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

:root {
    --primary: #7749f8;
    --primary-light: #9775fa;
    --dark: #212529;
    --light: #f8f9fa;
    --gray: #868e96;
    --danger: #fa5252;
    --border: #e9ecef;
    --success: #40c057;
}

body {
    font-family: sans-serif;
    background-color: #f1f3f5;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
    color: var(--dark);
}

.container {
    width: 100%;
    max-width: 500px;
    overflow: hidden;
    background-color: #fff;
    border-radius: 12px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.2);
}

.header {
    background-color: var(--primary);
    color: #fff;
    padding: 20px 25px;
}

.header h1 {
    font-size: 24px;
    font-weight: 600;
    margin-bottom: 5px;
}

.header p {
    font-size: 14px;
    opacity: 0.9;
}

.input-bar {
    background-color: var(--light);
    padding: 20px 25px;
    display: flex;
    gap: 10px;
    border-bottom: 1px solid var(--border)
}

.input-bar input {
    flex: 1;
    padding: 12px 15px;
    border: 1px solid #dee2e6;
    font-size: 1rem;
    transition: all 0.2s ease;
    border-radius: 6px;
}

.input-bar input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(119, 73, 247, 0.15);
}

.input-bar button {
    background-color: var(--primary);
    color: white;
    width: 40px;
    height: 40px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s;
}

.input-bar button:hover {
    background-color: var(--primary-light);
}


.task-categories {
    display: flex;
    gap: 15px;
    border-bottom: 1px solid var(--border);
    padding: 15px 25px;
}

.task-category {
    padding: 5px 3px;
    cursor: pointer;
    color: var(--gray);
    border-bottom: 2px solid transparent;
    transition: all 0.2s;
}

.task-category:hover {
    color: var(--primary);
}

.task-category.active-category {
    color: var(--primary);
    border-bottom: 2px solid var(--primary);
    font-weight: 600;
}

.task-items {
    padding: 15px 0;
    max-height: 300px;
    overflow-y: auto;
}

#todo-list {
    list-style-type: none;
}

.todo-item {
    padding: 12px 15px;
    display: flex;
    align-items: center;
    transition: background-color 0.2s;
}

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

.checkbox-container {
    margin-right: 15px;
}

.todo-checkbox {
    opacity: 0;
    position: absolute;
}

.checkmark {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 2px solid #dee2e6;
    border-radius: 4px;
    position: relative;
    cursor: pointer;
    transition: all 0.2s;
}

.todo-checkbox:checked + .checkmark {
    background-color: var(--success);
    border-color: var(--success);
}

.todo-checkbox:checked + .checkmark::after {
    content: "";
    position:absolute;
    left: 6px;
    top: 2px;
    width: 5px;
    height: 10px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

.todo-item-text {
    flex:1;
    font-size: 1rem;
    transition: all 0.2s;
    word-break: break-word;
}

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

.delete-btn {
    background: none;
    border: none;
    color:var(--gray);
    cursor: pointer;
    font-size: 16px;
    opacity: 0;
    transition: all 0.2s;
}

.todo-item:hover .delete-btn {
    opacity: 1;
}

.delete-btn:hover {
    color: var(--danger);
    background-color: rgba(253, 216, 216);
    border-radius: 6px;
    padding: 4px 4px;
}

.empty-state {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction:column;
    padding: 40px 0;
    color:var(--gray);
    text-align: center;
    transition: all 0.3s ease;
}

.empty-state i {
    font-size: 60px;
    opacity: 0.7;
    margin-bottom: 10px;
    transition: all 0.3s ease;
}

.hidden {
    display: none;
}

footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 25px;
    border-top: 1px solid var(--border);
    background-color: var(--light);
    font-size: 14px;
}

#items-left {
    color:var(--gray);
}

#clear-completed {
    background:none;
    border: none;
    cursor: pointer;
    color:var(--gray);
    transition: all 0.2s;
}

#clear-completed:hover {
    color:var(--danger);
}