.sp-shell {
  --sp-core-background: #ffffff;
  --sp-core-subtle: #f7f8fa;
  --sp-core-border: #dfe5ef;
  --sp-core-ink: #21242c;
  --sp-core-muted: #545b68;
  --sp-core-blue: #1865f2;
  --sp-core-blue-soft: #eef4ff;
  --sp-learning-green: #008522;
  --sp-learning-green-soft: #edf8ef;
  --sp-learning-gold: #805600;
  --sp-learning-gold-soft: #fff7e6;
  --sp-learning-red: #b42318;
  --sp-learning-red-soft: #fff1f0;
  box-sizing: border-box;
  max-width: 1040px;
  margin: 0 auto;
  padding: 24px;
  color: var(--sp-core-ink);
  font-family: "Be Vietnam Pro", sans-serif;
  font-size: 16px;
  line-height: 1.5;
}

.sp-shell *,
.sp-shell *::before,
.sp-shell *::after { box-sizing: border-box; }
.sp-shell button,
.sp-shell a { font: inherit; }
.sp-shell a { color: inherit; text-decoration: none; }
.sp-shell button { color: inherit; }
.sp-shell :focus-visible { outline: 3px solid var(--sp-core-blue); outline-offset: 3px; }
.sp-shell h1,
.sp-shell h2,
.sp-shell h3,
.sp-shell p { margin-top: 0; }

.sp-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  min-height: 48px;
  margin-bottom: 24px;
}
.sp-back {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 44px;
  color: var(--sp-core-muted);
  font-weight: 650;
}
.sp-back:hover,
.sp-text-link:hover,
.sp-video-meta a:hover { color: var(--sp-core-blue); }
.sp-header-tag,
.sp-eyebrow {
  color: #3d526f;
  font-size: 12px;
  font-weight: 750;
  letter-spacing: .06em;
}
.sp-header-tag { white-space: nowrap; }
.sp-crumb { margin: -16px 0 20px; color: var(--sp-core-muted); font-size: 14px; }

.sp-course-hero {
  padding: 28px;
  border: 1px solid var(--sp-core-border);
  border-radius: 20px;
  background: var(--sp-core-subtle);
}
.sp-eyebrow { margin-bottom: 8px; }
.sp-course-hero h1,
.sp-topic-hero h1,
.sp-learning-step h1 { margin-bottom: 8px; font-size: clamp(24px, 4vw, 32px); line-height: 1.25; letter-spacing: -.025em; }
.sp-course-hero > p:not(.sp-eyebrow),
.sp-topic-hero p:not(.sp-eyebrow),
.sp-lead { max-width: 680px; margin-bottom: 20px; color: var(--sp-core-muted); font-size: 16px; line-height: 1.6; }
.sp-course-stats { display: flex; flex-wrap: wrap; gap: 28px; margin: 24px 0 20px; }
.sp-course-stats div,
.sp-result-score div { display: grid; gap: 2px; }
.sp-course-stats strong { font-size: 24px; line-height: 1.2; }
.sp-course-stats span,
.sp-result-score span { color: var(--sp-core-muted); font-size: 14px; }
.sp-course-progress { max-width: 620px; }
.sp-progress-label { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 8px; color: var(--sp-core-muted); font-size: 14px; }
.sp-progress-track { height: 8px; overflow: hidden; border-radius: 999px; background: #dce4f0; }
.sp-progress-track > span { display: block; height: 100%; min-width: 0; border-radius: inherit; background: var(--sp-core-blue); transition: width .2s ease; }

.sp-section { margin-top: 32px; }
.sp-section-heading { display: flex; align-items: end; justify-content: space-between; gap: 16px; margin-bottom: 16px; }
.sp-section-heading h2 { margin: 0; font-size: 22px; line-height: 1.3; }
.sp-free-note { flex: 0 0 auto; padding: 7px 11px; border-radius: 999px; background: var(--sp-learning-green-soft); color: var(--sp-learning-green); font-size: 13px; font-weight: 700; }
.sp-topic-list { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
.sp-topic-card {
  display: flex;
  align-items: center;
  gap: 14px;
  min-height: 86px;
  padding: 16px;
  border: 1px solid var(--sp-core-border);
  border-radius: 14px;
  background: var(--sp-core-background);
  transition: border-color .15s ease, background .15s ease;
}
.sp-topic-card:hover { border-color: #8aaef8; background: var(--sp-core-blue-soft); }
.sp-topic-index { display: grid; width: 42px; height: 42px; flex: 0 0 42px; place-items: center; border-radius: 12px; background: var(--sp-core-blue-soft); color: var(--sp-core-blue); font-size: 14px; font-weight: 800; }
.sp-topic-copy { display: grid; min-width: 0; gap: 4px; }
.sp-topic-copy strong { font-size: 16px; line-height: 1.35; }
.sp-topic-copy small { color: var(--sp-core-muted); font-size: 13px; line-height: 1.4; }
.sp-arrow { margin-left: auto; color: var(--sp-core-blue); font-size: 20px; }
.sp-footnote { margin: 20px 0 0; color: var(--sp-core-muted); font-size: 13px; }

.sp-topic-hero { display: flex; align-items: center; gap: 18px; margin-bottom: 24px; }
.sp-topic-mark { display: grid; width: 64px; height: 64px; flex: 0 0 64px; place-items: center; border-radius: 18px; background: var(--sp-core-blue-soft); color: var(--sp-core-blue); font-size: 20px; font-weight: 800; }
.sp-topic-hero h1 { margin-bottom: 4px; }
.sp-topic-hero p:not(.sp-eyebrow) { margin-bottom: 0; font-size: 14px; }
.sp-lesson-list { display: grid; gap: 12px; }
.sp-lesson-card { display: flex; align-items: center; gap: 18px; padding: 18px; border: 1px solid var(--sp-core-border); border-radius: 14px; background: var(--sp-core-background); }
.sp-lesson-number { flex: 0 0 58px; color: #4b5870; font-size: 12px; font-weight: 800; }
.sp-lesson-main { min-width: 0; flex: 1; }
.sp-lesson-main h3 { margin: 0 0 4px; font-size: 16px; line-height: 1.4; }
.sp-lesson-main p { margin: 0 0 8px; color: var(--sp-core-muted); font-size: 14px; }
.sp-lesson-meta { display: flex; flex-wrap: wrap; gap: 8px; }
.sp-status,
.sp-free-tag,
.sp-due-tag { display: inline-flex; align-items: center; min-height: 26px; padding: 3px 8px; border-radius: 999px; font-size: 12px; font-weight: 700; }
.sp-status--new { background: #f0f2f5; color: #404855; }
.sp-status--learning { background: var(--sp-learning-gold-soft); color: var(--sp-learning-gold); }
.sp-status--mastered,
.sp-status--strong { background: var(--sp-learning-green-soft); color: var(--sp-learning-green); }
.sp-complete-tag { display: inline-flex; align-items: center; min-height: 26px; padding: 3px 8px; border-radius: 999px; background: var(--sp-learning-green-soft); color: #145a25; font-size: 12px; font-weight: 700; }
.sp-free-tag { background: var(--sp-core-blue-soft); color: #174cae; }
.sp-due-tag { background: var(--sp-learning-gold-soft); color: var(--sp-learning-gold); }
.sp-prerequisite-tag { display: inline-flex; align-items: center; min-height: 26px; padding: 3px 8px; border-radius: 999px; background: #f1edff; color: #51409a; font-size: 12px; font-weight: 700; }

.sp-button { display: inline-flex; align-items: center; justify-content: center; gap: 8px; min-height: 48px; padding: 10px 16px; border: 1px solid transparent; border-radius: 12px; cursor: pointer; font-size: 15px; font-weight: 750; line-height: 1.35; text-align: center; transition: background .15s ease, border-color .15s ease, transform .15s ease; }
.sp-button:hover:not(:disabled) { transform: translateY(-1px); }
.sp-button:disabled { cursor: not-allowed; opacity: .5; }
.sp-button--primary { background: var(--sp-core-blue); color: #fff !important; }
.sp-button--primary:hover:not(:disabled) { background: #124fc3; }
.sp-button--secondary { flex: 0 0 auto; border-color: #a8bbdb; background: #fff; color: #174cae; }
.sp-button--secondary:hover:not(:disabled) { background: var(--sp-core-blue-soft); }
.sp-button--text { min-height: 44px; padding: 8px 10px; border: 0; background: transparent; color: #174cae; text-decoration: underline; text-underline-offset: 3px; }
.sp-text-link,
.sp-back-link { display: inline-flex; align-items: center; min-height: 44px; margin-top: 18px; color: #174cae; font-size: 14px; font-weight: 700; }
.sp-back-link { padding: 0; border: 0; background: transparent; cursor: pointer; }

.sp-shell--learning { max-width: 820px; }
.sp-progress { margin: 0 0 24px; }
.sp-learning-step { padding: 24px; border: 1px solid var(--sp-core-border); border-radius: 18px; background: #fff; }
.sp-learning-step > .sp-eyebrow { margin-bottom: 8px; }
.sp-learning-step h2 { margin: 0 0 14px; font-size: 21px; line-height: 1.45; }
.sp-step-symbol { display: grid; width: 56px; height: 56px; margin-bottom: 18px; place-items: center; border-radius: 16px; background: var(--sp-core-blue-soft); color: var(--sp-core-blue); font-size: 25px; }
.sp-learning-note,
.sp-takeaway { margin: 20px 0; padding: 16px; border: 1px solid #d6e1f2; border-radius: 12px; background: #f7faff; }
.sp-learning-note strong,
.sp-takeaway strong { display: block; margin-bottom: 5px; }
.sp-learning-note p,
.sp-takeaway p { margin: 0; color: var(--sp-core-ink); }
.sp-learning-note small { display: block; margin-top: 8px; color: var(--sp-core-muted); font-size: 13px; line-height: 1.5; }
.sp-word-list { display: grid; gap: 10px; margin: 22px 0; }
.sp-word { display: grid; grid-template-columns: minmax(90px, .75fr) 28px minmax(0, 1.25fr); align-items: center; gap: 12px; min-height: 56px; padding: 10px 14px; border: 1px solid var(--sp-core-border); border-radius: 12px; }
.sp-word strong { color: #174cae; }
.sp-word > span:nth-child(2) { color: var(--sp-core-muted); text-align: center; }
.sp-step-actions { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-top: 24px; }

.sp-video-card { overflow: hidden; border: 1px solid var(--sp-core-border); border-radius: 14px; background: #fff; }
.sp-video-poster { display: grid; width: 100%; min-height: 220px; place-content: center; gap: 8px; border: 0; background: #edf3fb; color: #174cae; cursor: pointer; font-size: 16px; font-weight: 750; }
.sp-video-poster small { color: var(--sp-core-muted); font-size: 13px; font-weight: 500; }
.sp-play-icon { display: grid; width: 56px; height: 56px; margin: 0 auto 4px; place-items: center; border-radius: 50%; background: var(--sp-core-blue); color: #fff; font-size: 21px; }
.sp-video-frame { position: relative; width: 100%; aspect-ratio: 16 / 9; background: #14243e; }
.sp-video-frame iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }
.sp-video-meta { display: grid; gap: 4px; padding: 14px 16px; }
.sp-video-meta strong { font-size: 15px; }
.sp-video-meta span,
.sp-video-meta a { color: var(--sp-core-muted); font-size: 13px; }
.sp-video-meta a { width: fit-content; min-height: 44px; display: inline-flex; align-items: center; color: #174cae; font-weight: 650; }
.sp-video-technical-note { color: var(--sp-core-muted); font-size: 12px; line-height: 1.45; }
.sp-video-fit { margin: 12px 0; padding: 12px 14px; border: 1px solid #d6e1f2; border-radius: 10px; background: #f7faff; color: var(--sp-core-ink); }
.sp-video-fit strong { display: block; margin-bottom: 4px; font-size: 14px; }
.sp-video-fit p { margin: 0; font-size: 14px; line-height: 1.55; }
.sp-video-fit--gap { border-color: #ead7a1; background: #fffaf0; }
.sp-video-error { margin: 12px 0; padding: 12px 14px; border-radius: 10px; background: var(--sp-learning-gold-soft); color: var(--sp-learning-gold); font-size: 14px; }
.sp-video-fallback { margin: 10px 0 0; color: var(--sp-core-muted); font-size: 13px; line-height: 1.5; }
.sp-video-fallback a { color: #174cae; font-weight: 700; text-decoration: underline; text-underline-offset: 2px; }

.sp-question-text { font-size: 18px !important; line-height: 1.6 !important; }
.sp-question-context { margin: 0 0 14px; padding: 14px 16px; border-left: 4px solid #3154dc; border-radius: 0 12px 12px 0; background: #f3f6ff; color: #1f2e4a; font-size: 16px; line-height: 1.6; }
.sp-question-context-translation { margin: -6px 0 16px; color: #3c4b63; font-size: 16px; line-height: 1.6; }
.sp-question-translation { margin: -4px 0 16px; color: #3c4b63; font-size: 16px; line-height: 1.6; }
.sp-question-actions { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 8px; margin: 0 0 14px; }
.sp-question-note { color: var(--sp-core-muted); font-size: 13px; }
.sp-choices { display: grid; gap: 10px; }
.sp-choice { display: flex; align-items: flex-start; gap: 12px; width: 100%; min-height: 56px; padding: 12px; border: 1px solid #cbd5e4; border-radius: 12px; background: #fff; cursor: pointer; text-align: left; }
.sp-choice:hover:not(:disabled) { border-color: #6f96e9; background: var(--sp-core-blue-soft); }
.sp-choice.is-selected { border-color: var(--sp-core-blue); box-shadow: inset 0 0 0 1px var(--sp-core-blue); background: #f3f7ff; }
.sp-choice:disabled { cursor: default; opacity: 1; }
.sp-choice.is-correct { border-color: var(--sp-learning-green); background: var(--sp-learning-green-soft); }
.sp-choice.is-incorrect { border-color: var(--sp-learning-red); background: var(--sp-learning-red-soft); }
.sp-choice-letter { display: grid; width: 30px; height: 30px; flex: 0 0 30px; place-items: center; border-radius: 50%; background: #edf1f7; color: #354154; font-size: 14px; font-weight: 800; }
.sp-choice.is-selected .sp-choice-letter { background: var(--sp-core-blue); color: #fff; }
.sp-choice.is-correct .sp-choice-letter { background: var(--sp-learning-green); color: #fff; }
.sp-choice-copy { display: grid; gap: 5px; min-width: 0; padding-top: 2px; font-size: 16px; line-height: 1.5; }
.sp-choice-translation { color: #3c4b63; }
.sp-choice-state { margin-left: auto; color: var(--sp-learning-green); font-size: 18px; font-weight: 800; }
.sp-choice.is-incorrect .sp-choice-state { color: var(--sp-learning-red); }
.sp-feedback { display: flex; align-items: flex-start; gap: 10px; margin-top: 16px; padding: 14px; border: 1px solid; border-radius: 12px; }
.sp-feedback--success { border-color: #9fcda6; background: var(--sp-learning-green-soft); color: #145a25; }
.sp-feedback--try { border-color: #edb1ad; background: var(--sp-learning-red-soft); color: #7f1d1d; }
.sp-feedback-icon { display: grid; width: 28px; height: 28px; flex: 0 0 28px; place-items: center; border-radius: 50%; background: #fff; font-weight: 800; }
.sp-feedback strong { display: block; margin: 1px 0 4px; font-size: 15px; }
.sp-feedback p { margin: 0; color: var(--sp-core-ink); font-size: 14px; line-height: 1.5; }
.sp-feedback small { display: block; margin-top: 6px; color: var(--sp-core-muted); font-size: 13px; }
.sp-hint { margin-top: 14px; padding: 12px 14px; border-left: 4px solid #805600; border-radius: 0 10px 10px 0; background: var(--sp-learning-gold-soft); }
.sp-hint p { margin: 3px 0 0; color: var(--sp-core-ink); font-size: 14px; }
.sp-result { text-align: center; }
.sp-result .sp-lead { margin-right: auto; margin-left: auto; }
.sp-result-mark { display: grid; width: 64px; height: 64px; margin: 0 auto 18px; place-items: center; border-radius: 50%; background: var(--sp-learning-gold-soft); color: var(--sp-learning-gold); font-size: 30px; font-weight: 800; }
.sp-result-mark.is-success { background: var(--sp-learning-green-soft); color: var(--sp-learning-green); }
.sp-result-score { display: flex; justify-content: center; gap: 48px; margin: 22px 0; }
.sp-result-score strong { font-size: 28px; line-height: 1.2; }
.sp-result-status { color: var(--sp-core-muted); font-size: 14px; }
.sp-result .sp-takeaway { text-align: left; }
.sp-result .sp-step-actions { justify-content: center; }
.sp-result-course { justify-content: center; }
.sp-review-note { color: var(--sp-learning-gold); font-weight: 700; }
.sp-prerequisite-list { display: grid; gap: 10px; margin: 20px 0; }
.sp-prerequisite-link { display: flex; align-items: center; justify-content: space-between; gap: 12px; min-height: 48px; padding: 10px 14px; border: 1px solid var(--sp-core-border); border-radius: 10px; background: #fff; color: #174cae !important; font-size: 15px; font-weight: 700; }
.sp-prerequisite-link:hover { background: var(--sp-core-blue-soft); }

.sp-locked { max-width: 620px; margin: 48px auto; padding: 32px; border: 1px solid var(--sp-core-border); border-radius: 18px; background: var(--sp-core-subtle); text-align: center; }
.sp-locked h1 { margin: 0 0 12px; font-size: 26px; line-height: 1.3; }
.sp-locked p:not(.sp-eyebrow) { margin: 0 auto 22px; color: var(--sp-core-muted); line-height: 1.6; }
.sp-locked-icon { margin-bottom: 16px; font-size: 32px; }
.sp-locked .sp-text-link { display: flex; justify-content: center; }

@media (max-width: 760px) {
  .sp-shell { padding: 16px; }
  .sp-course-hero { padding: 22px; }
  .sp-topic-list { grid-template-columns: 1fr; }
  .sp-lesson-card { align-items: flex-start; flex-wrap: wrap; gap: 10px 14px; }
  .sp-lesson-number { flex-basis: 48px; padding-top: 4px; }
  .sp-lesson-main { flex-basis: calc(100% - 70px); }
  .sp-lesson-card .sp-button { margin-left: 62px; }
  .sp-learning-step { padding: 20px; }
}
@media (max-width: 480px) {
  .sp-shell { padding: 12px; }
  .sp-header { margin-bottom: 16px; }
  .sp-header-tag { font-size: 10px; }
  .sp-course-hero { padding: 18px; border-radius: 16px; }
  .sp-course-stats { gap: 14px 22px; }
  .sp-course-stats strong { font-size: 21px; }
  .sp-section-heading { align-items: flex-start; flex-direction: column; }
  .sp-topic-card { min-height: 78px; padding: 12px; }
  .sp-topic-copy small { font-size: 12px; }
  .sp-topic-hero { align-items: flex-start; gap: 12px; }
  .sp-topic-mark { width: 48px; height: 48px; flex-basis: 48px; border-radius: 14px; font-size: 16px; }
  .sp-lesson-card { padding: 14px; }
  .sp-lesson-main { flex-basis: calc(100% - 62px); }
  .sp-lesson-card .sp-button { width: calc(100% - 62px); margin-left: 62px; }
  .sp-learning-step { padding: 16px; }
  .sp-learning-step h2 { font-size: 18px; }
  .sp-question-text { font-size: 16px !important; line-height: 1.6 !important; }
  .sp-question-actions { align-items: flex-start; flex-direction: column; }
  .sp-choice { gap: 9px; padding: 10px; }
  .sp-choice-copy { font-size: 16px; }
  .sp-word { grid-template-columns: minmax(74px, .75fr) 20px minmax(0, 1.25fr); gap: 8px; padding: 10px; }
  .sp-step-actions { align-items: stretch; flex-direction: column; }
  .sp-step-actions > .sp-button { width: 100%; }
  .sp-video-poster { min-height: 180px; }
  .sp-result-score { gap: 28px; }
  .sp-locked { margin: 24px auto; padding: 22px 16px; }
}
@media (prefers-reduced-motion: reduce) {
  .sp-shell *, .sp-shell *::before, .sp-shell *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; }
}