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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background: #f0f2f5;
    color: #1a1a2e;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    padding-top: 60px;
}

.container {
    width: 100%;
    max-width: 520px;
    padding: 0 16px;
}

h1 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 24px;
    text-align: center;
}

#task-form {
    display: flex;
    gap: 8px;
    margin-bottom: 24px;
}

#task-input {
    flex: 1;
    padding: 12px 16px;
    border: 2px solid #ddd;
    border-radius: 8px;
    font-size: 16px;
    outline: none;
    transition: border-color 0.2s;
}

#task-input:focus {
    border-color: #4a6cf7;
}

#task-form button {
    padding: 12px 24px;
    background: #4a6cf7;
    color: #fff;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s;
}

#task-form button:hover {
    background: #3a5ce5;
}

#task-list {
    list-style: none;
}

.task-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 14px 16px;
    background: #fff;
    border-radius: 8px;
    margin-bottom: 8px;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
    transition: opacity 0.2s;
}

.task-item.completed .task-title {
    text-decoration: line-through;
    opacity: 0.5;
}

.task-checkbox {
    width: 20px;
    height: 20px;
    cursor: pointer;
    accent-color: #4a6cf7;
}

.task-title {
    flex: 1;
    font-size: 16px;
}

.task-delete {
    background: none;
    border: none;
    color: #e74c3c;
    font-size: 18px;
    cursor: pointer;
    padding: 4px 8px;
    border-radius: 4px;
    opacity: 0.6;
    transition: opacity 0.2s;
}

.task-delete:hover {
    opacity: 1;
}

.empty {
    text-align: center;
    color: #888;
    font-size: 14px;
    margin-top: 16px;
}