:root {
  --bg0: #f4f8ff;
  --bg1: #eefbf5;
  --ink: #101828;
  --mute: #5b667a;
  --card: #ffffff;
  --line: rgba(16, 24, 40, 0.08);
  --blue: #2f6bff;
  --blue-soft: #dbe6ff;
  --lime: #b6f34d;
  --lime-ink: #2a4a00;
  --pink: #ff4f8b;
  --pink-soft: #ffe0eb;
  --cyan: #2ad4c9;
  --shadow: 0 16px 40px rgba(47, 107, 255, 0.1);
  --font: "Nunito", system-ui, sans-serif;
  --display: "Space Grotesk", system-ui, sans-serif;
  --ease: cubic-bezier(0.2, 0.9, 0.2, 1);
  --r: 22px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font);
  color: var(--ink);
  background:
    radial-gradient(900px 500px at 100% -5%, rgba(47, 107, 255, 0.22), transparent 55%),
    radial-gradient(700px 480px at -5% 20%, rgba(182, 243, 77, 0.28), transparent 50%),
    radial-gradient(600px 420px at 70% 100%, rgba(255, 79, 139, 0.14), transparent 45%),
    linear-gradient(180deg, var(--bg0), var(--bg1));
  background-attachment: fixed;
  line-height: 1.55;
}

.blob {
  position: fixed;
  border-radius: 50%;
  filter: blur(40px);
  opacity: 0.45;
  pointer-events: none;
  z-index: 0;
  animation: floaty 10s ease-in-out infinite alternate;
}
.blob.a { width: 280px; height: 280px; background: #9ec0ff; top: 12%; left: -60px; }
.blob.b { width: 220px; height: 220px; background: #d8ff8a; bottom: 18%; right: -40px; animation-delay: -3s; }
@keyframes floaty {
  from { transform: translateY(0) scale(1); }
  to { transform: translateY(24px) scale(1.08); }
}

.shell {
  position: relative;
  z-index: 1;
  max-width: 1040px;
  margin: 0 auto;
  padding: 0 20px 90px;
}

.top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 16px 0;
  position: sticky;
  top: 0;
  z-index: 30;
  background: linear-gradient(to bottom, rgba(244, 248, 255, 0.94), rgba(244, 248, 255, 0.7), transparent);
  backdrop-filter: blur(10px);
}

.logo {
  border: 0;
  background: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 10px;
  font: inherit;
  color: inherit;
  padding: 0;
}
.logo-badge {
  width: 38px;
  height: 38px;
  border-radius: 14px;
  background: linear-gradient(135deg, var(--blue), var(--cyan));
  color: #fff;
  display: grid;
  place-items: center;
  font-family: var(--display);
  font-weight: 700;
  font-size: 14px;
  box-shadow: 0 8px 20px rgba(47, 107, 255, 0.35);
  transform: rotate(-6deg);
}
.logo strong {
  display: block;
  font-family: var(--display);
  font-size: 18px;
  letter-spacing: -0.03em;
}
.logo small {
  display: block;
  font-size: 11px;
  font-weight: 700;
  color: var(--mute);
}

.menu { display: flex; flex-wrap: wrap; gap: 6px; justify-content: flex-end; }
.menu button {
  border: 0;
  background: transparent;
  color: var(--mute);
  font: inherit;
  font-size: 13px;
  font-weight: 800;
  padding: 9px 13px;
  border-radius: 999px;
  cursor: pointer;
  transition: 0.2s var(--ease);
}
.menu button:hover,
.menu button.active {
  background: var(--ink);
  color: #fff;
}

.burger {
  display: none;
  border: 0;
  background: var(--ink);
  color: #fff;
  font: inherit;
  font-weight: 800;
  font-size: 13px;
  padding: 10px 14px;
  border-radius: 999px;
  cursor: pointer;
}

@media (max-width: 720px) {
  .burger { display: inline-flex; }
  .menu { display: none; }
  .menu.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    right: 20px;
    top: 66px;
    background: #fff;
    border: 1px solid var(--line);
    border-radius: 18px;
    padding: 8px;
    box-shadow: var(--shadow);
    width: min(220px, calc(100vw - 40px));
  }
}

.view { display: none; animation: pop 0.4s var(--ease); }
.view.on { display: block; }
@keyframes pop {
  from { opacity: 0; transform: translateY(10px) scale(0.99); }
  to { opacity: 1; transform: none; }
}

.hero {
  min-height: calc(100vh - 100px);
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 24px 0 36px;
}

.sticker {
  display: inline-flex;
  font-size: 12px;
  font-weight: 800;
  padding: 7px 12px;
  border-radius: 999px;
  background: var(--lime);
  color: var(--lime-ink);
  margin-bottom: 16px;
  transform: rotate(-2deg);
  width: fit-content;
}

.brand {
  font-family: var(--display);
  font-size: clamp(52px, 11vw, 92px);
  font-weight: 700;
  letter-spacing: -0.06em;
  line-height: 0.92;
  margin: 0 0 18px;
  max-width: 8ch;
}
.brand em {
  font-style: normal;
  background: linear-gradient(120deg, var(--blue), var(--pink));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.problem-label {
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--blue);
  margin-bottom: 10px;
}

.problem {
  font-family: var(--display);
  font-size: clamp(20px, 3vw, 28px);
  font-weight: 600;
  letter-spacing: -0.03em;
  line-height: 1.3;
  max-width: 22em;
  margin: 0 0 14px;
}

.problem-note {
  max-width: 42em;
  color: var(--mute);
  font-size: 15.5px;
  font-weight: 600;
  margin: 0 0 22px;
}

.global-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 28px;
}
.chip {
  font-size: 12px;
  font-weight: 800;
  padding: 7px 11px;
  border-radius: 999px;
  background: var(--blue-soft);
  color: var(--blue);
}
.chip.lime { background: #eaffc2; color: var(--lime-ink); }
.chip.pink { background: var(--pink-soft); color: #b01f52; }

.cta-row { display: flex; flex-wrap: wrap; gap: 10px; }
.btn {
  border: 0;
  font: inherit;
  font-size: 14px;
  font-weight: 800;
  padding: 13px 18px;
  border-radius: 999px;
  cursor: pointer;
  transition: transform 0.2s var(--ease);
}
.btn:hover { transform: translateY(-2px); }
.btn-main {
  background: var(--ink);
  color: #fff;
  box-shadow: 0 12px 28px rgba(16, 24, 40, 0.22);
}
.btn-fun { background: var(--lime); color: var(--lime-ink); }
.btn-ghost {
  background: #fff;
  color: var(--ink);
  border: 1px solid var(--line);
}

.scroll-hint {
  margin-top: 44px;
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--mute);
  animation: bounce 1.8s ease-in-out infinite;
}
@keyframes bounce {
  0%, 100% { transform: translateY(0); opacity: 0.5; }
  50% { transform: translateY(5px); opacity: 1; }
}

.kicker {
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--blue);
  margin: 34px 0 8px;
}
.title {
  font-family: var(--display);
  font-size: clamp(28px, 4.5vw, 38px);
  letter-spacing: -0.04em;
  margin: 0 0 8px;
}
.lead {
  color: var(--mute);
  font-weight: 600;
  max-width: 42em;
  margin: 0 0 18px;
}

.parts {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
}
@media (max-width: 720px) { .parts { grid-template-columns: 1fr; } }

.part {
  text-align: left;
  border: 1px solid var(--line);
  background: #fff;
  border-radius: var(--r);
  padding: 18px;
  cursor: pointer;
  font: inherit;
  color: inherit;
  box-shadow: var(--shadow);
  transition: transform 0.2s var(--ease), border-color 0.2s var(--ease);
  display: grid;
  gap: 6px;
}
.part:hover {
  transform: translateY(-3px) rotate(-0.3deg);
  border-color: rgba(47, 107, 255, 0.35);
}
.part .n {
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--blue);
}
.part strong {
  font-family: var(--display);
  font-size: 22px;
  letter-spacing: -0.03em;
}
.part span {
  font-size: 14px;
  color: var(--mute);
  font-weight: 600;
}
.part .go {
  margin-top: 8px;
  font-size: 13px;
  font-weight: 800;
  color: var(--pink);
}

.snap {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 12px;
  margin-top: 8px;
}
@media (max-width: 720px) { .snap { grid-template-columns: 1fr; } }
.snap > * {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--r);
  padding: 20px;
  box-shadow: var(--shadow);
}
.snap h3 {
  font-family: var(--display);
  font-size: 22px;
  margin: 0 0 8px;
  letter-spacing: -0.03em;
}
.chips { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 12px; }

.page-head { padding: 24px 0 16px; max-width: 740px; }
.back {
  border: 0;
  background: var(--blue-soft);
  color: var(--blue);
  font: inherit;
  font-size: 13px;
  font-weight: 800;
  padding: 8px 12px;
  border-radius: 999px;
  cursor: pointer;
  margin-bottom: 14px;
}
.page-head h1 {
  font-family: var(--display);
  font-size: clamp(30px, 5vw, 44px);
  letter-spacing: -0.04em;
  margin: 0 0 8px;
  line-height: 1.05;
}
.page-head p { margin: 0; color: var(--mute); font-weight: 600; }

.stack { display: grid; gap: 12px; }
.block {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--r);
  padding: 18px 20px;
  box-shadow: var(--shadow);
}
.block h2, .block h3 {
  font-family: var(--display);
  letter-spacing: -0.03em;
  margin: 0 0 8px;
}
.block h2 { font-size: 22px; }
.block h3 { font-size: 17px; }
.block p, .block li { color: var(--mute); font-weight: 600; font-size: 14.5px; }
.block ul, .block ol { margin: 8px 0; padding-left: 1.15em; }
.block strong { color: var(--ink); }

table { width: 100%; border-collapse: collapse; font-size: 14px; }
th, td {
  text-align: left;
  padding: 9px 6px;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}
th {
  color: var(--mute);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.tech-card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--r);
  overflow: hidden;
  box-shadow: var(--shadow);
}
.tech-head {
  width: 100%;
  border: 0;
  background: transparent;
  text-align: left;
  padding: 16px 18px;
  cursor: pointer;
  font: inherit;
  display: flex;
  gap: 12px;
  align-items: flex-start;
  color: inherit;
}
.tech-head:hover { background: #f8faff; }
.tech-num {
  flex: 0 0 auto;
  width: 42px;
  height: 42px;
  border-radius: 14px;
  display: grid;
  place-items: center;
  font-family: var(--display);
  font-weight: 700;
  font-size: 12px;
  color: #fff;
}
.tech-head h2 {
  font-family: var(--display);
  font-size: 18px;
  margin: 0 0 4px;
  letter-spacing: -0.03em;
}
.tech-head p {
  margin: 0;
  color: var(--mute);
  font-weight: 600;
  font-size: 13.5px;
}
.tech-chevron {
  margin-left: auto;
  font-weight: 800;
  color: var(--blue);
  transition: transform 0.2s var(--ease);
}
.tech-card.open .tech-chevron { transform: rotate(90deg); }
.tech-body {
  display: none;
  padding: 0 18px 18px 72px;
  border-top: 1px solid var(--line);
}
.tech-card.open .tech-body { display: block; padding-top: 14px; }
@media (max-width: 700px) { .tech-body { padding-left: 18px; } }

.cols {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin: 10px 0;
}
@media (max-width: 700px) { .cols { grid-template-columns: 1fr; } }

.mini {
  background: #f6f8ff;
  border-radius: 14px;
  padding: 12px;
}
.mini.good { background: #f3ffe3; }
.mini.bad { background: #fff0f5; }
.mini h4 {
  margin: 0 0 6px;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 800;
  color: var(--ink);
}
.mini p, .mini li {
  margin: 0;
  font-size: 13.5px;
  color: var(--mute);
  font-weight: 600;
}
.mini ul { margin: 0; padding-left: 1.1em; }

.links { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 12px; }
.links a {
  text-decoration: none;
  font-size: 13px;
  font-weight: 800;
  padding: 8px 12px;
  border-radius: 999px;
  background: var(--ink);
  color: #fff;
}
.links a.alt { background: var(--blue-soft); color: var(--blue); }

.tag-row { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 8px; }
.tag {
  font-size: 11px;
  font-weight: 800;
  padding: 4px 9px;
  border-radius: 999px;
  background: #eef2ff;
  color: #5b4ddb;
}

.problem-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 10px;
}
.p-card {
  text-align: left;
  border: 1px solid var(--line);
  background: #fff;
  border-radius: 18px;
  padding: 15px;
  cursor: pointer;
  font: inherit;
  color: inherit;
  box-shadow: var(--shadow);
  transition: transform 0.2s var(--ease);
}
.p-card:hover { transform: translateY(-3px); }
.p-card .id {
  font-size: 12px;
  font-weight: 800;
  color: var(--pink);
  margin-bottom: 4px;
}
.p-card strong {
  display: block;
  font-family: var(--display);
  font-size: 16px;
  margin-bottom: 4px;
}
.p-card span { font-size: 13px; color: var(--mute); font-weight: 600; }

.subnav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 14px;
}
.subnav button {
  border: 1px solid var(--line);
  background: #fff;
  font: inherit;
  font-size: 12.5px;
  font-weight: 800;
  padding: 8px 12px;
  border-radius: 999px;
  cursor: pointer;
  color: var(--mute);
}
.subnav button.on {
  background: var(--ink);
  color: #fff;
  border-color: var(--ink);
}

.panel { display: none; }
.panel.on { display: block; }

.rpanel, .cpanel { display: none; }
.rpanel.on, .cpanel.on { display: block; }

.prose h2 { margin-top: 0; }
.prose h3 {
  font-family: var(--display);
  font-size: 17px;
  margin: 18px 0 8px;
}
.prose p {
  color: var(--mute);
  font-weight: 600;
  font-size: 14.5px;
  margin: 0 0 12px;
  line-height: 1.65;
}
.prose ul, .prose ol {
  color: var(--mute);
  font-weight: 600;
  font-size: 14.5px;
  margin: 0 0 14px;
  padding-left: 1.25em;
  line-height: 1.65;
}
.prose li { margin-bottom: 6px; }

.eq {
  font-family: var(--display);
  font-size: 14.5px;
  background: #f6f8ff;
  padding: 12px 14px;
  border-radius: 12px;
  line-height: 1.75;
  overflow-x: auto;
}

.table-wrap {
  overflow-x: auto;
  margin: 14px 0 4px;
  border-radius: 14px;
  border: 1px solid var(--line);
}
.table-wrap table { margin: 0; }
.table-wrap th, .table-wrap td {
  padding: 10px 12px;
  vertical-align: top;
}

.note-sci {
  font-size: 13px;
  font-weight: 700;
  color: var(--mute);
  background: #fff8e8;
  border: 1px solid rgba(232, 160, 74, 0.35);
  border-radius: 12px;
  padding: 10px 12px;
  margin: 10px 0;
}

.footer-note {
  margin-top: 36px;
  font-size: 12px;
  color: var(--mute);
  font-weight: 700;
}