/* Base styles */
* { box-sizing: border-box; }
html, body {
  height: 100%;
  margin: 0;
  padding: 0;
  overflow: auto;
}
body {
  font-family: 'Segoe UI', sans-serif;
  background: #f9fafb;
  color: #333;
  display: flex;
  flex-direction: column;
}

h1 {
  font-size: 28px;
  margin-bottom: 10px;
  padding-left: 10px;
  text-align: center;
}


/* AOC buttons */
.aoc-buttons {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 12px;
  margin: 5px 0 10px;
}
.aoc-button {
  padding: 12px 20px;
  border-radius: 30px;
  border: none;
  background: #e0f2fe;
  color: #0369a1;
  cursor: pointer;
  font-size: 16px;
  transition: all 0.3s ease;
}
.aoc-button:hover,
.aoc-button.active {
  background: #0369a1;
  color: #fff;
}

/* Calendar columns and boxes */
.course-grid {
  flex: 1;
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  padding: 10px;
}
.course-column,
.course-column-1 {
  flex: 1;
  min-width: 280px;
  max-height: calc(100vh - 100px);
  overflow-y: auto;
  background: #fff;
  border: 1px solid #808080;
  border-radius: 12px;
  padding: 0 20px 10px;
  box-shadow: 0 4px 10px rgba(0,0,0,0.08);
  position: relative;
}
.course-column {
  max-width: 90%;
}
.course-column h3,
.course-column-1 h3 {
  position: sticky;
  top: 0;
  margin: 0.2em 0 0.2em;
  padding: 8px 0;
  background: #fff;
  font-size: 18px;
  border-bottom: 1px solid #ddd;
  text-align: center;
  z-index: 1;
}
.column-header {
  position: sticky;
  top: 0;
  background: #fff;
  z-index: 1;
  padding: 2px 0 8px;
}
.course-box {
  background: #f1f5f9;
  border-radius: 10px;
  padding: 12px;
  margin-bottom: 12px;
  border: 2px solid transparent;
  transition: border-color 0.3s ease;
}
.course-box:hover { border-color: #3b82f6; }
.course-title {
  font-weight: bold;
  margin-bottom: 5px;
  font-size: 16px;
}
.course-desc {
  font-size: 14px;
  color: #555;
  display: block;
}

ul { padding-left: 20px; margin-top: 10px; }
li { margin-bottom: 6px; }

.expand-btn {
  position: absolute;
  top: 8px;
  right: 8px;
  background: none;
  border: none;
  font-size: 1.2rem;
  cursor: pointer;
  z-index: 1;
}

.choice-group {
  border: 2px dashed green;
  border-radius: 8px;
  padding: 0.8rem;
  margin-bottom: 1rem;
}
.choice-label {
  font-weight: 600;
  margin-bottom: 0.5rem;
}

/* width of the scrollbar */
.course-column::-webkit-scrollbar,
.course-column-1::-webkit-scrollbar {
  width: 6px;
}

/* the track (background) of the scrollbar */
.course-column::-webkit-scrollbar-track,
.course-column-1::-webkit-scrollbar-track {
  background: #f0f0f0;
  border-radius: 12px;
  margin: 6px; /* optional: adds padding around the thumb */
}

/* the draggable thumb */
.course-column::-webkit-scrollbar-thumb,
.course-column-1::-webkit-scrollbar-thumb {
  background: #888;
  border-radius: 12px;
  border: 2px solid transparent;
  background-clip: padding-box;
}

/* thumb hover state */
.course-column::-webkit-scrollbar-thumb:hover,
.course-column-1::-webkit-scrollbar-thumb:hover {
  background: #555;
}