.problem-index {
  text-align: center;
  padding: 2rem;
}

.page-title {
  font-size: 3rem;
  color: rgb(4, 216, 4);
  margin-bottom: 1rem;
}

.tagline {
  font-size: 1.8rem;
  color: #444;
  margin-bottom: 3rem;
}

.problem-list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 2rem;
  max-width: 1000px;
  margin: 0 auto;
}
.problem-list a {
  text-decoration: none;
}

.problem-card {
  background-color: #ffffff;
  border-radius: 16px;
  padding: 2rem;
  width: 30%; /* About 3 per row */
  min-width: 250px;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
  transition: transform 0.2s ease, box-shadow 0.3s ease;
  text-align: left;
  box-sizing: border-box;
}
.problem-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.15);
}

.problem-card .category {
  font-size: 2rem;
  font-weight: bold;
  color: #222;
  margin-bottom: 1rem;
}

.problem-card .grade {
  font-size: 1.6rem;
  color: #555;
}


@media (max-width: 900px) {
  .problem-card {
    width: 45%;
  }
}

@media (max-width: 600px) {
  .problem-card {
    width: 90%;
  }
}