object-position:49% 50%}
.hero-visual:after {background:linear-gradient(180deg,#08142080,transparent 35%,#091726ed)}
.visual-top,.visual-bottom {left:1.75rem;right:1.75rem}
.visual-top .eyebrow {max-width:160px;color:#e8f2ff}
.visual-index {color:#d1e1f4;font-size:.7rem}
.visual-question {font-size:clamp(1.6rem,2.3vw,2rem);line-height:1.25}
.glass-link {gap:1rem;background:#142638a6;border-color:#7189a3;border-radius:6px}
.glass-link:hover {background:#263f5b}
.hero-shell .principles {border-top-color:#465a724f;border-bottom:0;color:#c6d5e7;padding-block:1.25rem;font-size:.78rem}
.principles span:before {color:var(--sky);content:"↗";font-size:.85rem}
.featured {background:transparent;border-radius:0;padding-top:4.75rem;padding-bottom:4.75rem;margin-block:0;max-width:1280px;grid-template-columns:1.05fr 1fr;gap:4rem}
.featured-intro h2 {font-size:clamp(2.2rem,3.4vw,3rem)}
.featured-intro .feature-lesson-title {font-size:1.18rem;font-weight:600;color:var(--ink)!important;margin-bottom:.8rem}
.featured-intro>p:not(.eyebrow):not(.small-meta) {font-size:.97rem}
.experiment-preview {border-radius:var(--radius);padding:1.7rem;border:1px solid #334860;box-shadow:0 18px 40px #14223812}
.lab-caption {color:#c5d6e9;font-size:.66rem}
.preview-values {margin-block:2.2rem;gap:1rem}
.preview-values>span {border-radius:7px;background:#1c3046;border-color:#496079;color:#c6d4e5}
.preview-values>span.selected {background:#c9e1ff;border-color:#c9e1ff;color:#142238}
.lab-caption.bottom {border-color:#3f536b}
.entry-section {padding-top:2.75rem;padding-bottom:2.5rem}
.section-heading {margin-bottom:2rem}
.section-heading>p {max-width:24rem;font-size:.87rem}
.path-grid {gap:1rem}
.path-card {border-radius:9px;min-height:255px;padding:1.35rem;gap:1.2rem;box-shadow:var(--shadow)}
.card-code {flex-wrap:wrap}
.planned {background:#f0f3f7;color:#516075;padding:.2rem .45rem;border-radius:4px;font-size:.64rem}
.card-title {font-size:1.5rem}
.card-description {font-size:.85rem}
.card-action {display:flex;align-items:center;justify-content:space-between;gap:.8rem;margin-top:auto;padding-top:.8rem;border-top:1px solid var(--line);font-size:.78rem;font-weight:600}
.path-card:hover,.path-card[aria-expanded=true] {background:#fff;border-color:var(--blue);box-shadow:0 10px 28px #14223810}
.plan-detail {border-radius:0 8px 8px 0;font-size:.94rem}
.subject-section {padding-top:3.25rem;padding-bottom:3.5rem}
.subject-grid {gap:0 2.5rem}
.subject-grid button,.subject-grid>a {background:transparent;min-height:76px;padding-inline:.75rem;font-size:.95rem}
.subject-grid>a {background:#eaf1fd;border-top-color:#bccfeb}
.subject-grid button:hover,.subject-grid>a:hover,.subject-grid button[aria-expanded=true] {background:#e4ecf8}
.subject-status {font-size:.71rem}
.available {background:transparent;color:#154ba0;padding:.2rem 0}
.approach {padding-top:3.75rem;padding-bottom:4.75rem;border-top:1px solid var(--line)}
.approach-grid {list-style:none;display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:2rem;padding:0;margin:2.25rem 0 1rem}
.approach-grid li {padding-right:1.5rem}
.approach-number {font:.78rem var(--mono);color:var(--blue);display:inline-flex;width:2.3rem;height:2.3rem;align-items:center;justify-content:center;border:1px solid #bccde4;border-radius:50%;margin-bottom:1.2rem}
.approach-grid h3 {font-size:1.25rem;margin-bottom:.65rem}
.approach-grid p {font-size:.92rem;color:var(--muted)}
.site-footer {background:var(--navy);padding-top:2.75rem}
.footer-top {border-color:#3f536b}
.footer-top>p {font-size:.97rem}
.footer-bottom p {color:#c5d3e4}
.footer-links {display:flex;gap:1.5rem;flex-wrap:wrap;padding-top:1.25rem}
.footer-links a {color:#d0e2f9;font-size:.8rem;min-height:44px;display:inline-flex;align-items:center;text-decoration:none}
.footer-links a:hover {text-decoration:underline}

/* Reading and account surfaces share the same visual language. */
.lesson-hero {padding-top:2rem;padding-bottom:2.75rem}
.lesson-hero h1 {font-size:clamp(2.75rem,4.8vw,4.5rem);max-width:850px}
.lesson-hero h1 em {font-family:inherit;font-style:normal;font-weight:600;color:var(--blue)}
.lesson-hero .eyebrow {margin-bottom:1rem}
.lesson-subtitle {font-size:1.2rem}
.lesson-lede {font-size:1.02rem;max-width:46rem}
.lesson-tags span {background:#fff;border-radius:5px}
.lesson-layout {grid-template-columns:215px minmax(0,1fr);gap:2.5rem}
.lesson-sidebar {top:7.5rem;padding-top:1rem}
.lesson-sidebar nav a {border-left:2px solid transparent;padding:.7rem .8rem;font-size:.8rem;border-radius:0 5px 5px 0}
.lesson-sidebar nav a:hover,.lesson-sidebar nav a[aria-current="location"] {text-decoration:none;background:#e7eef9;color:#154ba0;border-left-color:var(--blue)}
.lesson-section {padding:2.25rem 0}
.lesson-section h2 {font-size:clamp(1.8rem,2.7vw,2.4rem)}
.lesson-section>div>p {color:#45566c}
.demo,.research-card,.scenario,.knowledge-check,.concept-pair>div,.lesson-end {border-radius:9px}
.knowledge-check {background:#fff;box-shadow:var(--shadow)}
.answer {border-radius:5px;background:#f1f4f8}
.research-card {background:#edf2f8}
.transcript,.debrief {background:#fff;border-radius:7px}
.lesson-account {max-width:1184px;margin:0 auto 3rem;padding:2rem;background:#fff;border-radius:9px}
.lesson-account h2 {font-size:1.7rem}
.account-page {padding-top:3rem}
.account-heading h1 {font-size:clamp(2.5rem,4.5vw,3.8rem)}
.account-heading>p:last-child {font-size:1.02rem}
.account-card {border-radius:var(--radius);background:#fff;box-shadow:var(--shadow)}
.account-aside {border-radius:var(--radius);background:#eaf0f8}
.account-card input,.account-card textarea,.account-card select {border-color:#a4b2c3;border-radius:6px}
.account-nav a {text-decoration:none}
.account-nav a[aria-current="page"] {color:#154ba0;font-weight:600;box-shadow:inset 0 -2px var(--blue)}
.account-card h2,.account-aside h2 {font-size:1.6rem}
@media(hover:hover) and (prefers-reduced-motion:no-preference) {
  .path-card,.experiment-preview {transition:transform 220ms var(--ease),box-shadow 220ms var(--ease),border-color 220ms var(--ease)}
  .path-card:hover,.experiment-preview:hover {transform:translateY(-3px)}
}
@media(max-width:1100px) {
  .home-hero,.featured {gap:2rem}
  .site-header nav {width:auto;gap:.7rem}
  .hero-visual {height:max(470px,28rem)}
  .home-hero h1 {font-size:4rem}
  .lesson-layout {grid-template-columns:185px minmax(0,1fr);gap:1.75rem}
  .lesson-sidebar nav {grid-template-columns:1fr}
  .lesson-sidebar {position:sticky}
}
@media(max-width:900px) {
  .site-header {position:static;flex-wrap:wrap;gap:.7rem}
  .site-header nav {width:100%;justify-content:flex-start;gap:.5rem 1rem}
  .site-header .nav-account {margin-left:auto}
  .home-hero {grid-template-columns:1fr;padding-top:3rem;gap:2.25rem}
  .hero-intro {max-width:36rem}
  .hero-visual {height:max(400px,25rem)}
  .hero-visual img {object-position:50% 55%}
  .featured {grid-template-columns:1fr;padding-block:3rem}
  .featured-intro>p:not(.eyebrow):not(.small-meta) {max-width:40rem}
  .principles {flex-wrap:wrap;justify-content:flex-start;gap:.6rem 1.5rem}
  .path-grid {grid-template-columns:repeat(2,minmax(0,1fr))}
  .path-card {min-height:235px}
  .subject-grid {grid-template-columns:1fr}
  .lesson-layout {grid-template-columns:1fr;gap:0}
  .lesson-sidebar {position:static;padding-bottom:1.75rem}
  .lesson-sidebar nav {grid-template-columns:repeat(2,minmax(0,1fr))}
  .lesson-account {margin-inline:1.25rem}
  html {scroll-padding-top:1.5rem}
  .approach-grid {gap:1.25rem}
}
@media(max-width:600px) {
  .site-header {padding-inline:1.25rem}
  .brand-caption {font-size:.6rem}
  .site-header nav {gap:.25rem .75rem}
  .site-header nav a {font-size:.75rem}
  .site-header .nav-lesson,.nav-account {padding-inline:.65rem}
  .draft-strip {justify-content:flex-start;gap:.2rem .65rem;padding-inline:1.25rem}
  .home-hero {padding-top:2.5rem;padding-bottom:2rem}
  .home-hero h1 {font-size:clamp(3.2rem,12vw,4rem)}
  .hero-intro {font-size:1rem}
  .hero-actions {align-items:flex-start;flex-direction:column;gap:.6rem}
  .hero-visual {height:max(370px,23rem)}
  .visual-top,.visual-bottom {left:1.25rem;right:1.25rem}
  .visual-question {font-size:1.75rem}
  .hero-shell .principles {font-size:.74rem;gap:.5rem}
  .principles span {width:100%}
  .featured {gap:1.75rem}
  .experiment-preview {padding:1.2rem}
  .entry-section {padding-top:2rem;padding-bottom:2rem}
  .path-card {padding:1rem;gap:.9rem}
  .card-title {font-size:1.22rem}
  .card-description {font-size:.8rem}
  .card-action {font-size:.74rem}
  .subject-grid button,.subject-grid>a {padding-inline:.2rem;gap:.75rem}
  .subject-grid>a {padding-inline:.5rem}
  .subject-status {white-space:normal;text-align:right;max-width:5.5rem}
  .approach {padding-block:2.75rem}
  .approach-grid {grid-template-columns:1fr;gap:1.25rem}
  .approach-grid li {padding-right:0;border-bottom:1px solid var(--line);padding-bottom:.5rem}
  .approach-number {margin-bottom:1rem}
  .lesson-hero h1 {font-size:clamp(2.5rem,10vw,3.5rem)}
  .lesson-sidebar nav a {font-size:.78rem}
  .lesson-account {padding:1.25rem}
  .account-heading h1 {font-size:2.6rem}
}
@media(max-width:360px) {
  .site-header nav {display:grid;grid-template-columns:1fr 1fr;gap:.25rem .65rem}
  .site-header .nav-account {margin-left:0;justify-content:center}
  .path-grid {grid-template-columns:1fr}
  .path-card {min-height:220px}
}
@media(prefers-reduced-motion:reduce) {
  html {scroll-behavior:auto}
  *,*::before,*::after {animation:none!important;transition:none!important}
  .path-card:hover,.experiment-preview:hover,.button:active {transform:none}
}
@media(max-width:620px) {
  .site-header nav {display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:.15rem .6rem}
  .site-header nav a {justify-content:center;text-align:center;font-size:.75rem}
  .site-header .nav-account {margin-left:0;justify-content:center}
  .site-header .nav-lesson {padding:.6rem .3rem}
}
@media print {
  .site-header,.footer-links {display:none}
  .hero-shell {background:#fff;color:#142238}
  .hero-intro,.hero-note {color:#526174}
  .lesson-layout {display:block}
  .lesson-sidebar {display:none}
}