/* Reset and base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
    color: #333;
}

.container {
    max-width: 600px;
    margin: 0 auto;
    background: white;
    border-radius: 15px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    overflow: hidden;
}

/* Header */
header {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    color: white;
    text-align: center;
    padding: 30px 20px;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
    font-weight: 300;
}

header p {
    opacity: 0.9;
    font-size: 1.1rem;
}

/* Main content */
main {
    padding: 30px;
}

/* Todo input section */
.todo-input-section {
    display: flex;
    gap: 10px;
    margin-bottom: 30px;
}

.input-group {
    flex: 1;
    display: flex;
    gap: 5px;
    align-items: center;
}

#todoInput {
    flex: 1;
    padding: 15px 20px;
    border: 2px solid #e1e8ed;
    border-radius: 25px;
    font-size: 1rem;
    outline: none;
    transition: all 0.3s ease;
}

#todoInput:focus {
    border-color: #4facfe;
    box-shadow: 0 0 0 3px rgba(79, 172, 254, 0.1);
}

.date-input-container {
    display: flex;
    align-items: center;
    gap: 5px;
}

.date-toggle-btn {
    padding: 12px;
    background: #f8f9fa;
    border: 2px solid #e1e8ed;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1rem;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 45px;
    height: 45px;
}

.date-toggle-btn:hover {
    background: #e9ecef;
    border-color: #4facfe;
}

.date-toggle-btn.active {
    background: #4facfe;
    border-color: #4facfe;
    color: white;
}

.date-input {
    padding: 12px 15px;
    border: 2px solid #e1e8ed;
    border-radius: 20px;
    font-size: 0.9rem;
    outline: none;
    transition: all 0.3s ease;
    min-width: 150px;
}

.date-input:focus {
    border-color: #4facfe;
    box-shadow: 0 0 0 3px rgba(79, 172, 254, 0.1);
}

.date-input.hidden {
    display: none;
}

#addBtn {
    padding: 15px 25px;
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    color: white;
    border: none;
    border-radius: 25px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    min-width: 80px;
}

#addBtn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(79, 172, 254, 0.4);
}

#addBtn:active {
    transform: translateY(0);
}

/* Todo controls */
.todo-controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    flex-wrap: wrap;
    gap: 15px;
}

.filter-buttons {
    display: flex;
    gap: 5px;
}

.filter-btn {
    padding: 8px 16px;
    border: 2px solid #e1e8ed;
    background: white;
    border-radius: 20px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.9rem;
}

.filter-btn:hover {
    border-color: #4facfe;
    color: #4facfe;
}

.filter-btn.active {
    background: #4facfe;
    border-color: #4facfe;
    color: white;
}

.todo-stats {
    color: #666;
    font-size: 0.9rem;
}

/* Todo list */
.todo-list {
    list-style: none;
    margin-bottom: 20px;
}

.todo-item {
    display: flex;
    align-items: center;
    padding: 15px 0;
    border-bottom: 1px solid #f0f0f0;
    transition: all 0.3s ease;
}

.todo-item:hover {
    background: #f8f9fa;
    margin: 0 -15px;
    padding-left: 15px;
    padding-right: 15px;
    border-radius: 8px;
}

.todo-item.completed {
    opacity: 0.6;
}

.todo-item.overdue {
    border-left: 4px solid #e74c3c;
    background: linear-gradient(90deg, rgba(231, 76, 60, 0.05) 0%, transparent 100%);
}

.todo-item.overdue:hover {
    background: linear-gradient(90deg, rgba(231, 76, 60, 0.1) 0%, rgba(248, 249, 250, 1) 100%);
}

.todo-checkbox {
    width: 20px;
    height: 20px;
    border: 2px solid #ddd;
    border-radius: 50%;
    margin-right: 15px;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    flex-shrink: 0;
}

.todo-checkbox:hover {
    border-color: #4facfe;
}

.todo-checkbox.checked {
    background: #4facfe;
    border-color: #4facfe;
}

.todo-checkbox.checked::after {
    content: '✓';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: white;
    font-size: 12px;
    font-weight: bold;
}

.todo-text {
    flex: 1;
    font-size: 1rem;
    line-height: 1.4;
    cursor: pointer;
    transition: all 0.3s ease;
}

.todo-text.completed {
    text-decoration: line-through;
    color: #999;
}

.todo-text.editing {
    background: white;
    border: 2px solid #4facfe;
    border-radius: 5px;
    padding: 5px 10px;
    outline: none;
    width: 100%;
}

.edit-date-container {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-top: 8px;
}

.editing-date {
    flex: 1;
    padding: 8px 12px;
    border: 2px solid #e1e8ed;
    border-radius: 15px;
    font-size: 0.85rem;
    outline: none;
    transition: all 0.3s ease;
    background: white;
}

.editing-date:focus {
    border-color: #4facfe;
    box-shadow: 0 0 0 3px rgba(79, 172, 254, 0.1);
}

.clear-date-btn {
    padding: 6px 10px;
    background: #f8f9fa;
    border: 2px solid #e1e8ed;
    border-radius: 50%;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    color: #999;
}

.clear-date-btn:hover {
    background: #e74c3c;
    border-color: #e74c3c;
    color: white;
}

.todo-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.todo-due-date {
    font-size: 0.8rem;
    color: #666;
    font-style: italic;
}

.todo-due-date.overdue {
    color: #e74c3c;
    font-weight: 600;
}

.todo-due-date.due-soon {
    color: #f39c12;
    font-weight: 500;
}

.todo-actions-btn {
    display: flex;
    gap: 5px;
    opacity: 0;
    transition: opacity 0.3s ease;
}

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

.edit-btn, .delete-btn {
    padding: 5px 10px;
    border: none;
    border-radius: 15px;
    cursor: pointer;
    font-size: 0.8rem;
    transition: all 0.3s ease;
}

.edit-btn {
    background: #ffeaa7;
    color: #d63031;
}

.edit-btn:hover {
    background: #fdcb6e;
}

.delete-btn {
    background: #fab1a0;
    color: #e17055;
}

.delete-btn:hover {
    background: #e84393;
    color: white;
}

/* Todo actions */
.todo-actions {
    text-align: center;
    margin-top: 20px;
}

.clear-btn {
    padding: 10px 20px;
    background: #fd79a8;
    color: white;
    border: none;
    border-radius: 20px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.9rem;
}

.clear-btn:hover {
    background: #e84393;
    transform: translateY(-2px);
}

.clear-btn:disabled {
    background: #ddd;
    cursor: not-allowed;
    transform: none;
}

/* Footer */
footer {
    text-align: center;
    padding: 20px;
    background: #f8f9fa;
    color: #666;
    font-size: 0.9rem;
}

/* Feedback section */
.feedback-section {
    background: linear-gradient(135deg, #e9ecef 0%, #dee2e6 100%);
    padding: 25px 30px;
    text-align: center;
    border-top: 1px solid #e1e8ed;
}

.feedback-section h3 {
    color: #495057;
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 10px;
}

.feedback-section p {
    color: #6c757d;
    font-size: 0.95rem;
    line-height: 1.5;
    margin-bottom: 20px;
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}

.feedback-links {
    display: flex;
    gap: 15px;
    justify-content: center;
    flex-wrap: wrap;
}

.feedback-btn {
    display: inline-block;
    padding: 12px 24px;
    background: #495057;
    color: white;
    text-decoration: none;
    border-radius: 25px;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.3s ease;
    border: 2px solid #495057;
}

.feedback-btn:hover {
    background: #343a40;
    border-color: #343a40;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(73, 80, 87, 0.3);
}

.feedback-btn:active {
    transform: translateY(0);
}

/* Empty state */
.empty-state {
    text-align: center;
    padding: 40px 20px;
    color: #999;
}

.empty-state h3 {
    margin-bottom: 10px;
    font-weight: 300;
}

/* Responsive design */
@media (max-width: 768px) {
    .container {
        margin: 10px;
        border-radius: 10px;
    }
    
    header h1 {
        font-size: 2rem;
    }
    
    main {
        padding: 20px;
    }
    
    .todo-input-section {
        flex-direction: column;
    }
    
    #addBtn {
        align-self: stretch;
    }
    
    .todo-controls {
        flex-direction: column;
        align-items: stretch;
        text-align: center;
    }
    
    .filter-buttons {
        justify-content: center;
    }
    
    /* Feedback section responsive */
    .feedback-section {
        padding: 20px 15px;
    }
    
    .feedback-section h3 {
        font-size: 1.1rem;
    }
    
    .feedback-section p {
        font-size: 0.9rem;
        margin-bottom: 15px;
    }
    
    .feedback-links {
        flex-direction: column;
        gap: 10px;
    }
    
    .feedback-btn {
        padding: 14px 20px;
        font-size: 0.95rem;
    }
}

/* Animations */
@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.todo-item {
    animation: slideIn 0.3s ease;
}

@keyframes fadeOut {
    from {
        opacity: 1;
        transform: scale(1);
    }
    to {
        opacity: 0;
        transform: scale(0.8);
    }
}

.todo-item.removing {
    animation: fadeOut 0.3s ease forwards;
}