:root {
    /* Light mode variables */
    --primary-color: #4a6da7;
    --secondary-color: #eef2f7;
    --card-color: #ffffff;
    --text-color: #333333;
    --border-color: #e1e5ea;
    --hover-color: #f5f8fc;
    --delete-color: #e74c3c;
    --success-color: #2ecc71;
    --board-bg: #f7f9fc;
    --modal-bg: #ffffff;
    --header-text: #ffffff;
    --card-shadow: rgba(0,0,0,0.05);
    --modal-shadow: rgba(0,0,0,0.2);
    --secondary-text: #666666;
    --muted-text: #888888;
    --completed-color: #ddeedb;
    --warning-color: #f39c12;
    --sprint-active: #d5f5e3;
    --sprint-planned: #e8f8f5;
    --dashboard-bg: #f8f9fa;
    --calendar-today: #e8f4fc;
    --chart-colors: #4a6da7, #2ecc71, #f39c12, #e74c3c, #9b59b6;
}

[data-theme="dark"] {
    --primary-color: #5d82c1;
    --secondary-color: #1e2430;
    --card-color: #2d3748;
    --text-color: #e2e8f0;
    --border-color: #3d4a5c;
    --hover-color: #3f4e61;
    --delete-color: #e53e3e;
    --success-color: #38a169;
    --board-bg: #252d3b;
    --modal-bg: #2d3748;
    --header-text: #e2e8f0;
    --card-shadow: rgba(0,0,0,0.3);
    --modal-shadow: rgba(0,0,0,0.5);
    --secondary-text: #a0aec0;
    --muted-text: #718096;
    --completed-color: #2f3c2e;
    --warning-color: #d68910;
    --sprint-active: #2c4c3b;
    --sprint-planned: #2c4a4a;
    --dashboard-bg: #1a202c;
    --calendar-today: #2b4055;
    --chart-colors: #5d82c1, #38a169, #d68910, #e53e3e, #b96df8;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: var(--secondary-color);
    color: var(--text-color);
    min-height: 100vh;
    transition: background-color 0.3s ease, color 0.3s ease;
}

header {
    background-color: var(--primary-color);
    color: var(--header-text);
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    transition: background-color 0.3s ease;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    letter-spacing: 1px;
}

.actions {
    display: flex;
    gap: 1rem;
}

button {
    background-color: white;
    color: var(--primary-color);
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    cursor: pointer;
    font-weight: 500;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

button:hover {
    background-color: var(--hover-color);
    transform: translateY(-2px);
}

button.delete {
    color: var(--delete-color);
}

button.success {
    background-color: var(--success-color);
    color: white;
}

.container {
    display: flex;
    flex-direction: column;
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem;
    height: calc(100vh - 70px);
}

.board-container {
    display: flex;
    flex-grow: 1;
    gap: 1.5rem;
    overflow-x: auto;
    padding-bottom: 1rem;
}

.board {
    background-color: var(--board-bg);
    border-radius: 6px;
    min-width: 280px;
    width: 280px;
    display: flex;
    flex-direction: column;
    box-shadow: 0 3px 5px var(--card-shadow);
    max-height: 100%;
    flex-shrink: 0;
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

.board-header {
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.board-title {
    font-weight: 600;
    color: var(--primary-color);
}

.board-count {
    background-color: var(--primary-color);
    color: white;
    border-radius: 50%;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
}

.board-cards {
    padding: 1rem;
    flex-grow: 1;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.add-card {
    margin-top: auto;
    padding: 1rem;
    text-align: center;
}

.card {
    background-color: var(--card-color);
    border-radius: 4px;
    padding: 1rem;
    box-shadow: 0 2px 4px var(--card-shadow);
    cursor: pointer;
    transition: all 0.2s ease, background-color 0.3s ease;
    border-left: 3px solid var(--primary-color);
}

.card.has-due-date {
    border-top: 2px solid var(--warning-color);
}

.card.overdue {
    border-top: 2px solid var(--delete-color);
}

.card.completed {
    background-color: var(--completed-color);
}

.card:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 10px rgba(0,0,0,0.1);
}

.card-title {
    font-weight: 600;
    margin-bottom: 0.5rem;
    font-size: 1rem;
}

.card-tasks {
    font-size: 0.9rem;
    color: #666;
    margin-top: 0.8rem;
}

.card-task {
    display: flex;
    align-items: baseline;
    gap: 0.5rem;
    margin-bottom: 0.3rem;
}

.card-task-marker {
    display: inline-block;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background-color: var(--primary-color);
    opacity: 0.6;
    flex-shrink: 0;
}

.card-description {
    margin-top: 0.8rem;
    font-size: 0.85rem;
    color: var(--muted-text);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.card-dates {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-top: 0.8rem;
    font-size: 0.8rem;
    color: var(--secondary-text);
}

.card-due-date {
    display: flex;
    align-items: center;
    gap: 0.3rem;
}

.card-due-date.overdue {
    color: var(--delete-color);
    font-weight: 500;
}

.card-sprint {
    display: inline-block;
    padding: 0.2rem 0.4rem;
    background-color: var(--sprint-planned);
    border-radius: 3px;
    font-size: 0.75rem;
    font-weight: 500;
}

.card-sprint.active {
    background-color: var(--sprint-active);
}

    
.card-project {
    margin-top: 0.8rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.card-project-name {
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--primary-color);
    background-color: rgba(74, 109, 167, 0.1);
    padding: 0.2rem 0.5rem;
    border-radius: 3px;
}

.card-number {
    font-size: 0.8rem;
    font-weight: 600;
    color: #aaa;
}

.dragging {
    opacity: 0.5;
}

.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
}

.modal.show {
    opacity: 1;
    visibility: visible;
}

.modal-content {
    background-color: var(--modal-bg);
    border-radius: 6px;
    width: 90%;
    max-width: 600px;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: 0 5px 15px var(--modal-shadow);
    transform: translateY(-50px);
    transition: transform 0.3s ease, background-color 0.3s ease;
}

.modal.show .modal-content {
    transform: translateY(0);
}

.modal-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-title {
    font-weight: 600;
    font-size: 1.2rem;
    color: var(--primary-color);
}

.close-modal {
    background: none;
    border: none;
    font-size: 1.5rem;
    color: #999;
    cursor: pointer;
    padding: 0;
}

.modal-body {
    padding: 1.5rem;
}

.form-group {
    margin-bottom: 1.5rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: #555;
}

input, textarea, select {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 1rem;
    background-color: var(--modal-bg);
    color: var(--text-color);
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

input:focus, textarea:focus, select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(74, 109, 167, 0.2);
}

input[type="date"] {
    font-family: inherit;
}

input[type="checkbox"] {
    width: auto;
}

.objective-form {
    display: flex;
    margin-bottom: 1rem;
}

.objective-label {
    flex-shrink: 0;
    padding: 0.75rem;
    background-color: var(--primary-color);
    color: white;
    border-radius: 4px 0 0 4px;
    font-weight: 500;
    min-width: 70px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.objective-input {
    flex-grow: 1;
    border-radius: 0 4px 4px 0;
}

.subtasks-container {
    margin-top: 1.5rem;
}

.subtask-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.subtask-title {
    font-weight: 600;
    color: #555;
}

.subtasks-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.subtask-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.subtask-checkbox {
    width: auto;
}

.subtask-input {
    flex-grow: 1;
}

.subtask-delete {
    background: none;
    border: none;
    color: #999;
    cursor: pointer;
    padding: 0.3rem;
    transition: color 0.2s ease;
}

.subtask-delete:hover {
    color: var(--delete-color);
}

.add-subtask {
    margin-top: 0.75rem;
    width: 100%;
}

.modal-footer {
    padding: 1rem 1.5rem;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: flex-end;
    gap: 1rem;
}

.projects-list {
    max-height: 400px;
    overflow-y: auto;
}

.project-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.project-item:last-child {
    border-bottom: none;
}

.project-actions {
    display: flex;
    gap: 0.5rem;
}

/* Theme toggle switch */
.theme-switch {
    display: flex;
    align-items: center;
    margin-right: 1rem;
}

.theme-switch-label {
    margin-right: 0.5rem;
    color: var(--header-text);
    font-size: 0.9rem;
}

.switch {
    position: relative;
    display: inline-block;
    width: 40px;
    height: 20px;
}

.switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #ccc;
    transition: .4s;
    border-radius: 34px;
}

.slider:before {
    position: absolute;
    content: "";
    height: 16px;
    width: 16px;
    left: 2px;
    bottom: 2px;
    background-color: white;
    transition: .4s;
    border-radius: 50%;
}

input:checked + .slider {
    background-color: #2d3748;
}

input:checked + .slider:before {
    transform: translateX(20px);
}

/* Calendar styles */
.calendar-container {
    background-color: var(--board-bg);
    border-radius: 6px;
    box-shadow: 0 3px 5px var(--card-shadow);
    margin-bottom: 1.5rem;
    transition: background-color 0.3s ease;
    display: none;
}

.calendar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.calendar-title {
    font-weight: 600;
    color: var(--primary-color);
}

.calendar-nav {
    display: flex;
    gap: 0.5rem;
}

.calendar-body {
    padding: 1rem;
}

.calendar-grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 0.5rem;
}

.calendar-day-header {
    text-align: center;
    font-weight: 500;
    color: var(--secondary-text);
    font-size: 0.85rem;
    padding: 0.5rem 0;
}

.calendar-day {
    aspect-ratio: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 0.5rem;
    border-radius: 4px;
    cursor: pointer;
    border: 1px solid transparent;
    position: relative;
    overflow: hidden;
}

.calendar-day:hover {
    background-color: var(--hover-color);
}

.calendar-day.today {
    background-color: var(--calendar-today);
    font-weight: bold;
}

.calendar-day.selected {
    border-color: var(--primary-color);
}

.calendar-day.has-cards::after {
    content: "";
    position: absolute;
    bottom: 3px;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background-color: var(--primary-color);
}

.calendar-day-number {
    font-size: 0.9rem;
}

.calendar-day.other-month {
    color: var(--muted-text);
}

/* Sprint planning styles */
.sprint-container {
    margin-bottom: 1.5rem;
    display: none;
}

.sprint-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.sprint-title {
    font-weight: 600;
    color: var(--primary-color);
}

.sprint-list {
    display: flex;
    gap: 1rem;
    overflow-x: auto;
    padding-bottom: 0.5rem;
}

.sprint-item {
    flex: 0 0 280px;
    background-color: var(--board-bg);
    border-radius: 6px;
    padding: 1rem;
    box-shadow: 0 2px 4px var(--card-shadow);
    transition: background-color 0.3s ease;
    border-left: 3px solid var(--primary-color);
}

.sprint-item.active {
    border-left-color: var(--success-color);
}

.sprint-item-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
}

.sprint-name {
    font-weight: 600;
}

.sprint-dates {
    font-size: 0.85rem;
    color: var(--secondary-text);
    margin-bottom: 0.75rem;
}

.sprint-progress {
    height: 6px;
    background-color: var(--border-color);
    border-radius: 3px;
    overflow: hidden;
    margin-top: 0.5rem;
}

.sprint-progress-bar {
    height: 100%;
    background-color: var(--primary-color);
    width: 0;
}

.sprint-stats {
    display: flex;
    justify-content: space-between;
    margin-top: 0.75rem;
    font-size: 0.85rem;
}

/* Dashboard styles */
.dashboard-container {
    background-color: var(--dashboard-bg);
    border-radius: 6px;
    padding: 1.5rem;
    box-shadow: 0 3px 5px var(--card-shadow);
    margin-bottom: 1.5rem;
    transition: background-color 0.3s ease;
    display: none;
}

.dashboard-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.dashboard-title {
    font-weight: 600;
    color: var(--primary-color);
}

.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
}

.metric-card {
    background-color: var(--card-color);
    border-radius: 6px;
    padding: 1.25rem;
    box-shadow: 0 2px 4px var(--card-shadow);
    transition: background-color 0.3s ease;
}

.metric-title {
    font-size: 0.9rem;
    color: var(--secondary-text);
    margin-bottom: 0.5rem;
}

.metric-value {
    font-size: 1.75rem;
    font-weight: 600;
    color: var(--primary-color);
}

.metric-comparison {
    font-size: 0.85rem;
    margin-top: 0.5rem;
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

.comparison-up {
    color: var(--success-color);
}

.comparison-down {
    color: var(--delete-color);
}

.chart-container {
    background-color: var(--card-color);
    border-radius: 6px;
    padding: 1.25rem;
    box-shadow: 0 2px 4px var(--card-shadow);
    grid-column: span 2;
    height: 250px;
    position: relative;
    transition: background-color 0.3s ease;
}

.tabs {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.tab {
    padding: 0.75rem 1rem;
    cursor: pointer;
    border-bottom: 2px solid transparent;
    transition: all 0.2s ease;
}

.tab.active {
    border-bottom-color: var(--primary-color);
    color: var(--primary-color);
    font-weight: 500;
}

.tab:hover {
    background-color: var(--hover-color);
}

@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }
    
    .board {
        min-width: 250px;
        width: 250px;
    }
    
    .board-container {
        gap: 1rem;
    }
    
    .dashboard-grid {
        grid-template-columns: 1fr;
    }
    
    .chart-container {
        grid-column: span 1;
    }
}