:root {
  --background: #071219;
  --foreground: #e8f0dc;
  --ink: #e8f0dc;
  --muted: #82959a;
  --faint: #40565b;
  --line: rgba(150, 180, 177, 0.17);
  --green: #c8f05b;
  --orange: #ffad58;
  --red: #ff6f61;
  --radius: 3px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; min-width: 320px; background: var(--background); color: var(--foreground); font-family: Arial, Helvetica, sans-serif; font-size: 16px; }
button, a { font: inherit; }
button { cursor: pointer; }
button:disabled { cursor: default; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }

.app-shell { min-height: 100vh; overflow: hidden; position: relative; background: radial-gradient(circle at 78% -10%, rgba(46, 91, 85, .22), transparent 31rem), #071219; }
.app-shell::before { content: ''; position: absolute; inset: 0; pointer-events: none; opacity: .17; background-image: linear-gradient(rgba(198, 240, 91, .06) 1px, transparent 1px), linear-gradient(90deg, rgba(198, 240, 91, .06) 1px, transparent 1px); background-size: 32px 32px; mask-image: linear-gradient(to bottom, black, transparent 70%); }
.scanlines { position: fixed; inset: 0; z-index: 4; pointer-events: none; opacity: .06; background: repeating-linear-gradient(0deg, transparent 0, transparent 3px, #d5f7bb 4px); mix-blend-mode: screen; }
.topbar { height: 76px; padding: 0 clamp(20px, 4vw, 66px); display: flex; align-items: center; gap: 40px; border-bottom: 1px solid var(--line); position: relative; z-index: 2; background: rgba(7, 18, 25, .82); backdrop-filter: blur(10px); }
.brand { display: flex; align-items: center; gap: 12px; color: var(--ink); text-decoration: none; min-width: 220px; }
.brand__mark { width: 39px; height: 39px; display: grid; place-items: center; border: 1px solid var(--green); color: var(--green); font-family: 'Courier New', monospace; font-size: 15px; box-shadow: 4px 4px 0 rgba(200, 240, 91, .16); }
.brand strong, .brand small { display: block; }
.brand strong { font-family: 'Courier New', monospace; font-size: 15px; letter-spacing: .12em; }
.brand small { color: var(--muted); margin-top: 3px; font-size: 9px; letter-spacing: .11em; }
.main-nav { display: flex; align-items: center; gap: 28px; flex: 1; }
.nav-link { border: 0; background: transparent; color: var(--muted); padding: 28px 0 25px; font: 700 11px 'Courier New', monospace; letter-spacing: .14em; border-bottom: 2px solid transparent; }
.nav-link:hover, .nav-link--active { color: var(--green); }
.nav-link--active { border-bottom-color: var(--green); }
.nav-link--muted { margin-left: auto; }
.status-cluster { display: flex; align-items: center; gap: 15px; }
.streak { color: var(--orange); font: 700 10px 'Courier New', monospace; letter-spacing: .1em; white-space: nowrap; }
.streak span { font-size: 16px; vertical-align: -1px; }
.user-chip { width: 34px; height: 34px; display: grid; place-items: center; border: 1px solid var(--faint); color: var(--green); font: 700 11px 'Courier New', monospace; }

.layout { position: relative; z-index: 1; display: grid; grid-template-columns: 226px minmax(0, 1fr); gap: clamp(34px, 5vw, 92px); max-width: 1440px; margin: 0 auto; padding: 52px clamp(20px, 4vw, 66px) 76px; }
.sidebar { min-height: 660px; border-right: 1px solid var(--line); padding-right: 26px; display: flex; flex-direction: column; }
.sidebar__heading, .card__topline, .sidebar__footer, .card__index, .micro-label, .card__label, .eyebrow, .keyboard-hint, .question-count, .listen-card__readout, .mission-stamp span, .stats-row span, .week-bar small { font-family: 'Courier New', monospace; letter-spacing: .11em; }
.sidebar__heading { display: flex; justify-content: space-between; color: var(--muted); font-size: 10px; font-weight: 700; }
.sidebar__counter { color: var(--green); }
.progress-line { height: 3px; background: rgba(200, 240, 91, .15); margin: 17px 0 28px; }
.progress-line span { display: block; height: 100%; width: 16%; background: var(--green); box-shadow: 0 0 12px rgba(200, 240, 91, .4); transition: width .25s ease; }
.lesson-list { list-style: none; padding: 0; margin: 0; display: grid; gap: 6px; }
.lesson-item { min-height: 57px; display: grid; grid-template-columns: 30px 1fr; align-items: center; column-gap: 9px; color: var(--muted); position: relative; }
.lesson-item__number { width: 27px; height: 27px; display: grid; place-items: center; border: 1px solid var(--faint); color: var(--faint); font: 700 10px 'Courier New', monospace; }
.lesson-item__label { font-size: 13px; }
.lesson-item--active { color: var(--ink); }
.lesson-item--active::before { content: ''; position: absolute; left: -27px; width: 2px; height: 31px; background: var(--green); }
.lesson-item--active .lesson-item__number { border-color: var(--green); background: rgba(200, 240, 91, .11); color: var(--green); }
.lesson-item--locked { opacity: .42; }
.lesson-item__live { grid-column: 2; color: var(--green); font: 700 9px 'Courier New', monospace; letter-spacing: .1em; margin-top: -17px; }
.tip-box { border-top: 1px solid var(--line); margin-top: auto; padding-top: 20px; }
.tip-box__label { color: var(--orange); font: 700 9px 'Courier New', monospace; letter-spacing: .12em; }
.tip-box p { color: #9ba9a6; font-size: 12px; line-height: 1.65; margin: 9px 0 0; }
.sidebar__footer { color: var(--faint); font-size: 9px; margin-top: 28px; }
.pulse-dot, .eyebrow__dot { display: inline-block; width: 6px; height: 6px; border-radius: 50%; background: var(--green); box-shadow: 0 0 0 4px rgba(200, 240, 91, .1), 0 0 14px var(--green); vertical-align: 1px; }

.content { max-width: 940px; width: 100%; }
.content__intro { display: flex; align-items: flex-end; justify-content: space-between; gap: 20px; margin-bottom: 30px; }
.eyebrow { color: var(--green); font-size: 10px; font-weight: 700; margin: 0 0 13px; }
.eyebrow span:not(.eyebrow__dot) { color: var(--faint); }
.eyebrow__dot { margin-right: 9px; }
.eyebrow__dot--orange { background: var(--orange); box-shadow: 0 0 0 4px rgba(255, 173, 88, .1), 0 0 14px var(--orange); }
h1, h2 { font-family: 'Courier New', monospace; font-weight: 700; letter-spacing: -.04em; margin: 0; }
h1 { font-size: clamp(28px, 3.3vw, 46px); line-height: 1.05; }
h2 { font-size: clamp(24px, 2.6vw, 34px); line-height: 1.05; }
.intro-copy { color: var(--muted); font-size: 15px; line-height: 1.6; margin: 13px 0 0; max-width: 500px; }
.mission-stamp { border: 1px solid var(--line); padding: 11px 15px 10px; min-width: 92px; color: var(--muted); transform: rotate(-2deg); }
.mission-stamp span { display: block; font-size: 9px; }
.mission-stamp strong { color: var(--orange); display: block; font: 700 19px 'Courier New', monospace; margin-top: 5px; }
.lesson-grid { display: grid; grid-template-columns: minmax(0, 1.35fr) minmax(220px, .65fr); gap: 13px; }
.card { border: 1px solid var(--line); background: linear-gradient(135deg, rgba(18, 43, 49, .85), rgba(10, 28, 35, .92)); border-radius: var(--radius); box-shadow: 9px 9px 0 rgba(0, 0, 0, .15); }
.card__topline { display: flex; justify-content: space-between; align-items: center; color: var(--muted); font-size: 9px; font-weight: 700; }
.card__label { color: var(--green); }
.card__index { color: var(--faint); font-size: 9px; }
.principles-card { padding: 21px 25px 22px; }
.principles-card h2 { margin-top: 19px; font-size: clamp(22px, 2.5vw, 30px); }
.principles-copy { color: var(--muted); font-size: 14px; line-height: 1.6; max-width: 680px; margin: 10px 0 20px; }
.principles-copy strong { color: var(--ink); }
.signal-pair { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.principle-signal { display: grid; grid-template-columns: 44px 1fr auto; align-items: center; gap: 12px; text-align: left; border: 1px solid var(--line); border-radius: 2px; background: rgba(6, 20, 26, .52); color: var(--ink); padding: 13px 15px; }
.principle-signal:hover { border-color: var(--green); background: rgba(200, 240, 91, .07); }
.principle-signal__symbol { display: grid; place-items: center; width: 40px; height: 40px; color: var(--orange); font: 700 30px 'Courier New', monospace; }
.principle-signal__symbol--dot { font-size: 35px; }
.principle-signal span:nth-child(2) strong, .principle-signal span:nth-child(2) small { display: block; }
.principle-signal span:nth-child(2) strong { font: 700 12px 'Courier New', monospace; letter-spacing: .12em; }
.principle-signal span:nth-child(2) small { color: var(--muted); font: 10px 'Courier New', monospace; margin-top: 5px; }
.principle-signal__play { color: var(--faint); font-size: 12px; }
.timing-note { display: flex; align-items: center; gap: 13px; border-top: 1px solid var(--line); color: var(--muted); font-size: 12px; line-height: 1.5; margin-top: 18px; padding-top: 16px; }
.timing-note strong { color: var(--orange); }
.timing-note__icon { color: var(--green); font: 700 16px 'Courier New', monospace; white-space: nowrap; }
.lesson-card { min-height: 330px; padding: 21px 25px 22px; position: relative; overflow: hidden; }
.lesson-card::after { content: 'A'; position: absolute; color: rgba(200, 240, 91, .025); font: 700 260px 'Courier New', monospace; right: -6px; bottom: -63px; pointer-events: none; }
.letter-stage { min-height: 175px; display: grid; place-items: center; position: relative; }
.letter-stage__letter { color: var(--ink); font: 700 115px 'Courier New', monospace; line-height: 1; text-shadow: 5px 5px 0 rgba(200, 240, 91, .11); position: relative; z-index: 1; }
.letter-stage__code { color: var(--green); font: 700 13px 'Courier New', monospace; letter-spacing: .28em; position: absolute; bottom: 8px; z-index: 1; }
.letter-stage__orbit { position: absolute; width: 212px; height: 108px; border: 1px solid rgba(200, 240, 91, .21); border-radius: 50%; transform: rotate(-13deg); display: flex; justify-content: space-around; align-items: flex-start; padding-top: 4px; color: var(--orange); font: 700 12px 'Courier New', monospace; }
.letter-stage__orbit::after { content: ''; position: absolute; width: 6px; height: 6px; background: var(--orange); border-radius: 50%; bottom: 12px; left: 18px; box-shadow: 0 0 10px var(--orange); }
.lesson-card__footer { display: flex; justify-content: space-between; align-items: flex-end; position: relative; z-index: 1; border-top: 1px solid var(--line); padding-top: 17px; }
.micro-label { color: var(--faint); display: block; font-size: 9px; font-weight: 700; }
.lesson-card__footer p { color: var(--ink); font-size: 13px; line-height: 1.5; margin: 6px 0 0; }
.lesson-card__footer em { color: var(--muted); font-style: normal; font-size: 11px; }
.play-button, .continue-button { border: 1px solid var(--green); border-radius: 2px; background: var(--green); color: #101b19; font: 700 10px 'Courier New', monospace; letter-spacing: .09em; padding: 12px 13px; display: flex; align-items: center; gap: 9px; box-shadow: 4px 4px 0 rgba(200, 240, 91, .15); transition: transform .15s, box-shadow .15s; }
.play-button:hover, .continue-button:hover { transform: translate(2px, 2px); box-shadow: 2px 2px 0 rgba(200, 240, 91, .15); }
.play-button__icon { font-size: 9px; }
.listen-card { padding: 21px 20px 18px; display: flex; flex-direction: column; min-height: 330px; }
.listen-card__title { color: var(--ink); font-size: 14px; line-height: 1.4; margin: 23px 0 0; }
.speaker-icon, .challenge__speaker { color: var(--orange); font: 700 13px 'Courier New', monospace; letter-spacing: -4px; }
.waveform { flex: 1; display: flex; justify-content: center; align-items: center; gap: 5px; padding: 26px 0 14px; }
.waveform span { width: 3px; max-height: 78px; min-height: 9px; background: var(--green); opacity: .78; box-shadow: 0 0 9px rgba(200, 240, 91, .4); }
.waveform span:nth-child(3n) { background: var(--orange); }
.listen-card__readout { font-size: 9px; color: var(--muted); }
.listen-card__readout span { margin: 0 5px; }
.listen-card__readout span:first-child { margin-left: 0; }
.listen-card__button { display: flex; justify-content: space-between; align-items: center; width: 100%; border: 0; border-top: 1px solid var(--line); background: transparent; color: var(--ink); font: 700 10px 'Courier New', monospace; letter-spacing: .12em; padding: 15px 0 0; margin-top: 19px; }
.listen-card__button:hover { color: var(--green); }
.listen-card__button span { color: var(--green); font-size: 17px; }
.listen-actions { display: grid; grid-template-columns: 1fr 1fr; gap: 7px; margin-top: auto; }
.listen-actions button { border: 1px solid var(--line); border-radius: 2px; background: rgba(6, 20, 26, .52); color: var(--ink); padding: 9px 7px; font: 700 10px 'Courier New', monospace; }
.listen-actions button:hover { border-color: var(--orange); color: var(--orange); }
.listen-actions button span { color: var(--faint); margin-left: 5px; }

.practice-card { margin-top: 25px; padding: 25px; transition: border-color .2s, box-shadow .2s; }
.practice-card--focus { border-color: rgba(255, 173, 88, .55); box-shadow: 9px 9px 0 rgba(255, 173, 88, .09); }
.practice-card__heading { display: flex; justify-content: space-between; align-items: flex-start; }
.practice-card__heading .eyebrow { margin-bottom: 12px; }
.practice-card__score { text-align: right; color: var(--muted); font: 700 9px 'Courier New', monospace; letter-spacing: .11em; }
.practice-card__score strong { color: var(--orange); font: 700 30px 'Courier New', monospace; display: inline-block; margin: 6px 3px 0 0; letter-spacing: -.07em; }
.practice-card__score small { font-size: 10px; }
.challenge { min-height: 130px; display: grid; place-items: center; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); margin-top: 21px; position: relative; }
.challenge__audio { border: 0; background: transparent; color: var(--ink); display: flex; align-items: center; gap: 22px; padding: 13px 24px; }
.challenge__audio:hover .challenge__play { color: var(--green); transform: scale(1.1); }
.challenge__speaker { color: var(--orange); }
.challenge__play { color: var(--faint); font-size: 15px; transition: transform .15s, color .15s; }
.challenge__hint { position: absolute; bottom: 9px; color: var(--muted); font-size: 11px; letter-spacing: .02em; }
.signal { display: flex; align-items: center; gap: 9px; min-height: 34px; }
.signal__mark { display: block; background: var(--orange); box-shadow: 0 0 12px rgba(255, 173, 88, .4); }
.signal__mark--dot { width: 11px; height: 11px; border-radius: 50%; }
.signal__mark--dash { width: 36px; height: 11px; border-radius: 2px; }
.answer-grid { border: 0; padding: 0; min-width: 0; display: grid; grid-template-columns: repeat(4, 1fr); gap: 9px; margin-top: 18px; }
.answer-grid--pair { grid-template-columns: repeat(2, minmax(0, 1fr)); max-width: 620px; margin-left: auto; margin-right: auto; width: 100%; }
.answer { min-height: 74px; display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; border: 1px solid var(--line); border-radius: 2px; background: rgba(6, 20, 26, .58); color: var(--ink); padding: 12px 14px; transition: background .15s, border-color .15s, transform .15s; }
.answer:hover:not(:disabled) { border-color: var(--green); background: rgba(200, 240, 91, .08); transform: translateY(-2px); }
.answer strong { font: 700 25px 'Courier New', monospace; }
.answer__key { align-self: start; justify-self: start; color: var(--faint); font: 700 10px 'Courier New', monospace; }
.answer__mark { justify-self: end; font: 700 18px Arial, sans-serif; }
.answer--correct { border-color: var(--green); background: rgba(200, 240, 91, .15); color: var(--green); }
.answer--wrong { border-color: var(--red); background: rgba(255, 111, 97, .12); color: var(--red); }
.practice-card__bottom { display: flex; justify-content: space-between; align-items: center; margin-top: 18px; min-height: 31px; }
.keyboard-hint { color: var(--faint); font-size: 9px; }
kbd { border: 1px solid var(--faint); padding: 3px 5px; margin-left: 4px; font: 700 9px 'Courier New', monospace; color: var(--muted); }
.continue-button { padding: 9px 12px; }
.question-count { color: var(--muted); font-size: 9px; }

.reference-card { margin-top: 25px; padding: 21px 25px 20px; }
.reference-card h2 { font-size: clamp(21px, 2.3vw, 28px); margin-top: 17px; }
.reference-grid { display: grid; grid-template-columns: repeat(8, 1fr); gap: 7px; margin-top: 18px; }
.reference-grid div { border: 1px solid var(--line); background: rgba(6, 20, 26, .42); padding: 10px 7px; text-align: center; }
.reference-grid strong, .reference-grid span { display: block; }
.reference-grid strong { color: var(--ink); font: 700 16px 'Courier New', monospace; }
.reference-grid span { color: var(--green); font: 11px 'Courier New', monospace; margin-top: 7px; white-space: nowrap; }
.reference-note { color: var(--muted); font-size: 12px; margin: 15px 0 0; }

.lower-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 13px; margin-top: 25px; }
.stats-card, .week-card { padding: 19px 21px 18px; min-height: 158px; }
.stats-row { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; margin-top: 24px; }
.stats-row div { border-left: 1px solid var(--line); padding-left: 12px; }
.stats-row div:first-child { border-left: 2px solid var(--green); }
.stats-row strong { display: block; color: var(--ink); font: 700 24px 'Courier New', monospace; }
.stats-row span { display: block; color: var(--muted); font-size: 9px; line-height: 1.35; margin-top: 5px; letter-spacing: .02em; }
.week-bars { display: flex; height: 91px; align-items: end; justify-content: space-between; gap: 9px; margin-top: 12px; padding: 0 4px; }
.week-bar { height: 80px; flex: 1; display: flex; align-items: center; flex-direction: column; justify-content: end; gap: 8px; }
.week-bar__fill { display: block; width: 100%; max-width: 16px; min-height: 2px; background: rgba(200, 240, 91, .32); border-top: 2px solid rgba(200, 240, 91, .7); }
.week-bar__fill--active { background: var(--orange); border-top-color: var(--orange); box-shadow: 0 0 12px rgba(255, 173, 88, .4); }
.week-bar small { color: var(--faint); font-size: 9px; }
.noscript-message { position: fixed; inset: 15px; z-index: 10; background: var(--orange); color: #071219; padding: 18px; font-weight: 700; }

@media (max-width: 920px) { .topbar { gap: 18px; } .brand { min-width: auto; } .main-nav { gap: 16px; } .nav-link--muted { display: none; } .layout { gap: 32px; } .sidebar { width: 188px; } }
@media (max-width: 700px) {
  .topbar { height: 68px; padding: 0 18px; }
  .brand strong { font-size: 13px; }
  .brand small, .main-nav { display: none; }
  .status-cluster { margin-left: auto; }
  .layout { display: block; padding: 32px 18px 56px; }
  .sidebar { min-height: auto; width: auto; border-right: 0; border-bottom: 1px solid var(--line); padding: 0 0 22px; margin-bottom: 31px; }
  .lesson-list { grid-template-columns: repeat(4, 1fr); gap: 7px; }
  .lesson-item { min-height: 40px; display: block; }
  .lesson-item__number { display: inline-grid; margin-right: 6px; vertical-align: middle; }
  .lesson-item__label { font-size: 10px; display: inline; line-height: 1.25; }
  .lesson-item__live { display: none; }
  .lesson-item--active::before { display: none; }
  .tip-box, .sidebar__footer { display: none; }
  .content__intro { align-items: flex-start; }
  .mission-stamp { margin-top: 3px; }
  .lesson-grid, .lower-grid { grid-template-columns: 1fr; }
  .signal-pair { grid-template-columns: 1fr; }
  .reference-grid { grid-template-columns: repeat(4, 1fr); }
  .listen-card { min-height: 188px; }
  .waveform { padding: 15px 0 7px; }
  .answer-grid { grid-template-columns: repeat(2, 1fr); }
  .practice-card, .lesson-card { padding: 19px; }
  .keyboard-hint { display: none; }
}
@media (max-width: 430px) {
  .streak { font-size: 9px; }
  .content__intro { display: block; }
  .mission-stamp { display: inline-block; margin-top: 18px; }
  .lesson-card__footer { display: block; }
  .play-button { margin-top: 18px; width: 100%; justify-content: center; }
  .challenge__audio { gap: 13px; padding-left: 8px; padding-right: 8px; }
  .challenge__hint { position: static; text-align: center; padding-bottom: 9px; }
  .challenge { display: flex; flex-direction: column; }
  .timing-note { align-items: flex-start; }
  .stats-row { gap: 5px; }
  .stats-row strong { font-size: 19px; }
  .stats-row span { font-size: 8px; }
}