html {
    box-sizing: border-box;
}
*, *:before, *:after {
    box-sizing: inherit;
}
body { 
  font-family: 'Segoe UI', Arial, sans-serif; 
  background: #f9f9f9; 
  color: #333;
  line-height: 1.6;
  margin: 0; /* Ensure no default body margin */
  padding: 0; /* Ensure no default body padding */
}

.container { 
  max-width: 900px; 
  margin: 20px auto; 
  background: #fff; 
  border-radius: 12px; 
  box-shadow: 0 4px 12px rgba(0,0,0,0.1); 
  padding: 20px 32px 32px; 
  overflow-x: hidden; /* Prevent horizontal scroll from container content */
}

h1 { 
  text-align: center; 
  color: #1a237e; /* Dark blue */
  margin-bottom: 24px;
}

.objectives-block { 
  background: #e3f2fd; /* Light blue */
  border-left: 5px solid #1976d2; /* Medium blue */
  padding: 18px 24px; 
  border-radius: 8px; 
  margin-bottom: 24px; 
  font-size: 1.0em; 
}
.objectives-block ul {
  padding-left: 20px;
  margin-top: 8px;
  margin-bottom: 0;
}
.objectives-block li {
  margin-bottom: 4px;
}

.flow-diagram { 
  background: #f3e5f5; /* Light purple */
  border-left: 5px solid #8e24aa; /* Medium purple */
  padding: 16px; 
  border-radius: 8px; 
  font-family: 'Fira Mono', 'Consolas', monospace; 
  font-size: 0.95em; 
  margin-bottom: 24px; 
  white-space: pre; 
  overflow-x: auto;
}

.step { 
  margin-bottom: 36px; 
  padding: 20px;
  border: 1px solid #e0e0e0;
  border-radius: 8px;
  background-color: #ffffff;
}

.step-title { 
  font-size: 1.3em; 
  font-weight: bold; 
  margin-bottom: 12px; 
  color: #004d40; /* Dark teal */
}

.step-desc { 
  color: #333; 
  margin-bottom: 16px; 
  font-size: 1.0em; 
}
.step-desc code {
  background-color: #f0f0f0;
  padding: 2px 4px;
  border-radius: 4px;
  font-family: 'Fira Mono', Consolas, monospace;
}


.run-btn, .reset-btn, .quiz-btn { 
  background: #2196f3; /* Bright blue */
  color: #fff; 
  border: none; 
  border-radius: 4px; 
  padding: 8px 18px; 
  font-size: 0.95em; 
  cursor: pointer; 
  margin-bottom: 8px; 
  margin-right: 8px; 
  transition: background-color 0.2s ease;
}
.run-btn:hover, .reset-btn:hover, .quiz-btn:hover {
  background: #1976d2; /* Darker blue */
}
.run-btn:disabled, .reset-btn:disabled, .quiz-btn:disabled { 
  background: #bbb; 
  cursor: not-allowed;
}

.output { 
  background: #f5f5f5; 
  border-radius: 6px; 
  padding: 12px; 
  min-height: 40px; 
  margin-top: 12px; 
  font-family: monospace;
  white-space: pre-wrap;
  word-wrap: break-word;
  border: 1px solid #eee;
}
.output pre {
  margin: 0;
  font-size: 0.9em;
}

.CodeMirror { 
  font-size: 0.95em; 
  border-radius: 6px; 
  border: 1px solid #ddd; 
  margin-bottom: 12px;
}

.plot-img { 
  max-width: 100%; 
  border-radius: 6px; 
  margin-top: 12px; 
  border: 1px solid #ccc;
  display: block; /* Center if container is text-align center */
  margin-left: auto;
  margin-right: auto;
}

.slider-label { 
  font-weight: normal; 
  margin-right: 8px; 
  font-size: 0.95em;
  color: #555;
}

.slider-row { 
  margin-bottom: 24px; 
  display: flex; 
  flex-wrap: wrap;
  align-items: center; 
  gap: 12px 18px; 
  background: #fafafa;
  padding: 16px;
  border-radius: 8px;
  border: 1px solid #eee;
}
.slider-row input[type=range] { 
  width: 150px; 
  cursor: pointer;
}
.slider-value { 
  min-width: 40px; 
  display: inline-block; 
  text-align: right; 
  font-weight: bold;
  color: #1976d2;
  background-color: #e3f2fd;
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.9em;
}

.markdown { 
  background: #eef6fa; /* Very light blue */
  border-left: 5px solid #2196f3; /* Bright blue */
  padding: 16px 24px; 
  border-radius: 8px; 
  margin-bottom: 24px; 
  font-size: 1.0em; 
}
.markdown ul {
  padding-left: 20px;
  margin-top: 8px;
}
.markdown li {
  margin-bottom: 4px;
}
.markdown code {
  background-color: #d0e0f0;
  padding: 2px 4px;
  border-radius: 4px;
  font-family: 'Fira Mono', Consolas, monospace;
}

.quiz-block { 
  background: #fffbe6; /* Light yellow */
  border-left: 5px solid #ffd700; /* Gold */
  padding: 12px 18px; 
  border-radius: 8px; 
  margin-top: 20px; 
  margin-bottom: 10px; 
}
.quiz-block p {
  margin-top: 0;
  margin-bottom: 8px;
}
.quiz-answer { 
  margin-top: 10px; 
  color: #1a7f37; /* Dark green */
  font-weight: bold; 
  background-color: #e8f5e9; /* Light green */
  padding: 8px;
  border-radius: 4px;
}

.summary-block { 
  background: #e8f5e9; /* Light green */
  border-left: 5px solid #43a047; /* Medium green */
  padding: 18px 24px; 
  border-radius: 8px; 
  margin-top: 32px; 
  font-size: 1.05em; 
}
.summary-block ul {
  padding-left: 20px;
  margin-top: 8px;
}
.summary-block li {
  margin-bottom: 4px;
}

.pro-tip { 
  background: #e3ffe3; /* Very light green */
  border-left: 4px solid #43a047; /* Medium green */
  padding: 8px 14px; 
  border-radius: 5px; 
  margin: 10px 0; 
  font-size: 0.95em; 
  color: #256029; /* Darker green */
}

.next-block { 
  background: #fff3e0; /* Light orange */
  border-left: 4px solid #ff9800; /* Orange */
  padding: 10px 14px; 
  border-radius: 5px; 
  margin: 18px 0; 
  font-size: 0.95em; 
  color: #a65c00; /* Darker orange */
}

#diagnostic-log { 
  background: #f0f0f0; 
  border-left: 4px solid #ff9800; 
  padding: 10px 14px; 
  border-radius: 5px; 
  margin: 18px 0; 
  font-size: 0.85em; 
  color: #333;
  max-height: 150px;
  overflow-y: auto;
}
#diagnostic-log div {
  margin-bottom: 4px;
  border-bottom: 1px dashed #ddd;
  padding-bottom: 4px;
}
#diagnostic-log div:last-child {
  border-bottom: none;
}

/* Accessibility */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}