/* Modern CSS with contemporary design */
* {
    box-sizing: border-box;
}

body {
    font-family: 'Roboto', sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    margin: 0;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
}

#container {
    width: 100%;
    max-width: 500px;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-radius: 20px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    overflow: hidden;
    margin-bottom: 20px;
}

header h1 {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    margin: 0;
    padding: 25px 30px;
    font-size: 28px;
    font-weight: 500;
    display: flex;
    align-items: center;
    justify-content: space-between;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.add-button {
    background: rgba(255, 255, 255, 0.2);
    border: none;
    color: white;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 18px;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.add-button:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: scale(1.1);
}

.input-container {
    padding: 20px 30px;
    display: flex;
    gap: 10px;
    background: #f8f9fa;
    border-bottom: 1px solid #e9ecef;
}

#todo-input {
    flex: 1;
    padding: 15px 20px;
    border: 2px solid #e9ecef;
    border-radius: 25px;
    font-size: 16px;
    outline: none;
    transition: all 0.3s ease;
    background: white;
}

#todo-input:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.submit-button {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border: none;
    color: white;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 16px;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.submit-button:hover {
    transform: scale(1.05);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.3);
}

.stats {
    padding: 15px 30px;
    background: #f8f9fa;
    border-bottom: 1px solid #e9ecef;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 14px;
    color: #6c757d;
}

.clear-button {
    background: #dc3545;
    border: none;
    color: white;
    padding: 8px 12px;
    border-radius: 15px;
    cursor: pointer;
    font-size: 12px;
    transition: all 0.3s ease;
}

.clear-button:hover {
    background: #c82333;
    transform: translateY(-1px);
}

#todo-list {
    list-style: none;
    margin: 0;
    padding: 0;
    max-height: 400px;
    overflow-y: auto;
}

#todo-list li {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 30px;
    border-bottom: 1px solid #f1f3f4;
    background: white;
    transition: all 0.3s ease;
}

#todo-list li:hover {
    background: #f8f9fa;
}

#todo-list li:nth-child(even) {
    background: #fdfdfd;
}

#todo-list li:nth-child(even):hover {
    background: #f8f9fa;
}

.todo-content {
    display: flex;
    align-items: center;
    gap: 15px;
    flex: 1;
}

.complete-btn {
    background: none;
    border: none;
    color: #28a745;
    font-size: 20px;
    cursor: pointer;
    transition: all 0.3s ease;
    padding: 5px;
}

.complete-btn:hover {
    transform: scale(1.2);
}

.todo-text {
    font-size: 16px;
    color: #333;
    flex: 1;
}

.completed .todo-text {
    text-decoration: line-through;
    color: #6c757d;
}

.completed .complete-btn {
    color: #28a745;
}

.delete-btn {
    background: none;
    border: none;
    color: #dc3545;
    font-size: 16px;
    cursor: pointer;
    transition: all 0.3s ease;
    padding: 8px;
    border-radius: 50%;
    opacity: 0;
}

#todo-list li:hover .delete-btn {
    opacity: 1;
}

.delete-btn:hover {
    background: rgba(220, 53, 69, 0.1);
    transform: scale(1.1);
}

.empty-state {
    text-align: center;
    padding: 60px 30px;
    color: #6c757d;
}

.empty-state i {
    font-size: 48px;
    color: #28a745;
    margin-bottom: 20px;
}

.empty-state p {
    font-size: 18px;
    margin: 10px 0;
}

.sub-text {
    font-size: 14px;
    color: #adb5bd;
}

.credits {
    text-align: center;
    padding: 20px;
    color: rgba(255, 255, 255, 0.8);
    font-size: 14px;
}

.credits a {
    color: rgba(255, 255, 255, 0.9);
    text-decoration: none;
    font-weight: 500;
}

.credits a:hover {
    color: white;
    text-decoration: underline;
}

/* Responsive Design */
@media (max-width: 768px) {
    body {
        padding: 10px;
    }
    
    #container {
        max-width: 100%;
        border-radius: 15px;
    }
    
    header h1 {
        padding: 20px 20px;
        font-size: 24px;
    }
    
    .input-container {
        padding: 15px 20px;
    }
    
    .stats {
        padding: 12px 20px;
        flex-direction: column;
        gap: 10px;
        align-items: flex-start;
    }
    
    #todo-list li {
        padding: 15px 20px;
    }
    
    .todo-text {
        font-size: 15px;
    }
}

@media (max-width: 480px) {
    header h1 {
        font-size: 20px;
        padding: 15px 15px;
    }
    
    .input-container {
        padding: 12px 15px;
    }
    
    #todo-input {
        padding: 12px 15px;
        font-size: 14px;
    }
    
    .submit-button {
        width: 45px;
        height: 45px;
    }
    
    #todo-list li {
        padding: 12px 15px;
    }
}