body {
  margin: 0;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  background: #1a1a1a;
  font-family: Arial, sans-serif;
}

.container {
  position: relative;
  width: 300px;
  height: 300px;
}

.timer {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 48px;
  color: #fff;
  z-index: 1;
}

.timer-border {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 4px solid #333;
  border-radius: 50%;
  box-sizing: border-box;
}

.progress-bar {
  position: absolute;
  top: -4px;
  left: -4px;
  width: calc(100% + 8px);
  height: calc(100% + 8px);
  border: 4px solid #4CAF50;
  border-radius: 50%;
  box-sizing: border-box;
  clip-path: polygon(50% 0, 100% 0, 100% 100%, 0 100%, 0 0, 50% 0);
  transform-origin: center;
  transform: rotate(0deg);
  transition: transform 1s linear;
}

.timer-duration-selector {
  position: absolute;
  top: -50px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 10px;
}

.duration-btn {
  background: #333;
  border: none;
  color: white;
  padding: 5px 10px;
  border-radius: 15px;
  cursor: pointer;
  transition: background 0.3s;
}

.duration-btn:hover, .duration-btn.active {
  background: #4CAF50;
}

.controls {
  position: absolute;
  bottom: -50px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 20px;
}

.control-btn {
  background: #333;
  border: none;
  color: white;
  padding: 10px;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.3s;
}

.control-btn:hover {
  background: #444;
}