/* Variables y reset básico */
:root {
    --primary-color: #4f46e5;
    --secondary-color: #6366f1;
    --background-color: #f9fafb;
    --card-background: #ffffff;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --border-color: #e5e7eb;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 4px 6px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    background-color: var(--background-color);
    color: var(--text-primary);
    line-height: 1.6;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem;
}

/* Header */
.header {
    text-align: center;
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.header h1 {
    color: var(--primary-color);
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

.header p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Main Content */
.main-content {
    background: var(--card-background);
    border-radius: 12px;
    box-shadow: var(--shadow-lg);
    padding: 2rem;
    margin-bottom: 2rem;
}

/* Task Input Section */
.task-input-section {
    margin-bottom: 2rem;
}

.task-input-section h2 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

#task-form {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

#task-input {
    flex: 1;
    min-width: 250px;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: var(--transition);
}

#task-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

#task-priority {
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    background: var(--card-background);
    cursor: pointer;
    transition: var(--transition);
}

#task-priority:focus {
    outline: none;
    border-color: var(--primary-color);
}

.add-btn {
    padding: 0.75rem 1.5rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    white-space: nowrap;
}

.add-btn:hover {
    background: var(--secondary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

/* Task Filters */
.task-filters {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 0.5rem 1rem;
    background: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition);
    font-size: 0.9rem;
}

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

.filter-btn.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* Tasks List */
.tasks-list h2 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

#tasks-container {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

/* Task Item */
.task {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem;
    background: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    transition: var(--transition);
}

.task:hover {
    box-shadow: var(--shadow);
    transform: translateX(4px);
}

.task.completed {
    opacity: 0.7;
    background: #f3f4f6;
}

.task-content {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex: 1;
}

.task-checkbox {
    width: 20px;
    height: 20px;
    cursor: pointer;
}

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

.task-priority {
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    color: white;
    font-size: 0.75rem;
    font-weight: 600;
}

.delete-btn {
    padding: 0.5rem;
    background: #ef4444;
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: var(--transition);
    font-size: 1.1rem;
}

.delete-btn:hover {
    background: #dc2626;
    transform: scale(1.1);
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 3rem;
    color: var(--text-secondary);
}

.empty-state p {
    font-size: 1.1rem;
}

/* Footer */
.footer {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
    padding: 1rem 0;
}

/* Responsive Design */
@media (max-width: 600px) {
    .container {
        padding: 1rem;
    }

    .main-content {
        padding: 1.5rem;
    }

    .header h1 {
        font-size: 2rem;
    }

    #task-form {
        flex-direction: column;
    }

    #task-input {
        min-width: 100%;
    }

    .task-filters {
        justify-content: center;
    }
}

/* Animations */
.task {
    animation: slideIn 0.3s ease-out;
}

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

.task.completed .task-text {
    text-decoration: line-through;
}