/* ========================================
   TaskFlow - CSS Reset & Variables
   ======================================== */

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

:root {
    /* Cores principais */
    --color-primary: #4f46e5;
    --color-primary-hover: #4338ca;
    --color-primary-light: #eef2ff;
    --color-primary-focus: rgba(79, 70, 229, 0.25);

    /* Cores de estado */
    --color-success: #10b981;
    --color-success-hover: #059669;
    --color-danger: #ef4444;
    --color-danger-hover: #dc2626;
    --color-warning: #f59e0b;

    /* Cores neutras */
    --color-bg: #f8fafc;
    --color-surface: #ffffff;
    --color-surface-hover: #f1f5f9;
    --color-border: #e2e8f0;
    --color-border-hover: #cbd5e1;

    /* Texto */
    --color-text-primary: #1e293b;
    --color-text-secondary: #64748b;
    --color-text-muted: #94a3b8;
    --color-text-inverse: #ffffff;
    --color-text-link: #4f46e5;

    /* Sombras */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

    /* Raio de borda */
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 9999px;

    /* Espaçamento */
    --space-1: 4px;
    --space-2: 8px;
    --space-3: 12px;
    --space-4: 16px;
    --space-5: 20px;
    --space-6: 24px;
    --space-8: 32px;
    --space-10: 40px;
    --space-12: 48px;

    /* Tipografia */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;

    /* Transições */
    --transition-fast: 120ms ease;
    --transition-base: 200ms ease;
    --transition-slow: 300ms ease;

    /* Z-index */
    --z-dropdown: 100;
    --z-modal: 200;
    --z-toast: 300;
}

/* Tema escuro */
@media (prefers-color-scheme: dark) {
    :root {
        --color-bg: #0f172a;
        --color-surface: #1e293b;
        --color-surface-hover: #334155;
        --color-border: #334155;
        --color-border-hover: #475569;
        --color-text-primary: #f1f5f9;
        --color-text-secondary: #94a3b8;
        --color-text-muted: #64748b;
        --color-primary-light: #1e1b4b;
    }
}

/* ========================================
   Base Styles
   ======================================== */

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text-primary);
    background-color: var(--color-bg);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    padding: var(--space-6) var(--space-4);
}

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* ========================================
   App Container
   ======================================== */

.app-container {
    width: 100%;
    max-width: 640px;
    background: var(--color-surface);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--color-border);
    overflow: hidden;
    animation: slideUp var(--transition-slow) ease-out;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ========================================
   Header
   ======================================== */

.app-header {
    padding: var(--space-6) var(--space-6) var(--space-4);
    border-bottom: 1px solid var(--color-border);
    background: linear-gradient(180deg, var(--color-surface) 0%, var(--color-bg) 100%);
}

.header-content {
    text-align: center;
}

.logo {
    display: inline-flex;
    align-items: center;
    gap: var(--space-3);
    margin-bottom: var(--space-2);
}

.logo-icon {
    width: 36px;
    height: 36px;
    color: var(--color-primary);
}

.logo-text {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--color-text-primary);
    letter-spacing: -0.02em;
}

.header-subtitle {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    font-weight: 400;
}

/* ========================================
   Main Content
   ======================================== */

.app-main {
    padding: var(--space-6);
}

/* Form Section */
.task-form-section {
    margin-bottom: var(--space-6);
}

.task-form {
    display: flex;
    gap: var(--space-3);
}

.form-group {
    flex: 1;
}

.task-input {
    width: 100%;
    padding: var(--space-3) var(--space-4);
    font-size: var(--font-size-base);
    font-family: inherit;
    color: var(--color-text-primary);
    background: var(--color-surface);
    border: 2px solid var(--color-border);
    border-radius: var(--radius-lg);
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast), background-color var(--transition-fast);
}

.task-input::placeholder {
    color: var(--color-text-muted);
}

.task-input:hover {
    border-color: var(--color-border-hover);
}

.task-input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px var(--color-primary-focus);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-5);
    font-size: var(--font-size-sm);
    font-weight: 500;
    font-family: inherit;
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

.btn:focus-visible {
    outline: none;
    box-shadow: 0 0 0 3px var(--color-primary-focus);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-primary {
    background: var(--color-primary);
    color: var(--color-text-inverse);
}

.btn-primary:hover:not(:disabled) {
    background: var(--color-primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-primary:active:not(:disabled) {
    transform: translateY(0);
}

.btn-ghost {
    background: transparent;
    color: var(--color-text-secondary);
}

.btn-ghost:hover:not(:disabled) {
    background: var(--color-surface-hover);
    color: var(--color-text-primary);
}

.btn-icon {
    padding: var(--space-2);
    border-radius: var(--radius-md);
}

.btn-icon .btn-icon {
    width: 18px;
    height: 18px;
}

.btn-sm {
    padding: var(--space-2) var(--space-3);
    font-size: var(--font-size-xs);
}

.btn-icon svg {
    width: 18px;
    height: 18px;
    flex-shrink: 0;
}

/* ícones dentro dos botões de texto (ex.: "+ Adicionar", "Limpar concluídas"):
   tamanho fixo — sem isso, no celular o botão vira largura total e o ícone estica */
.btn > svg.btn-icon {
    width: 16px;
    height: 16px;
    padding: 0;
    flex-shrink: 0;
}

/* Filters Section */
.task-filters-section {
    margin-bottom: var(--space-5);
}

.filters-wrapper {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-4);
    flex-wrap: wrap;
}

.filter-tabs {
    display: flex;
    gap: var(--space-1);
    background: var(--color-bg);
    padding: var(--space-1);
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-border);
}

.filter-tab {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-2) var(--space-4);
    font-size: var(--font-size-sm);
    font-weight: 500;
    font-family: inherit;
    color: var(--color-text-secondary);
    background: transparent;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

.filter-tab:hover:not(.active) {
    color: var(--color-text-primary);
    background: var(--color-surface);
}

.filter-tab.active {
    color: var(--color-primary);
    background: var(--color-primary-light);
}

.filter-tab:focus-visible {
    outline: none;
    box-shadow: 0 0 0 2px var(--color-primary-focus);
}

.tab-label {
    font-weight: 500;
}

.tab-count {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 20px;
    height: 20px;
    padding: 0 var(--space-2);
    font-size: var(--font-size-xs);
    font-weight: 600;
    color: var(--color-text-muted);
    background: transparent;
    border-radius: var(--radius-full);
    transition: all var(--transition-fast);
}

.filter-tab.active .tab-count {
    color: var(--color-primary);
    background: var(--color-surface);
}

.filter-tab:not(.active) .tab-count {
    background: transparent;
}

.filter-actions {
    flex-shrink: 0;
}

/* Task List Section */
.task-list-section {
    margin-bottom: var(--space-6);
}

.task-list {
    list-style: none;
}

.task-item {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-4);
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    margin-bottom: var(--space-3);
    transition: all var(--transition-base);
    animation: taskEnter var(--transition-base) ease-out;
}

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

.task-item:hover {
    border-color: var(--color-border-hover);
    box-shadow: var(--shadow-sm);
}

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

.task-item.editing {
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px var(--color-primary-focus);
}

.task-item.removing {
    animation: taskExit var(--transition-base) ease-in forwards;
}

@keyframes taskExit {
    from {
        opacity: 1;
        transform: translateX(0);
    }
    to {
        opacity: 0;
        transform: translateX(-30px);
    }
}

/* Checkbox */
.task-checkbox-wrapper {
    position: relative;
    flex-shrink: 0;
}

.task-checkbox {
    position: absolute;
    opacity: 0;
    pointer-events: none;
}

.checkbox-label {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 24px;
    height: 24px;
    border: 2px solid var(--color-border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.checkbox-label:hover {
    border-color: var(--color-primary);
    background: var(--color-primary-light);
}

.task-checkbox:checked + .checkbox-label {
    background: var(--color-primary);
    border-color: var(--color-primary);
}

.task-checkbox:checked + .checkbox-label .check-icon {
    opacity: 1;
    transform: scale(1);
}

.check-icon {
    width: 14px;
    height: 14px;
    color: var(--color-text-inverse);
    opacity: 0;
    transform: scale(0.5);
    transition: all var(--transition-fast);
}

/* Task Content */
.task-content {
    flex: 1;
    min-width: 0;
    position: relative;
}

.task-text {
    font-size: var(--font-size-base);
    color: var(--color-text-primary);
    word-break: break-word;
    line-height: 1.5;
    transition: color var(--transition-fast);
}

.task-text-input {
    width: 100%;
    padding: var(--space-1) var(--space-2);
    font-size: var(--font-size-base);
    font-family: inherit;
    color: var(--color-text-primary);
    background: var(--color-surface);
    border: 2px solid var(--color-primary);
    border-radius: var(--radius-sm);
    outline: none;
}

.task-text-input:focus {
    box-shadow: 0 0 0 3px var(--color-primary-focus);
}

/* Task Actions */
.task-actions {
    display: flex;
    gap: var(--space-1);
    flex-shrink: 0;
    opacity: 0;
    transform: translateX(10px);
    transition: all var(--transition-fast);
}

.task-item:hover .task-actions,
.task-item:focus-within .task-actions {
    opacity: 1;
    transform: translateX(0);
}

.btn-edit:hover:not(:disabled) {
    background: var(--color-primary-light);
    color: var(--color-primary);
}

.btn-delete:hover:not(:disabled) {
    background: #fef2f2;
    color: var(--color-danger);
}

/* Empty State */
.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--space-10) var(--space-6);
    text-align: center;
    color: var(--color-text-secondary);
}

.empty-state.hidden {
    display: none;
}

.empty-icon {
    width: 64px;
    height: 64px;
    color: var(--color-text-muted);
    margin-bottom: var(--space-4);
    opacity: 0.5;
}

.empty-title {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--color-text-primary);
    margin-bottom: var(--space-2);
}

.empty-description {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    max-width: 280px;
}

/* Footer */
.app-footer {
    padding-top: var(--space-6);
    border-top: 1px solid var(--color-border);
}

.stats-summary {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-4);
    flex-wrap: wrap;
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.stat-item {
    display: flex;
    align-items: center;
    gap: var(--space-1);
}

.stat-item strong {
    color: var(--color-text-primary);
    font-weight: 600;
}

.stat-divider {
    width: 1px;
    height: 20px;
    background: var(--color-border);
}

/* ========================================
   Responsive
   ======================================== */

@media (max-width: 480px) {
    body {
        padding: var(--space-4) var(--space-3);
    }

    .app-main {
        padding: var(--space-4);
    }

    .app-header {
        padding: var(--space-5) var(--space-4) var(--space-3);
    }

    .logo-text {
        font-size: var(--font-size-xl);
    }

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

    .btn-primary {
        width: 100%;
    }

    .filters-wrapper {
        flex-direction: column;
        align-items: stretch;
    }

    .filter-tabs {
        width: 100%;
    }

    .filter-tab {
        flex: 1;
        justify-content: center;
        padding: var(--space-2) var(--space-3);
    }

    .filter-actions {
        width: 100%;
    }

    .btn-ghost {
        width: 100%;
        justify-content: center;
    }

    .stats-summary {
        gap: var(--space-3);
        font-size: var(--font-size-xs);
    }

    .stat-divider {
        display: none;
    }
}

/* celular/tablet (sem mouse) ou tela estreita: editar e excluir sempre visíveis
   (no computador eles aparecem ao passar o mouse) */
@media (hover: none), (max-width: 480px) {
    .task-actions {
        opacity: 1;
        transform: none;
    }
}

@media (max-width: 360px) {
    .task-item {
        padding: var(--space-3);
        gap: var(--space-2);
    }

    .task-actions {
        opacity: 1;
        transform: none;
    }

    .btn-icon {
        padding: var(--space-1);
    }
}

/* ========================================
   Reduced Motion
   ======================================== */

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}