styles.css

:root {
  --neon-inner: #35beaf;
  --neon-outer: #35b9aa;
  --completed-todo: #2ea396;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  min-height: 100vh;
  background: linear-gradient(180deg, #4d6f93 0%, #a84545a6 100%);
}

h1 {
  text-align: center;
  margin: 0;
  padding: 20px 0 0 0;
  color: #e1e1e1;
}

.container {
  padding: 50px 10px 0 10px;
  margin: 0 auto;
  width: 100%;
  max-width: 400px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 24px;
}

.search-input {
  padding: 0 10px;
  width: 100%;
  height: 45px;
  font-size: 20px;
  background: none;
  border: none;
  border-radius: 3px;
  outline: 2px solid #21303f;
  transition: .22s box-shadow, .22s color;
}

.search-input:focus-visible {
  box-shadow: 0 0 15px 15px var(--neon-outer), inset 0 0 25px 10px var(--neon-inner);
  color: #fff;
}

.search-input::placeholder {
  color: #3c3c3c;
  font-size: 16px;
  font-style: italic;
}

.todos-container {
  width: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: stretch;
  gap: 8px;
}

.todo-item {
  padding: 0 10px;
  height: 45px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 24px;
  border: 1px solid black;
}

.todo-item span {
  pointer-events: none;
  user-select: none;
}

.todo-item.completed {
  background-color: var(--completed-todo);
}

.todo-item.completed span {
  text-decoration: line-through;
}

.todo-item:hover {
  border: 1px solid var(--neon-inner);
  box-shadow: 0 0 10px 5px var(--neon-outer), inset 0 0 10px 5px var(--neon-inner);
  color: #fff;
}