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

/* BODY */
body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: #f4f4f9;
  color: #000;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  transition: 0.3s;
}

/* HEADER */
header {
  background-color: #ce8a0d;
  color: #fff;
  padding: 20px 0;
  text-align: center;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

/* NAVIGATION */
nav#menu {
  background-color: #bd7235;
}

nav#menu ul {
  display: flex;
  list-style: none;
  justify-content: center;
}

nav#menu li {
  margin: 0 15px;
}

nav#menu a {
  text-decoration: none;
  color: #fff;
  padding: 12px 20px;
  display: block;
  border-radius: 5px;
  transition: background 0.3s;
}

nav#menu a:hover {
  background-color: #773f0b;
}

/* CONTAINER */
.container {
  display: flex;
  padding: 20px;
  gap: 15px;
  flex: 1;
}

/* MAIN CONTENT */
main#content {
  flex: 3;
  background-color: #fff;
  padding: 20px;
  border-radius: 8px;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

/* SIDEBAR */
aside#sidebar {
  flex: 1;
  background-color: #e1e8f0;
  padding: 20px;
  border-radius: 8px;
}

aside#sidebar h2 {
  margin-bottom: 10px;
}

aside#sidebar ul {
  list-style: none;
}

aside#sidebar ul li {
  padding: 8px;
  cursor: pointer;
  border-bottom: 1px solid #ccc;
  transition: 0.3s;
}

aside#sidebar ul li:hover {
  background-color: #e2a54a;
  border-radius: 5px;
}

/* GENERAL BUTTONS */
button {
  border: none;
  border-radius: 5px;
  cursor: pointer;
  font-size: 14px;
  transition: all 0.3s ease;
  font-weight: 500;
}

/* EXERCISE 2 BUTTONS */
.exerciseButtonsContainer {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.exerciseBtn {
  background: linear-gradient(135deg, #bd7235 0%, #a0591e 100%);
  color: #fff;
  padding: 12px 20px;
  font-size: 15px;
  font-weight: 600;
  border: 2px solid transparent;
  box-shadow: 0 4px 6px rgba(189, 114, 53, 0.2);
}

.exerciseBtn:hover {
  background: linear-gradient(135deg, #a0591e 0%, #7d4419 100%);
  box-shadow: 0 6px 12px rgba(189, 114, 53, 0.3);
  transform: translateY(-2px);
}

.exerciseBtn:active {
  transform: translateY(0);
  box-shadow: 0 2px 4px rgba(189, 114, 53, 0.2);
}

/* EXERCISE 3 STYLES */
.exercise3Container {
  display: flex;
  flex-direction: column;
  gap: 15px;
}

.activityBox {
  margin-bottom: 10px;
}

.activityBox h3 {
  margin-bottom: 10px;
  font-size: 16px;
}

.activityBtn {
  background: linear-gradient(135deg, #bd7235 0%, #a0591e 100%);
  color: #fff;
  padding: 12px 24px;
  font-size: 14px;
  font-weight: 600;
  box-shadow: 0 4px 6px rgba(189, 114, 53, 0.2);
}

.activityBtn:hover {
  background: linear-gradient(135deg, #a0591e 0%, #7d4419 100%);
  box-shadow: 0 6px 12px rgba(189, 114, 53, 0.3);
  transform: translateY(-2px);
}

.activityBtn:active {
  transform: translateY(0);
}

.activityBox input {
  width: 100%;
  padding: 8px;
  margin-bottom: 8px;
  border: 2px solid #ddd;
  border-radius: 5px;
  font-size: 14px;
  transition: border-color 0.3s;
}

.activityBox input:focus {
  outline: none;
  border-color: #bd7235;
  box-shadow: 0 0 5px rgba(189, 114, 53, 0.2);
}

.calcInputGroup,
.todoInputGroup {
  display: flex;
  gap: 10px;
  margin-bottom: 8px;
}

.calcInputGroup input,
.todoInputGroup input {
  flex: 1;
  padding: 8px;
  border: 2px solid #ddd;
  border-radius: 5px;
  font-size: 14px;
}

.activityBox ul {
  list-style: none;
  padding: 0;
  margin-top: 10px;
}

.activityBox li {
  padding: 8px;
  background-color: #f5f5f5;
  border-left: 3px solid #bd7235;
  margin-bottom: 5px;
  border-radius: 3px;
}

.activityBox p {
  margin-top: 10px;
  font-size: 14px;
  color: #555;
}

.activityBox img {
  width: 200px;
  height: auto;
  border-radius: 5px;
  margin-bottom: 10px;
}

/* EXERCISE 4 STYLES */
.gradeCalculatorContainer {
  display: flex;
  gap: 30px;
  flex-wrap: wrap;
  margin-top: 20px;
}

.inputSection {
  flex: 1;
  min-width: 300px;
  padding: 20px;
  background: linear-gradient(135deg, #f5f5f5 0%, #e8e8e8 100%);
  border-radius: 8px;
  border-left: 4px solid #bd7235;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.inputSection h3 {
  margin-bottom: 20px;
  color: #bd7235;
  text-align: center;
  font-size: 18px;
}

.inputGroup {
  margin-bottom: 15px;
}

.inputGroup label {
  display: block;
  margin-bottom: 5px;
  font-weight: 600;
  color: #333;
}

.inputGroup input {
  width: 100%;
  padding: 10px;
  border: 2px solid #ddd;
  border-radius: 5px;
  font-size: 14px;
  transition: border-color 0.3s;
}

.inputGroup input:focus {
  outline: none;
  border-color: #bd7235;
  box-shadow: 0 0 5px rgba(189, 114, 53, 0.2);
}

.buttonGroup {
  display: flex;
  gap: 10px;
  margin-top: 20px;
}

.primaryBtn,
.secondaryBtn {
  flex: 1;
  padding: 12px;
  font-size: 16px;
  font-weight: 600;
  border-radius: 5px;
}

.primaryBtn {
  background: linear-gradient(135deg, #bd7235 0%, #a0591e 100%);
  color: #fff;
  box-shadow: 0 4px 6px rgba(189, 114, 53, 0.2);
}

.primaryBtn:hover {
  background: linear-gradient(135deg, #a0591e 0%, #7d4419 100%);
  box-shadow: 0 6px 12px rgba(189, 114, 53, 0.3);
  transform: translateY(-2px);
}

.secondaryBtn {
  background-color: #ddd;
  color: #333;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.secondaryBtn:hover {
  background-color: #ccc;
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
  transform: translateY(-2px);
}

.resultSection {
  flex: 1;
  min-width: 300px;
  padding: 20px;
  background: linear-gradient(135deg, #ce8a0d 0%, #bd7235 100%);
  color: #fff;
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(189, 114, 53, 0.3);
}

.resultSection h3 {
  margin-bottom: 20px;
  text-align: center;
  font-size: 20px;
}

.resultBox {
  background-color: rgba(255, 255, 255, 0.1);
  padding: 20px;
  border-radius: 5px;
  backdrop-filter: blur(10px);
}

.resultBox p {
  margin-bottom: 15px;
  font-size: 18px;
  line-height: 1.6;
}

.resultBox span {
  font-weight: bold;
  font-size: 24px;
  color: #ffd700;
}

/* FOOTER */
footer {
  background-color: #daa646;
  color: #fff;
  padding: 15px 0;
  text-align: center;
  margin-top: 20px;
}

/* DARK MODE */
.darkMode {
  background-color: #1a1a1a;
  color: #fff;
}

.darkMode main#content {
  background-color: #2a2a2a;
}

.darkMode aside#sidebar {
  background-color: #333;
}

.darkMode nav#menu {
  background-color: #222;
}

.darkMode header {
  background-color: #444;
}

.darkMode footer {
  background-color: #333;
}

.darkMode .activityBox li {
  background-color: #444;
  border-left-color: #e2a54a;
}

.darkMode .activityBox input {
  background-color: #444;
  color: #fff;
  border-color: #555;
}

.darkMode .activityBox input:focus {
  border-color: #e2a54a;
  box-shadow: 0 0 5px rgba(226, 165, 74, 0.2);
}

.darkMode .inputSection {
  background: linear-gradient(135deg, #333 0%, #2a2a2a 100%);
  border-left-color: #e2a54a;
}

.darkMode .inputSection h3 {
  color: #e2a54a;
}

.darkMode .inputGroup label {
  color: #ddd;
}

.darkMode .inputGroup input {
  background-color: #444;
  color: #fff;
  border-color: #555;
}

.darkMode .inputGroup input:focus {
  border-color: #e2a54a;
  box-shadow: 0 0 5px rgba(226, 165, 74, 0.2);
}

.darkMode .secondaryBtn {
  background-color: #444;
  color: #ddd;
}

.darkMode .secondaryBtn:hover {
  background-color: #555;
}

@media (max-width: 768px) {
  .container {
    flex-direction: column;
  }

  .gradeCalculatorContainer {
    flex-direction: column;
  }

  .inputSection,
  .resultSection {
    min-width: auto;
  }

  .buttonGroup {
    flex-direction: column;
  }

  .buttonGroup button {
    width: 100%;
  }

  .exerciseBtn {
    font-size: 14px;
    padding: 10px 16px;
  }
}