:root {
  --primary-color: #2c3e50;
  --accent-color: #3498db;
  --border-radius: 8px;
}
 
/* --- Universal Selector --- */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
 
/* --- Main content wrapper --- */
.content-wrapper {
  max-width: 860px;
  min-width: 300px;
  margin: 0 auto;
}
 
/* --- h1 Element Selector --- */
h1 {
  color: var(--primary-color, #2c3e50);
  font-size: 2.2rem;
  text-align: center;
  margin: 1rem 0 0.5rem 0;
  text-decoration: underline;
  text-decoration-color: var(--accent-color, #3498db);
}
 
/* --- h2 Element Selector --- */
h2 {
  color: rgb(100, 116, 139);
  text-align: center;
  font-size: 1rem;
  margin-top: 0.25rem;
  margin-bottom: 1.5rem;
  margin-left: 0;
  margin-right: 0;
}
 
/* --- h3 Element Selector --- */
h3 {
  color: #2c3e50;
  font-size: 1.2rem;
  padding: 0.5rem 0 0.25rem 0;
  border-bottom: 2px solid #e2e8f0;
  margin-bottom: 0.75rem;
}
 
/* --- Class Selector --- */
.section-card {
  background-color: #ffffff;
  border-style: solid;
  border-color: #dce1e7;
  border-width: 1px;
  border-radius: var(--border-radius, 8px);
  padding-top: 1.5rem;
  padding-bottom: 1.5rem;
  padding-left: 2rem;
  padding-right: 2rem;
  margin: 1.5rem 0 1.5rem 0;
}
 
/* --- Nested Selectors --- */
.section-card {
  & h3 {
    color: var(--primary-color, #2c3e50);
    border-bottom-color: var(--accent-color, #3498db);
  }
  & p {
    font-size: 0.95rem;
    line-height: 1.8;
  }
}
 
/* --- Attribute Selector --- */
input[type="checkbox"] {
  accent-color: var(--accent-color, #3498db);
  width: 1rem;
  height: 1rem;
  margin-right: 0.5rem;
}
 
/* --- Image styling --- */
img {
  display: block;
  width: 100%;
  max-width: 450px;
  min-width: 200px;
  height: auto;
  border: 3px solid #dce1e7;
  border-radius: var(--border-radius, 8px);
  margin: 1rem auto;
}
 
/* --- Video & Audio --- */
video, audio {
  display: block;
  width: 100%;
  max-width: 500px;
  margin: 1rem auto;
  border-radius: var(--border-radius, 8px);
}
 
/* --- Sticky agenda bar --- */
.agenda-bar {
  position: sticky;
  top: 0;
  background-color: #ffffff;
  border: 1px solid #dce1e7;
  border-radius: 4px;
  padding: 0.75rem 1.5rem;
  margin-bottom: 1.5rem;
  z-index: 100;
  box-shadow: 0 0.05cm 0.15cm rgba(0, 0, 0, 0.08);
}
 
.attendance-grid li {
  list-style: none;
  background-color: #f8fafc;
  border-radius: 4px;
  padding-top: 0.5rem;
  padding-bottom: 0.5rem;
  padding-left: 0.75rem;
  padding-right: 0.75rem;
}