body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    background-color: #f0f2f5;
    color: #333;
    display: flex;
    flex-direction: column; /* 요소를 세로로 정렬 */
    justify-content: flex-start; /* 요소를 상단에 배치 */
    align-items: center; /* 요소를 가로 중앙에 배치 */
    min-height: 100vh;
    margin: 0;
    padding: 20px;
}

.top-ad {
    width: 90%;
    max-width: 500px;
    background-color: #ffffff;
    border: 1px solid #e9ecef;
    border-radius: 8px;
    padding: 10px;
    text-align: center;
    margin-bottom: 20px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.container {
    width: 90%;
    max-width: 500px;
    background-color: #ffffff;
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    text-align: center;
    position: relative;
    overflow: hidden;
}

h1 {
    color: #333;
    font-size: 2.5rem;
    margin-bottom: 20px;
    font-weight: 700;
    letter-spacing: -0.5px;
}

.input-container {
    display: flex;
    gap: 10px;
    margin-bottom: 25px;
}

#todo-input {
    flex-grow: 1;
    padding: 12px 18px;
    border: 1px solid #ddd;
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.3s, box-shadow 0.3s;
}

#todo-input:focus {
    outline: none;
    border-color: #007bff;
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.25);
}

#add-button {
    padding: 12px 25px;
    border: none;
    background-color: #007bff;
    color: white;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: background-color 0.3s;
}

#add-button:hover {
    background-color: #0056b3;
}

#todo-list {
    list-style-type: none;
    padding: 0;
    margin: 0;
    text-align: left;
}

#todo-list li {
    background-color: #f8f9fa;
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 12px;
    font-size: 1.1rem;
    transition: all 0.3s ease;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    border-left: 4px solid transparent;
}

#todo-list li:hover {
    background-color: #e9ecef;
}

.completed {
    text-decoration: line-through;
    color: #adb5bd;
    border-color: #28a745;
    background-color: #e9f5f1;
}

.completed:hover {
    background-color: #d8e5e1;
}

/* 편집 모드일 때 텍스트를 구분하기 위한 스타일 */
li.editing {
    background-color: #fff3cd; /* 편집 모드 배경색 */
    border-color: #ffc107;
}

.edit-button {
    background-color: #ffc107;
    color: white;
    border: none;
    padding: 5px 10px;
    border-radius: 5px;
    cursor: pointer;
    font-size: 0.8rem;
    font-weight: 600;
    margin-left: 10px;
    transition: background-color 0.3s;
    flex-shrink: 0;
}

.edit-button:hover {
    background-color: #e0a800;
}

.tutorial {
    font-style: italic;
    color: #868e96;
    background-color: transparent !important;
    border-left: none !important;
    cursor: default !important;
}

.tutorial:hover {
    background-color: transparent !important;
}