:root {
    --bg-color: #f5f2ed;
    --container-bg: #ffffff;
    --text-color: #4a453e;
    --border-color: #e8e3d9;
    --input-bg: #faf9f7;
    --primary-color: #d2c8b1;
    --primary-hover: #bcaf94;
    --secondary-text: #9c9486;
    --completed-text: #b8b0a1;
    --li-border: #f0ede9;
    --delete-hover: #fff1f1;
    --delete-text: #ff8e8e;
    --shadow: rgba(0, 0, 0, 0.05);
}

[data-theme="dark"] {
    --bg-color: #1a1a1a;
    --container-bg: #2d2d2d;
    --text-color: #e0e0e0;
    --border-color: #404040;
    --input-bg: #383838;
    --primary-color: #a69a84;
    --primary-hover: #8e836f;
    --secondary-text: #a0a0a0;
    --completed-text: #666666;
    --li-border: #404040;
    --delete-hover: #4a3434;
    --delete-text: #ff6b6b;
    --shadow: rgba(0, 0, 0, 0.3);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, sans-serif;
    transition: background-color 0.3s, color 0.3s, border-color 0.3s;
}

body {
    background-color: var(--bg-color);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    color: var(--text-color);
}

.container {
    background-color: var(--container-bg);
    padding: 2.5rem;
    border-radius: 20px;
    box-shadow: 0 10px 30px var(--shadow);
    width: 100%;
    max-width: 400px;
    border: 1px solid var(--border-color);
    position: relative;
}

.header-actions {
    display: flex;
    justify-content: flex-end;
    margin-bottom: -10px;
}

.icon-btn {
    background: none;
    border: none;
    font-size: 1.2rem;
    cursor: pointer;
    padding: 8px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color 0.2s;
}

.icon-btn:hover {
    background-color: var(--border-color);
}

h1 {
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    text-align: center;
    font-weight: 600;
    letter-spacing: -0.5px;
}

.input-group {
    display: flex;
    gap: 10px;
    margin-bottom: 0.5rem;
}

input[type="text"] {
    flex: 1;
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    background-color: var(--input-bg);
    color: var(--text-color);
    outline: none;
}

input[type="text"]:focus {
    border-color: var(--primary-color);
}

button#add-btn {
    padding: 12px 20px;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 12px;
    cursor: pointer;
    font-weight: 500;
}

button#add-btn:hover {
    background-color: var(--primary-hover);
}

#counter {
    font-size: 0.85rem;
    color: var(--secondary-text);
    text-align: right;
    margin-bottom: 1.5rem;
}

ul {
    list-style: none;
}

li {
    display: flex;
    align-items: center;
    padding: 12px 0;
    border-bottom: 1px solid var(--li-border);
    gap: 12px;
    animation: fadeIn 0.3s ease;
}

li:last-child {
    border-bottom: none;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(5px); }
    to { opacity: 1; transform: translateY(0); }
}

input[type="checkbox"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
    accent-color: var(--primary-color);
}

.todo-text {
    flex: 1;
    font-size: 1rem;
}

.todo-text.completed {
    text-decoration: line-through;
    color: var(--completed-text);
}

.delete-btn {
    background: none;
    color: var(--secondary-text);
    padding: 4px 8px;
    font-size: 0.8rem;
    border: none;
    border-radius: 6px;
    cursor: pointer;
}

.delete-btn:hover {
    background-color: var(--delete-hover);
    color: var(--delete-text);
}