:root {
  --yd-bg: #F6F8FC;
  --yd-bg-soft: #EEF4FF;
  --yd-text-main: #0F172A;
  --yd-text-muted: #64748B;
  --yd-primary: #2563EB;
  --yd-primary-dark: #1D4ED8;
  --yd-accent: #22C55E;
  --yd-warm: #F59E0B;
  --yd-card: rgba(255,255,255,0.78);
  --yd-card-strong: rgba(255,255,255,0.92);
  --yd-border: rgba(148,163,184,0.22);
  --yd-border-strong: rgba(37,99,235,0.24);
  --yd-shadow: 0 24px 80px rgba(15, 23, 42, 0.10);
  --yd-shadow-soft: 0 14px 44px rgba(15, 23, 42, 0.07);
  --yd-radius-xl: 32px;
  --yd-radius-lg: 26px;
  --yd-radius-md: 20px;
  --yd-pill: 999px;
  --yd-blur: blur(22px) saturate(160%);
  --bg: var(--yd-bg);
  --surface: var(--yd-card);
  --surface-soft: var(--yd-card);
  --ink: var(--yd-text-main);
  --muted: var(--yd-text-muted);
  --line: var(--yd-border);
  --line-soft: var(--yd-border);
  --blue: var(--yd-primary);
  --blue-dark: var(--yd-primary-dark);
  --green: var(--yd-accent);
  --orange: var(--yd-warm);
  --radius: var(--yd-radius-lg);
  --shadow: var(--yd-shadow-soft);
  font-family: "Inter", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}


* {
  box-sizing: border-box;
}

body {
  color: var(--yd-text-main);
  background:
    radial-gradient(circle at 12% 8%, rgba(37, 99, 235, 0.13), transparent 30%),
    radial-gradient(circle at 82% 12%, rgba(124, 58, 237, 0.12), transparent 28%),
    radial-gradient(circle at 76% 78%, rgba(34, 197, 94, 0.10), transparent 30%),
    linear-gradient(135deg, #F8FBFF 0%, var(--yd-bg) 42%, #EEF4FF 100%);
  background-attachment: fixed;
  font-size: 16px;
  line-height: 1.65;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  opacity: 0.42;
  background-image:
    linear-gradient(rgba(37, 99, 235, 0.055) 1px, transparent 1px),
    linear-gradient(90deg, rgba(37, 99, 235, 0.055) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: linear-gradient(180deg, #000 0%, rgba(0,0,0,0.55) 52%, transparent 100%);
}

a,
button,
.button,
.pricing-card,
.tool-cover-card,
.task-item,
.pay-card,
.site-header {
  transition: transform 220ms ease, box-shadow 220ms ease, border-color 220ms ease, background 220ms ease, color 220ms ease, opacity 220ms ease;
}

.site-header {
  position: sticky;
  top: 14px;
  z-index: 50;
  width: min(1180px, calc(100% - 28px));
  min-height: 66px;
  margin: 14px auto 0;
  padding: 10px 12px 10px 18px;
  border: 1px solid rgba(148,163,184,0.22);
  border-radius: var(--yd-pill);
  background: rgba(255,255,255,0.76);
  backdrop-filter: var(--yd-blur);
  -webkit-backdrop-filter: var(--yd-blur);
  box-shadow: 0 18px 60px rgba(15,23,42,0.08);
}

.brand img {
  width: 174px;
  height: 38px;
  object-fit: contain;
}

.nav-links {
  gap: 4px;
  padding: 4px;
  border: 1px solid rgba(148,163,184,0.18);
  background: rgba(241,245,249,0.64);
  box-shadow: inset 0 1px 0 rgba(255,255,255,0.80);
}

.nav-links a,
.nav-action,
.nav-logout {
  min-height: 36px;
  padding: 0 16px;
  color: var(--yd-text-muted);
  border-radius: var(--yd-pill);
  font-size: 14px;
  font-weight: 700;
}

.nav-links a:hover {
  color: var(--yd-text-main);
  background: rgba(255,255,255,0.78);
}

.nav-links a.is-active {
  color: var(--yd-primary-dark);
  background: rgba(255,255,255,0.96);
  box-shadow: 0 10px 26px rgba(37,99,235,0.10);
}

.nav-action {
  color: #fff;
  border: 0;
  background: linear-gradient(135deg, var(--yd-primary), var(--yd-primary-dark));
  box-shadow: 0 16px 36px rgba(37,99,235,0.22);
}

.nav-action:hover,
.button.primary:hover,
.purchase-button:hover {
  transform: translateY(-1px);
  box-shadow: 0 20px 44px rgba(37,99,235,0.26);
}

main,
.page-shell {
  width: min(1180px, calc(100% - 40px));
}

.eyebrow,
.cover-kicker {
  color: var(--yd-primary);
  font-size: 12px;
  font-weight: 850;
  letter-spacing: 0.02em;
}

h1,
h2,
h3 {
  color: var(--yd-text-main);
  letter-spacing: 0;
}

.lead,
.muted,
.pricing-card p,
.tool-cover-card p,
.task-item p {
  color: var(--yd-text-muted);
  line-height: 1.72;
}

.button,
.purchase-button,
.standard-choice,
.pay-close {
  border-radius: var(--yd-pill);
}

.button {
  min-height: 44px;
  padding: 0 20px;
  border: 1px solid rgba(148,163,184,0.24);
  background: rgba(255,255,255,0.82);
  color: var(--yd-text-main);
  box-shadow: 0 12px 30px rgba(15,23,42,0.06);
  font-weight: 750;
}

.button.primary {
  color: #fff;
  border-color: transparent;
  background: linear-gradient(135deg, var(--yd-primary), var(--yd-primary-dark));
}

.button.secondary,
.button.ghost {
  color: var(--yd-primary-dark);
  background: rgba(255,255,255,0.70);
}

.hero {
  position: relative;
  min-height: calc(100vh - 116px);
  grid-template-columns: minmax(0, 0.95fr) minmax(420px, 1.05fr);
  gap: clamp(42px, 7vw, 96px);
  padding: clamp(54px, 7vw, 90px) 0 clamp(58px, 8vw, 96px);
}

.hero::before {
  content: "";
  position: absolute;
  inset: 18px -28px auto auto;
  width: 380px;
  height: 380px;
  border: 1px solid rgba(37,99,235,0.14);
  border-radius: 50%;
  background:
    radial-gradient(circle, rgba(37,99,235,0.09), transparent 58%);
  pointer-events: none;
}

.hero-copy {
  order: 1;
  position: relative;
  z-index: 2;
}

.hero-product {
  order: 2;
  position: relative;
  z-index: 2;
}

.hero h1 {
  max-width: 680px;
  margin-bottom: 22px;
  font-size: clamp(40px, 5.1vw, 64px);
  line-height: 1.03;
}

.hero .lead {
  max-width: 680px;
  font-size: clamp(16px, 1.45vw, 18px);
}

.promo-video-shell {
  border-radius: var(--yd-radius-xl);
  border: 1px solid rgba(148,163,184,0.26);
  background:
    linear-gradient(135deg, rgba(255,255,255,0.90), rgba(239,246,255,0.68)),
    var(--yd-card);
  box-shadow: var(--yd-shadow);
  backdrop-filter: var(--yd-blur);
  -webkit-backdrop-filter: var(--yd-blur);
}

.premium-product-preview {
  position: absolute;
  left: 26px;
  right: 26px;
  bottom: -26px;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 10px;
  padding: 12px;
  border: 1px solid rgba(148,163,184,0.24);
  border-radius: 24px;
  background: rgba(255,255,255,0.78);
  box-shadow: 0 18px 50px rgba(15,23,42,0.12);
  backdrop-filter: blur(18px) saturate(150%);
  -webkit-backdrop-filter: blur(18px) saturate(150%);
}

.premium-product-preview span {
  min-height: 54px;
  display: grid;
  place-items: center;
  border: 1px solid rgba(148,163,184,0.18);
  border-radius: 16px;
  color: var(--yd-text-main);
  background:
    radial-gradient(circle at 18% 18%, rgba(37,99,235,0.12), transparent 42%),
    rgba(248,250,252,0.86);
  font-size: 13px;
  font-weight: 800;
  text-align: center;
}

.promo-banner-section {
  width: min(1180px, calc(100vw - 40px));
  margin: clamp(-28px, -2.4vw, -12px) auto clamp(34px, 5vw, 64px);
  position: relative;
  z-index: 3;
}

.promo-banner-card {
  display: block;
  border-radius: clamp(18px, 2vw, 28px);
  overflow: hidden;
  box-shadow: 0 22px 60px rgba(37, 99, 235, 0.13);
  transition: transform 220ms ease, box-shadow 220ms ease;
}

.promo-banner-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 26px 70px rgba(37, 99, 235, 0.18);
}

.promo-banner-card img,
.tools-vip-banner-section img {
  display: block;
  width: 100%;
  height: auto;
}

.section,
.flow-section,
.final-cta,
.pricing-page,
.my-page {
  position: relative;
}

.advantage-grid article,
.flow-line article,
.pricing-card,
.referral-panel,
.pricing-seo-links a,
.task-panel,
.delivery-panel,
.task-item,
.pay-card,
.tools-search-bar,
.tools-hero-panel,
.tool-cover-card {
  border: 1px solid var(--yd-border);
  border-radius: var(--yd-radius-xl);
  background: var(--yd-card);
  box-shadow: var(--yd-shadow-soft);
  backdrop-filter: var(--yd-blur);
  -webkit-backdrop-filter: var(--yd-blur);
}

.advantage-grid article {
  padding: 26px;
}

.advantage-grid article span {
  color: var(--yd-primary);
}

.advantage-grid article:hover,
.pricing-card:hover,
.tool-cover-card:hover,
.task-item:hover {
  transform: translateY(-4px);
  border-color: rgba(37,99,235,0.28);
  box-shadow: 0 26px 70px rgba(37,99,235,0.11);
}

.flow-section {
  align-items: center;
  padding: clamp(42px, 7vw, 72px) 0;
}

.flow-line article {
  padding: 24px;
  min-width: 160px;
}

.flow-line i {
  background: linear-gradient(90deg, rgba(37,99,235,0.18), rgba(34,197,94,0.18));
}

.final-cta {
  overflow: hidden;
  margin: 54px 0 80px;
  padding: clamp(42px, 6vw, 68px);
  border: 1px solid rgba(37,99,235,0.18);
  border-radius: 36px;
  background:
    radial-gradient(circle at 18% 20%, rgba(37,99,235,0.18), transparent 34%),
    radial-gradient(circle at 86% 24%, rgba(124,58,237,0.14), transparent 32%),
    linear-gradient(135deg, rgba(255,255,255,0.86), rgba(238,244,255,0.78));
  box-shadow: var(--yd-shadow);
}

.final-cta::after {
  content: "";
  position: absolute;
  right: -80px;
  bottom: -110px;
  width: 300px;
  height: 300px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(34,197,94,0.18), transparent 64%);
  pointer-events: none;
}

.site-footer {
  width: min(1180px, calc(100% - 40px));
  margin: 0 auto 24px;
  border: 1px solid rgba(148,163,184,0.18);
  border-radius: 24px;
  background: rgba(255,255,255,0.58);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
}

body[data-page="pricing"] .pricing-page {
  padding: clamp(44px, 6vw, 76px) 0 76px;
}

.pricing-grid.store-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
  align-items: stretch;
}

.pricing-card {
  position: relative;
  overflow: hidden;
  padding: 26px;
  border-radius: var(--yd-radius-xl);
}

.pricing-card::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(circle at 80% 12%, rgba(37,99,235,0.10), transparent 34%),
    linear-gradient(180deg, rgba(255,255,255,0.28), transparent 46%);
}

.pricing-card > * {
  position: relative;
  z-index: 1;
}

.standard-pack-card {
  border-color: rgba(37,99,235,0.42);
  box-shadow: 0 26px 82px rgba(37,99,235,0.16);
}

.standard-pack-card::after {
  content: "推荐";
  position: absolute;
  top: 18px;
  right: 18px;
  z-index: 2;
  display: inline-flex;
  min-height: 30px;
  align-items: center;
  padding: 0 12px;
  border-radius: var(--yd-pill);
  color: #fff;
  background: linear-gradient(135deg, var(--yd-primary), #7C3AED);
  font-size: 12px;
  font-weight: 850;
}

.trial-badge,
.plan-policy-tags span,
.standard-price-line span,
.referral-rules article,
.pricing-seo-links a span,
.demo-badge,
.status-pill {
  border: 1px solid rgba(148,163,184,0.20);
  border-radius: var(--yd-pill);
  background: rgba(255,255,255,0.72);
}

body[data-page="pricing"] .trial-badge {
  position: absolute;
  top: 18px;
  right: 18px;
  left: auto;
  width: auto;
  min-width: 0;
  min-height: 30px;
  padding: 0 12px;
  color: #fff;
  background: linear-gradient(135deg, var(--yd-warm), #F97316);
  box-shadow: 0 12px 24px rgba(245,158,11,0.20);
}

body[data-page="pricing"] .pricing-seo-links a span {
  display: block;
  border: 0;
  border-radius: 0;
  background: transparent;
  padding: 0;
}

.plan-price strong {
  color: var(--yd-primary-dark);
  font-size: clamp(38px, 4vw, 54px);
  letter-spacing: -0.02em;
}

.standard-price-line {
  gap: 8px;
}

.standard-price-line span {
  color: var(--yd-primary-dark);
  font-weight: 850;
}

.plan-features {
  color: var(--yd-text-main);
}

.plan-features li {
  line-height: 1.62;
}

.plan-features li::marker {
  color: var(--yd-accent);
}

.referral-panel {
  margin-top: 24px;
  padding: 30px;
  background:
    radial-gradient(circle at 88% 20%, rgba(34,197,94,0.15), transparent 32%),
    rgba(255,255,255,0.76);
}

.referral-link-box {
  border-color: rgba(37,99,235,0.18);
  border-radius: 22px;
  background: rgba(248,250,252,0.76);
}

.standard-plan-sheet,
.pay-card {
  border-radius: 30px;
}

.qr-frame {
  border-radius: 24px;
  background: rgba(248,250,252,0.92);
}

body[data-page="tools"] {
  background:
    radial-gradient(circle at 10% 10%, rgba(37,99,235,0.12), transparent 28%),
    radial-gradient(circle at 88% 18%, rgba(124,58,237,0.10), transparent 26%),
    linear-gradient(135deg, #F8FBFF, #EEF4FF);
}

.tools-page {
  --tools-nav-space: 154px;
  --tools-page-width: min(1280px, calc(100vw - var(--tools-nav-space) - 48px));
  width: var(--tools-page-width);
  margin-left: calc(var(--tools-nav-space) + (100vw - var(--tools-nav-space) - var(--tools-page-width)) / 2);
  margin-right: auto;
  padding: clamp(36px, 5vw, 62px) 0 72px;
}

.tools-side-nav {
  position: fixed;
  left: 14px;
  top: 96px;
  bottom: 22px;
  z-index: 20;
  width: 126px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin: 0;
  padding: 10px;
  overflow: auto;
  border-radius: 22px;
  background: rgba(255,255,255,0.72);
  border: 1px solid rgba(148,163,184,0.18);
  box-shadow: var(--yd-shadow-soft);
  backdrop-filter: blur(18px);
}

.tools-side-nav button {
  position: relative;
  min-height: 38px;
  display: flex;
  align-items: center;
  border: 1px solid transparent;
  border-radius: var(--yd-pill);
  padding: 0 12px;
  color: var(--yd-text-muted);
  text-align: left;
  background: rgba(255,255,255,0.56);
  overflow: hidden;
  isolation: isolate;
  transition: color .22s ease, background .22s ease, border-color .22s ease, box-shadow .22s ease;
}

.tools-side-nav button::before {
  content: "";
  position: absolute;
  left: 50%;
  bottom: -58px;
  z-index: 1;
  width: 118px;
  height: 118px;
  border-radius: 50%;
  background:
    radial-gradient(circle at 35% 25%, rgba(255,255,255,.96), rgba(255,255,255,.28) 42%, transparent 64%),
    linear-gradient(135deg, rgba(219,234,254,.96), rgba(191,219,254,.92));
  transform: translateX(-50%) scale(0);
  transform-origin: 50% 88%;
  transition: transform 340ms cubic-bezier(.22, 1, .36, 1);
  pointer-events: none;
}

.tools-side-nav button span {
  position: relative;
  z-index: 2;
  display: block;
  line-height: 1;
}

.tools-side-nav button:hover {
  color: var(--yd-primary-dark);
  background: rgba(255,255,255,0.58);
}

.tools-side-nav button:hover::before {
  transform: translateX(-50%) scale(1);
}

.tools-side-nav button.is-active {
  color: var(--yd-primary-dark);
  border-color: rgba(37,99,235,0.18);
  background: linear-gradient(180deg, rgba(255,255,255,0.96), rgba(239,246,255,0.90));
  box-shadow: 0 10px 24px rgba(37,99,235,0.10), inset 0 1px 0 rgba(255,255,255,0.92);
}

.tools-side-nav button.is-active::before {
  display: none;
}

.tools-side-nav button.is-active::after {
  content: "";
  position: absolute;
  right: 11px;
  top: 50%;
  z-index: 3;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: #2563eb;
  transform: translateY(-50%) scale(1);
  transform-origin: center;
  animation: yd-side-nav-active-pop 360ms cubic-bezier(.18, 1.3, .35, 1) both;
}

@keyframes yd-side-nav-active-pop {
  0% {
    opacity: 0;
    transform: translateY(-50%) translateX(7px) scale(.45);
  }
  70% {
    opacity: 1;
    transform: translateY(-50%) translateX(-1px) scale(1.08);
  }
  100% {
    opacity: 1;
    transform: translateY(-50%) translateX(0) scale(1);
  }
}

.tools-catalog {
  gap: 18px;
}

.tools-hero-panel {
  position: relative;
  overflow: hidden;
  padding: clamp(30px, 5vw, 48px);
  background:
    radial-gradient(circle at 12% 18%, rgba(37,99,235,0.16), transparent 34%),
    radial-gradient(circle at 88% 20%, rgba(34,197,94,0.12), transparent 32%),
    rgba(255,255,255,0.72);
}

.tools-hero-panel h1 {
  margin: 0;
  font-size: clamp(36px, 4.8vw, 58px);
}

.tools-hero-panel p {
  max-width: 760px;
  margin: 12px 0 0;
  color: var(--yd-text-muted);
  font-size: 17px;
}

.tools-search-bar {
  grid-template-columns: 1fr;
  gap: 8px;
  min-height: auto;
  padding: 16px;
  border-radius: 26px;
}

.tools-vip-banner-section {
  overflow: hidden;
  margin: 0 0 12px;
  border-radius: clamp(14px, 1.5vw, 22px);
  box-shadow: 0 12px 32px rgba(37, 99, 235, 0.08);
}

.tools-search-bar label {
  color: var(--yd-text-main);
  font-size: 13px;
}

.tools-search-bar input {
  min-height: 48px;
  border-radius: var(--yd-pill);
  border-color: rgba(148,163,184,0.24);
  background: rgba(255,255,255,0.82);
  font-size: 16px;
}

.tool-cover-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
}

.tool-cover-card {
  min-height: 284px;
  padding: 20px;
  border-radius: 28px;
}

.tool-cover-card::before {
  opacity: 0.78;
}

.tool-cover-card h2 {
  font-size: 21px;
  line-height: 1.22;
}

.tool-cover-card p {
  font-size: 14px;
  line-height: 1.62;
}

.tool-cover-card b {
  display: inline-flex;
  width: fit-content;
  min-height: 34px;
  align-items: center;
  padding: 0 13px;
  border-radius: var(--yd-pill);
  color: var(--yd-primary-dark);
  background: rgba(255,255,255,0.78);
  border: 1px solid rgba(37,99,235,0.16);
  font-size: 13px;
}

.cover-visual {
  min-height: 92px;
  border-radius: 20px;
}

body[data-page="my"] .my-page {
  padding: clamp(42px, 6vw, 72px) 0 80px;
}

.dashboard-head {
  align-items: center;
  margin-bottom: 20px;
  padding: clamp(30px, 5vw, 48px);
  border: 1px solid var(--yd-border);
  border-radius: 34px;
  background:
    radial-gradient(circle at 82% 16%, rgba(37,99,235,0.14), transparent 32%),
    rgba(255,255,255,0.74);
  box-shadow: var(--yd-shadow-soft);
  backdrop-filter: var(--yd-blur);
}

.dashboard-head h1 {
  font-size: clamp(38px, 5vw, 58px);
}

.my-workspace {
  gap: 18px;
}

.task-panel,
.delivery-panel {
  padding: 24px;
}

.task-list {
  display: grid;
  gap: 14px;
}

.task-item {
  padding: 20px;
  border-radius: 24px;
}

.task-item.is-empty {
  min-height: 220px;
  align-items: center;
  justify-content: center;
  text-align: center;
  background:
    radial-gradient(circle at 50% 0%, rgba(37,99,235,0.12), transparent 42%),
    rgba(255,255,255,0.78);
}

.delivery-panel {
  margin-top: 18px;
}

.login-sheet,
.pay-sheet {
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.login-card,
.pay-card {
  border: 1px solid rgba(148,163,184,0.24);
  background: rgba(255,255,255,0.88);
  box-shadow: 0 28px 90px rgba(15,23,42,0.18);
  backdrop-filter: var(--yd-blur);
}

.wechat-login-box,
.wechat-login-qr {
  border-radius: 22px;
}

@media (max-width: 1180px) {
  .pricing-grid.store-grid,
  .tool-cover-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

  .hero-product,
  .hero-copy {
    order: initial;
  }
}

@media (max-width: 760px) {
  body {
    font-size: 15px;
  }

  .site-header {
    top: 8px;
    width: calc(100% - 20px);
    align-items: flex-start;
    border-radius: 24px;
    flex-wrap: wrap;
  }

  .brand img {
    width: 138px;
    height: 34px;
  }

  .nav-links {
    order: 3;
    width: 100%;
    overflow-x: auto;
    justify-content: flex-start;
  }

  .nav-links a {
    flex: 0 0 auto;
  }

  main,
  .page-shell,
  .tools-page,
  .site-footer {
    width: min(100% - 24px, 1180px);
  }

  .tools-page {
    margin-left: auto;
    margin-right: auto;
  }

  .hero {
    min-height: auto;
    padding: 38px 0 60px;
  }

  .hero h1 {
    font-size: clamp(38px, 11vw, 42px);
  }

  .premium-product-preview {
    position: static;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    margin-top: 12px;
  }

  .pricing-grid.store-grid,
  .tool-cover-grid {
    grid-template-columns: 1fr;
  }

  .tools-side-nav {
    position: static;
    width: auto;
    flex-direction: row;
    overflow-x: auto;
    flex-wrap: nowrap;
    margin-bottom: 14px;
  }

  .tools-side-nav button {
    flex: 0 0 auto;
    text-align: center;
  }

  .final-cta,
  .dashboard-head,
  .tools-hero-panel {
    padding: 26px;
  }
}

/* Premium tool-card system: unified SaaS-style tiles for the classroom toolbox. */
body[data-page="tools"] .tool-cover-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
  align-items: stretch;
}

body[data-page="tools"] .tool-cover-card {
  --tool-accent: #3B82F6;
  --tool-accent-2: #38BDF8;
  --tool-soft: rgba(59,130,246,0.08);
  position: relative;
  min-height: 268px;
  padding: 18px;
  border: 1px solid rgba(148,163,184,0.24);
  border-radius: 26px;
  background:
    linear-gradient(180deg, rgba(255,255,255,0.82), rgba(255,255,255,0.64)),
    radial-gradient(circle at 82% 12%, var(--tool-soft), transparent 34%);
  box-shadow: 0 18px 45px rgba(15,23,42,0.075);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  overflow: hidden;
  isolation: isolate;
  transition:
    transform 210ms ease,
    box-shadow 210ms ease,
    border-color 210ms ease,
    background 210ms ease;
}

body[data-page="tools"] .tool-cover-card::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -2;
  opacity: 1;
  background:
    linear-gradient(135deg, rgba(255,255,255,0.72), rgba(255,255,255,0.20)),
    radial-gradient(circle at 16% 14%, rgba(255,255,255,0.98), transparent 24%),
    radial-gradient(circle at 92% 2%, color-mix(in srgb, var(--tool-accent) 18%, transparent), transparent 34%),
    radial-gradient(circle at 84% 18%, color-mix(in srgb, var(--tool-accent-2) 10%, transparent), transparent 28%);
}

body[data-page="tools"] .tool-cover-card::after {
  content: "";
  position: absolute;
  left: 18px;
  right: 18px;
  top: 0;
  height: 3px;
  border-radius: 0 0 999px 999px;
  background: linear-gradient(90deg, var(--tool-accent), var(--tool-accent-2));
  opacity: 0.58;
}

body[data-page="tools"] .tool-cover-card:hover {
  transform: translateY(-4px);
  border-color: color-mix(in srgb, var(--tool-accent) 28%, rgba(148,163,184,0.24));
  box-shadow: 0 26px 70px rgba(15,23,42,0.12);
}

body[data-page="tools"] .tool-cover-card > * {
  position: relative;
  z-index: 1;
}

body[data-page="tools"] .cover-kicker {
  display: inline-flex;
  width: fit-content;
  min-height: 24px;
  align-items: center;
  padding: 0 9px;
  border: 1px solid color-mix(in srgb, var(--tool-accent) 22%, rgba(148,163,184,0.22));
  border-radius: 999px;
  color: var(--tool-accent);
  background: rgba(255,255,255,0.66);
  font-size: 11px;
  font-weight: 850;
  letter-spacing: 0.01em;
}

body[data-page="tools"] .tool-cover-card h2 {
  min-height: 52px;
  margin: 12px 0 8px;
  color: var(--yd-text-main);
  font-size: 20px;
  line-height: 1.28;
  letter-spacing: 0;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

body[data-page="tools"] .tool-cover-card p {
  min-height: 66px;
  margin: 0;
  color: var(--yd-text-muted);
  font-size: 13.5px;
  line-height: 1.62;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

body[data-page="tools"] .cover-visual {
  position: relative;
  min-height: 94px;
  margin: 14px 0 0;
  border: 1px solid rgba(148,163,184,0.20);
  border-radius: 20px;
  background:
    linear-gradient(rgba(37,99,235,0.055) 1px, transparent 1px),
    linear-gradient(90deg, rgba(37,99,235,0.055) 1px, transparent 1px),
    radial-gradient(circle at 70% 20%, color-mix(in srgb, var(--tool-accent) 18%, transparent), transparent 36%),
    rgba(255,255,255,0.72);
  background-size: 18px 18px, 18px 18px, auto, auto;
  box-shadow: inset 0 1px 0 rgba(255,255,255,0.72);
  overflow: hidden;
}

body[data-page="tools"] .cover-visual::after {
  content: "";
  position: absolute;
  inset: auto 14px 12px;
  height: 5px;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--tool-accent), var(--tool-accent-2));
  opacity: 0.18;
}

body[data-page="tools"] .tool-cover-card b {
  display: inline-flex;
  width: fit-content;
  min-height: 30px;
  align-items: center;
  justify-content: center;
  margin-top: 14px;
  padding: 0 12px;
  border: 1px solid color-mix(in srgb, var(--tool-accent) 20%, rgba(148,163,184,0.24));
  border-radius: 999px;
  color: var(--tool-accent);
  background: rgba(255,255,255,0.70);
  font-size: 12px;
  font-weight: 850;
}

body[data-page="tools"] .tool-cover-card:hover b {
  color: #fff;
  background: linear-gradient(135deg, var(--tool-accent), var(--tool-accent-2));
}

body[data-page="tools"] .tool-cover-card[data-category="tool"] {
  --tool-accent: #3B82F6;
  --tool-accent-2: #38BDF8;
  --tool-soft: rgba(59,130,246,0.08);
}

body[data-page="tools"] .tool-cover-card[data-category="math"] {
  --tool-accent: #4F46E5;
  --tool-accent-2: #06B6D4;
  --tool-soft: rgba(79,70,229,0.08);
}

body[data-page="tools"] .tool-cover-card[data-category="physics"] {
  --tool-accent: #0284C7;
  --tool-accent-2: #D97706;
  --tool-soft: rgba(2,132,199,0.08);
}

body[data-page="tools"] .tool-cover-card[data-category="chemistry"] {
  --tool-accent: #059669;
  --tool-accent-2: #0891B2;
  --tool-soft: rgba(5,150,105,0.08);
}

body[data-page="tools"] .tool-cover-card[data-category="english"] {
  --tool-accent: #7C3AED;
  --tool-accent-2: #A855F7;
  --tool-soft: rgba(124,58,237,0.08);
}

body[data-page="tools"] .tool-cover-card[data-category="biology"] {
  --tool-accent: #16A34A;
  --tool-accent-2: #65A30D;
  --tool-soft: rgba(22,163,74,0.08);
}

body[data-page="tools"] .tool-cover-card[data-category="geography"] {
  --tool-accent: #0F766E;
  --tool-accent-2: #2563EB;
  --tool-soft: rgba(15,118,110,0.08);
}

body[data-page="tools"] .tool-cover-card[data-category="history"] {
  --tool-accent: #B45309;
  --tool-accent-2: #BE123C;
  --tool-soft: rgba(180,83,9,0.08);
}

body[data-page="tools"] .name-visual strong,
body[data-page="tools"] .timer-visual strong {
  color: var(--yd-text-main);
  font-size: clamp(24px, 2.2vw, 32px);
}

body[data-page="tools"] .name-visual em,
body[data-page="tools"] .timer-visual em,
body[data-page="tools"] .score-visual em {
  color: var(--yd-text-muted);
}

body[data-page="tools"] .math-cover .cover-visual strong,
body[data-page="tools"] .physics-cover .cover-visual strong,
body[data-page="tools"] .chemistry-cover .cover-visual strong,
body[data-page="tools"] .biology-cover .cover-visual strong,
body[data-page="tools"] .geography-cover .cover-visual strong,
body[data-page="tools"] .history-cover .cover-visual strong {
  color: var(--yd-text-main);
  font-size: 18px;
  font-weight: 900;
}

body[data-page="tools"] .math-cover .cover-visual,
body[data-page="tools"] .physics-cover .cover-visual {
  background:
    linear-gradient(rgba(37,99,235,0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(37,99,235,0.06) 1px, transparent 1px),
    radial-gradient(circle at 74% 18%, color-mix(in srgb, var(--tool-accent) 16%, transparent), transparent 34%),
    rgba(255,255,255,0.74);
  background-size: 18px 18px, 18px 18px, auto, auto;
}

body[data-page="tools"] .group-visual {
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 8px;
  padding: 16px;
}

body[data-page="tools"] .group-visual span {
  display: grid;
  min-height: 42px;
  place-items: center;
  border-radius: 14px;
  color: var(--yd-text-main);
  background: rgba(255,255,255,0.70);
  font-size: 12px;
  font-weight: 850;
}

body[data-page="tools"] .quiet-visual {
  grid-auto-flow: column;
  gap: 8px;
}

body[data-page="tools"] .quiet-visual i {
  width: 12px;
  border-radius: 999px;
  background: linear-gradient(180deg, var(--tool-accent), var(--tool-accent-2));
}

body[data-page="tools"] .quiet-visual i:nth-child(1) { height: 34px; }
body[data-page="tools"] .quiet-visual i:nth-child(2) { height: 56px; }
body[data-page="tools"] .quiet-visual i:nth-child(3) { height: 42px; }

body[data-page="tools"] .quiet-visual strong {
  margin-left: 4px;
  color: var(--yd-text-main);
}

@media (max-width: 1180px) {
  body[data-page="tools"] .tool-cover-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (max-width: 900px) {
  body[data-page="tools"] .tool-cover-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 640px) {
  body[data-page="tools"] .tool-cover-grid {
    grid-template-columns: 1fr;
  }

  body[data-page="tools"] .tool-cover-card {
    min-height: 246px;
    padding: 16px;
  }
}

/* Generated tool card covers: unified AI-made entrance visuals. */
body[data-page="tools"] .tool-cover-card {
  min-height: 278px;
  justify-content: flex-start;
  gap: 0;
}

body[data-page="tools"] .tool-cover-card h2 {
  min-height: 48px;
  margin-bottom: 0;
}

body[data-page="tools"] .tool-cover-card p {
  display: none !important;
}

body[data-page="tools"] .cover-visual {
  display: none !important;
}

body[data-page="tools"] .cover-image {
  position: relative;
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  margin: 14px 0 0;
  border: 1px solid color-mix(in srgb, var(--tool-accent) 18%, rgba(148,163,184,0.18));
  border-radius: 20px;
  background:
    linear-gradient(135deg, rgba(255,255,255,0.85), rgba(255,255,255,0.42)),
    radial-gradient(circle at 78% 18%, color-mix(in srgb, var(--tool-accent) 16%, transparent), transparent 42%);
  box-shadow:
    inset 0 1px 0 rgba(255,255,255,0.75),
    0 14px 30px rgba(15,23,42,0.07);
  overflow: hidden;
}

body[data-page="tools"] .cover-image img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  transform: scale(1.01);
  transition: transform 240ms ease, filter 240ms ease;
}

body[data-page="tools"] .cover-image::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(180deg, rgba(255,255,255,0.03), rgba(15,23,42,0.08)),
    radial-gradient(circle at 86% 12%, color-mix(in srgb, var(--tool-accent-2) 16%, transparent), transparent 36%);
}

body[data-page="tools"] .tool-cover-card:hover .cover-image img {
  transform: scale(1.055);
  filter: saturate(1.05) contrast(1.02);
}

@media (max-width: 640px) {
  body[data-page="tools"] .tool-cover-card {
    min-height: 270px;
  }
}

/* Tool cards are fully clickable; hide redundant open buttons. */
body[data-page="tools"] .tool-cover-card b {
  display: none !important;
}

/* React Bits PillNav-inspired native navigation */
.pill-nav-shell.site-header {
  --pill-nav-base: rgba(255, 255, 255, 0.82);
  --pill-nav-surface: rgba(255, 255, 255, 0.94);
  --pill-nav-text: #0f172a;
  --pill-nav-hover-text: #1d4ed8;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  overflow: visible;
}

.pill-nav-shell .brand {
  flex: 0 0 auto;
  min-height: 48px;
  padding: 5px 16px;
  border: 1px solid rgba(148, 163, 184, 0.20);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.88);
  box-shadow: inset 0 1px 0 rgba(255,255,255,0.82), 0 12px 30px rgba(15, 23, 42, 0.06);
  overflow: hidden;
}

.pill-nav-shell .brand img {
  width: 168px;
  height: 36px;
  object-fit: contain;
  transition: transform 260ms ease;
}

.pill-nav-shell .brand:hover img {
  transform: rotate(1deg) scale(1.035);
}

.pill-nav-shell .nav-links.pill-nav-items {
  position: relative;
  height: 48px;
  display: inline-flex;
  align-items: stretch;
  justify-content: center;
  gap: 3px;
  margin: 0 auto;
  padding: 4px;
  border: 1px solid rgba(148, 163, 184, 0.20);
  border-radius: 999px;
  background: var(--pill-nav-base);
  box-shadow: inset 0 1px 0 rgba(255,255,255,0.82), 0 14px 34px rgba(15, 23, 42, 0.07);
}

.pill-nav-shell .nav-links.pill-nav-items a {
  position: relative;
  min-height: 40px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0 18px;
  border: 1px solid transparent;
  border-radius: 999px;
  background: rgba(255,255,255,0.58) !important;
  color: var(--pill-nav-text) !important;
  box-shadow: none;
  overflow: hidden;
  isolation: isolate;
  font-size: 14px;
  font-weight: 800;
  line-height: 1;
  white-space: nowrap;
}

.pill-nav-shell .nav-links.pill-nav-items a .hover-circle {
  position: absolute;
  left: 50%;
  bottom: -54px;
  z-index: 1;
  width: 136px;
  height: 136px;
  border-radius: 50%;
  background:
    radial-gradient(circle at 35% 25%, rgba(255,255,255,0.96), rgba(255,255,255,0.28) 42%, transparent 64%),
    linear-gradient(135deg, rgba(219,234,254,0.96), rgba(191,219,254,0.92));
  transform: translateX(-50%) scale(0);
  transform-origin: 50% 88%;
  transition: transform 340ms cubic-bezier(.22, 1, .36, 1);
  pointer-events: none;
}

.pill-nav-shell .nav-links.pill-nav-items a .label-stack {
  position: relative;
  z-index: 2;
  display: inline-block;
  height: 1em;
  line-height: 1;
  overflow: hidden;
}

.pill-nav-shell .nav-links.pill-nav-items a .pill-label,
.pill-nav-shell .nav-links.pill-nav-items a .pill-label-hover {
  display: block;
  line-height: 1;
  transition: transform 260ms cubic-bezier(.22, 1, .36, 1), opacity 220ms ease;
}

.pill-nav-shell .nav-links.pill-nav-items a .pill-label {
  color: inherit;
}

.pill-nav-shell .nav-links.pill-nav-items a .pill-label-hover {
  position: absolute;
  inset: 0 auto auto 0;
  color: var(--pill-nav-hover-text);
  opacity: 0;
  transform: translateY(155%);
}

.pill-nav-shell .nav-links.pill-nav-items a:hover .hover-circle {
  transform: translateX(-50%) scale(1);
}

.pill-nav-shell .nav-links.pill-nav-items a:hover .pill-label {
  transform: translateY(-155%);
}

.pill-nav-shell .nav-links.pill-nav-items a:hover .pill-label-hover {
  opacity: 1;
  transform: translateY(0);
}

.pill-nav-shell .nav-links.pill-nav-items a.is-active::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: -4px;
  z-index: 4;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: #2563eb;
  transform: translateX(-50%) scale(1);
  transform-origin: center;
  animation: yd-pill-active-pop 360ms cubic-bezier(.18, 1.3, .35, 1) both;
}

.pill-nav-shell .nav-links.pill-nav-items a.is-active {
  color: #1d4ed8 !important;
  border-color: rgba(37,99,235,0.18);
  background: linear-gradient(180deg, rgba(255,255,255,0.98), rgba(239,246,255,0.92)) !important;
  box-shadow: 0 10px 24px rgba(37,99,235,0.10), inset 0 1px 0 rgba(255,255,255,0.92);
  overflow: visible;
}

.pill-nav-shell .nav-links.pill-nav-items a.is-active .hover-circle {
  display: none;
}

.pill-nav-shell .nav-links.pill-nav-items a.is-active:hover .pill-label {
  transform: none;
}

.pill-nav-shell .nav-links.pill-nav-items a.is-active:hover .pill-label-hover {
  opacity: 0;
  transform: translateY(155%);
}

@keyframes yd-pill-active-pop {
  0% {
    opacity: 0;
    transform: translateX(-50%) translateY(7px) scale(.45);
  }
  70% {
    opacity: 1;
    transform: translateX(-50%) translateY(-1px) scale(1.08);
  }
  100% {
    opacity: 1;
    transform: translateX(-50%) translateY(0) scale(1);
  }
}

.pill-nav-shell .nav-user-group {
  flex: 0 0 auto;
  height: 48px;
  display: inline-flex;
  align-items: stretch;
  gap: 3px;
  padding: 4px;
  border: 1px solid rgba(148, 163, 184, 0.20);
  border-radius: 999px;
  background: var(--pill-nav-base);
  box-shadow: inset 0 1px 0 rgba(255,255,255,0.82), 0 14px 34px rgba(15, 23, 42, 0.07);
}

.pill-nav-shell .nav-action,
.pill-nav-shell .nav-logout {
  position: relative;
  min-height: 40px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0 18px;
  border: 1px solid transparent;
  border-radius: 999px;
  background: rgba(255,255,255,0.58) !important;
  color: var(--pill-nav-text) !important;
  box-shadow: none;
  overflow: hidden;
  isolation: isolate;
  font-size: 14px;
  font-weight: 800;
  line-height: 1;
  white-space: nowrap;
  cursor: pointer;
}

.pill-nav-shell .nav-action.is-user {
  max-width: 132px;
}

.pill-nav-shell .nav-action .hover-circle,
.pill-nav-shell .nav-logout .hover-circle {
  position: absolute;
  left: 50%;
  bottom: -54px;
  z-index: 1;
  width: 136px;
  height: 136px;
  border-radius: 50%;
  background:
    radial-gradient(circle at 35% 25%, rgba(255,255,255,0.96), rgba(255,255,255,0.28) 42%, transparent 64%),
    linear-gradient(135deg, rgba(219,234,254,0.96), rgba(191,219,254,0.92));
  transform: translateX(-50%) scale(0);
  transform-origin: 50% 88%;
  transition: transform 340ms cubic-bezier(.22, 1, .36, 1);
  pointer-events: none;
}

.pill-nav-shell .nav-action .label-stack,
.pill-nav-shell .nav-logout .label-stack {
  position: relative;
  z-index: 2;
  display: inline-block;
  max-width: 100%;
  height: 1em;
  line-height: 1;
  overflow: hidden;
  text-overflow: ellipsis;
}

.pill-nav-shell .nav-action .pill-label,
.pill-nav-shell .nav-action .pill-label-hover,
.pill-nav-shell .nav-logout .pill-label,
.pill-nav-shell .nav-logout .pill-label-hover {
  display: block;
  max-width: 100%;
  line-height: 1;
  overflow: hidden;
  text-overflow: ellipsis;
  transition: transform 260ms cubic-bezier(.22, 1, .36, 1), opacity 220ms ease;
}

.pill-nav-shell .nav-action .pill-label-hover,
.pill-nav-shell .nav-logout .pill-label-hover {
  position: absolute;
  inset: 0 auto auto 0;
  color: var(--pill-nav-hover-text);
  opacity: 0;
  transform: translateY(155%);
}

.pill-nav-shell .nav-action:hover .hover-circle,
.pill-nav-shell .nav-logout:hover .hover-circle {
  transform: translateX(-50%) scale(1);
}

.pill-nav-shell .nav-action:hover .pill-label,
.pill-nav-shell .nav-logout:hover .pill-label {
  transform: translateY(-155%);
}

.pill-nav-shell .nav-action:hover .pill-label-hover,
.pill-nav-shell .nav-logout:hover .pill-label-hover {
  opacity: 1;
  transform: translateY(0);
}

.pill-mobile-menu-button,
.pill-mobile-menu-popover {
  display: none;
}

@media (max-width: 860px) {
  .pill-nav-shell.site-header {
    min-height: 62px;
    padding: 9px 10px 9px 12px;
  }

  .pill-nav-shell .brand {
    min-height: 44px;
    padding: 5px 12px;
  }

  .pill-nav-shell .brand img {
    width: 142px;
    height: 32px;
  }

  .pill-nav-shell .nav-links.pill-nav-items {
    display: none;
  }

  .pill-nav-shell .nav-user-group {
    height: 44px;
    padding: 3px;
  }

  .pill-nav-shell .nav-action,
  .pill-nav-shell .nav-logout {
    min-height: 38px;
    padding: 0 12px;
    font-size: 13px;
  }

  .pill-nav-shell .nav-action.is-user {
    max-width: 92px;
  }

  .pill-mobile-menu-button {
    flex: 0 0 auto;
    width: 44px;
    height: 44px;
    display: inline-flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 5px;
    border: 0;
    border-radius: 999px;
    background: rgba(255,255,255,0.86);
    box-shadow: 0 12px 28px rgba(15, 23, 42, 0.08), inset 0 1px 0 rgba(255,255,255,0.88);
  }

  .pill-mobile-menu-button span {
    width: 17px;
    height: 2px;
    border-radius: 999px;
    background: #2563eb;
    transition: transform 220ms ease;
  }

  .pill-nav-shell.is-pill-menu-open .pill-mobile-menu-button span:first-child {
    transform: translateY(3.5px) rotate(45deg);
  }

  .pill-nav-shell.is-pill-menu-open .pill-mobile-menu-button span:last-child {
    transform: translateY(-3.5px) rotate(-45deg);
  }

  .pill-mobile-menu-popover {
    position: absolute;
    left: 12px;
    right: 12px;
    top: calc(100% + 8px);
    z-index: 80;
    display: grid;
    gap: 4px;
    padding: 5px;
    border: 1px solid rgba(148, 163, 184, 0.22);
    border-radius: 26px;
    background: rgba(255,255,255,0.92);
    box-shadow: 0 24px 60px rgba(15, 23, 42, 0.13);
    backdrop-filter: blur(18px) saturate(150%);
  }

  .pill-mobile-menu-popover[hidden] {
    display: none;
  }

  .pill-mobile-menu-popover a {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 42px;
    border-radius: 999px;
    color: #101827;
    font-size: 14px;
    font-weight: 800;
  }

  .pill-mobile-menu-popover a.is-active {
    color: #1d4ed8;
    background: linear-gradient(180deg, rgba(255,255,255,0.98), rgba(239,246,255,0.92));
    box-shadow: inset 0 0 0 1px rgba(37,99,235,0.16);
  }
}