* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Verdana', sans-serif;
  background: #edf2f5;
  color: #000;
  overflow-y: scroll;
}

.container {
  max-width: 960px;
  margin: 40px auto;
  background: #ffffff;
  padding: 20px 40px;
  border: 1px solid #ccc;
  border-radius: 4px;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 2px solid #e0e0e0;
  padding-bottom: 10px;
  margin-bottom: 20px;
}

header h1 {
  font-size: 24px;
  color: #003366;
}

#timer {
  font-size: 16px;
  font-weight: bold;
}

.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 25px;
  border-bottom: 1px solid #ccc;
  padding-bottom: 10px;
}

.tabs button {
  padding: 6px 12px;
  border: 1px solid #ccc;
  background: #f9f9f9;
  color: #003366;
  cursor: pointer;
  font-size: 14px;
  border-radius: 4px 4px 0 0;
  transition: background 0.2s ease;
}

.tabs button:hover {
  background: #e0e0e0;
}

.tabs button.active {
  background: #ffffff;
  border-bottom: 2px solid white;
  font-weight: bold;
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}

.tab-content h2 {
  text-align: center;
  color: #003366;
  font-size: 20px;
  margin-bottom: 15px;
  border-bottom: 1px solid #ccc;
  padding-bottom: 5px;
}

code {
  font-family: Consolas, monospace;
  color: crimson;
  background-color: #f3f3f3;
  padding: 2px;
  font-size: 16px;
}

pre {
  background: #f3f3f3;
  border-left: 5px solid #4682b4;
  padding: 10px;
  margin-bottom: 20px;
  overflow-x: auto;
  font-family: Consolas, monospace;
  font-size: 14px;
}

footer {
  margin-top: 50px;
  text-align: center;
  font-size: 12px;
  color: #666;
  border-top: 1px solid #ccc;
  padding-top: 15px;
}

.limits {
  text-align: center;
  font-size: 13px;
  color: #666;
  margin-bottom: 15px;
}

.tab-content h3 {
  margin-top: 30px;
  margin-bottom: 10px;
  font-size: 16px;
  color: #002244;
}

.tab-content p {
  margin: 10px 0 15px;
  line-height: 1.6;
}

.problem-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 15px;
}

.problem-table th,
.problem-table td {
  padding: 10px;
  border: 1px solid #ccc;
  text-align: left;
  font-size: 14px;
}

.problem-table th {
  background-color: #f2f2f2;
  color: #003366;
}

.problem-table td a {
  color: #007bff;
  text-decoration: none;
}

.problem-table td a:hover {
  text-decoration: underline;
}