/* ============================================ */
/* CSS VARIABLES                                */
/* ============================================ */
:root {
    --color-primary: #007bff;
    --color-primary-dark: #0056b3;
    --color-secondary: #6c757d;
    --color-success: #28a745;
    --color-danger: #dc3545;
    --color-warning: #ffc107;
    --color-info: #17a2b8;
    --color-light: #f5f5f5;
    --color-dark: #343a40;
    --color-white: #f5f5f5;
    --color-border: #f5f5f5;
    --color-text: #333333;
    --color-text-light: #555555;
    --color-bg: #f5f5f5;

    --font-size-sm: 14px;
    --font-size-base: 16px;
    --font-size-lg: 18px;
    --font-size-xl: 20px;
    --font-size-h2: 28px;

    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;

    --border-radius-sm: 4px;
    --border-radius-md: 8px;
    --border-radius-lg: 12px;

    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
}
/* ============================================ */
/* DARK MODE VARIABLES                          */
/* ============================================ */
html.dark {
    --color-light: #111827;      
    --color-white: #111827;      
    --color-border: #111827;     
    --color-text: #f3f4f6;       
    --color-text-light: #9ca3af; 
    --color-bg: #111827;         
}

/* ============================================ */
/* APP LAYOUT                                   */
/* ============================================ */
body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: var(--color-text);
    display: grid;
    grid-template-columns: 250px 1fr;
    grid-template-rows: auto 1fr auto;
    min-height: 100vh;
}

header {
    position: sticky;
    top: 0;
    z-index: 100;
    grid-column: 1 / -1;
    grid-row: 1;
    box-shadow: var(--shadow-md);
}

header h1 {
    margin: 0;
}

nav ul {
    display: flex;
    gap: var(--spacing-lg);
    list-style: none;
    margin: 0;
    padding: 0;
}

nav li {
    list-style: none;
}

nav a {
    color: white;
    font-weight: 500;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--border-radius-md);
    transition: background-color 0.3s ease;
    text-decoration: none;
}

nav a:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

main {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
    grid-column: 2;
    grid-row: 2;
    overflow-y: auto;
}

aside {
    background-color: var(--color-light);
    padding: var(--spacing-lg);
    border-right: 1px solid var(--color-border);
    overflow-y: auto;
    grid-column: 1;
    grid-row: 2;
    display: flex;
    flex-direction: column;
}

footer {
    padding: var(--spacing-lg);
    text-align: center;
    background-color: var(--color-light);
    border-top: 1px solid var(--color-border);
    grid-column: 1 / -1;
    grid-row: 3;
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.footer-author {
    margin-left: auto;
    font-size: var(--font-size-sm);
    color: rgba(255, 255, 255, 0.6);
}

/* ============================================ */
/* DIALOG "ACERCA DE"                           */
/* ============================================ */
.about-dialog {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    margin: 0;
    width: min(480px, 90vw);
    border: none;
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    background-color: var(--color-white);
    color: var(--color-text);
    box-shadow: var(--shadow-lg);
}

.about-dialog::backdrop {
    background-color: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(2px);
}

.about-dialog__close {
    position: absolute;
    top: var(--spacing-md);
    right: var(--spacing-md);
    width: 32px;
    height: 32px;
    border: none;
    border-radius: 50%;
    background: none;
    font-size: 20px;
    line-height: 1;
    cursor: pointer;
    color: var(--color-text-light);
    display: flex;
    align-items: center;
    justify-content: center;
}

.about-dialog__close:hover {
    background-color: rgba(0, 0, 0, 0.08);
    color: var(--color-text);
}

.about-dialog__title {
    font-size: var(--font-size-xl);
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    color: var(--color-primary);
}

.about-dialog__body {
    font-size: var(--font-size-base);
    line-height: 1.6;
    margin-bottom: var(--spacing-sm);
    color: var(--color-text);
}

.about-dialog__author {
    margin-top: var(--spacing-lg);
    font-size: var(--font-size-sm);
    color: var(--color-text-light);
    text-align: right;
}

html.dark .about-dialog {
    background-color: #1f2937;
    color: #f3f4f6;
}

html.dark .about-dialog__close:hover {
    background-color: rgba(255, 255, 255, 0.1);
    color: #f3f4f6;
}

/* ============================================ */
/* DIALOG DE CONFIRMACION                        */
/* ============================================ */
.confirm-dialog {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    margin: 0;
    width: min(420px, 90vw);
    border: none;
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    background-color: var(--color-white);
    color: var(--color-text);
    box-shadow: var(--shadow-lg);
}

.confirm-dialog::backdrop {
    background-color: rgba(0, 0, 0, 0.45);
}

.confirm-dialog__title {
    margin: 0 0 var(--spacing-sm) 0;
    font-size: var(--font-size-lg);
    color: var(--color-primary);
}

.confirm-dialog__message {
    margin: 0 0 var(--spacing-lg) 0;
    line-height: 1.5;
    color: var(--color-text);
}

.confirm-dialog__actions {
    display: flex;
    justify-content: flex-end;
    gap: var(--spacing-sm);
}

.confirm-dialog__btn {
    border: none;
    border-radius: var(--border-radius-md);
    padding: 10px 14px;
    font-weight: 600;
    cursor: pointer;
}

.confirm-dialog__btn--secondary {
    background-color: #e5e7eb;
    color: #1f2937;
}

.confirm-dialog__btn--secondary:hover {
    background-color: #d1d5db;
}

.confirm-dialog__btn--primary {
    background-color: var(--color-primary);
    color: white;
}

.confirm-dialog__btn--primary:hover {
    background-color: var(--color-primary-dark);
}

html.dark .confirm-dialog {
    background-color: #1f2937;
    color: #f3f4f6;
}

html.dark .confirm-dialog__message {
    color: #d1d5db;
}

html.dark .confirm-dialog__btn--secondary {
    background-color: #374151;
    color: #f3f4f6;
}

html.dark .confirm-dialog__btn--secondary:hover {
    background-color: #4b5563;
}

html.dark .network-state--loading {
    background-color: rgba(56, 189, 248, 0.12);
    border-color: rgba(56, 189, 248, 0.2);
    color: #bae6fd;
}

html.dark .network-state--error {
    background-color: rgba(248, 113, 113, 0.14);
    border-color: rgba(248, 113, 113, 0.24);
    color: #fecaca;
}

html.dark .tasks-empty-message,
html.dark .tasks-loading-message,
html.dark .tasks-error-message {
    background-color: rgba(255, 255, 255, 0.03);
    border-color: rgba(255, 255, 255, 0.08);
    color: #cbd5e1;
}

html.dark .tasks-error-message {
    background-color: rgba(248, 113, 113, 0.1);
    border-color: rgba(248, 113, 113, 0.18);
    color: #fecaca;
}

/* ============================================ */
/* FORM                                         */
/* ============================================ */
form {
    background-color: var(--color-light);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-sm);
}

.form-row {
    display: flex;
    gap: var(--spacing-md);
    align-items: flex-end;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.form-group.flex-grow {
    flex: 1;
}

label {
    font-weight: 500;
    display: block;
}

input[type="text"],
input[type="email"],
input[type="password"],
input[type="number"],
textarea,
select {
    font-family: inherit;
    font-size: 16px;
    min-height: 44px;
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-md);
    transition: border-color 0.3s ease, box-shadow 0.3s ease, background-color 0.2s ease;
}

textarea {
    resize: vertical;
    min-height: 120px;
}

input[type="text"]:hover,
textarea:hover,
select:hover {
    border-color: var(--color-primary);
    background-color: rgba(0, 123, 255, 0.02);
}

input[type="text"]:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.15);
    background-color: var(--color-white);
}

input[type="submit"],
button {
    font-family: inherit;
    cursor: pointer;
    font-size: var(--font-size-base);
    font-weight: 500;
    min-height: 44px;
    padding: var(--spacing-sm) var(--spacing-lg);
    background-color: var(--color-primary);
    color: white;
    border: none;
    border-radius: var(--border-radius-md);
    transition: background-color 0.3s ease, transform 0.2s ease, box-shadow 0.3s ease;
}

input[type="submit"]:hover,
button:hover {
    background-color: var(--color-primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

input[type="submit"]:active,
button:active {
    transform: translateY(0);
    box-shadow: var(--shadow-md);
}

input[type="submit"]:disabled,
button:disabled {
    background-color: var(--color-secondary);
    cursor: not-allowed;
    opacity: 0.6;
    transform: none;
}

/* ============================================ */
/* SIDEBAR — filters and categories             */
/* ============================================ */
aside p {
    font-weight: 500;
    font-size: var(--font-size-sm);
    color: var(--color-text-light);
    margin-bottom: var(--spacing-md);
    cursor: pointer;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--border-radius-md);
    transition: background-color 0.3s ease;
}

aside p:hover {
    background-color: var(--color-white);
    color: var(--color-primary);
}

aside ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

aside li {
    list-style: none;
    padding: var(--spacing-sm) var(--spacing-md);
    margin-bottom: var(--spacing-sm);
    background-color: var(--color-white);
    border-radius: var(--border-radius-md);
    cursor: pointer;
    transition: background-color 0.3s ease;
}

aside li:hover {
    background-color: var(--color-primary);
    color: var(--color-white);
}

.categories-title {
    cursor: default;
    padding: var(--spacing-sm) var(--spacing-md);
    transition: none;
}

.categories-title:hover {
    background-color: transparent;
    color: var(--color-text-light);
}

.categories-list {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.category-item {
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--color-white);
    border-radius: var(--border-radius-md);
    cursor: pointer;
    font-size: var(--font-size-sm);
    color: var(--color-text);
    border: 2px solid transparent;
    transition: all 0.3s ease;
}

.category-item:hover {
    background-color: var(--color-light);
    transform: translateX(4px);
}

.category-item.active {
    background-color: var(--color-primary);
    color: var(--color-white);
    border-color: var(--color-primary-dark);
    font-weight: 500;
}

/* ============================================ */
/* FILTER BUTTONS                               */
/* ============================================ */
.filter-section {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.filter-btn {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-weight: 500;
    font-size: var(--font-size-sm);
    color: var(--color-text-light);
    margin-bottom: 0;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--border-radius-md);
    cursor: pointer;
    transition: all 0.3s ease;
    background-color: transparent;
    border: 2px solid transparent;
}

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

.filter-btn.active {
    background-color: var(--color-primary);
    color: var(--color-white);
    border-color: var(--color-primary-dark);
    border-left: 4px solid var(--color-primary-dark);
}

.counter {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background-color: rgba(0, 0, 0, 0.1);
    color: inherit;
    border-radius: 50%;
    width: 28px;
    height: 28px;
    font-weight: 700;
    font-size: var(--font-size-sm);
}

.filter-btn.active .counter {
    background-color: rgba(255, 255, 255, 0.3);
}

/* ============================================ */
/* SEARCH SECTION                               */
/* ============================================ */
.search-section {
    padding: var(--spacing-lg);
    background-color: var(--color-white);
    margin-bottom: var(--spacing-md);
}

.search-container {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
}

#searchInput {
    flex: 1;
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: var(--font-size-base);
    border: 2px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

#searchInput::placeholder {
    color: var(--color-text-light);
}

#searchInput:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.15);
}

.mark-all-btn {
    background-color: var(--color-success);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--border-radius-lg);
    white-space: nowrap;
}

.mark-all-btn:hover {
    background-color: #20c997;
}

.delete-completed-btn {
    background-color: var(--color-danger);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--border-radius-lg);
    white-space: nowrap;
}

.delete-completed-btn:hover {
    background-color: #c82333;
}

.sort-btn {
    background-color: var(--color-secondary);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--border-radius-lg);
    white-space: nowrap;
}

.sort-btn:hover {
    background-color: #5a6268;
}

.network-state {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--border-radius-lg);
    border: 1px solid transparent;
}

.network-state[hidden] {
    display: none;
}

.network-state__content {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.network-state__message {
    margin: 0;
    font-size: var(--font-size-sm);
    line-height: 1.5;
}

.network-state__retry {
    width: auto;
    min-height: 38px;
    padding: 8px 14px;
    border-radius: 999px;
}

.network-state--loading {
    background-color: rgba(23, 162, 184, 0.08);
    border-color: rgba(23, 162, 184, 0.18);
    color: #0f4c5c;
}

.network-state--error {
    background-color: rgba(220, 53, 69, 0.08);
    border-color: rgba(220, 53, 69, 0.18);
    color: #7f1d1d;
}

.loading-spinner {
    width: 18px;
    height: 18px;
    border-radius: 50%;
    border: 2px solid rgba(0, 123, 255, 0.18);
    border-top-color: var(--color-primary);
    animation: spin 0.8s linear infinite;
    flex-shrink: 0;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* ============================================ */
/* CATEGORY QUICK PICKER                        */
/* ============================================ */
.category-quick-picker {
    margin-top: var(--spacing-sm);
    padding: var(--spacing-sm);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-md);
    background-color: var(--color-white);
    box-shadow: var(--shadow-md);
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.category-chip {
    width: auto;
    min-height: 34px;
    padding: 6px 12px;
    border-radius: 999px;
    font-size: var(--font-size-sm);
    background-color: rgba(0, 123, 255, 0.12);
    color: var(--color-primary-dark);
    border: 1px solid rgba(0, 86, 179, 0.2);
    box-shadow: none;
    transform: none;
}

.category-chip:hover {
    background-color: rgba(0, 123, 255, 0.22);
    color: var(--color-primary-dark);
    box-shadow: none;
    transform: none;
}

.category-chip:active {
    box-shadow: none;
    transform: none;
}

.quick-picker-empty {
    margin: 0;
    color: var(--color-text-light);
    font-size: var(--font-size-sm);
}

/* ============================================ */
/* TASK LIST                                    */
/* ============================================ */
.tasks-list {
    flex: 1;
    overflow-y: auto;
    padding: var(--spacing-lg);
    background-color: var(--color-white);
}

#tasksList {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.tasks-empty-message,
.tasks-loading-message,
.tasks-error-message {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
    min-height: 180px;
    padding: var(--spacing-lg);
    border-radius: var(--border-radius-lg);
    border: 2px dashed var(--color-border);
    background-color: rgba(0, 123, 255, 0.03);
    color: var(--color-text-light);
    text-align: center;
    line-height: 1.6;
}

.tasks-error-message {
    background-color: rgba(220, 53, 69, 0.05);
    border-color: rgba(220, 53, 69, 0.18);
    color: #991b1b;
}

.task-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    background-color: var(--color-white);
    border: 2px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-md) var(--spacing-lg);
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
}

.task-item:hover {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

.task-checkbox {
    width: 24px;
    height: 24px;
    min-width: 24px;
    cursor: pointer;
    accent-color: var(--color-primary);
}

.task-content {
    flex: 1;
    padding: var(--spacing-sm) 0;
}

.task-title {
    margin: 0 0 var(--spacing-xs);
    font-size: var(--font-size-lg);
    font-weight: 700;
    color: var(--color-text);
}

.task-description {
    margin: 0;
    font-size: var(--font-size-sm);
    color: var(--color-text-light);
}

.task-status {
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-sm);
    font-weight: 500;
    background-color: var(--color-info);
    color: white;
    white-space: nowrap;
}

.task-item.completed {
    opacity: 0.6;
    background-color: var(--color-light);
}

.task-item.completed .task-title {
    text-decoration: line-through;
    color: var(--color-text-light);
}

/* ============================================ */
/* TASK BUTTONS                                 */
/* ============================================ */
.task-buttons {
    display: flex;
    gap: var(--spacing-md);
    margin-left: auto;
}

.delete-btn {
    background-color: var(--color-danger);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-sm);
}

.delete-btn:hover {
    background-color: #c82333;
    box-shadow: 0 4px 8px rgba(220, 53, 69, 0.3);
}

.edit-btn {
    background-color: var(--color-primary);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-sm);
}

.edit-btn:hover {
    background-color: var(--color-primary-dark);
    box-shadow: 0 4px 8px rgba(0, 123, 255, 0.3);
}

/* ============================================ */
/* STATS PANEL                                  */
/* ============================================ */
.stats-panel {
    width: 280px;
    background-color: var(--color-light);
    padding: var(--spacing-lg);
    border-left: 1px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-sm);
}

.stats-panel h3 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-lg);
    color: var(--color-primary);
    border-bottom: 2px solid var(--color-primary);
    padding-bottom: var(--spacing-md);
}

.stat-item {
    background-color: var(--color-white);
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    border-radius: var(--border-radius-md);
    box-shadow: var(--shadow-sm);
}

.stat-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-light);
    font-weight: 500;
    margin-bottom: var(--spacing-sm);
}

.stat-value {
    font-size: var(--font-size-h2);
    font-weight: 700;
    color: var(--color-primary);
}

.stat-item.success .stat-value { color: var(--color-success); }
.stat-item.warning .stat-value { color: var(--color-warning); }
.stat-item.info    .stat-value { color: var(--color-info); }

/* ============================================ */
/* RESPONSIVE                                   */
/* ============================================ */

/* Tablet */
@media (max-width: 768px) {
    :root {
        --spacing-lg: 16px;
        --spacing-xl: 24px;
    }

    body {
        grid-template-columns: 200px 1fr;
    }

    nav ul {
        flex-wrap: wrap;
        gap: var(--spacing-md);
    }

    .form-row {
        flex-direction: column;
        align-items: stretch;
    }

    .form-group.flex-grow {
        flex: none;
    }

    .task-item {
        flex-wrap: wrap;
        padding: var(--spacing-md);
    }

    .stats-panel {
        width: 100%;
        border-left: none;
        border-top: 1px solid var(--color-border);
    }
}

/* Mobile */
@media (max-width: 640px) {
    :root {
        --spacing-lg: 12px;
        --spacing-md: 12px;
    }

    body {
        grid-template-columns: 160px 1fr;
    }

    .search-container {
        flex-direction: column;
        gap: var(--spacing-sm);
    }

    .mark-all-btn,
    .delete-completed-btn,
    .sort-btn {
        width: 100%;
    }

    .task-item {
        padding: var(--spacing-sm) var(--spacing-md);
        gap: var(--spacing-xs);
    }

    .task-item:hover {
        transform: none;
    }

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

    .category-chip {
        width: auto;
    }
}

/* Small Mobile */
@media (max-width: 480px) {
    body {
        grid-template-columns: 1fr;
        grid-template-rows: auto 1fr auto auto;
    }

    header  { grid-column: 1; grid-row: 1; }
    main    { grid-column: 1; grid-row: 2; }
    aside   { grid-column: 1; grid-row: 3; border-right: none; border-top: 1px solid var(--color-border); }
    footer  { grid-column: 1; grid-row: 4; }

    input[type="submit"],
    button {
        width: 100%;
    }

    .task-item {
        flex-direction: column;
        align-items: flex-start;
    }

    .task-status {
        width: 100%;
        text-align: center;
        margin-left: 0;
        margin-top: var(--spacing-xs);
    }
}