* {
  box-sizing: border-box;
}

body {
  background: #f5f7fa;
  min-height: 100vh;
  margin: 0;
  font-family:
    -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Oxygen", "Ubuntu",
    "Cantarell", "Fira Sans", "Droid Sans", sans-serif;
  color: #2c3e50;
  line-height: 1.65;
  font-size: 16px;
}

main {
  background: #ffffff;
  border-radius: 12px;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
  padding: 48px 40px;
  margin: 32px auto;
  max-width: 900px;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  color: #1a2332;
  font-family:
    -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", sans-serif;
  font-weight: 600;
  line-height: 1.3;
  margin-bottom: 16px;
  margin-top: 24px;
}

h1 {
  font-size: 2.2rem;
  font-weight: 700;
  margin-top: 0;
  margin-bottom: 24px;
}

h2 {
  font-size: 1.75rem;
  margin-top: 32px;
  margin-bottom: 20px;
}

h3 {
  font-size: 1.4rem;
}

p {
  margin: 16px 0;
  text-align: left;
}

hr {
  border: none;
  border-top: 1px solid #e1e8ed;
  margin: 40px 0;
}

a,
.card-link {
  color: #4f7ce8;
  text-decoration: none;
  font-weight: 500;
  transition:
    color 0.2s ease,
    text-decoration 0.2s ease;
}

a:hover,
.card-link:hover {
  color: #2c5aa0;
  text-decoration: underline;
}

a:active,
.card-link:active {
  color: #1e3f5a;
}

/* Lists */
ul,
ol {
  margin: 16px 0;
  padding-left: 32px;
}

li {
  margin: 8px 0;
}

/* Code blocks */
code {
  background: #f4f6f9;
  color: #d63384;
  padding: 2px 6px;
  border-radius: 3px;
  font-family: "Courier New", monospace;
  font-size: 0.9em;
}

pre {
  background: #f4f6f9;
  padding: 16px;
  border-radius: 8px;
  overflow-x: auto;
  line-height: 1.4;
}

pre code {
  color: inherit;
  background: none;
  padding: 0;
}

/* Blockquote */
blockquote {
  border-left: 4px solid #4f7ce8;
  padding-left: 20px;
  margin-left: 0;
  color: #5a6c7d;
  font-style: italic;
}

/* Forms */
input,
select,
textarea {
  font-family: inherit;
  font-size: 1em;
  padding: 10px 12px;
  border: 1px solid #e1e8ed;
  border-radius: 6px;
  color: #2c3e50;
}

input:focus,
select:focus,
textarea:focus {
  outline: none;
  border-color: #4f7ce8;
  box-shadow: 0 0 0 3px rgba(79, 124, 232, 0.1);
}

button {
  padding: 10px 20px;
  background: #4f7ce8;
  color: white;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  font-weight: 500;
  transition: background 0.2s ease;
}

button:hover {
  background: #2c5aa0;
}

button:active {
  background: #1e3f5a;
}

/* Responsive design */
@media (max-width: 768px) {
  main {
    padding: 32px 24px;
    margin: 20px 16px;
    max-width: 100%;
  }

  h1 {
    font-size: 1.8rem;
  }

  h2 {
    font-size: 1.4rem;
  }

  h3 {
    font-size: 1.2rem;
  }

  body {
    font-size: 15px;
  }
}

@media (max-width: 480px) {
  main {
    padding: 24px 16px;
    margin: 12px;
    border-radius: 8px;
  }

  h1 {
    font-size: 1.5rem;
  }

  h2 {
    font-size: 1.25rem;
  }

  h3 {
    font-size: 1.1rem;
  }

  body {
    font-size: 14px;
  }

  ul,
  ol {
    padding-left: 24px;
  }
}