:root {
  --feature-paper: #fbfbf8;
  --feature-paper-soft: #f1f2ee;
  --feature-ink: #1d1d1b;
  --feature-muted: #686a66;
  --feature-line: rgb(29 29 27 / 0.14);
  --feature-blue: #3f94bd;
  --feature-blue-deep: #164d69;
  --feature-max: 1120px;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  background: var(--feature-paper);
}

body {
  margin: 0;
  overflow-x: hidden;
  background: var(--feature-paper);
  color: var(--feature-ink);
  font-family: "Helvetica Neue", Helvetica, Arial, "Noto Sans SC", sans-serif;
  line-height: 1.5;
}

main { padding: 0; }

a { color: inherit; }

a:focus-visible,
summary:focus-visible,
button:focus-visible {
  outline: 3px solid #205f7e;
  outline-offset: 4px;
}

.feature-page-shell {
  min-height: 100dvh;
  background: var(--feature-paper);
}

.feature-nav {
  width: 100%;
  min-height: 76px;
  position: absolute;
  inset: 0 0 auto;
  z-index: 10;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 30px;
  padding: 0 clamp(24px, 3.2vw, 52px);
}

.feature-brand {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  justify-self: start;
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: 0.01em;
  text-decoration: none;
}

.feature-brand img {
  width: 26px;
  height: 26px;
  border-radius: 7px;
}

.feature-nav nav {
  display: flex;
  align-items: center;
  gap: clamp(26px, 3vw, 48px);
}

.feature-nav nav a {
  font-size: 0.9rem;
  text-decoration: none;
  transition: opacity 180ms ease;
}

.feature-nav nav a:hover { opacity: 0.56; }

.feature-nav-cta,
.feature-button {
  min-height: 42px;
  width: fit-content;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--feature-ink);
  border-radius: 999px;
  padding: 0 20px;
  background: var(--feature-ink);
  color: #fdfdf9;
  font-size: 0.84rem;
  font-weight: 600;
  line-height: 1;
  text-decoration: none;
  white-space: nowrap;
  transition: transform 180ms ease, background-color 180ms ease;
}

.feature-nav-cta { justify-self: end; }
.feature-nav-cta:hover,
.feature-button:hover { background: #33332f; transform: translateY(-2px); }
.feature-nav-cta:active,
.feature-button:active { transform: translateY(1px) scale(0.98); }

.feature-stage {
  min-height: max(760px, 100dvh);
  position: relative;
  isolation: isolate;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  overflow: hidden;
  padding: 108px 24px 54px;
}

.feature-stage::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: linear-gradient(180deg, transparent 48%, rgb(251 251 248 / 0.24) 64%, var(--feature-paper) 82%);
}

.feature-stage-art {
  width: 100%;
  height: 78%;
  position: absolute;
  inset: 0 0 auto;
  z-index: -2;
  object-fit: cover;
  object-position: 50% 46%;
  filter: saturate(0.92) contrast(0.98);
  animation: feature-art-enter 1.25s cubic-bezier(0.16, 1, 0.3, 1) both;
}

.feature-stage-copy {
  width: min(760px, 100%);
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  animation: feature-copy-enter 780ms 140ms cubic-bezier(0.16, 1, 0.3, 1) both;
}

.feature-kicker {
  margin: 0 0 13px;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.feature-stage h1 {
  max-width: 760px;
  margin: 0;
  font-size: clamp(3.35rem, 6.3vw, 6.4rem);
  font-weight: 500;
  letter-spacing: -0.073em;
  line-height: 0.92;
  text-wrap: balance;
}

.feature-lead {
  max-width: 610px;
  margin: 22px 0 22px;
  color: #50524e;
  font-size: clamp(0.96rem, 1.2vw, 1.08rem);
  line-height: 1.55;
  text-wrap: pretty;
}

.feature-sources,
.feature-proof,
.feature-demo,
.feature-workflow,
.feature-faq,
.feature-footer {
  width: min(var(--feature-max), calc(100% - 48px));
  margin-inline: auto;
}

.feature-sources {
  padding: 44px 0 112px;
  text-align: center;
}

.feature-sources h2 {
  margin: 0 0 28px;
  color: #8a8c88;
  font-size: 0.73rem;
  font-weight: 500;
  letter-spacing: 0.03em;
}

.feature-sources ul {
  max-width: 760px;
  margin: 0 auto;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  align-items: center;
  list-style: none;
}

.feature-sources li {
  min-height: 46px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-left: 1px solid var(--feature-line);
  color: #777975;
  font-size: 0.82rem;
  font-weight: 600;
}

.feature-sources li:last-child { border-right: 1px solid var(--feature-line); }

.feature-proof { padding: 76px 0 132px; }

.feature-proof > h2,
.feature-workflow > h2,
.feature-faq > h2 {
  max-width: 620px;
  margin: 0;
  font-size: clamp(2.6rem, 5vw, 5.3rem);
  font-weight: 500;
  letter-spacing: -0.068em;
  line-height: 0.94;
  text-wrap: balance;
}

.feature-stats {
  margin-top: 42px;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.feature-stats > div {
  min-width: 0;
  padding: 0 clamp(18px, 3vw, 42px);
  border-left: 1px solid var(--feature-line);
}

.feature-stats > div:first-child { padding-left: 0; border-left: 0; }

.feature-stats strong {
  display: block;
  font-size: clamp(3.5rem, 7vw, 7.3rem);
  font-weight: 500;
  letter-spacing: -0.08em;
  line-height: 0.9;
}

.feature-stats span {
  display: block;
  margin-top: 13px;
  color: var(--feature-muted);
  font-size: 0.78rem;
}

.feature-pillars {
  margin: 58px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0;
  list-style: none;
}

.feature-pillars li {
  padding: 29px 34px 0 0;
  border-top: 1px solid var(--feature-line);
}

.feature-pillars li + li {
  padding-left: 34px;
  border-left: 1px solid var(--feature-line);
}

.feature-pillars li > span,
.feature-workflow li > div > span {
  color: #999b96;
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.08em;
}

.feature-pillars h3,
.feature-workflow h3 {
  margin: 16px 0 9px;
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: -0.025em;
}

.feature-pillars p,
.feature-workflow p,
.feature-demo-copy p,
.feature-faq details p,
.feature-footer p {
  margin: 0;
  color: var(--feature-muted);
  font-size: 0.83rem;
  line-height: 1.62;
}

.feature-demo {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(420px, 1fr);
  align-items: stretch;
  min-height: 420px;
  margin-bottom: 112px;
  overflow: hidden;
  border-radius: 12px;
  background: #efefeb;
}

.feature-demo-copy {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: clamp(36px, 6vw, 76px);
}

.feature-demo-copy h2 {
  max-width: 430px;
  margin: 0 0 30px;
  font-size: clamp(2.2rem, 4vw, 4.6rem);
  font-weight: 500;
  letter-spacing: -0.066em;
  line-height: 0.95;
  text-wrap: balance;
}

.feature-demo-copy p { max-width: 390px; }

.feature-demo-panel {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: clamp(26px, 5vw, 64px);
  background: #e5e5df;
}

.study-demo-card {
  width: 100%;
  display: block;
  padding: 0;
  overflow: hidden;
  border: 1px solid rgb(29 29 27 / 0.11);
  border-radius: 10px;
  background: #fffefb;
  box-shadow: 0 22px 50px rgb(51 57 53 / 0.11);
}

.study-demo-card summary {
  display: grid;
  gap: 7px;
  cursor: pointer;
  padding: 25px 26px 22px;
  list-style: none;
  font-size: clamp(1.15rem, 2vw, 1.72rem);
  font-weight: 550;
  letter-spacing: -0.04em;
  line-height: 1.08;
}

.study-demo-card summary::-webkit-details-marker { display: none; }

.study-demo-card summary small {
  color: var(--feature-muted);
  font-size: 0.68rem;
  font-weight: 500;
  letter-spacing: 0;
}

.study-demo-card > p {
  margin: 0;
  padding: 0 26px 25px;
  color: var(--feature-muted);
  font-size: 0.84rem;
}

.study-demo-source {
  margin: 0 26px 14px;
  padding: 16px;
  border-left: 2px solid var(--feature-blue);
  border-radius: 0 7px 7px 0;
  background: #eef4f5;
  color: var(--feature-muted);
  font-size: 0.76rem;
}

.study-demo-draft {
  margin: 0 26px 26px;
  padding: 19px;
  border-radius: 8px;
  background: #263d49;
  color: #fbfcf8;
}

.study-demo-draft strong {
  color: #c9eaf3;
  font-size: 0.64rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.study-demo-draft p {
  margin: 9px 0 13px;
  font-size: 1.04rem;
  line-height: 1.2;
}

.study-demo-draft span { color: #cbd7dc; font-size: 0.68rem; }

.study-demo-actions {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 6px;
  padding: 0 26px 26px;
}

.study-demo-actions button {
  min-width: 0;
  min-height: 38px;
  border: 1px solid var(--feature-line);
  border-radius: 999px;
  background: transparent;
  color: var(--feature-ink);
  font: inherit;
  font-size: 0.65rem;
  font-weight: 600;
}

.study-demo-actions button:hover,
.study-demo-actions button[aria-pressed="true"] {
  border-color: var(--feature-blue-deep);
  background: var(--feature-blue-deep);
  color: white;
}

.study-demo-result {
  min-height: 43px;
  margin: -8px 0 0;
  padding: 0 26px 22px !important;
  color: var(--feature-blue-deep) !important;
  font-size: 0.7rem !important;
  font-weight: 600;
}

.feature-sky {
  min-height: 620px;
  position: relative;
  isolation: isolate;
  display: grid;
  place-items: center;
  overflow: hidden;
  color: white;
  text-align: center;
}

.feature-sky::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: rgb(18 76 105 / 0.19);
}

.feature-sky > img {
  width: 100%;
  height: 100%;
  position: absolute;
  inset: 0;
  z-index: -2;
  object-fit: cover;
}

.feature-sky > div {
  width: min(680px, calc(100% - 42px));
  display: flex;
  flex-direction: column;
  align-items: center;
}

.feature-sky h2 {
  margin: 0;
  font-size: clamp(2.7rem, 5.4vw, 5.8rem);
  font-weight: 500;
  letter-spacing: -0.07em;
  line-height: 0.93;
  text-shadow: 0 2px 20px rgb(15 58 81 / 0.2);
  text-wrap: balance;
}

.feature-sky p {
  max-width: 580px;
  margin: 22px 0 25px;
  color: rgb(255 255 255 / 0.91);
  font-size: 0.9rem;
}

.feature-button--light {
  border-color: white;
  background: white;
  color: #24536b;
}

.feature-button--light:hover { background: #eef8fb; }

.feature-workflow { padding: 132px 0 80px; }
.feature-workflow > h2 { margin-bottom: 96px; }
.feature-workflow > ol { margin: 0; padding: 0; list-style: none; }

.feature-workflow li {
  min-height: 430px;
  display: grid;
  grid-template-columns: minmax(260px, 0.74fr) minmax(430px, 1.26fr);
  align-items: center;
  gap: clamp(50px, 9vw, 124px);
  padding: 56px 0;
}

.feature-workflow li:nth-child(even) > div:first-child { order: 2; }
.feature-workflow li:nth-child(even) > div:last-child { order: 1; }
.feature-workflow h3 { margin-top: 14px; font-size: clamp(1.7rem, 3vw, 2.8rem); }
.feature-workflow p { max-width: 380px; font-size: 0.88rem; }

.feature-workflow-visual {
  min-height: 330px;
  position: relative;
  overflow: hidden;
  display: grid;
  place-items: center;
  border-radius: 12px;
  background: #eff0ec;
}

.feature-workflow-visual b {
  width: min(70%, 330px);
  min-height: 120px;
  z-index: 2;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid rgb(29 29 27 / 0.11);
  border-radius: 9px;
  padding: 28px;
  background: rgb(255 255 252 / 0.92);
  box-shadow: 0 18px 48px rgb(52 62 58 / 0.12);
  font-size: 0.92rem;
  font-weight: 600;
  text-align: center;
}

.feature-workflow-visual i {
  width: 43%;
  height: 82px;
  position: absolute;
  border-radius: 8px;
  background: #dbe5e3;
  transform: translate(-48%, -67%) rotate(-6deg);
}

.feature-workflow-visual i:nth-of-type(2) {
  background: #cbdce0;
  transform: translate(52%, 70%) rotate(7deg);
}

.feature-workflow-visual i:nth-of-type(3) {
  width: 118px;
  height: 118px;
  border-radius: 50%;
  background: #d8e9ef;
  transform: translate(182%, -92%);
}

.feature-workflow-visual--2 { background: #edf3f4; }
.feature-workflow-visual--2 i { background: #cfe0e5; }
.feature-workflow-visual--3 { background: #f1f0eb; }
.feature-workflow-visual--3 i { background: #e3e0d4; }

.feature-faq {
  max-width: 780px;
  padding: 92px 0 132px;
}

.feature-faq > h2 { margin-bottom: 42px; }

.feature-faq details {
  border-top: 1px solid var(--feature-line);
  padding: 22px 0;
}

.feature-faq details:last-child { border-bottom: 1px solid var(--feature-line); }

.feature-faq summary {
  cursor: pointer;
  font-size: 0.95rem;
  font-weight: 600;
  list-style-position: outside;
}

.feature-faq details p {
  max-width: 620px;
  margin-top: 14px;
  font-size: 0.86rem;
}

.feature-footer {
  width: 100%;
  min-height: 360px;
  position: relative;
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 80px;
  border: 0;
  padding: 190px clamp(24px, 5vw, 80px) 45px;
  color: #26312f;
  background-image: linear-gradient(180deg, var(--feature-paper), rgb(251 251 248 / 0.08) 55%), url("/feature-footer.jpg");
  background-position: center bottom;
  background-size: cover;
}

.feature-footer > div:first-child { max-width: 460px; }
.feature-footer p { margin-top: 18px; color: #414b48; }

.feature-footer > div:last-child {
  display: grid;
  justify-items: end;
  gap: 9px;
  color: #414b48;
  font-size: 0.72rem;
}

.feature-footer > div:last-child a { text-underline-offset: 4px; }

@keyframes feature-art-enter {
  from { opacity: 0; transform: scale(1.035); }
  to { opacity: 1; transform: scale(1); }
}

@keyframes feature-copy-enter {
  from { opacity: 0; transform: translateY(24px); }
  to { opacity: 1; transform: translateY(0); }
}

@supports (animation-timeline: view()) {
  .feature-proof,
  .feature-demo,
  .feature-workflow li,
  .feature-faq {
    animation: feature-reveal linear both;
    animation-timeline: view();
    animation-range: entry 8% cover 32%;
  }

  @keyframes feature-reveal {
    from { opacity: 0; transform: translateY(34px); }
    to { opacity: 1; transform: translateY(0); }
  }
}

@media (max-width: 800px) {
  .feature-nav {
    min-height: 64px;
    grid-template-columns: 1fr auto;
    padding-inline: 18px;
  }

  .feature-nav nav { display: none; }
  .feature-nav-cta { min-height: 38px; padding-inline: 15px; font-size: 0.72rem; }
  .feature-stage { min-height: 790px; padding: 90px 18px 38px; }
  .feature-stage-art { height: 66%; object-position: 52% center; }
  .feature-stage::after { background: linear-gradient(180deg, transparent 40%, rgb(251 251 248 / 0.28) 55%, var(--feature-paper) 72%); }
  .feature-stage h1 { font-size: clamp(3.25rem, 14vw, 5rem); line-height: 0.91; }
  .feature-page-shell--ai-flashcards .feature-stage h1 { font-size: clamp(2.65rem, 11vw, 3.45rem); }
  .feature-lead { max-width: 520px; margin-top: 19px; font-size: 0.91rem; }
  .feature-sources,
  .feature-proof,
  .feature-demo,
  .feature-workflow,
  .feature-faq { width: min(100% - 28px, var(--feature-max)); }
  .feature-sources { padding: 30px 0 76px; }
  .feature-sources ul { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .feature-sources li:nth-child(3) { border-top: 1px solid var(--feature-line); }
  .feature-sources li:nth-child(4) { border-top: 1px solid var(--feature-line); border-right: 1px solid var(--feature-line); }
  .feature-proof { padding: 54px 0 88px; }
  .feature-proof > h2,
  .feature-workflow > h2,
  .feature-faq > h2 { font-size: clamp(2.65rem, 12vw, 4rem); }
  .feature-stats { grid-template-columns: 1fr; margin-top: 40px; }
  .feature-stats > div,
  .feature-stats > div:first-child { padding: 20px 0; border: 0; border-top: 1px solid var(--feature-line); }
  .feature-stats strong { font-size: 4.6rem; }
  .feature-pillars { grid-template-columns: 1fr; margin-top: 30px; }
  .feature-pillars li,
  .feature-pillars li + li { padding: 24px 0; border: 0; border-top: 1px solid var(--feature-line); }
  .feature-demo { grid-template-columns: 1fr; margin-bottom: 76px; }
  .feature-demo-copy { min-height: 300px; padding: 34px 28px; }
  .feature-demo-panel { min-height: 360px; padding: 28px 20px; }
  .feature-sky { min-height: 590px; }
  .feature-sky > img { object-position: 57% center; }
  .feature-sky h2 { font-size: clamp(2.8rem, 13vw, 4.6rem); }
  .feature-workflow { padding: 90px 0 42px; }
  .feature-workflow > h2 { margin-bottom: 58px; }
  .feature-workflow li { min-height: 0; grid-template-columns: 1fr; gap: 32px; padding: 44px 0 64px; }
  .feature-workflow li:nth-child(even) > div:first-child,
  .feature-workflow li:nth-child(even) > div:last-child { order: initial; }
  .feature-workflow-visual { min-height: 290px; }
  .feature-workflow-visual i:nth-of-type(3) { transform: translate(125%, -92%); }
  .feature-faq { padding: 70px 0 90px; }
  .feature-footer { min-height: 430px; flex-direction: column; align-items: flex-start; justify-content: flex-end; gap: 40px; padding: 180px 22px 34px; }
  .feature-footer > div:last-child { justify-items: start; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}