/* Reset default margins and ensure full height */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: #f5f5f5;
  color: #333;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 20px;
}

/* Heading */
h1 {
  font-size: 2rem;
  margin-bottom: 1.5rem;
  color: #2c3e50;
}

/* Timer display */
#timer {
  font-size: 3.5rem;
  font-weight: bold;
  background-color: #fff;
  padding: 1rem 2rem;
  border-radius: 10px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  margin-bottom: 1.5rem;
  color: #e74c3c;
  text-align: center;
  min-width: 150px;
}

/* Button container */
.btns {
  display: flex;
  gap: 1rem;
  margin-bottom: 2rem;
}

/* Buttons */
button {
  font-size: 1rem;
  padding: 0.75rem 1.5rem;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  color: #fff;
  transition: background-color 0.3s, transform 0.1s;
}

#startBtn {
  background-color: #2ecc71;
}

#startBtn:hover {
  background-color: #27ae60;
}

#stopBtn {
  background-color: #e74c3c;
}

#stopBtn:hover {
  background-color: #c0392b;
}

#resetBtn {
  background-color: #3498db;
}

#resetBtn:hover {
  background-color: #2980b9;
}

button:active {
  transform: scale(0.95);
}

/* Session log (minimal styling for future use) */
#sessionLog {
  list-style: none;
  font-size: 0.9rem;
  color: #7f8c8d;
}

/* Responsive adjustments */
@media (max-width: 400px) {
  #timer {
    font-size: 2.5rem;
    padding: 0.75rem 1.5rem;
  }

  button {
    padding: 0.5rem 1rem;
    font-size: 0.9rem;
  }
}