:root {
  --dark-color: #160d08;
  --light-color: #fffefc;
  --background-color: #cccdc6;
  --neutral-color: #e8e9eb;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  background-color: var(--background-color);
  color: var(--dark-color);
}

.box {
  box-shadow: 5px 5px 5px rgba(0, 0, 0, 0.1);
  border-radius: 10px;
  border-style: none;
  background-color: var(--light-color);
}

header h1 {
  padding: 20px 0;
  text-align: center;
  color: var(--dark-color);
  font-size: 3.5rem;
  cursor: pointer;
}

.category-area {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 10px;
}

.category {
  height: 46px;
  min-width: 64px;
  padding: 0 24px;
  cursor: pointer;
  font-size: 1rem;
  transition: all 0.8s ease;
}

.category.active {
  color: var(--light-color);
  font-weight: bold;
  background-color: var(--dark-color);
}

.category:hover {
  transform: translateY(-10px);
}

.main-card {
  width: 80%;
  max-width: 800px;
  margin: 2rem auto;
  padding: 40px;
  display: flex;
  flex-direction: column;
  gap: 25px;
}

.main-card .header-area {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.main-card .header-area h2 {
  letter-spacing: 3px;
  font-size: 2rem;
}

.main-card .header-area h2 i {
  margin-right: 10px;
}

.create-area {
  display: flex;
  gap: 20px;
}

.create-area input {
  padding: 20px;
  border: none;
  border-radius: 15px;
  font-size: 1rem;
  background-color: var(--neutral-color);
  transition: box-shadow 0.1s ease;
  flex: 1;
}

.create-area input::placeholder {
  color: var(--neutral-color);
}

.create-area input:focus {
  outline: none;
  box-shadow: 0 0 5px var(--dark-color);
}

.create-area button {
  cursor: pointer;
  width: 10%;
  border: none;
  border-radius: 15px;
  background-color: var(--dark-color);
  transition: transform 0.3s;
}

.create-area button:hover {
  transform: scale(1.05);
}

.create-area button i {
  font-size: 1.2rem;
  color: var(--light-color);
}

.list-items {
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.list-item {
  display: flex;
  align-items: center;
  gap: 5px;
}

.list-item .checkbox input {
  display: none;
}

.checkbox_icon {
  display: inline-block;
  width: 20px;
  height: 20px;
  background-color: transparent;
  border: 1px solid var(--background-color);
  position: relative;
  cursor: pointer;
}

.checkbox_icon::before,
.checkbox_icon::after {
  content: '';
  display: inline-block;
  width: 1px;
  height: 0;
  background-color: green;
  position: absolute;
  transform-origin: left top;
}

.checkbox_icon::before {
  top: 9px;
  left: 2px;
  transform: rotate(-45deg);
}

.checkbox_icon::after {
  top: 16px;
  left: 9px;
  transform: rotate(-135deg);
}

.checkbox input:checked + .checkbox_icon {
  border-color: green;
}

.checkbox input:checked + .checkbox_icon::before {
  height: 10px;
  transition: all 0.15s ease;
}

.checkbox input:checked + .checkbox_icon::after {
  height: 20px;
  transition: all 0.15s ease 0.15s;
}

.checkbox.checked + .todo-title {
  color: var(--background-color);
  text-decoration: line-through;
}

.todo-title {
  font-size: 1rem;
  padding: 15px;
  flex: 1;
  border: none;
  border-radius: 15px;
  transition: box-shadow 0.3s ease;
}

.todo-title:focus {
  outline: none;
  box-shadow: 0 0 5px var(--dark-color);
}

.todo-title:disabled {
  background-color: var(--light-color);
  color: black;
}

.actions-btn {
  width: 50px;
  border: none;
  border-radius: 5px;
  padding: 10px 0;
  cursor: pointer;
  background-color: var(--neutral-color);
}

.actions-btn:hover {
  background-color: #e2e3e5;
}

.create-area input {
  padding: 20px;
  border: none;
  border-radius: 15px;
  font-size: 1rem;
  background-color: var(--neutral-color);
  transition: box-shadow 0.3s ease;
  flex: 1;
}

.create-area input::placeholder {
  color: #3e424b;
}

.create-area input:focus {
  outline: none;
  box-shadow: 0 0 5px var(--dark-color);
}

.alert-area {
  position: absolute;
  top: 10px;
  left: 10px;
}

.alert {
  color: white;
  font-size: 14px;
  padding: 15px 20px;
  border-radius: 15px;
  background-color: #aaa;
  margin: 0 auto;
  text-align: center;
}

.alert.alert-success {
  background-color: green;
  opacity: 0.7;
}

.alert.alert-error {
  background-color: palevioletred;
}

.fallback-contents {
  display: none;
  padding: 20px 0;
  font-size: 1.5rem;
  text-align: center;
  color: gray;
}