/*
 * ⚠️ Nav 스타일은 별도 파일 `nav.css`로 분리했습니다.
 *    → index.html에서 `nav.css`를 함께 로드하는지 확인하세요.
 */


/* ============================================
   Card base
   ============================================ */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: var(--space-6);
}
.card--lg { padding: var(--space-8); border-radius: var(--r-xl); }
.card--elevated { box-shadow: var(--shadow-md); border-color: transparent; }
.card--quiet { border-color: transparent; box-shadow: none; background: var(--surface-2); }

/* ============================================
   HERO SECTION
   ============================================ */
.hero {
  position: relative;
  overflow: hidden;
  background: var(--brand-primary-100);
  padding: 48px 0 64px;
}
.hero__grid {
  display: grid;
  grid-template-columns: 1.05fr .95fr;
  gap: 60px;
  align-items: center;
}
.hero__title { margin: 0 0 24px; }
.hero__lead {
  margin: 0 0 40px;
  max-width: 540px;
  font-size: 20px;
}
.hero__actions {
  display: flex;
  gap: 12px;
  align-items: center;
  width: 100%;
}
.hero__lecture-form {
  width: min(100%, 600px);
}
.hero__lecture-input-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 106px;
  gap: 8px;
  height: 66px;
  padding: 6px;
  border: 2px solid #FFD600;
  border-radius: var(--r-pill);
  background: #fff;
  box-shadow: none;
}
.hero__lecture-input {
  width: 100%;
  min-width: 0;
  height: 50px;
  padding: 0 20px;
  border: 0;
  background: transparent;
  color: var(--text-strong);
  font: inherit;
  font-size: 15px;
  font-weight: var(--fw-bold);
  outline: none;
}
.hero__lecture-input::placeholder {
  color: #B7BEC7;
  opacity: 1;
}
.hero__lecture-input-row:focus-within {
  border-color: #FFD600;
  box-shadow: 0 0 0 3px rgba(255, 214, 0, 0.22);
}
.hero__lecture-submit {
  width: 106px;
  height: 50px;
  padding: 0 18px;
  border: 0;
  border-radius: var(--r-pill);
  background: #FFD600;
  color: var(--brand-navy-900);
  font: inherit;
  font-size: 15px;
  font-weight: var(--fw-heavy);
  cursor: pointer;
}
.hero__lecture-submit:hover {
  background: #F2CB00;
}
.hero__lecture-submit:focus-visible {
  outline: 3px solid var(--brand-primary-300);
  outline-offset: 2px;
}
.hero__lecture-submit:disabled {
  cursor: wait;
  opacity: 0.68;
}
.hero__lecture-error {
  min-height: 22px;
  margin: var(--space-2) 0 0;
  color: #b42318;
  font-size: 14px;
  font-weight: var(--fw-semibold);
}

/* Right visual */
.hero__visual {
  position: relative;
  height: 420px;
}
.hero__mascot {
  position: absolute;
  right: -20px;
  bottom: 0;
  width: 420px;
  height: auto;
  filter: drop-shadow(0 30px 40px rgba(31, 138, 217, .18));
}

/* Bottom tags */
.hero__tags {
  margin-top: 32px;
  display: flex;
  gap: 12px;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
}
.hero__tags-label {
  font-size: 15px;
  font-weight: var(--fw-bold);
  color: var(--text-secondary);
  margin-right: 12px;
}
.hero__tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 9px 16px;
  border-radius: var(--r-pill);
  font-weight: var(--fw-heavy);
  font-size: 15px;
  border: 1.5px solid transparent;
}
.hero__tag--yellow {
  background: var(--brand-accent-100);
  color: var(--brand-accent-700);
  border-color: rgba(122, 90, 0, 0.13);
}
.hero__tag--blue {
  background: var(--brand-primary-100);
  color: var(--brand-primary-500);
  border-color: rgba(31, 138, 217, 0.13);
}
.hero__tag-hash {
  font-family: var(--font-mono);
  font-weight: var(--fw-heavy);
  opacity: 0.65;
}

/* ============================================
   PROBLEMS SECTION
   ============================================ */
.problems {
  padding: var(--space-32) 0;
  background: var(--surface);
}
.problems__header { text-align: center; margin-bottom: 72px; }
.problems__eyebrow {
  display: inline-block;
  font-size: 16px;
  font-weight: var(--fw-bold);
  color: var(--brand-primary-500);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  margin-bottom: 16px;
}
.problems__grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}
.problems__card {
  padding: 32px;
  border-radius: var(--r-xl);
  display: flex;
  flex-direction: column;
  gap: 14px;
  background: var(--bg);
}
.problems__card--highlight { background: var(--brand-accent-100); }
.problems__emoji { font-size: 48px; line-height: 1; }
.problems__title {
  font-size: 20px;
  font-weight: var(--fw-heavy);
  line-height: 1.35;
  letter-spacing: var(--tracking-normal);
  color: var(--text-strong);
}
.problems__body {
  font-size: 15px;
  color: var(--text-secondary);
  line-height: 1.65;
}

/* ============================================
   VALUE SECTION (Knowledge State Estimator)
   ============================================ */
.value {
  padding: var(--space-32) 0;
  background: var(--bg);
}
.value__header { text-align: center; margin-bottom: 72px; }
.value__eyebrow {
  display: inline-block;
  font-size: 16px;
  font-weight: var(--fw-bold);
  color: var(--brand-primary-500);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  margin-bottom: 16px;
}
.value__title { text-align: center; }
.value__title-accent { color: var(--brand-primary-500); }
.value__grid {
  display: grid;
  grid-template-columns: 1.15fr 1fr;
  gap: 24px;
}

/* Estimator diagram card */
.estimator {
  background: linear-gradient(180deg, #fff 0%, var(--brand-primary-50) 100%);
  border: 1px solid var(--border);
  border-radius: var(--r-xl);
  padding: 36px;
  position: relative;
  overflow: hidden;
}
.estimator__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 24px;
  gap: 12px;
  flex-wrap: wrap;
}
.estimator__label {
  font-size: 15px;
  font-weight: var(--fw-heavy);
  color: var(--brand-primary-500);
  text-transform: uppercase;
  letter-spacing: var(--tracking-wide);
}
.estimator__live {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: var(--fw-bold);
  color: var(--text-secondary);
  padding: 6px 14px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--r-pill);
}
.estimator__live-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--brand-primary-500);
  animation: pulse 1.6s ease-in-out infinite;
}
@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50%      { opacity: .4; transform: scale(1.5); }
}
.estimator__diagram { width: 100%; height: auto; }
.estimator__callout {
  font-size: 15px;
  color: var(--text-secondary);
  margin-top: 24px;
  line-height: 1.7;
  padding: 18px 20px;
  background: #fff;
  border-radius: var(--r-md);
  border: 1px solid var(--border);
  text-wrap: pretty;
  word-break: keep-all;
}

/* Right — 3 differentiator cards */
.value__cards {
  display: flex;
  flex-direction: column;
  gap: 16px;
}
.value-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--r-xl);
  padding: 26px 28px 26px 32px;
  display: flex;
  gap: 22px;
  position: relative;
  overflow: hidden;
}
.value-card__accent {
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 6px;
}
.value-card__accent--yellow { background: var(--brand-accent-500); }
.value-card__accent--blue   { background: var(--brand-primary-500); }
.value-card__icon {
  font-size: 38px;
  width: 68px;
  height: 68px;
  border-radius: 18px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}
.value-card__icon--yellow { background: var(--brand-accent-100); }
.value-card__icon--blue   { background: var(--brand-primary-100); }
.value-card__body { flex: 1; min-width: 0; }
.value-card__meta {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 8px;
  flex-wrap: wrap;
}
.value-card__num {
  font-size: 14px;
  font-weight: var(--fw-heavy);
  letter-spacing: var(--tracking-wide);
}
.value-card__num--yellow { color: var(--brand-accent-700); }
.value-card__num--blue   { color: var(--brand-primary-500); }
.value-card__title {
  font-size: 22px;
  font-weight: var(--fw-heavy);
  margin-bottom: 10px;
  line-height: 1.3;
  letter-spacing: var(--tracking-normal);
  text-wrap: balance;
}
.value-card__desc {
  font-size: 15px;
  color: var(--text-secondary);
  line-height: 1.65;
  text-wrap: pretty;
  word-break: keep-all;
}

/* ============================================
   COMPARISON SECTION
   ============================================ */
.compare {
  padding: var(--space-32) 0;
  background: var(--surface);
}
.compare__header { text-align: center; margin-bottom: 64px; }
.compare__eyebrow {
  display: inline-block;
  font-size: 16px;
  font-weight: var(--fw-bold);
  color: var(--brand-primary-500);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  margin-bottom: 16px;
}
.compare__sub {
  font-size: 18px;
  color: var(--text-secondary);
  margin-top: 18px;
  max-width: 620px;
  margin-left: auto;
  margin-right: auto;
  line-height: 1.6;
}

.compare__table {
  max-width: 1080px;
  margin: 0 auto;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--r-2xl);
  overflow: hidden;
  box-shadow: 0 20px 40px rgba(11, 27, 52, 0.06);
}
.compare__thead,
.compare__row {
  display: grid;
  grid-template-columns: 210px 1fr 1.15fr;
}
.compare__thead {
  background: var(--brand-navy-900);
}
.compare__th {
  padding: 24px 28px;
}
.compare__th--label {
  font-size: 13px;
  font-weight: var(--fw-heavy);
  color: rgba(255, 255, 255, 0.5);
  text-transform: uppercase;
  letter-spacing: var(--tracking-wide);
}
.compare__th--old {
  border-left: 1px solid rgba(255, 255, 255, 0.08);
  color: var(--brand-navy-300);
}
.compare__th--gp {
  border-left: 2px solid var(--brand-accent-500);
  background: linear-gradient(180deg, rgba(255, 206, 31, 0.15) 0%, transparent 100%);
  color: #fff;
  position: relative;
}
.compare__th-eyebrow {
  font-size: 13px;
  font-weight: var(--fw-bold);
  opacity: 0.5;
  text-transform: uppercase;
  letter-spacing: var(--tracking-wide);
  margin-bottom: 6px;
}
.compare__th--gp .compare__th-eyebrow { opacity: 0.7; color: var(--brand-accent-500); }
.compare__th-name {
  font-size: 20px;
  font-weight: var(--fw-heavy);
  display: flex;
  align-items: center;
  gap: 10px;
}
.compare__th--gp .compare__th-name { height: 26px; }
.compare__reco-tag {
  position: absolute;
  top: -1px;
  right: 24px;
  padding: 4px 12px;
  background: var(--brand-accent-500);
  color: var(--brand-navy-900);
  font-size: 12px;
  font-weight: var(--fw-heavy);
  border-radius: 0 0 var(--r-sm) var(--r-sm);
}

.compare__row {
  border-top: 1px solid var(--divider);
  background: #fff;
}
.compare__row--hot {
  background: linear-gradient(90deg, #fff 0%, #fff 50%, #FFF9E0 100%);
}
.compare__cell {
  padding: 22px 28px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.compare__cell--topic {
  font-size: 16px;
  font-weight: var(--fw-bold);
  color: var(--text-strong);
}
.compare__cell--old {
  border-left: 1px solid var(--divider);
  font-size: 16px;
  color: var(--brand-navy-300);
}
.compare__cell--old.line-through { text-decoration: line-through; }
.compare__cell--gp {
  border-left: 1px solid var(--brand-accent-200);
  background: linear-gradient(90deg, var(--brand-primary-50) 0%, #fff 100%);
  font-size: 17px;
  font-weight: var(--fw-bold);
  color: var(--text-strong);
  gap: 12px;
  position: relative;
}
.compare__row--hot .compare__cell--gp {
  border-left: 2px solid var(--brand-accent-500);
  background: #FFF9E0;
  font-weight: var(--fw-heavy);
}
.compare__x-badge, .compare__check-badge {
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-weight: var(--fw-black);
  flex-shrink: 0;
}
.compare__x-badge {
  width: 24px;
  height: 24px;
  background: var(--divider);
  color: var(--brand-navy-300);
  font-size: 14px;
}
.compare__check-badge {
  width: 28px;
  height: 28px;
  background: var(--brand-primary-500);
  color: #fff;
  font-size: 15px;
  box-shadow: 0 4px 12px rgba(31, 138, 217, 0.3);
}
.compare__row--hot .compare__check-badge {
  background: var(--brand-accent-500);
  color: var(--brand-navy-900);
  box-shadow: 0 4px 12px rgba(255, 206, 31, 0.5);
}
.compare__key-diff {
  padding: 4px 10px;
  background: var(--brand-navy-900);
  color: var(--brand-accent-500);
  font-size: 11px;
  font-weight: var(--fw-heavy);
  border-radius: var(--r-pill);
  letter-spacing: 0.04em;
}
.compare__cell-content { flex: 1; }

/* ============================================
   HOW SECTION (4 engines)
   ============================================ */
.how {
  padding: var(--space-32) 0;
  background: linear-gradient(180deg, var(--bg) 0%, var(--brand-primary-100) 100%);
}
.how__header { text-align: center; margin-bottom: 24px; }
.how__eyebrow {
  display: inline-block;
  font-size: 16px;
  font-weight: var(--fw-bold);
  color: var(--brand-primary-500);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  margin-bottom: 18px;
}
.how__title {
  font-size: 56px;
  font-weight: var(--fw-black);
  line-height: 1.1;
  letter-spacing: var(--tracking-tight);
  text-wrap: balance;
  color: var(--text-strong);
  margin: 0;
}

/* PEDAGOGY × AI bridge */
.bridge {
  max-width: 820px;
  margin: 44px auto 56px;
  padding: 18px 28px;
  background: #fff;
  border: 1.5px solid var(--border);
  border-radius: var(--r-xl);
  box-shadow: 0 12px 32px rgba(11, 27, 52, 0.08);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 22px;
  flex-wrap: wrap;
}
.bridge__chip {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 10px 18px;
  border-radius: var(--r-md);
  border: 1.5px solid;
}
.bridge__chip--pedagogy {
  background: var(--brand-accent-100);
  border-color: var(--brand-accent-500);
}
.bridge__chip--ai {
  background: var(--brand-primary-100);
  border-color: var(--brand-primary-500);
}
.bridge__chip-icon { font-size: 20px; }
.bridge__chip-body { text-align: left; line-height: 1.15; }
.bridge__chip-sub {
  font-size: 11px;
  font-weight: var(--fw-heavy);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.bridge__chip--pedagogy .bridge__chip-sub { color: var(--brand-accent-700); }
.bridge__chip--ai .bridge__chip-sub { color: var(--brand-primary-700); }
.bridge__chip-main {
  font-size: 17px;
  font-weight: var(--fw-black);
  color: var(--text-strong);
  letter-spacing: var(--tracking-normal);
}
.bridge__divider {
  font-size: 26px;
  font-weight: var(--fw-black);
  color: var(--text-strong);
  font-family: var(--font-mono);
  opacity: 0.35;
}

/* Engine cards */
.how__grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 22px;
}
.engine-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--r-xl);
  padding: 36px;
  position: relative;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  gap: 22px;
  min-height: 380px;
}
.engine-card__watermark {
  position: absolute;
  top: -34px;
  right: -20px;
  font-size: 150px;
  font-weight: var(--fw-black);
  color: var(--brand-primary-50);
  line-height: 1;
  letter-spacing: 0;
  pointer-events: none;
}
.engine-card__head {
  display: flex;
  align-items: center;
  gap: 16px;
  position: relative;
}
.engine-card__icon {
  width: 64px;
  height: 64px;
  border-radius: 18px;
  background: linear-gradient(135deg, var(--brand-accent-100) 0%, var(--brand-accent-400) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 34px;
  box-shadow: 0 8px 20px rgba(255, 206, 31, 0.3);
}
.engine-card__label {
  font-size: 15px;
  font-weight: var(--fw-heavy);
  color: var(--brand-primary-500);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.engine-card__catch {
  font-size: 26px;
  font-weight: var(--fw-heavy);
  line-height: 1.3;
  color: var(--text-strong);
  white-space: pre-line;
  margin-bottom: 14px;
  letter-spacing: var(--tracking-snug);
  text-wrap: balance;
}
.engine-card__value {
  font-size: 15.5px;
  color: var(--text-secondary);
  line-height: 1.65;
  text-wrap: pretty;
  word-break: keep-all;
}

.engine-card__pedagogy {
  margin-top: auto;
  padding: 14px 18px;
  background: var(--brand-accent-100);
  border-radius: var(--r-md);
  border: 1.5px solid var(--brand-accent-200);
  display: flex;
  align-items: center;
  gap: 12px;
}
.engine-card__pedagogy-tag {
  font-size: 11px;
  font-weight: var(--fw-black);
  color: var(--brand-accent-700);
  background: var(--brand-accent-500);
  padding: 5px 10px;
  border-radius: var(--r-xs);
  letter-spacing: 0.08em;
  flex-shrink: 0;
}
.engine-card__pedagogy-text {
  font-size: 14.5px;
  font-weight: var(--fw-bold);
  color: var(--text-strong);
  line-height: 1.4;
}

.engine-card__ai {
  padding: 14px 18px;
  background: var(--brand-primary-100);
  border-radius: var(--r-md);
  border: 1.5px solid var(--brand-primary-200);
}
.engine-card__ai-row {
  display: flex;
  align-items: flex-start;
  gap: 12px;
}
.engine-card__ai-tag {
  font-size: 11px;
  font-weight: var(--fw-black);
  color: #fff;
  background: var(--brand-primary-500);
  padding: 5px 10px;
  border-radius: var(--r-xs);
  letter-spacing: 0.08em;
  flex-shrink: 0;
  margin-top: 2px;
}
.engine-card__ai-chips {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}
.engine-card__ai-chip {
  padding: 6px 12px;
  background: #fff;
  border-radius: var(--r-pill);
  font-size: 12.5px;
  color: var(--brand-primary-700);
  font-weight: var(--fw-bold);
  border: 1px solid var(--brand-primary-200);
}

/* ============================================
   PRODUCT SECTION (3 steps)
   ============================================ */
.product {
  padding: var(--space-32) 0;
  background: var(--surface);
}
.product__header { text-align: center; margin-bottom: 28px; }
.product__eyebrow {
  display: inline-block;
  font-size: 16px;
  font-weight: var(--fw-bold);
  color: var(--brand-primary-500);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  margin-bottom: 16px;
}
.product__sub {
  font-size: 18px;
  color: var(--text-secondary);
  margin-top: 18px;
  max-width: 620px;
  margin-left: auto;
  margin-right: auto;
  line-height: 1.6;
}

.step-indicator {
  max-width: 820px;
  margin: 0 auto 88px;
  display: flex;
  align-items: center;
  gap: 14px;
  justify-content: center;
}
.step-indicator__chip {
  flex: 1;
  padding: 16px 20px;
  border-radius: var(--r-lg);
  display: flex;
  align-items: center;
  gap: 12px;
  background: var(--brand-primary-50);
  color: var(--text-strong);
}
.step-indicator__chip--active {
  background: var(--brand-primary-500);
  color: #fff;
}
.step-indicator__num {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: #fff;
  color: var(--text-strong);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: var(--fw-black);
  font-size: 17px;
  flex-shrink: 0;
}
.step-indicator__chip--active .step-indicator__num {
  background: var(--brand-accent-500);
}
.step-indicator__label {
  font-size: 17px;
  font-weight: var(--fw-heavy);
  letter-spacing: 0;
}
.step-indicator__desc {
  font-size: 13px;
  opacity: 0.75;
  margin-top: 2px;
}
.step-indicator__arrow {
  color: var(--border-strong);
  font-size: 22px;
  font-weight: var(--fw-black);
}

.step-block {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: center;
  margin-bottom: 128px;
}
.step-block:last-child { margin-bottom: 0; }
.step-badge {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 8px 16px;
  border-radius: var(--r-pill);
  font-size: 14px;
  font-weight: var(--fw-heavy);
  letter-spacing: var(--tracking-wide);
  margin-bottom: 20px;
}
.step-badge--blue {
  background: var(--brand-primary-100);
  color: var(--brand-primary-700);
}
.step-badge--yellow {
  background: var(--brand-accent-100);
  color: var(--brand-accent-700);
}
.step-badge__num {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  font-weight: var(--fw-black);
}
.step-badge--blue .step-badge__num { background: var(--brand-primary-500); color: #fff; }
.step-badge--yellow .step-badge__num { background: var(--brand-accent-500); color: var(--brand-navy-900); }
.step-block__title {
  margin: 0 0 20px;
  font-size: 40px;
  font-weight: var(--fw-black);
  line-height: 1.2;
  letter-spacing: var(--tracking-snug);
  color: var(--text-strong);
}
.step-block__title-accent { color: var(--brand-primary-500); }
.step-block__body {
  font-size: 18px;
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: 28px;
  text-wrap: pretty;
  word-break: keep-all;
}
.step-feature-list { display: grid; gap: 12px; }
.step-feature {
  display: flex;
  gap: 14px;
  align-items: center;
  padding: 14px 18px;
  border-radius: var(--r-md);
}
.step-feature--blue { background: var(--brand-primary-50); }
.step-feature--yellow {
  background: #FFF9E0;
  border: 1px solid var(--brand-accent-200);
  align-items: flex-start;
}
.step-feature__icon { font-size: 22px; }
.step-feature--yellow .step-feature__icon { margin-top: 2px; }
.step-feature__title {
  font-size: 16px;
  font-weight: var(--fw-heavy);
  color: var(--text-strong);
}
.step-feature__sub {
  font-size: 13px;
  color: var(--brand-accent-700);
  margin-top: 3px;
}
.step-feature__body { flex: 1; }

.step-mock {
  padding: 24px;
  background: var(--bg);
  border-radius: 22px;
}

/* Step 1 · lecture mock */
.mock-lecture__video {
  background: var(--brand-navy-900);
  border-radius: 14px;
  aspect-ratio: 16/10;
  display: flex;
  align-items: center;
  justify-content: center;
  color: rgba(255, 255, 255, 0.5);
  font-size: 13px;
  position: relative;
  overflow: hidden;
  font-weight: var(--fw-medium);
}
.mock-lecture__video-progress {
  position: absolute;
  bottom: 14px;
  left: 14px;
  right: 14px;
  height: 5px;
  background: rgba(255, 255, 255, 0.2);
  border-radius: var(--r-pill);
}
.mock-lecture__video-progress-fill {
  width: 73%;
  height: 100%;
  background: var(--brand-accent-500);
  border-radius: var(--r-pill);
}
.mock-lecture__chat {
  margin-top: 18px;
  padding: 18px;
  background: #fff;
  border-radius: 14px;
  border: 1px solid var(--border);
}
.mock-lecture__chat-row { display: flex; gap: 12px; align-items: flex-start; }
.mock-avatar {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--brand-accent-100);
  overflow: hidden;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  flex-shrink: 0;
}
.mock-avatar img {
  width: 48px;
  margin-top: -2px;
  height: auto;
}
.mock-lecture__meta {
  font-size: 12.5px;
  font-weight: var(--fw-heavy);
  color: var(--text-secondary);
  margin-bottom: 6px;
}
.mock-lecture__bubble {
  font-size: 14.5px;
  background: var(--brand-accent-100);
  padding: 12px 14px;
  border-radius: 4px 12px 12px 12px;
  line-height: 1.55;
}
.mock-lecture__actions {
  display: flex;
  gap: 10px;
  margin-top: 12px;
}

/* Step 2 · quiz mock */
.mock-quiz {
  background: #fff;
  border-radius: 14px;
  padding: 24px;
  border: 1px solid var(--border);
}
.mock-quiz__head {
  display: flex;
  justify-content: space-between;
  margin-bottom: 18px;
}
.mock-quiz__badge {
  display: inline-flex;
  align-items: center;
  background: var(--brand-navy-900);
  color: #fff;
  height: 28px;
  padding: 0 12px;
  border-radius: var(--r-pill);
  font-size: 12.5px;
  font-weight: var(--fw-bold);
}
.mock-quiz__time {
  font-size: 13px;
  color: var(--text-secondary);
  font-weight: var(--fw-semibold);
}
.mock-quiz__question {
  font-size: 16px;
  font-weight: var(--fw-heavy);
  margin-bottom: 14px;
  color: var(--text-strong);
}
.mock-quiz__source {
  padding: 14px;
  background: var(--bg);
  border-radius: 10px;
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 14px;
  font-family: serif;
  line-height: 1.55;
}
.mock-quiz__options { display: flex; flex-direction: column; gap: 8px; margin-bottom: 14px; }
.mock-quiz__option {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  font-size: 14px;
  font-weight: var(--fw-medium);
}
.mock-quiz__option--active {
  border-color: var(--brand-primary-400);
  background: var(--brand-primary-100);
  font-weight: var(--fw-bold);
  color: var(--text-strong);
}
.mock-quiz__radio {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  border: 2px solid var(--border-strong);
  background: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
}
.mock-quiz__option--active .mock-quiz__radio {
  border-color: var(--brand-primary-400);
  background: var(--brand-primary-400);
}
.mock-quiz__radio-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: #fff;
}
.mock-quiz__confidence {
  padding: 14px;
  background: var(--brand-primary-50);
  border-radius: var(--r-md);
}
.mock-quiz__confidence-label {
  font-size: 12.5px;
  font-weight: var(--fw-heavy);
  color: var(--text-secondary);
  margin-bottom: 8px;
}
.mock-quiz__confidence-row { display: flex; gap: 6px; }
.mock-quiz__confidence-btn {
  flex: 1;
  padding: 8px 6px;
  border-radius: var(--r-sm);
  background: #fff;
  color: var(--text-secondary);
  font-size: 12px;
  text-align: center;
  font-weight: var(--fw-bold);
  border: 1px solid var(--border-strong);
  cursor: pointer;
  font-family: inherit;
}
.mock-quiz__confidence-btn--active {
  background: var(--brand-primary-500);
  color: #fff;
}

/* Step 2 · signals list */
.signal-box {
  display: grid;
  gap: 10px;
  padding: 20px;
  background: var(--brand-primary-50);
  border-radius: var(--r-lg);
}
.signal-box__title {
  font-size: 13px;
  font-weight: var(--fw-heavy);
  color: var(--text-secondary);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 4px;
}
.signal-row {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  background: #fff;
  border-radius: var(--r-md);
  border: 1px solid var(--border);
}
.signal-row__circle {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  color: #fff;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  font-weight: var(--fw-heavy);
  flex-shrink: 0;
}
.signal-row__label {
  font-size: 15px;
  font-weight: var(--fw-heavy);
  color: var(--text-strong);
  flex: 1;
}
.signal-row__sub {
  font-size: 12.5px;
  color: var(--text-secondary);
  font-weight: var(--fw-semibold);
}

/* Step 3 · coverage map */
.mock-coverage {
  background: #fff;
  border-radius: 14px;
  padding: 24px;
  border: 1px solid var(--border);
}
.mock-coverage__head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 18px;
}
.mock-coverage__eyebrow {
  font-size: 12.5px;
  font-weight: var(--fw-heavy);
  color: var(--text-secondary);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
}
.mock-coverage__title {
  font-size: 22px;
  font-weight: var(--fw-black);
  margin-top: 4px;
  color: var(--text-strong);
  letter-spacing: var(--tracking-normal);
}
.mock-coverage__big {
  font-size: 32px;
  font-weight: var(--fw-black);
  color: var(--brand-primary-500);
  line-height: 1;
  letter-spacing: var(--tracking-snug);
}
.mock-coverage__big-unit {
  font-size: 16px;
  color: var(--brand-navy-300);
}
.mock-coverage__big-sub {
  font-size: 11px;
  color: var(--text-secondary);
  font-weight: var(--fw-bold);
  margin-top: 2px;
}
.mock-coverage__heatmap {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 4px;
  margin-bottom: 16px;
}
.mock-coverage__cell {
  aspect-ratio: 1;
  border-radius: 3px;
}
.mock-coverage__cell--s0 { background: var(--divider); }
.mock-coverage__cell--s1 { background: var(--brand-primary-200); }
.mock-coverage__cell--s2 { background: var(--brand-primary-400); }
.mock-coverage__cell--s3 {
  background: var(--brand-accent-500);
  box-shadow: 0 0 0 1px var(--warn-500);
}
.mock-coverage__legend {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}
.mock-coverage__legend-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  font-weight: var(--fw-bold);
  color: var(--text-secondary);
}
.mock-coverage__swatch { width: 12px; height: 12px; border-radius: 3px; }
.mock-coverage__section-bars {
  padding: 14px;
  background: var(--surface-2);
  border-radius: 10px;
  display: grid;
  gap: 8px;
}
.section-bar {
  display: flex;
  align-items: center;
  gap: 10px;
}
.section-bar__label {
  font-size: 12px;
  font-weight: var(--fw-bold);
  min-width: 92px;
}
.section-bar__track {
  flex: 1;
  height: 6px;
  background: var(--divider);
  border-radius: var(--r-pill);
  overflow: hidden;
}
.section-bar__fill {
  height: 100%;
  border-radius: var(--r-pill);
}
.section-bar__pct {
  font-size: 12px;
  font-weight: var(--fw-heavy);
  color: var(--text-strong);
  min-width: 34px;
  text-align: right;
}

/* ============================================
   FINAL CTA SECTION
   ============================================ */
.final-cta {
  padding: var(--space-32) 0;
  background: var(--brand-navy-900);
  color: #fff;
  position: relative;
  overflow: hidden;
}
.final-cta::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at 30% 40%, rgba(47, 161, 235, 0.15) 0%, transparent 50%);
}
.final-cta__inner {
  position: relative;
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 60px;
  align-items: center;
}
.final-cta__title {
  font-size: 60px;
  font-weight: var(--fw-heavy);
  color: #fff;
  margin: 0 0 28px;
  line-height: 1.05;
  letter-spacing: var(--tracking-tight);
}
.final-cta__body {
  font-size: 20px;
  color: rgba(255, 255, 255, 0.75);
  margin-bottom: 40px;
  line-height: 1.6;
  max-width: 540px;
}
.final-cta__visual {
  position: relative;
  height: 320px;
  display: flex;
  align-items: flex-end;
  justify-content: center;
}
.final-cta__visual img {
  width: 440px;
  height: auto;
  filter: drop-shadow(0 30px 40px rgba(0, 0, 0, 0.3));
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
  background: var(--brand-navy-900);
  color: rgba(255, 255, 255, 0.7);
  padding: 48px 0 32px;
}
.footer__top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 48px;
  margin-bottom: 32px;
}
.footer__brand-name {
  color: var(--brand-accent-500);
  font-weight: var(--fw-heavy);
  font-size: 17px;
  margin-bottom: 12px;
}
.footer__brand-info {
  font-size: 13px;
  line-height: 1.85;
  max-width: 460px;
}
.footer__copyright {
  font-size: 12px;
  margin-top: 16px;
  color: rgba(255, 255, 255, 0.4);
}
.footer__cols {
  display: flex;
  flex-direction: column;
  gap: 20px;
  font-size: 13px;
}
.footer__col-title {
  color: #fff;
  font-weight: var(--fw-bold);
  margin-bottom: 10px;
}
.footer__col-links {
  display: grid;
  gap: 6px;
}
.footer__link {
  color: inherit;
  text-decoration: none;
}
.footer__link:hover { color: #fff; }
.footer__disclaimer {
  font-size: 11px;
  color: rgba(255, 255, 255, 0.4);
  padding-top: 20px;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  line-height: 1.7;
}

/* ============================================
   LECTURE START MODAL
   ============================================ */
body.lecture-start-modal-open {
  overflow: hidden;
}

.lecture-start-modal {
  position: fixed;
  inset: 0;
  z-index: 1000;
  display: none;
  align-items: center;
  justify-content: center;
  padding: var(--space-6);
}

.lecture-start-modal.is-active {
  display: flex;
}

.lecture-start-modal__backdrop {
  position: absolute;
  inset: 0;
  background: rgba(11, 27, 52, 0.64);
}

.lecture-start-modal__dialog {
  position: relative;
  width: min(100%, 680px);
  padding: var(--space-10);
  border: 1px solid var(--border);
  border-radius: var(--r-xl);
  background: #fff;
  box-shadow: var(--shadow-lg);
}

.lecture-start-modal__close {
  position: absolute;
  top: var(--space-4);
  right: var(--space-4);
  width: 44px;
  height: 44px;
  padding: 0;
  border: 0;
  border-radius: 50%;
  background: var(--brand-primary-50);
  color: var(--text-strong);
  font-size: 28px;
  line-height: 1;
  cursor: pointer;
}

.lecture-start-modal__eyebrow {
  display: inline-block;
  margin-bottom: var(--space-3);
  color: var(--brand-primary-500);
  font-size: 14px;
  font-weight: var(--fw-heavy);
}

.lecture-start-modal__title {
  max-width: calc(100% - 52px);
  margin: 0 0 var(--space-3);
  color: var(--text-strong);
  font-size: 30px;
  line-height: 1.3;
}

.lecture-start-modal__description {
  margin: 0 0 var(--space-6);
  color: var(--text-secondary);
  font-size: 16px;
}

.lecture-start-modal__label {
  display: block;
  margin-bottom: var(--space-2);
  color: var(--text-strong);
  font-size: 14px;
  font-weight: var(--fw-bold);
}

.lecture-start-modal__input-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: var(--space-3);
}

.lecture-start-modal__input {
  width: 100%;
  min-width: 0;
  height: 54px;
  padding: 0 var(--space-4);
  border: 1px solid var(--border-strong);
  border-radius: 14px;
  color: var(--text-strong);
  font: inherit;
  outline: none;
}

.lecture-start-modal__input:focus {
  border-color: var(--brand-primary-500);
  box-shadow: 0 0 0 3px var(--brand-primary-100);
}

.lecture-start-modal__error {
  min-height: 22px;
  margin: var(--space-2) 0 0;
  color: #b42318;
  font-size: 14px;
  font-weight: var(--fw-semibold);
}

/* ============================================
   Responsive (basic — Landing is desktop-first 1440)
   ============================================ */
@media (max-width: 1024px) {
  .hero__grid,
  .value__grid,
  .final-cta__inner,
  .step-block { grid-template-columns: 1fr; gap: 40px; }
  .problems__grid { grid-template-columns: repeat(2, 1fr); }
  .how__grid { grid-template-columns: 1fr; }
  .compare__thead, .compare__row { grid-template-columns: 140px 1fr 1fr; }

  .hero,
  .problems,
  .value,
  .compare,
  .how,
  .product,
  .final-cta {
    padding-top: var(--space-24);
    padding-bottom: var(--space-24);
  }

  .hero__visual {
    width: min(100%, 680px);
    margin: 0 auto;
  }

  .step-block {
    margin-bottom: var(--space-24);
  }

  .step-indicator {
    margin-bottom: var(--space-16);
  }

  .final-cta__visual {
    height: 280px;
  }
}

@media (max-width: 768px) {
  .t-display {
    font-size: 42px;
  }

  .t-h1,
  .how__title {
    font-size: 36px;
  }

  .hero,
  .problems,
  .value,
  .compare,
  .how,
  .product,
  .final-cta {
    padding-top: var(--space-20);
    padding-bottom: var(--space-20);
  }

  .hero__lead,
  .step-block__body,
  .product__sub,
  .compare__sub {
    font-size: 17px;
  }

  .hero__actions,
  .hero__actions .btn,
  .final-cta .btn {
    width: 100%;
  }

  .hero__lecture-form {
    width: 100%;
  }

  .hero__lecture-input-row {
    grid-template-columns: minmax(0, 1fr) 96px;
  }

  .hero__lecture-input {
    padding: 0 12px;
    font-size: 14px;
  }

  .hero__lecture-submit {
    width: 96px;
    padding: 0 12px;
  }

  .hero__visual {
    height: auto;
  }

  .hero__mascot {
    position: relative;
    right: auto;
    bottom: auto;
    width: min(100%, 420px);
    margin: 0 auto;
  }

  .hero__tags {
    margin-top: var(--space-12);
  }

  .problems__header,
  .value__header,
  .compare__header {
    margin-bottom: var(--space-12);
  }

  .value-card,
  .engine-card,
  .estimator {
    padding: var(--space-6);
  }

  .engine-card {
    min-height: 0;
  }

  .compare__table {
    max-width: 100%;
    overflow-x: auto;
  }

  .compare__thead,
  .compare__row {
    min-width: 720px;
  }

  .step-indicator {
    flex-direction: column;
    align-items: stretch;
  }

  .step-indicator__chip {
    width: 100%;
  }

  .step-indicator__arrow {
    align-self: center;
    transform: rotate(90deg);
  }

  .step-block__title {
    font-size: 32px;
  }

  .step-mock,
  .mock-quiz,
  .mock-coverage {
    padding: var(--space-4);
  }

  .mock-quiz__confidence-row {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .final-cta__title {
    font-size: 42px;
  }

  .final-cta__body {
    font-size: 18px;
  }

  .final-cta__visual {
    height: 220px;
  }

  .final-cta__visual img {
    width: min(100%, 360px);
  }

  .landing-shell > .footer {
    min-height: 0;
  }

  .landing-shell > .footer .footer-inner {
    min-height: 0;
    height: auto;
  }
}

@media (max-width: 560px) {
  .t-display {
    font-size: 36px;
  }

  .t-h1,
  .how__title {
    font-size: 31px;
  }

  .hero {
    padding-top: var(--space-10);
    padding-bottom: var(--space-12);
  }

  .hero__grid {
    gap: var(--space-6);
  }

  .hero__lead br,
  .final-cta__title br,
  .step-block__title br {
    display: none;
  }

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

  .hero__visual {
    display: block;
    height: 210px;
  }

  .hero__mascot {
    position: absolute;
    left: 0;
    bottom: 0;
    width: 220px;
    margin: 0;
  }

  .hero__tags {
    flex-wrap: nowrap;
    justify-content: flex-start;
    margin-top: var(--space-5);
    padding-bottom: var(--space-1);
    overflow-x: auto;
  }

  .hero__tags-label {
    display: none;
  }

  .hero__tag {
    flex-shrink: 0;
  }

  .problems__card,
  .value-card,
  .engine-card,
  .estimator {
    padding: var(--space-5);
  }

  .value-card {
    gap: var(--space-3);
  }

  .value-card__icon {
    width: 52px;
    height: 52px;
    font-size: 28px;
    border-radius: var(--r-md);
  }

  .engine-card__head,
  .engine-card__pedagogy,
  .engine-card__ai-row,
  .signal-row {
    align-items: flex-start;
  }

  .engine-card__pedagogy,
  .engine-card__ai-row,
  .signal-row {
    flex-wrap: wrap;
  }

  .signal-row__sub {
    width: 100%;
    padding-left: 38px;
  }

  .mock-lecture__actions {
    flex-wrap: wrap;
  }

  .mock-coverage__head {
    align-items: flex-start;
    gap: var(--space-3);
  }

  .mock-coverage__title {
    font-size: 18px;
  }

  .mock-coverage__heatmap {
    grid-template-columns: repeat(8, 1fr);
  }

  .section-bar {
    display: grid;
    grid-template-columns: 1fr auto;
  }

  .section-bar__label {
    min-width: 0;
  }

  .section-bar__track {
    grid-column: 1 / -1;
    grid-row: 2;
  }

  .section-bar__pct {
    grid-column: 2;
    grid-row: 1;
  }

  .final-cta__title {
    font-size: 36px;
  }

  .landing-shell > .footer .footer-bottom,
  .landing-shell > .footer .footer-bottom-right {
    align-items: flex-start;
    flex-direction: column;
    gap: var(--space-4);
  }

  .lecture-start-modal {
    align-items: flex-end;
    padding: 0;
  }

  .lecture-start-modal__dialog {
    width: 100%;
    max-height: calc(100vh - var(--space-6));
    padding: var(--space-8) var(--space-4) var(--space-6);
    border-radius: var(--r-xl) var(--r-xl) 0 0;
    overflow-y: auto;
  }

  .lecture-start-modal__title {
    font-size: 24px;
  }

  .lecture-start-modal__input-row {
    grid-template-columns: 1fr;
  }

  .lecture-start-modal__input-row .btn {
    width: 100%;
  }
}