* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: Roboto, Arial, sans-serif;
}

body {
  background-color: #f8f9fa;
  color: #3c4043;
}

/* Navbar Styling */
.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 16px;
  background: white;
  border-bottom: 1px solid #e0e0e0;
  height: 64px;
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav-left,
.nav-right {
  display: flex;
  align-items: center;
  gap: 12px;
}

/* Small Google Logo Configuration */
.nav-left img {
  height: 18px;
  width: auto;
  margin-top: 2px;
}

.product-name {
  font-size: 22px;
  color: #5f6368;
  margin-left: 4px;
}

/* Guest Avatar Profile */
.profile-circle.guest {
  width: 32px;
  height: 32px;
  background: #5f6368;
  color: white;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
  font-size: 14px;
}

.icon-btn {
  background: none;
  border: none;
  padding: 8px;
  border-radius: 50%;
  cursor: pointer;
  color: #5f6368;
  display: flex;
}

.icon-btn:hover {
  background-color: #f1f3f4;
}

/* Empty Dashboard State */
.main-container {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: calc(100vh - 64px);
  padding: 24px;
}

.empty-state {
  text-align: center;
  max-width: 400px;
}

.empty-img {
  width: 180px;
  height: auto;
  margin-bottom: 16px;
}

.empty-state h2 {
  font-size: 24px;
  font-weight: 400;
  margin-bottom: 8px;
  color: #202124;
}

.empty-state p {
  font-size: 14px;
  color: #5f6368;
  margin-bottom: 24px;
}

.action-btn {
  background-color: #1a73e8;
  color: white;
  border: none;
  padding: 10px 24px;
  font-size: 14px;
  font-weight: 500;
  border-radius: 4px;
  cursor: pointer;
  box-shadow: 0 1px 2px 0 rgba(60, 64, 67, 0.3);
}

.action-btn:hover {
  background-color: #1557b0;
}

/* Modal Popup Window Overlay */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(32, 33, 36, 0.6);
  display: none;
  justify-content: center;
  align-items: center;
  z-index: 1000;
}

.modal-card {
  background: white;
  width: 100%;
  max-width: 480px;
  border-radius: 8px;
  box-shadow: 0 12px 15px 0 rgba(0, 0, 0, 0.24);
  overflow: hidden;
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 24px;
  border-bottom: 1px solid #e0e0e0;
}

.modal-header h3 {
  font-size: 18px;
  font-weight: 400;
  color: #202124;
}

.modal-body {
  padding: 24px;
}

.modal-instruction {
  font-size: 14px;
  color: #3c4043;
  margin-bottom: 20px;
}

.input-container {
  position: relative;
}

#class-code-input {
  width: 100%;
  padding: 16px;
  font-size: 16px;
  border: 1px solid #dadce0;
  border-radius: 4px;
  outline: none;
  transition: border-color 0.15s;
}

#class-code-input:focus {
  border-color: #1a73e8;
  border-width: 2px;
  padding: 15px;
}

.error-msg {
  display: none;
  color: #d93025;
  font-size: 12px;
  margin-top: 6px;
}

.modal-footer {
  display: flex;
  justify-content: flex-end;
  gap: 8px;
  padding: 12px 24px;
  background-color: #f8f9fa;
}

.text-btn {
  background: none;
  border: none;
  padding: 10px 16px;
  font-size: 14px;
  font-weight: 500;
  color: #5f6368;
  border-radius: 4px;
  cursor: pointer;
}

.text-btn:hover {
  background-color: #f1f3f4;
}

.submit-btn {
  background: none;
  border: none;
  padding: 10px 16px;
  font-size: 14px;
  font-weight: 500;
  color: #1a73e8;
  border-radius: 4px;
  cursor: pointer;
}

.submit-btn:disabled {
  color: #bcc1c6;
  cursor: default;
}

.submit-btn:not(:disabled):hover {
  background-color: #e8f0fe;
}