/* ===========================
   CSS Reset & Base Styles
   =========================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Nike Color Palette - Bold Orange & Black */
    --primary-color: #FF6B00;
    --primary-hover: #E55D00;
    --primary-light: #FFB380;
    --success-color: #00C853;
    --danger-color: #FF1744;
    --warning-color: #FF6B00;
    --text-primary: #111111;
    --text-secondary: #333333;
    --text-muted: #666666;
    --bg-primary: #FFFFFF;
    --bg-secondary: #F8F8F8;
    --border-color: #E0E0E0;
    --shadow-sm: 0 2px 4px rgba(255, 107, 0, 0.15);
    --shadow-md: 0 4px 12px rgba(255, 107, 0, 0.2);
    --shadow-lg: 0 8px 24px rgba(255, 107, 0, 0.25);
    --shadow-xl: 0 12px 32px rgba(255, 107, 0, 0.3);

    /* Category Colors - Nike Energy */
    --category-work: #FF6B00;
    --category-personal: #FF1744;
    --category-shopping: #9C27B0;
    --category-health: #00C853;
    --category-other: #666666;

    /* Priority Colors */
    --priority-high: #FF1744;
    --priority-medium: #FF6B00;
    --priority-low: #00C853;

    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 2rem;

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;

    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-full: 9999px;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 200ms ease;
    --transition-slow: 300ms ease;
}

/* Dark Mode Variables - Nike Dark Theme */
body.dark-mode {
    --text-primary: #FFFFFF;
    --text-secondary: #CCCCCC;
    --text-muted: #999999;
    --bg-primary: #1E1E1E;
    --bg-secondary: #111111;
    --border-color: #333333;
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.5);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.6);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.7);
    --shadow-xl: 0 12px 32px rgba(0, 0, 0, 0.8);
}

body {
    font-family: var(--font-family);
    background: linear-gradient(135deg, #1a1a1a 0%, #2d2d2d 50%, #1a1a1a 100%);
    background-size: 400% 400%;
    animation: gradientShift 10s ease infinite;
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-lg);
    position: relative;
    overflow-x: hidden;
}

/* Add Nike Orange Accent Elements */
body::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at 30% 50%, rgba(255, 107, 0, 0.1) 0%, transparent 50%);
    animation: rotate 20s linear infinite;
    pointer-events: none;
}

@keyframes rotate {
    from {
        transform: rotate(0deg);
    }

    to {
        transform: rotate(360deg);
    }
}

/* Bold Animated Gradient Background */
@keyframes gradientShift {
    0% {
        background-position: 0% 50%;
    }

    50% {
        background-position: 100% 50%;
    }

    100% {
        background-position: 0% 50%;
    }
}

/* Dark Mode Gradient - Even Deeper */
body.dark-mode {
    background: linear-gradient(135deg, #000000 0%, #1a1a1a 50%, #000000 100%);
    background-size: 400% 400%;
    animation: gradientShiftDark 10s ease infinite;
}

@keyframes gradientShiftDark {
    0% {
        background-position: 0% 50%;
    }

    50% {
        background-position: 100% 50%;
    }

    100% {
        background-position: 0% 50%;
    }
}

/* ===========================
   Container & Layout
   =========================== */
.container {
    width: 100%;
    max-width: 800px;
    background: var(--bg-secondary);
    backdrop-filter: blur(20px);
    background: rgba(255, 255, 255, 0.98);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl), 0 0 0 2px rgba(255, 107, 0, 0.2);
    overflow: hidden;
    animation: fadeInUp 0.4s ease;
    border: 2px solid rgba(255, 107, 0, 0.3);
}

body.dark-mode .container {
    background: rgba(17, 17, 17, 0.98);
    border: 2px solid rgba(255, 107, 0, 0.5);
    box-shadow: var(--shadow-xl), 0 0 20px rgba(255, 107, 0, 0.2);
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ===========================
   Header
   =========================== */
.header {
    background: linear-gradient(135deg, #FF6B00 0%, #E55D00 50%, #111111 100%);
    color: white;
    padding: var(--spacing-xl);
    position: relative;
    overflow: hidden;
}

.header::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255, 255, 255, 0.15) 0%, transparent 70%);
    animation: pulse 3s ease-in-out infinite;
}

@keyframes pulse {

    0%,
    100% {
        transform: scale(1);
        opacity: 0.6;
    }

    50% {
        transform: scale(1.2);
        opacity: 1;
    }
}

.header-content {
    position: relative;
    z-index: 1;
}

.title {
    font-size: var(--font-size-2xl);
    font-weight: 900;
    margin-bottom: var(--spacing-xs);
    letter-spacing: 0.1em;
    text-transform: uppercase;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

.subtitle {
    font-size: var(--font-size-sm);
    opacity: 0.95;
    font-weight: 400;
    letter-spacing: 0.05em;
}

.dark-mode-toggle {
    position: absolute;
    top: var(--spacing-lg);
    right: var(--spacing-lg);
    background: rgba(255, 255, 255, 0.2);
    border: 1px solid rgba(255, 255, 255, 0.3);
    color: white;
    padding: var(--spacing-sm);
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-base);
    z-index: 2;
    display: flex;
    align-items: center;
    justify-content: center;
}

.dark-mode-toggle:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: scale(1.1) rotate(15deg);
}

.moon-icon.hidden,
.sun-icon.hidden {
    display: none;
}

/* ===========================
   Main Content
   =========================== */
.main-content {
    padding: var(--spacing-xl);
}

/* ===========================
   Search Section
   =========================== */
.search-section {
    margin-bottom: var(--spacing-lg);
}

.search-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.search-icon {
    position: absolute;
    left: var(--spacing-md);
    color: var(--text-muted);
    pointer-events: none;
}

.search-input {
    width: 100%;
    padding: var(--spacing-md) var(--spacing-md) var(--spacing-md) 2.75rem;
    font-size: var(--font-size-base);
    font-family: var(--font-family);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    transition: all var(--transition-base);
    outline: none;
}

.search-input:focus {
    border-color: var(--primary-color);
    background: var(--bg-secondary);
    box-shadow: 0 0 0 3px var(--primary-light);
}

/* ===========================
   Add Task Section
   =========================== */
.add-task-section {
    margin-bottom: var(--spacing-lg);
}

.input-wrapper {
    display: grid;
    grid-template-columns: 1fr auto auto auto auto;
    gap: var(--spacing-sm);
}

.task-input {
    padding: var(--spacing-md);
    font-size: var(--font-size-base);
    font-family: var(--font-family);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    transition: all var(--transition-base);
    outline: none;
}

.task-input:focus {
    border-color: var(--primary-color);
    background: var(--bg-secondary);
    box-shadow: 0 0 0 3px var(--primary-light);
}

.due-date-input,
.category-input,
.priority-input {
    padding: var(--spacing-md);
    font-size: var(--font-size-sm);
    font-family: var(--font-family);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    cursor: pointer;
    transition: all var(--transition-base);
    outline: none;
}

.due-date-input:focus,
.category-input:focus,
.priority-input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--primary-light);
}

.add-btn {
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: var(--font-size-base);
    font-weight: 700;
    font-family: var(--font-family);
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-hover) 100%);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    transition: all var(--transition-base);
    white-space: nowrap;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.add-btn:hover {
    background: linear-gradient(135deg, var(--primary-hover) 0%, #CC4A00 100%);
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 8px 24px rgba(255, 107, 0, 0.4), 0 0 20px rgba(255, 107, 0, 0.3);
}

.add-btn:active {
    transform: translateY(-1px) scale(1.02);
}

/* ===========================
   Filter Section
   =========================== */
.filter-section {
    margin-bottom: var(--spacing-lg);
}

.filter-tabs {
    display: flex;
    gap: var(--spacing-sm);
    background: var(--bg-primary);
    padding: var(--spacing-xs);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-sm);
}

.filter-btn {
    flex: 1;
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-sm);
    font-weight: 600;
    font-family: var(--font-family);
    background: transparent;
    color: var(--text-secondary);
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.filter-btn:hover {
    color: var(--text-primary);
    background: rgba(255, 107, 0, 0.1);
}

.filter-btn.active {
    background: var(--primary-color);
    color: white;
    box-shadow: 0 4px 12px rgba(255, 107, 0, 0.3);
    font-weight: 700;
}

.category-filter {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.category-filter-btn {
    padding: var(--spacing-xs) var(--spacing-md);
    font-size: var(--font-size-xs);
    font-weight: 600;
    font-family: var(--font-family);
    background: var(--bg-primary);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.category-filter-btn:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
}

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

.category-filter-btn[data-category="work"].active {
    background: var(--category-work);
    border-color: var(--category-work);
}

.category-filter-btn[data-category="personal"].active {
    background: var(--category-personal);
    border-color: var(--category-personal);
}

.category-filter-btn[data-category="shopping"].active {
    background: var(--category-shopping);
    border-color: var(--category-shopping);
}

.category-filter-btn[data-category="health"].active {
    background: var(--category-health);
    border-color: var(--category-health);
}

.category-filter-btn[data-category="other"].active {
    background: var(--category-other);
    border-color: var(--category-other);
}

/* ===========================
   Task List
   =========================== */
.task-list-section {
    margin-bottom: var(--spacing-lg);
    min-height: 200px;
}

.task-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.task-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--bg-primary);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
    animation: slideIn 0.3s ease;
    cursor: grab;
    position: relative;
}

.task-item:active {
    cursor: grabbing;
}

.task-item.dragging {
    opacity: 0.5;
    transform: scale(0.95);
}

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

    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.task-item:hover {
    border-color: var(--primary-color);
    box-shadow: 0 6px 20px rgba(255, 107, 0, 0.25), 0 0 12px rgba(255, 107, 0, 0.15);
    transform: translateY(-3px);
}

.task-item.completed {
    opacity: 0.7;
}

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

/* Priority Indicator */
.task-item::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 4px;
    border-radius: var(--radius-md) 0 0 var(--radius-md);
}

.task-item.priority-high::before {
    background: var(--priority-high);
}

.task-item.priority-medium::before {
    background: var(--priority-medium);
}

.task-item.priority-low::before {
    background: var(--priority-low);
}

/* Checkbox */
.task-checkbox {
    appearance: none;
    width: 22px;
    height: 22px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    cursor: pointer;
    position: relative;
    transition: all var(--transition-base);
    flex-shrink: 0;
    margin-left: var(--spacing-xs);
}

.task-checkbox:hover {
    border-color: var(--primary-color);
    transform: scale(1.1);
}

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

.task-checkbox:checked::after {
    content: '';
    position: absolute;
    left: 6px;
    top: 2px;
    width: 5px;
    height: 10px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

/* Task Content */
.task-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.task-text {
    font-size: var(--font-size-base);
    color: var(--text-primary);
    word-break: break-word;
    font-weight: 500;
    cursor: pointer;
}

.task-text:hover {
    color: var(--primary-color);
}

.task-meta {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.task-category,
.task-priority,
.task-due-date {
    padding: 2px var(--spacing-sm);
    font-size: var(--font-size-xs);
    font-weight: 600;
    border-radius: var(--radius-sm);
    display: inline-flex;
    align-items: center;
    gap: 4px;
}

.task-category.work {
    background: rgba(59, 130, 246, 0.1);
    color: var(--category-work);
}

.task-category.personal {
    background: rgba(139, 92, 246, 0.1);
    color: var(--category-personal);
}

.task-category.shopping {
    background: rgba(236, 72, 153, 0.1);
    color: var(--category-shopping);
}

.task-category.health {
    background: rgba(16, 185, 129, 0.1);
    color: var(--category-health);
}

.task-category.other {
    background: rgba(107, 114, 128, 0.1);
    color: var(--category-other);
}

.task-priority.high {
    background: rgba(239, 68, 68, 0.1);
    color: var(--priority-high);
}

.task-priority.medium {
    background: rgba(245, 158, 11, 0.1);
    color: var(--priority-medium);
}

.task-priority.low {
    background: rgba(16, 185, 129, 0.1);
    color: var(--priority-low);
}

.task-due-date {
    background: rgba(99, 102, 241, 0.1);
    color: var(--primary-color);
}

.task-due-date.overdue {
    background: rgba(239, 68, 68, 0.1);
    color: var(--danger-color);
}

/* Task Actions */
.task-actions {
    display: flex;
    gap: var(--spacing-xs);
}

.edit-btn,
.delete-btn {
    padding: var(--spacing-xs);
    background: transparent;
    color: var(--text-muted);
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.edit-btn:hover {
    background: var(--primary-color);
    color: white;
    transform: scale(1.15);
    box-shadow: 0 4px 12px rgba(255, 107, 0, 0.4);
}

.delete-btn:hover {
    background: var(--danger-color);
    color: white;
    transform: scale(1.15);
    box-shadow: 0 4px 12px rgba(255, 23, 68, 0.4);
}

.edit-btn svg,
.delete-btn svg {
    width: 18px;
    height: 18px;
}

/* ===========================
   Empty State
   =========================== */
.empty-state {
    text-align: center;
    padding: var(--spacing-xl);
    color: var(--text-muted);
}

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

.empty-state svg {
    color: var(--text-muted);
    margin-bottom: var(--spacing-md);
    opacity: 0.5;
}

.empty-state p {
    font-size: var(--font-size-base);
}

/* ===========================
   Task Summary Footer
   =========================== */
.task-summary {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--spacing-lg);
    border-top: 2px solid var(--border-color);
}

.task-count {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    font-weight: 600;
}

.clear-btn {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-sm);
    font-weight: 600;
    font-family: var(--font-family);
    background: transparent;
    color: var(--text-secondary);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.clear-btn:hover {
    background: var(--danger-color);
    color: white;
    border-color: var(--danger-color);
    transform: translateY(-2px) scale(1.05);
    box-shadow: 0 6px 16px rgba(255, 23, 68, 0.3);
}

/* ===========================
   Modal
   =========================== */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(5px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    animation: fadeIn 0.2s ease;
}

.modal.hidden {
    display: none;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

.modal-content {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-xl);
    width: 90%;
    max-width: 500px;
    animation: slideUp 0.3s ease;
}

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

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg);
    border-bottom: 2px solid var(--border-color);
}

.modal-header h2 {
    font-size: var(--font-size-xl);
    color: var(--text-primary);
}

.modal-close {
    background: transparent;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: var(--spacing-xs);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.modal-close:hover {
    background: var(--danger-color);
    color: white;
}

.modal-body {
    padding: var(--spacing-lg);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.edit-task-input,
.edit-due-date-input,
.edit-category-input,
.edit-priority-input {
    width: 100%;
    padding: var(--spacing-md);
    font-size: var(--font-size-base);
    font-family: var(--font-family);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    outline: none;
    transition: all var(--transition-base);
}

.edit-task-input:focus,
.edit-due-date-input:focus,
.edit-category-input:focus,
.edit-priority-input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--primary-light);
}

.modal-footer {
    display: flex;
    justify-content: flex-end;
    gap: var(--spacing-sm);
    padding: var(--spacing-lg);
    border-top: 2px solid var(--border-color);
}

.btn-primary,
.btn-secondary {
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-size-base);
    font-weight: 600;
    font-family: var(--font-family);
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-base);
}

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

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 8px 20px rgba(255, 107, 0, 0.4);
}

.btn-secondary {
    background: var(--bg-primary);
    color: var(--text-primary);
    border: 2px solid var(--border-color);
}

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

/* ===========================
   Responsive Design
   =========================== */
@media (max-width: 768px) {
    .input-wrapper {
        grid-template-columns: 1fr;
    }

    .add-btn {
        justify-content: center;
    }

    .category-filter {
        justify-content: center;
    }
}

@media (max-width: 640px) {
    body {
        padding: var(--spacing-md);
    }

    .header {
        padding: var(--spacing-lg);
    }

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

    .main-content {
        padding: var(--spacing-lg);
    }
}