:root {
  --bg: #0a0a0a;
  --card: rgba(22, 22, 22, 0.72);
  --card-border: rgba(255, 255, 255, 0.06);
  --text: rgba(255, 255, 255, 0.92);
  --muted: rgba(255, 255, 255, 0.62);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial,
    "Apple Color Emoji", "Segoe UI Emoji";
}

.topbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 64px;
  display: flex;
  align-items: center;
  z-index: 20;
  background: rgba(10, 10, 10, 0.78);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  box-shadow: 0 10px 28px rgba(0, 0, 0, 0.38);
}

.brand {
  font-weight: 700;
  letter-spacing: 0.14em;
  font-size: 14px;
  opacity: 0.9;
}

.handbook-name {
  font-weight: 650;
  letter-spacing: 0.02em;
  font-size: 13px;
  color: rgba(255, 255, 255, 0.85);
}

.brand__logo {
  height: 26px;
  width: auto;
  display: block;
  filter: drop-shadow(0 6px 18px rgba(0, 0, 0, 0.45));
}

.page {
  position: relative;
  min-height: 100vh;
  padding-top: 86px;
  padding-bottom: 56px;
  overflow: hidden;
}

.page__bg {
  position: absolute;
  inset: 0;
  background-image: url("../images/bg.jpg");
  background-size: contain;
  background-position: left bottom;
  background-repeat: no-repeat;
  filter: saturate(1.05) contrast(1.06) brightness(1.08);
  opacity: 0.82;
}

@media (min-width: 992px) {
  .page__bg {
    background-size: cover;
    background-position: center;
  }
}

.page__overlay {
  position: absolute;
  inset: 0;
  background: radial-gradient(1200px 700px at 50% 15%,
      rgba(0, 0, 0, 0.08),
      rgba(0, 0, 0, 0.48)),
    linear-gradient(rgba(0, 0, 0, 0.34), rgba(0, 0, 0, 0.58));
}

.page__content {
  position: relative;
  z-index: 10;
}

.hero-block {
  display: inline-block;
  text-align: center;
}

.page__title {
  margin-top: 6px;
  font-size: clamp(24px, 3.2vw, 34px);
  line-height: 1.12;
  font-weight: 750;
  text-align: center;
}

.page__subtitle {
  margin-top: 10px;
  margin-bottom: 0;
  max-width: 100%;
  color: var(--muted);
  font-size: 12.5px;
  text-align: center;
  margin-left: auto;
  margin-right: auto;
}

.topic-page .page__title {
  text-align: left;
}

.topic-page .page__subtitle {
  text-align: left;
  margin-left: 0;
  margin-right: 0;
}

.topic-card {
  display: block;
  text-decoration: none;
  color: var(--text);
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: 12px;
  padding: 12px 12px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.25);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  margin-bottom: 16px;
  text-align: left;
  transition: transform 140ms ease, background 140ms ease, border-color 140ms ease;
}

.topic-card--content {
  border: none;
}

.topic-grid .topic-card {
  margin-bottom: 0;
  height: 100%;
}

.topic-grid .topic-card__title {
  padding-bottom: 8px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.10);
}

.topic-grid .topic-card__desc {
  margin-top: 8px;
}

.topic-card:hover {
  transform: translateY(-2px);
  background: rgba(28, 28, 28, 0.78);
  border-color: rgba(255, 255, 255, 0.10);
  color: var(--text);
}

.topic-card__title {
  font-weight: 700;
  font-size: 14px;
  line-height: 1.25;
  display: block;
}

.topic-card__desc {
  margin-top: 6px;
  color: var(--muted);
  font-size: 10.75px;
  line-height: 1.35;
  overflow-wrap: anywhere;
  margin-left: 0;
  padding-left: 0;
  text-indent: 0;
  display: block;
  white-space: normal;
}

.footer {
  text-align: center;
  color: rgba(255, 255, 255, 0.55);
  font-size: 12px;
}

.footer__links {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px 16px;
  margin-bottom: 10px;
}

.footer__link {
  color: rgba(255, 255, 255, 0.55);
  text-decoration: none;
}

.footer__link:hover {
  color: rgba(255, 255, 255, 0.8);
  text-decoration: underline;
}

.footer__note {
  opacity: 0.85;
}

@media (max-width: 576px) {
  .page__content {
    padding-left: 18px;
    padding-right: 18px;
  }

  .topic-grid {
    max-width: 430px;
    margin-left: auto;
    margin-right: auto;
    --bs-gutter-x: 18px;
    --bs-gutter-y: 14px;
  }

  .topic-card {
    padding: 12px 12px;
    border-radius: 14px;
  }

  .topic-card__title {
    font-size: 12.5px;
  }

  .topic-card__desc {
    font-size: 10.5px;
    line-height: 1.3;
    display: -webkit-box;
    line-clamp: 2;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
  }

  .footer {
    margin-top: 38px !important;
  }

  .footer__links {
    gap: 8px 14px;
  }
}

.topic-topbar-link {
  color: rgba(255, 255, 255, 0.78);
  text-decoration: none;
  font-size: 13px;
}

.topic-topbar-link:hover {
  color: rgba(255, 255, 255, 0.92);
  text-decoration: underline;
}

.section-divider {
  height: 1px;
  background: rgba(255, 255, 255, 0.10);
}

.topic-nav {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-top: 28px;
}

.topic-nav a {
  color: rgba(255, 255, 255, 0.80);
  text-decoration: none;
  font-size: 13px;
}

.topic-nav a:hover {
  color: rgba(255, 255, 255, 0.95);
  text-decoration: underline;
}

.topic-nav .is-disabled {
  opacity: 0.35;
  pointer-events: none;
}

.topic-content {
  margin-top: 18px;
}

.topic-section {
  margin-top: 22px;
}

.topic-section__title {
  font-weight: 750;
  font-size: 14px;
  letter-spacing: 0.02em;
  color: rgba(255, 255, 255, 0.92);
  margin-bottom: 10px;
}

.topic-text {
  font-size: 13.5px;
  line-height: 1.7;
  color: rgba(255, 255, 255, 0.72);
  margin: 0;
}

.topic-text+.topic-text {
  margin-top: 10px;
}

.arrow-list {
  list-style: none;
  padding-left: 0;
  margin: 10px 0 0 0;
}

.arrow-box {
  margin-top: 12px;
  padding: 10px 10px;
  border-radius: 10px;
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.arrow-box .arrow-list {
  margin-top: 0;
}

.arrow-list li {
  display: flex;
  gap: 8px;
  align-items: flex-start;
  margin-top: 8px;
  color: rgba(255, 255, 255, 0.74);
  font-size: 13.5px;
  line-height: 1.55;
}

.arrow-list li::before {
  content: "\2192";
  color: rgba(255, 255, 255, 0.78);
  margin-top: 1px;
}

.topic-image {
  width: 100%;
  height: auto;
  border-radius: 12px;
  border: 1px solid rgba(255, 255, 255, 0.10);
  display: block;
}