:root {
  color-scheme: light;
  --paper: #fef7ec;
  --ink: #151922;
  --muted: #4a5463;
  --accent: #ff5c48;
  --accent-strong: #e04a32;
  --teal: #1b9aaa;
  --gold: #f4b860;
  --card: #ffffff;
  --border: rgba(21, 25, 34, 0.08);
  --shadow: 0 24px 60px rgba(15, 23, 42, 0.12);
  --display: "Space Grotesk", "Noto Sans SC", sans-serif;
  --body: "Noto Sans SC", "Space Grotesk", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: radial-gradient(circle at top left, #ffffff 0%, #fef7ec 40%, #edf2f8 100%);
  color: var(--ink);
  font-family: var(--body);
  line-height: 1.6;
  min-height: 100vh;
}

a {
  color: inherit;
  text-decoration: none;
}

a:hover {
  color: var(--accent-strong);
}

.backdrop {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
}

.orb {
  position: absolute;
  width: 420px;
  height: 420px;
  border-radius: 50%;
  opacity: 0.35;
  animation: float 18s ease-in-out infinite;
}

.orb-one {
  background: radial-gradient(circle, rgba(255, 92, 72, 0.45) 0%, rgba(255, 92, 72, 0) 70%);
  top: -120px;
  left: -80px;
}

.orb-two {
  background: radial-gradient(circle, rgba(27, 154, 170, 0.4) 0%, rgba(27, 154, 170, 0) 70%);
  right: -140px;
  bottom: -120px;
  animation-delay: -6s;
}

.gridline {
  position: absolute;
  inset: 0;
  background-image: linear-gradient(transparent 94%, rgba(21, 25, 34, 0.05) 95%),
    linear-gradient(90deg, transparent 94%, rgba(21, 25, 34, 0.05) 95%);
  background-size: 80px 80px;
  opacity: 0.25;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 5;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 6vw;
  backdrop-filter: blur(8px);
  background: rgba(254, 247, 236, 0.85);
  border-bottom: 1px solid var(--border);
  gap: 16px;
  flex-wrap: wrap;
}

.brand {
  display: flex;
  gap: 10px;
  align-items: center;
  font-family: var(--display);
  font-weight: 600;
}

.brand-label {
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--ink);
  color: var(--paper);
  font-size: 0.75rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.brand-id {
  font-size: 1.05rem;
}

.navlinks {
  display: flex;
  gap: 18px;
  font-size: 0.9rem;
  flex-wrap: wrap;
}

.navlinks a {
  padding: 6px 8px;
  border-radius: 999px;
  transition: background 0.2s ease, color 0.2s ease;
}

.navlinks a:hover {
  background: rgba(21, 25, 34, 0.06);
  color: var(--ink);
}

.toggles {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.lang-toggle,
.level-toggle {
  display: inline-flex;
  gap: 6px;
  background: var(--card);
  border-radius: 999px;
  padding: 4px;
  border: 1px solid var(--border);
  align-items: center;
}

.level-label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--muted);
  padding-left: 8px;
}

.lang-toggle button,
.level-toggle button {
  border: none;
  background: transparent;
  font-family: var(--display);
  font-size: 0.85rem;
  padding: 6px 14px;
  border-radius: 999px;
  cursor: pointer;
  color: var(--muted);
  transition: all 0.2s ease;
}

.lang-toggle button[aria-pressed="true"],
.level-toggle button[aria-pressed="true"] {
  background: var(--ink);
  color: var(--paper);
}

.page {
  padding: 40px 6vw 80px;
  display: flex;
  flex-direction: column;
  gap: 48px;
  max-width: 1200px;
  margin: 0 auto;
}

.hero {
  display: grid;
  gap: 32px;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  align-items: center;
}

.hero-text {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.hero-text h1 {
  font-family: var(--display);
  font-size: clamp(2.2rem, 4vw, 3.6rem);
  margin: 0.2rem 0 1rem;
  line-height: 1.1;
}

.lede {
  font-size: 1.1rem;
  max-width: 540px;
  color: var(--muted);
}

.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 20px;
}

.tag {
  padding: 6px 12px;
  border-radius: 999px;
  background: rgba(27, 154, 170, 0.1);
  color: var(--teal);
  font-size: 0.85rem;
  font-weight: 600;
}

.hero-card {
  background: var(--card);
  padding: 24px;
  border-radius: 24px;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
}

.hero-card h2 {
  margin-top: 0;
  font-family: var(--display);
  font-size: 1.4rem;
}

.hero-card ul {
  padding-left: 18px;
  margin: 0;
  color: var(--muted);
}

.search-row {
  display: flex;
  align-items: center;
  gap: 14px;
  background: rgba(255, 255, 255, 0.85);
  border: 1px solid var(--border);
  padding: 12px 14px;
  border-radius: 16px;
  box-shadow: 0 16px 30px rgba(15, 23, 42, 0.08);
}

.search-row input {
  flex: 1;
  border: none;
  outline: none;
  background: transparent;
  padding: 8px 6px;
  font-size: 1rem;
}

.count {
  font-size: 0.9rem;
  color: var(--muted);
}

.paper-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
}

.paper-card {
  background: var(--card);
  padding: 22px;
  border-radius: 18px;
  border: 1px solid var(--border);
  box-shadow: 0 18px 32px rgba(15, 23, 42, 0.08);
  display: flex;
  flex-direction: column;
  gap: 10px;
  transition: transform 0.2s ease;
}

.paper-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 24px 36px rgba(15, 23, 42, 0.12);
}

.hidden-card {
  display: none;
}

.paper-card h3 {
  margin: 0;
  font-family: var(--display);
  font-size: 1.2rem;
}

.pill-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.pill {
  padding: 4px 10px;
  border-radius: 999px;
  background: rgba(21, 25, 34, 0.06);
  font-size: 0.8rem;
  color: var(--muted);
}

.card {
  background: var(--card);
  padding: 22px;
  border-radius: 20px;
  border: 1px solid var(--border);
  box-shadow: 0 20px 40px rgba(15, 23, 42, 0.08);
}

.card h2,
.card h3 {
  font-family: var(--display);
  margin-top: 0;
}

.step-list {
  margin: 0;
  padding-left: 20px;
  color: var(--muted);
}

.view.hidden {
  display: none;
}

.paper-hero {
  display: grid;
  gap: 24px;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  align-items: center;
  margin-bottom: 10px;
}

.paper-title {
  font-family: var(--display);
  font-size: clamp(2rem, 3.4vw, 3rem);
  margin: 0 0 12px;
}

.paper-subtitle {
  color: var(--muted);
  margin: 0 0 16px;
}

.paper-meta {
  display: grid;
  gap: 16px;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.meta-card {
  background: var(--card);
  border-radius: 18px;
  padding: 16px;
  border: 1px solid var(--border);
}

.meta-card h3 {
  margin-top: 0;
  font-family: var(--display);
}

.meta-list {
  margin: 0;
  padding-left: 18px;
  color: var(--muted);
}

.paper-sections {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.section-card {
  background: var(--card);
  border-radius: 22px;
  padding: 22px;
  border: 1px solid var(--border);
  box-shadow: 0 20px 40px rgba(15, 23, 42, 0.08);
}

.section-card h2 {
  margin-top: 0;
  font-family: var(--display);
}

.note {
  margin-top: 12px;
  font-size: 0.95rem;
  color: var(--muted);
  border-left: 3px solid rgba(27, 154, 170, 0.4);
  padding-left: 12px;
}

.code {
  font-family: "JetBrains Mono", "SFMono-Regular", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.9rem;
  background: rgba(21, 25, 34, 0.06);
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid rgba(21, 25, 34, 0.08);
  margin-top: 0;
}

.back-btn {
  border: 1px solid var(--border);
  background: var(--card);
  border-radius: 999px;
  padding: 10px 16px;
  cursor: pointer;
  font-family: var(--display);
  margin-bottom: 16px;
  box-shadow: 0 10px 20px rgba(15, 23, 42, 0.08);
}

.footer {
  padding: 30px 8vw 50px;
  color: var(--muted);
  font-size: 0.95rem;
}

.lang[data-lang="zh"] {
  display: none;
}

html[data-lang="zh"] .lang[data-lang="zh"] {
  display: initial;
}

html[data-lang="zh"] .lang[data-lang="en"] {
  display: none;
}

html[data-lang="en"] .lang[data-lang="en"] {
  display: initial;
}

html[data-lang="en"] .lang[data-lang="zh"] {
  display: none;
}

.level {
  display: none;
}

html[data-level="hs"] .level[data-level="hs"],
html[data-level="grad"] .level[data-level="grad"] {
  display: block;
}

.muted {
  color: var(--muted);
}

@keyframes float {
  0%, 100% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(28px);
  }
}

@media (max-width: 900px) {
  .topbar {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (max-width: 600px) {
  .page {
    padding: 28px 6vw 60px;
  }

  .hero-card {
    padding: 18px;
  }
}