body {
  margin: 0;
  font-family: -apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,'Helvetica Neue',Arial,sans-serif;
  background: #f5f5f7;
  color: #1d1d1f;
}

body.night-mode {
  background-color: #181818;
  color: #e0e0e0;
}

body.night-mode .sidebar {
  background: #232323;
}

body.night-mode .main-content {
  background: #222;
}

body.night-mode .logo-blue {
  color: #4fc3f7;
}

body.night-mode a {
  color: #90caf9;
}

body.night-mode .night-mode-btn {
  background: transparent !important;
  border: none !important;
  box-shadow: none !important;
  padding: 0.2em;
  cursor: pointer;
}

body.night-mode .card {
  background: #232323;
  color: #e0e0e0;
  box-shadow: 0 2px 12px rgba(0,0,0,0.25);
}

body.night-mode .card:hover {
  box-shadow: 0 8px 24px rgba(79,195,247,0.18);
}

body.night-mode .card-title {
  color: #4fc3f7;
}

body.night-mode .card-desc {
  color: #b0b0b0;
}

body.night-mode .category-title {
  color: #e0e0e0;
}

.container {
  display: flex;
  min-height: 100vh;
}
.sidebar {
  width: 240px;
  background: #fff;
  box-shadow: 2px 0 8px rgba(0,0,0,0.04);
  padding: 32px 0 0 0;
  position: sticky;
  top: 0;
  height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
}
.logo {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 50px;
  letter-spacing: 1px;
}
.logo-blue {
  color: #0071e3;
}
.logo-img {
  height: 38px;
  width: 38px;
  vertical-align: middle;
  margin-right: 10px;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,113,227,0.08);
}
#category-nav {
  width: 100%;
}
.category-item {
  padding: 14px 32px;
  cursor: pointer;
  font-size: 1.1rem;
  border-left: 4px solid transparent;
  transition: background 0.2s, border-color 0.2s;
}
.category-item.active, .category-item:hover {
  background: #f5f5f7;
  border-left: 4px solid #0071e3;
  color: #0071e3;
}
.main-content {
  flex: 1;
  padding: 48px 40px 40px 40px;
  overflow-y: auto;
}
.category-section {
  margin-bottom: 56px;
}
.category-title {
  font-size: 1.6rem;
  font-weight: 600;
  margin-bottom: 24px;
  letter-spacing: 1px;
  color: #1d1d1f;
}
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(270px, 1fr));
  gap: 24px;
}
.card {
  background: #fff;
  border-radius: 18px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.07);
  padding: 24px 20px 18px 20px;
  min-height: 120px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: box-shadow 0.2s, transform 0.2s;
  text-decoration: none;
  color: inherit;
}
.card:hover {
  box-shadow: 0 8px 24px rgba(0,113,227,0.13);
  transform: translateY(-4px) scale(1.03);
}
.card-title {
  font-size: 1.1rem;
  font-weight: 500;
  margin-bottom: 8px;
  color: #0071e3;
}
.card-desc {
  font-size: 0.98rem;
  color: #86868b;
  margin-bottom: 6px;
}
@media (max-width: 900px) {
  .container {
    flex-direction: column;
  }
  .sidebar {
    width: 100%;
    height: auto;
    flex-direction: row;
    padding: 0;
    box-shadow: none;
    border-bottom: 1px solid #eee;
  }
  .main-content {
    padding: 24px 8px;
  }
  .category-section {
    margin-bottom: 36px;
  }
  .cards {
    gap: 12px;
  }
  .card {
    width: 100%;
    min-width: 0;
  }
}
@media (max-width: 600px) {
  .sidebar {
    display: none;
    position: fixed;
    left: 0; top: 0;
    width: 70vw;
    height: 100vh;
    background: #fff;
    z-index: 1000;
    flex-direction: column;
    box-shadow: 2px 0 8px rgba(0,0,0,0.08);
    transition: transform 0.3s;
    transform: translateX(-100%);
  }
  .sidebar.active {
    display: flex;
    transform: translateX(0);
  }
  .hamburger {
    display: block;
    position: fixed;
    left: 16px; top: 16px;
    width: 36px; height: 36px;
    z-index: 1100;
    background: none;
    border: none;
    cursor: pointer;
  }
}
.hamburger {
  display: none;
}
.night-mode-btn {
  background: transparent !important;
  border: none !important;
  box-shadow: none !important;
  padding: 0.2em;
  cursor: pointer;
}
.site-logo {
  height: 24px;
  width: 24px;
  margin-right: 8px;
  vertical-align: middle;
  background: none;
  border-radius: 0;
  border: none;
  box-sizing: border-box;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: visible;
  padding: 0;
}
.site-logo img {
  width: 24px;
  height: 24px;
  object-fit: contain;
  display: block;
  border-radius: 0;
}