:root {
  --pe-bg: #060d18;
  --pe-panel: #0b1523;
  --pe-panel-2: #0e1c2d;
  --pe-line: rgba(135, 158, 190, .18);
  --pe-ink: #eaf1fc;
  --pe-muted: #8294ad;
  --pe-orange: #ff7338;
  --pe-pink: #ff2d78;
  --pe-cyan: #25d9e8;
  --pe-gold: #d7a945;
  --pe-good: #39d98a;
  --display: var(--font-display, 'Archivo', sans-serif);
  --body: var(--font-body, 'Hanken Grotesk', sans-serif);
  --mono: var(--font-mono, 'JetBrains Mono', monospace);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; min-height: 100vh; color: var(--pe-ink); background: var(--pe-bg); font-family: var(--body); }
button, input, textarea, select { font: inherit; }
button { cursor: pointer; }
.skip-link { position: fixed; left: 1rem; top: -5rem; z-index: 1000; padding: .8rem 1rem; color: #07101d; background: var(--pe-cyan); border-radius: .4rem; }
.skip-link:focus { top: 1rem; }
.signal-grid { position: fixed; inset: 0; pointer-events: none; opacity: .18; background-image: linear-gradient(rgba(37,217,232,.08) 1px, transparent 1px), linear-gradient(90deg, rgba(37,217,232,.08) 1px, transparent 1px); background-size: 68px 68px; mask-image: radial-gradient(circle at 68% 18%, black, transparent 70%); }

.course-chrome { position: sticky; top: 0; z-index: 50; min-height: 66px; display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; gap: 1rem; padding: .8rem clamp(1rem, 3vw, 2.4rem); border-bottom: 1px solid var(--pe-line); background: rgba(6,13,24,.92); backdrop-filter: blur(18px); }
.brand { display: inline-flex; align-items: center; gap: .8rem; width: max-content; color: var(--pe-ink); text-decoration: none; font: 600 .68rem var(--mono); letter-spacing: .14em; text-transform: uppercase; }
.brand img { width: auto; height: 30px; display: block; }
.course-identity { display: flex; align-items: center; gap: .65rem; font: 600 .66rem var(--mono); letter-spacing: .13em; text-transform: uppercase; color: var(--pe-muted); }
.live-dot { width: 7px; height: 7px; border-radius: 50%; background: var(--pe-good); box-shadow: 0 0 14px var(--pe-good); }
.mobile-menu { display: none; justify-self: end; }

.primary-nav { position: sticky; top: 66px; z-index: 45; display: flex; justify-content: center; gap: .25rem; padding: .65rem 1rem; background: rgba(8,17,30,.94); border-bottom: 1px solid var(--pe-line); backdrop-filter: blur(16px); overflow-x: auto; }
.primary-nav button { flex: 0 0 auto; padding: .55rem .85rem; border: 1px solid transparent; border-radius: .35rem; color: var(--pe-muted); background: transparent; font: 600 .64rem var(--mono); letter-spacing: .08em; text-transform: uppercase; }
.primary-nav button:hover, .primary-nav button:focus-visible { color: var(--pe-ink); border-color: var(--pe-line); }
.primary-nav button.active { color: #07101d; background: var(--pe-orange); }

.view { display: none; position: relative; z-index: 1; }
.view.active { display: block; animation: view-in .36s cubic-bezier(.16,1,.3,1); }
@keyframes view-in { from { opacity: 0; translate: 0 10px; } }
.course-shell { display: grid; grid-template-columns: 325px minmax(0, 1fr); min-height: calc(100vh - 120px); }
.course-rail { position: sticky; top: 117px; height: calc(100vh - 117px); overflow: hidden; padding: 2rem 1.25rem; border-right: 1px solid var(--pe-line); background: rgba(7,16,29,.88); }
.rail-heading { padding: 0 .45rem 1.2rem; }
.eyebrow { margin: 0 0 .55rem; color: var(--pe-cyan); font: 600 .62rem var(--mono); letter-spacing: .14em; text-transform: uppercase; }
.rail-heading h1 { margin: 0 0 1.2rem; font: 800 1.45rem/1.08 var(--display); letter-spacing: -.02em; }
.progress-line { height: 4px; overflow: hidden; background: rgba(255,255,255,.08); }
.progress-line span { display: block; height: 100%; width: 0; background: linear-gradient(90deg, var(--pe-orange), var(--pe-pink)); transition: width .4s ease; }
.progress-copy { margin: .6rem 0 0; color: var(--pe-muted); font: .66rem var(--mono); }
.week-filter { display: grid; gap: .35rem; padding: 0 .45rem 1rem; color: var(--pe-muted); font: 600 .62rem var(--mono); letter-spacing: .1em; text-transform: uppercase; }
select, input, textarea { width: 100%; color: var(--pe-ink); background: rgba(4,11,20,.78); border: 1px solid var(--pe-line); border-radius: .4rem; padding: .72rem .8rem; }
textarea { resize: vertical; line-height: 1.55; }
select:focus, input:focus, textarea:focus, button:focus-visible { outline: 2px solid var(--pe-cyan); outline-offset: 2px; }
.lesson-list { height: calc(100% - 180px); overflow-y: auto; padding: 0 .35rem 5rem; scrollbar-width: thin; }
.lesson-nav { width: 100%; display: grid; grid-template-columns: 38px 1fr auto; align-items: center; gap: .65rem; padding: .75rem .55rem; color: var(--pe-muted); text-align: left; border: 0; border-bottom: 1px solid rgba(135,158,190,.1); background: transparent; }
.lesson-nav:hover { color: var(--pe-ink); background: rgba(255,255,255,.025); }
.lesson-nav.active { color: var(--pe-ink); background: linear-gradient(90deg, rgba(255,115,56,.12), transparent); box-shadow: inset 3px 0 var(--pe-orange); }
.lesson-nav.done .day-index { color: var(--pe-good); }
.day-index { color: var(--pe-orange); font: 600 .63rem var(--mono); }
.day-name { font-size: .78rem; line-height: 1.25; }
.day-state { font-size: .68rem; color: var(--pe-good); }

.lesson-stage { width: min(1120px, calc(100% - 3rem)); margin: 0 auto; padding: clamp(2rem, 5vw, 4.5rem) 0 5rem; }
.lesson-topline { display: flex; justify-content: space-between; gap: 2rem; align-items: end; padding-bottom: 1.7rem; border-bottom: 1px solid var(--pe-line); }
.lesson-topline h2 { max-width: 820px; margin: 0; font: 800 clamp(2rem, 5vw, 4.6rem)/.98 var(--display); letter-spacing: -.045em; }
.lesson-meta { flex: 0 0 auto; color: var(--pe-muted); font: .65rem/1.7 var(--mono); text-align: right; text-transform: uppercase; }
.prompt-signal { display: grid; grid-template-columns: repeat(7, auto); align-items: center; gap: 1rem; margin: 2rem 0; padding: 1.1rem 1.2rem; background: #07111e; border: 1px solid var(--pe-line); border-radius: .5rem; overflow-x: auto; }
.prompt-signal div { display: flex; align-items: center; gap: .55rem; white-space: nowrap; }
.prompt-signal span { color: var(--pe-orange); font: .58rem var(--mono); }
.prompt-signal strong { font: 700 .73rem var(--mono); letter-spacing: .08em; text-transform: uppercase; }
.prompt-signal i { width: clamp(24px, 5vw, 90px); height: 1px; background: linear-gradient(90deg, var(--pe-orange), var(--pe-cyan)); position: relative; }
.prompt-signal i::after { content: ''; position: absolute; right: -1px; top: -3px; border-left: 6px solid var(--pe-cyan); border-top: 3px solid transparent; border-bottom: 3px solid transparent; }

.lesson-media { margin: 2rem 0; padding: 1.25rem; background: linear-gradient(145deg, rgba(14,28,45,.95), rgba(7,17,30,.95)); border: 1px solid var(--pe-line); border-radius: .65rem; }
.section-head { display: flex; justify-content: space-between; gap: 1rem; align-items: end; margin-bottom: 1rem; }
.section-head h3 { margin: 0; font: 800 1.4rem var(--display); }
.asset-status { flex: 0 0 auto; color: var(--pe-gold); font: 600 .58rem var(--mono); letter-spacing: .09em; text-transform: uppercase; }
.media-grid { display: grid; grid-template-columns: repeat(2, minmax(0,1fr)); gap: .75rem; }
.media-item { margin: 0; overflow: hidden; border: 1px solid var(--pe-line); border-radius: .45rem; background: #030912; }
.media-item:first-child { grid-column: 1 / -1; }
.media-item img, .media-item video { display: block; width: 100%; aspect-ratio: 16 / 9; object-fit: cover; background: #030912; }
.media-item figcaption { display: flex; justify-content: space-between; gap: 1rem; padding: .7rem .8rem; font-size: .75rem; }
.media-item figcaption span { color: var(--pe-cyan); font: .58rem var(--mono); text-transform: uppercase; }
.media-empty { grid-column: 1 / -1; min-height: 300px; display: grid; place-items: center; text-align: center; padding: 2rem; background: radial-gradient(circle at 50% 10%, rgba(37,217,232,.12), transparent 55%), #050d18; border: 1px dashed rgba(37,217,232,.28); }
.media-empty strong { display: block; margin: .4rem 0; font: 800 clamp(1.4rem, 3vw, 2.3rem) var(--display); }
.media-empty p { margin: 0; color: var(--pe-muted); }

.lesson-copy { padding: clamp(1.5rem, 4vw, 3rem); background: var(--pe-panel); border: 1px solid var(--pe-line); }
.lesson-deck { max-width: 760px; margin: 0 0 2.5rem; color: #d9e4f4; font-size: clamp(1.15rem, 2vw, 1.45rem); line-height: 1.5; }
.copy-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 3rem; }
.copy-grid ul, .copy-grid ol { padding-left: 1.25rem; color: var(--pe-muted); }
.copy-grid li { margin-bottom: .75rem; padding-left: .35rem; }
.copy-grid li::marker { color: var(--pe-orange); font-family: var(--mono); }
.challenge-card { margin-top: 2.2rem; padding: 1.3rem 1.4rem; border-left: 3px solid var(--pe-pink); background: rgba(255,45,120,.06); }
.challenge-card p:not(.eyebrow) { font-size: 1.05rem; }
.challenge-card button, .actions button, .lesson-actions button, .tool-card > button, .toolbar button, .import-button { border: 0; border-radius: .35rem; padding: .72rem 1rem; color: #07101d; background: var(--pe-orange); font: 700 .64rem var(--mono); letter-spacing: .08em; text-transform: uppercase; }
.lesson-note-card { margin-top: 1.5rem; padding: 1.4rem; background: var(--pe-panel-2); border: 1px solid var(--pe-line); }
.actions { display: flex; gap: .6rem; flex-wrap: wrap; margin-top: .8rem; }
button.secondary { color: var(--pe-ink); background: transparent; border: 1px solid var(--pe-line); }
.lesson-actions { display: grid; grid-template-columns: 1fr 1.35fr 1fr; gap: .7rem; margin-top: 1.5rem; }
.lesson-actions .finish { background: linear-gradient(90deg, var(--pe-orange), var(--pe-pink)); }

/* Lesson body — the actual teaching content */
.lesson-body { max-width: 800px; margin: 0 0 2.2rem; }
.lesson-body > * { margin: 0 0 1.15rem; }
.lesson-body > *:last-child { margin-bottom: 0; }
.body-h { color: var(--pe-ink); font: 800 clamp(1.2rem, 2.2vw, 1.6rem)/1.15 var(--display); letter-spacing: -.01em; margin-top: 2rem; }
.body-p { color: #cdd9ec; font-size: 1.02rem; line-height: 1.72; }
.body-list { padding-left: 1.3rem; color: #cdd9ec; }
.body-list li { margin-bottom: .55rem; line-height: 1.6; }
.body-list li::marker { color: var(--pe-orange); }
.body-callout { padding: 1.1rem 1.25rem; border-left: 3px solid var(--pe-cyan); background: rgba(37,217,232,.06); }
.body-callout.tone-pitfall { border-left-color: var(--pe-pink); background: rgba(255,45,120,.07); }
.body-callout.tone-tip { border-left-color: var(--pe-good); background: rgba(57,217,138,.07); }
.body-callout.tone-note { border-left-color: var(--pe-gold); background: rgba(215,169,69,.07); }
.callout-title { margin: 0 0 .35rem; color: var(--pe-ink); font: 700 .68rem var(--mono); letter-spacing: .1em; text-transform: uppercase; }
.callout-text { margin: 0; color: #cdd9ec; line-height: 1.6; }
.body-prompt { border: 1px solid var(--pe-line); border-radius: .5rem; overflow: hidden; background: #050d18; }
.prompt-head { display: flex; justify-content: space-between; align-items: center; gap: 1rem; padding: .55rem .75rem; background: rgba(37,217,232,.08); border-bottom: 1px solid var(--pe-line); }
.prompt-label { color: var(--pe-cyan); font: 600 .6rem var(--mono); letter-spacing: .12em; text-transform: uppercase; }
.prompt-copy { padding: .35rem .7rem; color: var(--pe-cyan); background: transparent; border: 1px solid rgba(37,217,232,.4); border-radius: .3rem; font: 600 .58rem var(--mono); letter-spacing: .08em; text-transform: uppercase; }
.prompt-copy:hover { color: #07101d; background: var(--pe-cyan); }
.prompt-text { margin: 0; padding: 1rem 1.1rem; color: #dce7f7; font: .86rem/1.6 var(--mono); white-space: pre-wrap; overflow-x: auto; }

/* Go-deeper references */
.lesson-references { max-width: 800px; margin: 0 0 .5rem; }
.reference-list { display: flex; flex-wrap: wrap; gap: .6rem; }
.reference-item { display: inline-flex; align-items: center; gap: .6rem; padding: .55rem .8rem; color: var(--pe-ink); text-decoration: none; background: var(--pe-panel-2); border: 1px solid var(--pe-line); border-radius: .4rem; }
.reference-item:hover { border-color: var(--pe-cyan); }
.ref-kind { color: var(--pe-cyan); font: 600 .56rem var(--mono); letter-spacing: .1em; text-transform: uppercase; }
.ref-label { font-size: .82rem; }

.utility-view { width: min(1180px, calc(100% - 2rem)); margin: 0 auto; padding: clamp(2rem, 5vw, 5rem) 0 6rem; }
.utility-intro { max-width: 780px; margin-bottom: 2.5rem; }
.utility-intro h2 { margin: 0 0 .8rem; font: 800 clamp(2.4rem, 6vw, 5.2rem)/.95 var(--display); letter-spacing: -.05em; }
.utility-intro > p:last-child { color: var(--pe-muted); font-size: 1.1rem; }
.tool-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.tutor-layout { grid-template-columns: minmax(0, 1.15fr) minmax(300px, .85fr); }
.tool-card { padding: 1.4rem; background: var(--pe-panel); border: 1px solid var(--pe-line); border-radius: .55rem; }
.tool-card label { display: grid; gap: .45rem; margin-bottom: 1rem; color: var(--pe-muted); font: 600 .65rem var(--mono); letter-spacing: .06em; text-transform: uppercase; }
.mode-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: .5rem; margin-bottom: 1.2rem; }
.mode-button { min-height: 66px; padding: .7rem; color: var(--pe-muted); background: rgba(4,11,20,.7); border: 1px solid var(--pe-line); border-radius: .35rem; font: 600 .65rem var(--mono); }
.mode-button.active { color: #07101d; background: var(--pe-cyan); }
.key-mount { margin-top: 1.2rem; }

/* AI Tutor gate — the course is free, this one feature is unlocked by password */
.tutor-lock { display: grid; place-items: center; padding: clamp(1.5rem, 5vw, 3.5rem) 1rem; }
.tutor-lock-card { width: min(440px, 100%); padding: 2.2rem 2rem; text-align: center; background: var(--pe-panel); border: 1px solid var(--pe-line); border-radius: .7rem; }
.tutor-lock-icon { color: var(--pe-orange); margin-bottom: 1rem; }
.tutor-lock-card h3 { margin: .2rem 0 .7rem; font: 800 clamp(1.35rem, 3vw, 1.7rem) var(--display); }
.tutor-lock-card p:not(.eyebrow):not(.tutor-lock-msg) { color: var(--pe-muted); line-height: 1.6; }
.tutor-lock-card form { display: grid; gap: .8rem; margin-top: 1.5rem; }
.tutor-lock-card input { text-align: center; }
.tutor-lock-card button { border: 0; border-radius: .4rem; padding: .85rem 1rem; color: #07101d; background: linear-gradient(90deg, var(--pe-orange), var(--pe-pink)); font: 700 .66rem var(--mono); letter-spacing: .09em; text-transform: uppercase; }
.tutor-lock-msg { min-height: 1.2em; margin: .8rem 0 0; color: var(--pe-pink); font-size: .82rem; }
.result { min-height: 260px; color: #dce7f7; white-space: pre-wrap; line-height: 1.65; }
.result-card { position: sticky; top: 135px; align-self: start; }
.toolbar { display: flex; gap: .7rem; margin-bottom: 1rem; }
.toolbar input { flex: 1; }
.toolbar button { flex: 0 0 auto; }
.notebook-grid, .portfolio-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: .8rem; }
.note-card, .artifact-card, .library-entry { padding: 1rem; background: var(--pe-panel); border: 1px solid var(--pe-line); }
.note-card h3, .artifact-card h3, .library-entry h3 { margin: .3rem 0 .6rem; font: 800 1rem var(--display); }
.note-card p, .artifact-card p, .library-entry p { color: var(--pe-muted); font-size: .85rem; white-space: pre-wrap; }
.library-list { display: grid; gap: .7rem; max-height: 650px; overflow: auto; }
.version-chip { display: inline-block; margin-right: .4rem; color: var(--pe-cyan); font: .58rem var(--mono); }
.ab-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.variant-label { color: var(--pe-orange); font: 700 .65rem var(--mono); letter-spacing: .12em; }
.rubric-card { margin-top: 1rem; }
.rubric-card .result { margin-top: 1.4rem; min-height: 150px; padding: 1rem; background: #050d18; }
.artifact-card { display: flex; flex-direction: column; min-height: 220px; }
.artifact-card label { margin-top: auto; display: flex; align-items: center; gap: .55rem; color: var(--pe-muted); }
.artifact-card input { width: auto; accent-color: var(--pe-good); }
.score-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: .8rem; margin-bottom: 1.5rem; }
.score-card { padding: 1.2rem; border-top: 3px solid var(--pe-cyan); background: var(--pe-panel); }
.score-card strong { display: block; font: 800 2.7rem var(--display); }
.score-card span { color: var(--pe-muted); font: .62rem var(--mono); letter-spacing: .08em; text-transform: uppercase; }
.week-map { display: grid; grid-template-columns: repeat(6, 1fr); gap: .6rem; margin-bottom: 1.5rem; }
.week-card { padding: .9rem; background: var(--pe-panel); border: 1px solid var(--pe-line); }
.week-card strong { display: block; font: 800 1.3rem var(--display); }
.week-card span { color: var(--pe-muted); font-size: .75rem; }
.import-button { position: relative; display: inline-flex; align-items: center; cursor: pointer; }
.import-button input { position: absolute; opacity: 0; pointer-events: none; }
.noscript { margin: 2rem; padding: 1rem; color: var(--pe-ink); background: #351725; }

@media (max-width: 980px) {
  .course-shell { grid-template-columns: 260px minmax(0, 1fr); }
  .lesson-stage { width: min(100% - 2rem, 900px); }
  .notebook-grid, .portfolio-grid { grid-template-columns: repeat(2, 1fr); }
  .score-grid { grid-template-columns: repeat(2, 1fr); }
  .week-map { grid-template-columns: repeat(3, 1fr); }
}

@media (max-width: 760px) {
  .course-chrome { grid-template-columns: 1fr auto; }
  .course-identity { display: none; }
  .mobile-menu { display: block; color: var(--pe-ink); border: 1px solid var(--pe-line); background: transparent; padding: .5rem .7rem; }
  .primary-nav { display: none; top: 66px; justify-content: flex-start; }
  .primary-nav.open { display: flex; }
  .course-shell { display: block; }
  .course-rail { position: relative; top: auto; height: auto; border-right: 0; border-bottom: 1px solid var(--pe-line); }
  .lesson-list { display: flex; height: auto; overflow-x: auto; padding: 0; }
  .lesson-nav { flex: 0 0 210px; }
  .lesson-topline { display: block; }
  .lesson-meta { text-align: left; margin-top: 1rem; }
  .prompt-signal { grid-template-columns: repeat(7, max-content); }
  .copy-grid, .tool-grid, .tutor-layout, .ab-grid { grid-template-columns: 1fr; }
  .media-grid { grid-template-columns: 1fr; }
  .media-item:first-child { grid-column: auto; }
  .result-card { position: static; }
  .notebook-grid, .portfolio-grid { grid-template-columns: 1fr; }
  .mode-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 480px) {
  .brand span { display: none; }
  .lesson-stage { width: calc(100% - 1rem); }
  .lesson-copy { padding: 1.2rem; }
  .lesson-actions { grid-template-columns: 1fr; }
  .score-grid, .week-map { grid-template-columns: 1fr 1fr; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; scroll-behavior: auto !important; transition-duration: .01ms !important; }
}