.about-page {
  --about-surface: #ffffff;
  --about-soft: #f4f5f2;
  --about-line: #e1e3de;
  --about-line-strong: #cfd2ca;
  --about-shadow: 0 18px 55px rgba(25, 32, 27, 0.07);

  max-width: 820px;
  margin: 0 auto;
  color: var(--fg);
}

.about-page > h1 {
  margin: 4px 0 28px;
  text-align: left;
  font-size: clamp(36px, 6vw, 52px);
  font-weight: 850;
  line-height: 1.08;
  letter-spacing: -0.055em;
}

.about-tabs {
  position: sticky;
  top: 14px;
  z-index: 20;
  margin: 0 0 30px;
  padding: 7px;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 6px;
  border: 1px solid rgba(207, 210, 202, 0.9);
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.88);
  box-shadow: 0 8px 30px rgba(25, 32, 27, 0.06);
  backdrop-filter: blur(14px);
}

.about-tab {
  min-width: 0;
  height: 44px;
  padding: 0 14px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 0;
  border-radius: 10px;
  background: transparent;
  color: var(--muted);
  font-size: 14px;
  font-weight: 720;
  white-space: nowrap;
  transition:
    background 0.18s ease,
    color 0.18s ease,
    transform 0.18s ease;
}

.about-tab:hover {
  transform: translateY(-1px);
  background: var(--about-soft);
  color: var(--fg);
}

.about-tab.active {
  border-color: transparent;
  background: var(--fg);
  color: #ffffff;
}

.about-tab:focus-visible,
.about-section a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.about-section {
  display: none;
  scroll-margin-top: 96px;
  margin: 0;
  padding: 34px 36px 38px;
  border: 1px solid var(--about-line);
  border-radius: 22px;
  background: var(--about-surface);
  box-shadow: var(--about-shadow);
}

.about-section.active {
  display: block;
  animation: about-panel-in 0.2s ease-out;
}

@keyframes about-panel-in {
  from {
    opacity: 0;
    transform: translateY(5px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.about-section h2 {
  margin: 0 0 28px;
  padding-bottom: 22px;
  border-bottom: 1px solid var(--about-line);
  font-size: clamp(25px, 4vw, 32px);
  font-weight: 850;
  line-height: 1.2;
  letter-spacing: -0.045em;
}

.about-section h3 {
  margin: 34px 0 12px;
  padding-top: 28px;
  border-top: 1px solid var(--about-line);
  font-size: 17px;
  font-weight: 800;
  line-height: 1.35;
  letter-spacing: -0.03em;
}

.about-section h2 + h3 {
  margin-top: 0;
  padding-top: 0;
  border-top: 0;
}

.about-section ul {
  margin: 0;
}

.about-section > ul {
  padding: 0;
  list-style: none;
}

.about-section > ul > li {
  position: relative;
  margin: 0;
  padding: 13px 0 13px 18px;
  border-bottom: 1px solid #eceee9;
  line-height: 1.65;
}

.about-section > ul > li:last-child {
  border-bottom: 0;
}

.about-section > ul > li::before {
  content: "";
  position: absolute;
  top: 1.55em;
  left: 1px;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--accent);
}

.about-section li > ul {
  margin: 12px 0 2px;
  padding: 14px 18px 14px 36px;
  border-radius: 13px;
  background: var(--about-soft);
}

.about-section li > ul > li {
  margin: 6px 0;
  color: #5f665f;
  line-height: 1.55;
}

.about-section li > ul > li::marker {
  color: #a4aaa2;
}

.about-section strong {
  color: var(--fg);
  font-weight: 780;
}

.about-section a {
  color: var(--accent);
  font-weight: 650;
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 4px;
  transition: color 0.15s ease;
}

.about-section a:hover {
  color: #1c4632;
}

.about-more-link {
  margin-top: 2px;
  padding: 7px 11px;
  display: inline-flex;
  align-items: center;
  border: 1px solid var(--about-line-strong);
  border-radius: 9px;
  background: var(--about-surface);
  color: var(--fg) !important;
  font-size: 13px;
  font-weight: 750 !important;
  text-decoration: none !important;
}

.about-more-link:hover {
  border-color: var(--fg);
  background: var(--fg);
  color: #ffffff !important;
}

#contests > ul,
#operations > ul {
  font-variant-numeric: tabular-nums;
}

#contests > ul > li,
#operations > ul > li {
  padding-top: 15px;
  padding-bottom: 15px;
  color: var(--muted);
}

#contests > ul > li a,
#operations > ul > li a {
  color: var(--fg);
  font-weight: 720;
}

@media (prefers-reduced-motion: reduce) {
  .about-section.active {
    animation: none;
  }

  .about-tab,
  .about-more-link {
    transition: none;
  }
}

@media (max-width: 720px) {
  .about-page {
    max-width: 100%;
  }

  .about-page > h1 {
    margin-bottom: 22px;
    font-size: 34px;
  }

  .about-tabs {
    top: 8px;
    margin-right: -2px;
    margin-bottom: 22px;
    margin-left: -2px;
    padding: 6px;
    display: flex;
    gap: 5px;
    overflow-x: auto;
    border-radius: 14px;
    scrollbar-width: none;
  }

  .about-tabs::-webkit-scrollbar {
    display: none;
  }

  .about-tab {
    flex: 0 0 auto;
    height: 40px;
    padding: 0 13px;
    font-size: 13px;
  }

  .about-section {
    padding: 25px 20px 28px;
    border-radius: 17px;
    box-shadow: 0 12px 35px rgba(25, 32, 27, 0.055);
  }

  .about-section h2 {
    margin-bottom: 22px;
    padding-bottom: 18px;
    font-size: 25px;
  }

  .about-section h3 {
    margin-top: 28px;
    padding-top: 23px;
    font-size: 16px;
  }

  .about-section > ul > li {
    padding-top: 12px;
    padding-bottom: 12px;
    padding-left: 15px;
    font-size: 14px;
  }

  .about-section > ul > li::before {
    width: 4px;
    height: 4px;
  }

  .about-section li > ul {
    margin-top: 10px;
    padding: 12px 14px 12px 30px;
  }
}