body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  background-color: #f4f4f4;
}
header {
  background-color: #4CAF50;
  color: white;
  padding: 1em;
  text-align: center;
}
main {
  padding: 2em;
  max-width: 900px;
  margin: auto;
}
#navigation {
  display: flex;
  justify-content: center;
  align-items: center;
  margin-bottom: 1em;
}
#navigation button, #day-selector {
  margin: 0 10px;
  padding: 0.5em 1em;
  cursor: pointer;
}
section {
  background: white;
  padding: 1em;
  margin-bottom: 2em;
  border-radius: 8px;
}
h1, h2, h3 {
  margin-top: 0;
}
button {
  padding: 0.5em 1em;
  cursor: pointer;
}
footer {
  background-color: #333;
  color: white;
  text-align: center;
  padding: 1em;
  margin-top: 2em;
}
#timer-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin-bottom: 1em;
  background-color: #e0f7fa;
  padding: 1em;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

#timer {
  font-family: 'Courier New', Courier, monospace;
  font-size: 2em;
  color: #00796b;
  margin-top: 0.5em;
  letter-spacing: 2px;
}

#progress-container {
  margin-top: 0.5em;
  font-weight: 600;
  font-size: 1.1em;
  color: #fff;
}