:root {
  color-scheme: dark;
  --page: #09111f;
  --surface: #101b2d;
  --surface-raised: #142239;
  --surface-muted: #1a2940;
  --ink: #edf7ff;
  --muted: #92a5be;
  --line: rgba(155, 190, 226, 0.18);
  --cyan: #5be7f3;
  --lime: #c7f464;
  --violet: #a892ff;
  --orange: #ffb36b;
  --shadow: 0 20px 65px rgba(0, 0, 0, 0.28);
  --header-height: 72px;
}

[data-theme="light"] {
  color-scheme: light;
  --page: #eef6ff;
  --surface: #ffffff;
  --surface-raised: #f7fbff;
  --surface-muted: #e8f1fb;
  --ink: #122033;
  --muted: #60738c;
  --line: rgba(24, 57, 92, 0.15);
  --cyan: #007f99;
  --lime: #5d8f00;
  --violet: #654bd2;
  --orange: #bc5f00;
  --shadow: 0 20px 65px rgba(32, 65, 99, 0.12);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-width: 320px;
  overflow-x: hidden;
  background: var(--page);
  color: var(--ink);
  font-family: Inter, "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  line-height: 1.65;
}
button, input { font: inherit; letter-spacing: 0; }
button, a { -webkit-tap-highlight-color: transparent; }
a { color: inherit; }
button:focus-visible, a:focus-visible, input:focus-visible { outline: 2px solid var(--cyan); outline-offset: 3px; }

.ambient-grid {
  position: fixed;
  z-index: -2;
  inset: 0;
  opacity: .32;
  pointer-events: none;
  background-image: linear-gradient(var(--line) 1px, transparent 1px), linear-gradient(90deg, var(--line) 1px, transparent 1px);
  background-size: 54px 54px;
  mask-image: linear-gradient(to bottom, #000 0%, transparent 78%);
}

.site-header {
  position: sticky; z-index: 20; top: 0; display: flex; min-height: var(--header-height);
  align-items: center; justify-content: space-between; padding: 10px clamp(18px, 5vw, 80px);
  border-bottom: 1px solid var(--line); background: color-mix(in srgb, var(--page) 86%, transparent);
  backdrop-filter: blur(18px);
}
.brand { display: inline-flex; gap: 11px; align-items: center; text-decoration: none; }
.brand-mark { display: grid; width: 38px; height: 38px; place-items: center; border: 1px solid var(--cyan); color: var(--cyan); font-weight: 900; clip-path: polygon(22% 0, 100% 0, 100% 78%, 78% 100%, 0 100%, 0 22%); }
.brand strong, .brand small { display: block; }
.brand strong { font-size: 15px; letter-spacing: .04em; }
.brand small { margin-top: 1px; color: var(--muted); font-size: 9px; letter-spacing: .14em; }
.top-nav { display: flex; gap: 26px; margin-left: auto; margin-right: 30px; font-size: 13px; }
.top-nav a { color: var(--muted); text-decoration: none; transition: color .2s ease; }
.top-nav a:hover { color: var(--cyan); }
.header-actions { display: flex; gap: 8px; }
.icon-button { display: grid; width: 38px; height: 38px; place-items: center; border: 1px solid var(--line); background: var(--surface); color: var(--ink); cursor: pointer; transition: border-color .2s ease, transform .2s ease; }
.icon-button:hover { border-color: var(--cyan); color: var(--cyan); transform: translateY(-2px); }
.mobile-only { display: none; }

.hero { display: grid; min-height: min(690px, calc(100vh - var(--header-height))); grid-template-columns: minmax(0, 1.05fr) minmax(370px, .95fr); align-items: center; gap: 40px; width: min(1220px, calc(100% - 44px)); margin: 0 auto; padding: clamp(72px, 10vw, 128px) 0 74px; }
.eyebrow { margin: 0 0 12px; color: var(--cyan); font-size: 11px; font-weight: 800; letter-spacing: .14em; }
.eyebrow span { display: inline-block; width: 38px; height: 1px; margin: 0 8px 4px; background: var(--lime); }
.hero h1 { max-width: 700px; margin: 0; font-size: clamp(43px, 6vw, 82px); line-height: 1.06; letter-spacing: 0; }
.hero h1 span { color: var(--lime); }
.hero-lead { max-width: 570px; margin: 25px 0 30px; color: var(--muted); font-size: 17px; }
.hero-actions { display: flex; flex-wrap: wrap; align-items: center; gap: 22px; }
.primary-button { display: inline-flex; gap: 18px; align-items: center; padding: 12px 16px 12px 20px; background: var(--lime); color: #0c1725; font-size: 13px; font-weight: 800; text-decoration: none; transition: transform .2s ease, box-shadow .2s ease; }
.primary-button span { font-size: 18px; }
.primary-button:hover { box-shadow: 5px 5px 0 var(--cyan); transform: translate(-2px, -2px); }
.text-link { color: var(--muted); font-size: 13px; text-decoration: none; }
.text-link:hover { color: var(--cyan); }
.hero-visual { position: relative; min-height: 400px; }
.orbit { position: absolute; border: 1px solid var(--line); border-radius: 50%; transform: rotate(-26deg); animation: spin 18s linear infinite; }
.orbit-one { inset: 34px 38px; border-right-color: var(--cyan); border-bottom-color: var(--cyan); }
.orbit-two { inset: 102px 0; border-left-color: var(--lime); border-top-color: var(--lime); animation-direction: reverse; animation-duration: 14s; }
.core-signal { position: absolute; z-index: 2; top: 50%; left: 50%; display: grid; width: 183px; height: 183px; place-content: center; border: 1px solid var(--cyan); background: color-mix(in srgb, var(--surface) 88%, transparent); box-shadow: inset 0 0 42px color-mix(in srgb, var(--cyan) 15%, transparent), var(--shadow); text-align: center; transform: translate(-50%, -50%) rotate(45deg); }
.core-signal > * { transform: rotate(-45deg); }
.core-signal span { color: var(--lime); font-size: 11px; font-weight: 800; }
.core-signal strong { margin-top: 7px; font-size: 17px; letter-spacing: .08em; line-height: 1.27; }
.signal-card { position: absolute; z-index: 3; width: 183px; padding: 14px 15px; border: 1px solid var(--line); background: color-mix(in srgb, var(--surface-raised) 90%, transparent); box-shadow: var(--shadow); backdrop-filter: blur(8px); animation: float 4s ease-in-out infinite; }
.signal-card small, .signal-card strong { display: block; }
.signal-card small { color: var(--muted); font-size: 9px; letter-spacing: .12em; }
.signal-card strong { margin-top: 3px; font-size: 12px; }
.signal-card i { display: block; height: 2px; margin-top: 12px; background: var(--cyan); }
.signal-ai { top: 22px; right: 2%; border-top-color: var(--cyan); }
.signal-en { bottom: 20px; left: 0; border-top-color: var(--lime); animation-delay: -1.5s; }
.signal-en i { background: var(--lime); }
.spark { position: absolute; z-index: 1; width: 8px; height: 8px; background: var(--cyan); box-shadow: 0 0 18px var(--cyan); animation: pulse 2s ease-in-out infinite; }
.spark-a { top: 20%; left: 16%; }.spark-b { right: 11%; bottom: 28%; background: var(--lime); box-shadow: 0 0 18px var(--lime); animation-delay: .7s; }.spark-c { bottom: 7%; right: 37%; background: var(--violet); box-shadow: 0 0 18px var(--violet); animation-delay: 1.2s; }

.tracks { display: grid; grid-template-columns: 1fr 1fr; gap: 1px; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); background: var(--line); }
.track-card { position: relative; min-height: 310px; padding: clamp(30px, 4vw, 56px) clamp(28px, 6vw, 90px); overflow: hidden; border: 0; background: var(--surface); color: var(--ink); cursor: pointer; text-align: left; transition: background .25s ease; }
.track-card::after { position: absolute; top: -110px; right: -95px; width: 270px; height: 270px; border: 1px solid currentColor; border-radius: 50%; content: ""; opacity: .12; transition: transform .4s ease; }
.track-card:hover::after, .track-card.active::after { transform: scale(1.25); }
.tech-track { color: var(--cyan); }.english-track { color: var(--lime); }
.track-card > * { position: relative; z-index: 1; }
.track-index { color: var(--muted); font-size: 11px; font-weight: 800; letter-spacing: .08em; }
.track-card strong { display: block; margin-top: 24px; color: var(--ink); font-size: clamp(28px, 3.5vw, 45px); line-height: 1.17; }
.track-card p { max-width: 390px; margin: 15px 0 0; color: var(--muted); font-size: 14px; }
.track-arrow { position: absolute; right: clamp(30px, 6vw, 80px); bottom: 32px; font-size: 29px; transition: transform .25s ease; }
.track-card:hover .track-arrow, .track-card.active .track-arrow { transform: translate(5px, 5px); }
.tech-track.active { background: color-mix(in srgb, var(--cyan) 6%, var(--surface)); }.english-track.active { background: color-mix(in srgb, var(--lime) 6%, var(--surface)); }

.explore-section { width: min(1220px, calc(100% - 44px)); margin: 0 auto; padding: 102px 0 92px; }
.section-heading { display: flex; align-items: end; justify-content: space-between; gap: 35px; margin-bottom: 40px; }
.section-heading h2 { margin: 0; font-size: clamp(30px, 4vw, 49px); line-height: 1.15; }
.section-heading > p { max-width: 340px; margin: 0; color: var(--muted); font-size: 14px; }
.app-shell { display: grid; grid-template-columns: 285px minmax(0, 1fr); min-height: 600px; border: 1px solid var(--line); background: color-mix(in srgb, var(--surface) 84%, transparent); box-shadow: var(--shadow); }
.library-panel { padding: 22px 16px; border-right: 1px solid var(--line); background: color-mix(in srgb, var(--surface-raised) 74%, transparent); }
.search-field { display: flex; height: 42px; align-items: center; gap: 8px; padding: 0 11px; border: 1px solid var(--line); background: var(--page); color: var(--muted); }
.search-field:focus-within { border-color: var(--cyan); box-shadow: 0 0 0 3px color-mix(in srgb, var(--cyan) 12%, transparent); }
.search-field input { width: 100%; border: 0; outline: 0; background: transparent; color: var(--ink); font-size: 13px; }
.category-list { display: flex; flex-wrap: wrap; gap: 7px; padding: 18px 0; border-bottom: 1px solid var(--line); }
.category-button, .text-button { border: 0; background: transparent; }
.category-button { padding: 5px 8px; border: 1px solid var(--line); color: var(--muted); cursor: pointer; font-size: 11px; }
.category-button:hover, .category-button.active { border-color: var(--cyan); background: color-mix(in srgb, var(--cyan) 10%, transparent); color: var(--cyan); }
.note-list-heading { display: flex; align-items: center; justify-content: space-between; margin: 17px 0 9px; color: var(--muted); font-size: 11px; }
.text-button { padding: 2px; color: var(--lime); cursor: pointer; font-size: 11px; }.text-button[aria-pressed="true"] { color: var(--orange); }
.note-list { display: grid; gap: 5px; }
.note-link { display: block; width: 100%; padding: 11px 10px; border: 1px solid transparent; background: transparent; color: inherit; cursor: pointer; text-align: left; transition: background .2s ease, border-color .2s ease; }
.note-link:hover { background: color-mix(in srgb, var(--surface-muted) 75%, transparent); }.note-link.active { border-color: var(--line); background: color-mix(in srgb, var(--cyan) 8%, transparent); }
.note-link strong, .note-link small { display: block; }.note-link strong { font-size: 13px; line-height: 1.45; }.note-link small { margin-top: 4px; color: var(--muted); font-size: 10px; }
.empty-list { padding: 22px 5px; color: var(--muted); font-size: 12px; text-align: center; }
.reading-pane { min-width: 0; padding: clamp(28px, 5vw, 65px); }
.article { max-width: 760px; animation: article-in .38s ease both; }
.article-topline { display: flex; align-items: center; justify-content: space-between; gap: 16px; }
.article-meta { display: flex; flex-wrap: wrap; gap: 8px 14px; color: var(--muted); font-size: 11px; }.article-meta .category { color: var(--cyan); font-weight: 800; }
.favorite-button { font-size: 18px; }.article h1 { max-width: 17em; margin: 17px 0 14px; font-size: clamp(32px, 4.3vw, 52px); line-height: 1.15; }.article-lead { max-width: 46em; margin: 0; color: var(--muted); font-size: 16px; }
.article-rule { display: flex; gap: 5px; margin: 29px 0 34px; }.article-rule span { width: 34px; height: 3px; background: var(--cyan); }.article-rule span:nth-child(2) { background: var(--lime); }.article-rule span:nth-child(3) { background: var(--violet); }
.article-section { margin: 34px 0; }.article-section h2 { margin: 0 0 11px; font-size: 21px; line-height: 1.4; }.article-section p { margin: 10px 0; font-size: 15px; }.article-section strong { color: var(--cyan); }
.insight-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px; margin-top: 17px; }.insight-card { padding: 14px; border: 1px solid var(--line); background: var(--surface-raised); }.insight-card strong { display: block; color: var(--lime); font-size: 12px; }.insight-card span { display: block; margin-top: 5px; color: var(--muted); font-size: 12px; }
.phrase-grid { display: grid; gap: 10px; margin-top: 16px; }.phrase-card { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 14px; padding: 15px; border-left: 2px solid var(--lime); background: var(--surface-raised); }.phrase-card blockquote { margin: 0; font-size: 16px; font-weight: 750; line-height: 1.4; }.phrase-card .translation { margin: 5px 0 0; color: var(--muted); font-size: 13px; }.phrase-card .usage-note { margin: 4px 0 0; color: var(--lime); font-size: 11px; }.phrase-actions { display: flex; gap: 5px; }.phrase-action { display: grid; width: 30px; height: 30px; place-items: center; border: 1px solid var(--line); background: transparent; color: var(--muted); cursor: pointer; }.phrase-action:hover { color: var(--cyan); border-color: var(--cyan); }
.code-sample { overflow-x: auto; margin: 16px 0 0; padding: 16px; border-left: 2px solid var(--cyan); background: #07101c; color: #dffbff; font: 12px/1.75 "SFMono-Regular", Consolas, monospace; white-space: pre-wrap; }
.article-tags { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 39px; padding-top: 20px; border-top: 1px solid var(--line); }.tag { padding: 4px 7px; border: 1px solid var(--line); color: var(--muted); font-size: 10px; }
.article-next { display: flex; align-items: center; justify-content: space-between; gap: 22px; margin-top: 27px; padding-top: 23px; border-top: 1px solid var(--line); }.article-next span { display: block; color: var(--muted); font-size: 10px; }.article-next button { max-width: 26em; padding: 0; border: 0; background: transparent; color: var(--cyan); cursor: pointer; font-weight: 700; text-align: right; }
.site-footer { display: flex; min-height: 118px; align-items: center; justify-content: space-between; gap: 28px; padding: 24px clamp(20px, 5vw, 80px); border-top: 1px solid var(--line); background: var(--surface); color: var(--muted); font-size: 12px; }.site-footer strong, .site-footer span { display: block; }.site-footer strong { color: var(--ink); }.site-footer nav { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 10px 20px; }.site-footer a:hover { color: var(--cyan); }
.toast { position: fixed; z-index: 50; right: 20px; bottom: 20px; max-width: min(360px, calc(100vw - 40px)); padding: 10px 14px; border: 1px solid var(--cyan); background: var(--surface); color: var(--ink); font-size: 13px; opacity: 0; pointer-events: none; transform: translateY(8px); transition: opacity .16s ease, transform .16s ease; }.toast.visible { opacity: 1; transform: translateY(0); }
.noscript { margin: 0; padding: 12px 20px; background: var(--orange); color: #171717; text-align: center; }
.static-page { min-height: calc(100vh - var(--header-height)); padding: clamp(42px, 8vw, 96px) 22px 80px; }.static-content { width: min(740px, 100%); margin: 0 auto; }.static-content h1 { font-size: clamp(34px, 5vw, 54px); }.static-content h2 { margin-top: 34px; }.static-content p { color: var(--muted); }.back-link { display: inline-block; margin-top: 22px; color: var(--cyan); }
@keyframes spin { to { transform: rotate(334deg); } } @keyframes float { 50% { transform: translateY(-10px); } } @keyframes pulse { 50% { opacity: .35; transform: scale(.7); } } @keyframes article-in { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: translateY(0); } }
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { scroll-behavior: auto !important; animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; } }
@media (max-width: 760px) {
  .top-nav { display: none; }.mobile-only { display: grid; }.hero { grid-template-columns: 1fr; min-height: auto; padding-top: 68px; }.hero-visual { min-height: 345px; max-width: 480px; width: 100%; margin: -7px auto 0; }.tracks { grid-template-columns: 1fr; }.track-card { min-height: 250px; }.explore-section { padding-top: 74px; }.section-heading { display: block; }.section-heading > p { margin-top: 15px; }.app-shell { position: relative; display: block; }.library-panel { position: fixed; z-index: 15; top: var(--header-height); left: 0; width: min(340px, 90vw); height: calc(100vh - var(--header-height)); overflow-y: auto; border: 1px solid var(--line); border-left: 0; box-shadow: var(--shadow); transform: translateX(-105%); transition: transform .25s ease; }.library-panel.open { transform: translateX(0); }.reading-pane { padding: 30px 20px 38px; }.article h1 { font-size: 34px; }.site-footer { display: block; }.site-footer nav { justify-content: flex-start; margin-top: 14px; }.signal-card { width: 153px; }.core-signal { width: 156px; height: 156px; }
}
@media (max-width: 440px) { .hero { width: min(100% - 32px, 1220px); }.explore-section { width: min(100% - 32px, 1220px); }.hero h1 { font-size: 42px; }.hero-visual { transform: scale(.92); transform-origin: top center; margin-bottom: -28px; }.insight-grid { grid-template-columns: 1fr; }.signal-ai { right: -4px; }.signal-en { left: -4px; } }