:root {
  --primary-color: #4285f4;
  --secondary-color: #34a853;
  --accent-color: #ea4335;
  --info-color: #fbbc05;
  --background-color: #f5f5f5;
  --text-color: #333;
  --border-color: #ddd;
  --card-background: #fff;
  --header-background: #4285f4;
  --header-text: #fff;
  --active-tab: #4285f4;
  --hover-tab: #d0e0ff;
}

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

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: var(--background-color);
  color: var(--text-color);
  line-height: 1.6;
  font-size: 16px;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 20px;
  background-color: var(--card-background);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

/* Header Styles */
header {
  background-color: var(--header-background);
  color: var(--header-text);
  padding: 15px 20px;
  border-radius: 5px 5px 0 0;
  margin-bottom: 20px;
  text-align: center;
}

header h1 {
  font-size: 24px;
  margin-top: 5px;
}

header h2 {
  font-size: 18px;
  font-weight: normal;
  opacity: 0.8;
}

/* Tabs Navigation */
.tabs {
  display: flex;
  overflow-x: auto;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 20px;
}

.tab {
  padding: 10px 15px;
  cursor: pointer;
  transition: background-color 0.3s;
  font-weight: 500;
  white-space: nowrap;
}

.tab:hover {
  background-color: var(--hover-tab);
}

.tab.active {
  border-bottom: 3px solid var(--active-tab);
  color: var(--active-tab);
  font-weight: 600;
}

/* Tab Content */
.tab-content > div {
  display: none;
}

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

/* Content Boxes */
.concept-box, .math-box, .info-box, .problems-box {
  padding: 15px;
  margin-bottom: 20px;
  border-radius: 5px;
  background-color: var(--card-background);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.info-title {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 15px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--primary-color);
  color: var(--primary-color);
}

/* Grid Layout */
.grid-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 350px));
  gap: 15px;
  margin-bottom: 20px;
}

.grid-item {
  padding: 15px;
  border-radius: 5px;
  background-color: rgba(240, 240, 240, 0.3);
  border: 1px solid var(--border-color);
}

.grid-item h4 {
  margin-bottom: 10px;
  color: var(--primary-color);
}

.grid-item ul {
  padding-left: 20px;
}

.grid-item li {
  margin-bottom: 5px;
}

/* Note Boxes */
.note-box, .important-box {
  padding: 15px;
  margin: 15px 0;
  border-radius: 5px;
  background-color: rgba(66, 133, 244, 0.1);
  border-left: 5px solid var(--primary-color);
}

.important-box {
  background-color: rgba(234, 67, 53, 0.1);
  border-left: 5px solid var(--accent-color);
}

/* Visual Elements */
.visual-container {
  display: flex;
  flex-wrap: wrap;
  gap: 15px;
  margin: 20px 0;
}

.chart-container {
  flex: 1;
  min-width: 250px;
  height: 300px;
  border: 1px solid var(--border-color);
  border-radius: 5px;
  overflow: hidden;
}

/* Calculator Elements */
.calculator-section {
  margin-bottom: 30px;
  padding: 15px;
  border: 1px solid var(--border-color);
  border-radius: 5px;
}

.calculator-input {
  margin-bottom: 12px;
}

.calculator-input label {
  display: block;
  margin-bottom: 5px;
  font-weight: 500;
}

.calculator-input input, .calculator-input select, textarea {
  width: 100%;
  padding: 8px 10px;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  font-size: 14px;
}

textarea {
  resize: vertical;
}

/* Buttons */
.action-button, .reset-button {
  padding: 8px 15px;
  margin-right: 10px;
  margin-bottom: 10px;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  font-weight: 500;
  transition: background-color 0.3s;
}

.action-button {
  background-color: var(--primary-color);
  color: white;
}

.reset-button {
  background-color: #f1f1f1;
  color: var(--text-color);
  border: 1px solid var(--border-color);
}

.action-button:hover {
  background-color: #3367d6;
}

.reset-button:hover {
  background-color: #e0e0e0;
}

/* Result Boxes */
.result-box {
  margin-top: 15px;
  padding: 15px;
  border: 1px solid var(--border-color);
  border-radius: 5px;
  background-color: rgba(240, 240, 240, 0.3);
}

.result-title {
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--primary-color);
}

.results-table {
  width: 100%;
  border-collapse: collapse;
}

.results-table td {
  padding: 5px 0;
  border-bottom: 1px solid var(--border-color);
}

.results-table td:first-child {
  font-weight: 500;
}

/* Formula Boxes */
.formula-box, .formula {
  padding: 10px;
  margin: 10px 0;
  background-color: rgba(240, 240, 240, 0.5);
  border-radius: 4px;
  font-family: 'Courier New', monospace;
  overflow-x: auto;
}

/* Calculator Tabs */
.calculator-tabs {
  display: flex;
  border-bottom: 1px solid var(--border-color);
  margin: 15px 0;
}

.calc-tab {
  padding: 8px 15px;
  cursor: pointer;
  transition: background-color 0.3s;
}

.calc-tab:hover {
  background-color: var(--hover-tab);
}

.calc-tab.active {
  border-bottom: 2px solid var(--active-tab);
  color: var(--active-tab);
  font-weight: 500;
}

.calc-tab-content {
  display: none;
  padding: 15px 0;
}

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

/* Practice Problems */
.problem {
  margin-bottom: 25px;
  padding-bottom: 15px;
  border-bottom: 1px solid var(--border-color);
}

.options {
  margin-top: 10px;
}

.option {
  padding: 8px 10px;
  margin-bottom: 5px;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  cursor: pointer;
  transition: background-color 0.3s;
}

.option:hover {
  background-color: var(--hover-tab);
}

.option.selected {
  background-color: rgba(66, 133, 244, 0.2);
  border-color: var(--primary-color);
}

.option.correct {
  background-color: rgba(52, 168, 83, 0.2);
  border-color: var(--secondary-color);
}

.option.incorrect {
  background-color: rgba(234, 67, 53, 0.2);
  border-color: var(--accent-color);
}

#answers {
  display: none;
  margin-top: 20px;
  padding: 15px;
  border: 1px solid var(--border-color);
  border-radius: 5px;
  background-color: rgba(240, 240, 240, 0.3);
}

.correct-answer {
  color: var(--secondary-color);
}

/* Responsive adjustments */
@media (max-width: 600px) {
  .grid-container {
    grid-template-columns: 1fr;
  }
  
  .visual-container {
    flex-direction: column;
  }
  
  .tabs {
    flex-wrap: wrap;
  }
  
  .tab {
    flex-grow: 1;
    text-align: center;
  }
}