* {
  box-sizing: border-box;
  font-family: 'Poppins', sans-serif;
}

body {
  background: linear-gradient(135deg, #74ABE2, #5563DE);
  color: #fff;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

.container {
  background: rgba(255, 255, 255, 0.1);
  padding: 30px;
  border-radius: 20px;
  width: 350px;
  box-shadow: 0 8px 20px rgba(0,0,0,0.2);
}

h1 {
  text-align: center;
  margin-bottom: 20px;
}

.input-group {
  display: flex;
  margin-bottom: 20px;
}

#taskInput {
  flex: 1;
  padding: 10px;
  border: none;
  outline: none;
  border-radius: 10px 0 0 10px;
}

#addBtn {
  padding: 10px 15px;
  border: none;
  cursor: pointer;
  background: #00bfa6;
  color: white;
  border-radius: 0 10px 10px 0;
  transition: 0.3s;
}

#addBtn:hover {
  background: #00a18b;
}

ul {
  list-style-type: none;
  padding: 0;
}

li {
  background: rgba(255, 255, 255, 0.15);
  margin: 8px 0;
  padding: 10px;
  border-radius: 10px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

li.completed {
  text-decoration: line-through;
  opacity: 0.6;
}

button.delete {
  background: #ff5e5e;
  border: none;
  color: white;
  padding: 5px 10px;
  border-radius: 6px;
  cursor: pointer;
}

button.delete:hover {
  background: #e14b4b;
}

:root {
  --bg-color: linear-gradient(135deg, #1e1f29, #2a2b38);
  --text-color: #ffffff;
  --card-color: rgba(255, 255, 255, 0.1);
  --accent: #00bfa6;
}

.light-mode {
  --bg-color: linear-gradient(135deg, #f1f3f6, #e0e5ec);
  --text-color: #222;
  --card-color: rgba(0, 0, 0, 0.05);
  --accent: #007bff;
}

body {
  background: var(--bg-color);
  color: var(--text-color);
  transition: all 0.4s ease;
}

#themeToggle {
  position: absolute;
  top: 20px;
  right: 20px;
  background: var(--accent);
  border: none;
  border-radius: 50%;
  padding: 10px;
  color: white;
  cursor: pointer;
  font-size: 18px;
  box-shadow: 0 0 10px rgba(0,0,0,0.3);
}

#themeToggle:hover {
  opacity: 0.9;
}

.container {
  background: var(--card-color);
  backdrop-filter: blur(12px);
}