:root {
    /* Light Theme */
    --bg-color: #f3f4f6;
    --text-primary: #111827;
    --text-secondary: #4b5563;
    --surface-bg: rgba(255, 255, 255, 0.7);
    --surface-border: rgba(255, 255, 255, 0.5);
    --card-bg: #ffffff;
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --danger-color: #ef4444;
    --danger-hover: #dc2626;
    
    /* Priority Colors */
    --priority-low: #10b981;
    --priority-low-bg: #d1fae5;
    --priority-medium: #f59e0b;
    --priority-medium-bg: #fef3c7;
    --priority-high: #ef4444;
    --priority-high-bg: #fee2e2;

    --column-bg: rgba(229, 231, 235, 0.5);
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --glass-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.07);
    --border-radius: 12px;
    --border-radius-sm: 8px;
    --transition: all 0.3s ease;
}

[data-theme="dark"] {
    --bg-color: #111827;
    --text-primary: #f9fafb;
    --text-secondary: #9ca3af;
    --surface-bg: rgba(31, 41, 55, 0.7);
    --surface-border: rgba(55, 65, 81, 0.5);
    --card-bg: #1f2937;
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --column-bg: rgba(17, 24, 39, 0.6);
    --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.3);
    
    --priority-low-bg: rgba(16, 185, 129, 0.2);
    --priority-medium-bg: rgba(245, 158, 11, 0.2);
    --priority-high-bg: rgba(239, 68, 68, 0.2);
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    transition: var(--transition);
    min-height: 100vh;
    background-image: radial-gradient(circle at top right, rgba(99, 102, 241, 0.1) 0%, transparent 40%),
                      radial-gradient(circle at bottom left, rgba(16, 185, 129, 0.05) 0%, transparent 40%);
    background-attachment: fixed;
}

.glass-effect {
    background: var(--surface-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--surface-border);
    box-shadow: var(--glass-shadow);
}

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

/* Header */
.app-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    padding: 1rem 1.5rem;
    border-radius: var(--border-radius);
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--primary-color);
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: -0.025em;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.search-container {
    position: relative;
}

.search-icon {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-secondary);
}

#searchInput {
    padding: 0.6rem 1rem 0.6rem 2.5rem;
    border-radius: 20px;
    border: 1px solid var(--surface-border);
    background: var(--card-bg);
    color: var(--text-primary);
    width: 250px;
    transition: var(--transition);
    font-family: inherit;
}

#searchInput:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
    width: 280px;
}

/* Buttons */
button {
    cursor: pointer;
    font-family: inherit;
    transition: var(--transition);
    border: none;
    outline: none;
}

.primary-btn {
    background: var(--primary-color);
    color: white;
    padding: 0.6rem 1.25rem;
    border-radius: 20px;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    box-shadow: var(--shadow-md);
}

.primary-btn:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-lg);
}

.secondary-btn {
    background: transparent;
    color: var(--text-secondary);
    padding: 0.6rem 1.25rem;
    border-radius: 20px;
    font-weight: 500;
    border: 1px solid var(--text-secondary);
}

.secondary-btn:hover {
    background: rgba(156, 163, 175, 0.1);
    color: var(--text-primary);
}

.icon-btn {
    background: var(--card-bg);
    color: var(--text-secondary);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    border: 1px solid var(--surface-border);
    box-shadow: var(--shadow-sm);
}

.icon-btn:hover {
    color: var(--primary-color);
    transform: scale(1.05);
}

/* Board Layout */
.board-container {
    display: flex;
    gap: 1.5rem;
    flex: 1;
    overflow-x: auto;
    padding-bottom: 1rem;
}

.board-column {
    flex: 1;
    min-width: 320px;
    border-radius: var(--border-radius);
    display: flex;
    flex-direction: column;
}

.column-header {
    padding: 1.25rem;
    border-bottom: 1px solid var(--surface-border);
}

.column-header h2 {
    font-size: 1.1rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.task-count {
    background: var(--surface-bg);
    padding: 0.1rem 0.6rem;
    border-radius: 12px;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
}

.column-body {
    padding: 1rem;
    flex: 1;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 1rem;
    min-height: 150px;
}

/* Scrollbar customization */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}
::-webkit-scrollbar-track {
    background: transparent;
}
::-webkit-scrollbar-thumb {
    background: rgba(156, 163, 175, 0.3);
    border-radius: 10px;
}
::-webkit-scrollbar-thumb:hover {
    background: rgba(156, 163, 175, 0.5);
}

/* Task Card */
.task-card {
    background: var(--card-bg);
    padding: 1.25rem;
    border-radius: var(--border-radius-sm);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--surface-border);
    cursor: grab;
    transition: transform 0.2s, box-shadow 0.2s;
    position: relative;
    animation: fadeIn 0.3s ease;
}

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

.task-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

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

.task-card.dragging {
    opacity: 0.5;
    box-shadow: var(--shadow-lg);
    transform: scale(1.02);
}

.task-badges {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.75rem;
}

.priority-badge {
    font-size: 0.75rem;
    font-weight: 600;
    padding: 0.2rem 0.6rem;
    border-radius: 10px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.priority-low { background: var(--priority-low-bg); color: var(--priority-low); }
.priority-medium { background: var(--priority-medium-bg); color: var(--priority-medium); }
.priority-high { background: var(--priority-high-bg); color: var(--priority-high); }

.status-badge {
    font-size: 0.7rem;
    font-weight: 600;
    padding: 0.2rem 0.5rem;
    border-radius: 10px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border: 1px solid var(--surface-border);
}
.status-todo { color: #3b82f6; background: rgba(59, 130, 246, 0.1); border-color: rgba(59, 130, 246, 0.2); }
.status-inprogress { color: #8b5cf6; background: rgba(139, 92, 246, 0.1); border-color: rgba(139, 92, 246, 0.2); }
.status-done { color: #10b981; background: rgba(16, 185, 129, 0.1); border-color: rgba(16, 185, 129, 0.2); }

.task-actions {
    display: flex;
    gap: 0.5rem;
    opacity: 0;
    transition: opacity 0.2s;
}

.task-card:hover .task-actions {
    opacity: 1;
}

.task-action-btn {
    background: transparent;
    color: var(--text-secondary);
    font-size: 0.9rem;
    padding: 0.2rem;
}

.task-action-btn:hover.edit-btn { color: var(--primary-color); }
.task-action-btn:hover.delete-btn { color: var(--danger-color); }

.task-title {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    line-height: 1.4;
    word-break: break-word;
}

.task-desc {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    line-height: 1.5;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

/* Toast Notifications */
.toast-container {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    display: flex;
    flex-direction: column;
    gap: 1rem;
    z-index: 2000;
}

.toast {
    background: var(--card-bg);
    color: var(--text-primary);
    padding: 1rem 1.5rem;
    border-radius: var(--border-radius-sm);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--surface-border);
    display: flex;
    align-items: center;
    gap: 0.75rem;
    min-width: 250px;
    animation: slideInRight 0.3s ease forwards;
    transition: opacity 0.3s ease;
}

.toast.hiding {
    opacity: 0;
}

.toast-icon { font-size: 1.25rem; }
.toast-icon.success { color: var(--priority-low); }
.toast-icon.error { color: var(--danger-color); }
.toast-icon.info { color: var(--primary-color); }

@keyframes slideInRight {
    from { transform: translateX(100%); opacity: 0; }
    to { transform: translateX(0); opacity: 1; }
}

/* Tags & Progress Bar */
.tag-pill {
    font-size: 0.7rem;
    padding: 0.2rem 0.5rem;
    border-radius: 4px;
    background: rgba(99, 102, 241, 0.15);
    color: var(--primary-color);
    display: inline-block;
    margin-right: 0.25rem;
    margin-top: 0.25rem;
    font-weight: 500;
}

.progress-container {
    margin-top: 0.75rem;
    margin-bottom: 0.5rem;
}

.progress-bar-bg {
    width: 100%;
    height: 6px;
    background: var(--surface-border);
    border-radius: 3px;
    overflow: hidden;
    position: relative;
}

.progress-bar-fill {
    height: 100%;
    background: var(--primary-color);
    border-radius: 3px;
    transition: width 0.3s ease;
}

.progress-text {
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-top: 0.25rem;
    display: flex;
    justify-content: space-between;
}

.subtask-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem;
    border-bottom: 1px solid var(--surface-border);
    font-size: 0.85rem;
}
.subtask-item input[type="checkbox"] {
    width: auto;
}
.subtask-item button {
    margin-left: auto;
    color: var(--danger-color);
    background: transparent;
    border: none;
    cursor: pointer;
}

.task-footer {
    display: flex;
    align-items: center;
    font-size: 0.8rem;
    color: var(--text-secondary);
    gap: 0.5rem;
}

.task-date i {
    margin-right: 0.25rem;
}

.task-date.overdue {
    color: var(--danger-color);
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.4);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(4px);
}

.modal.active {
    display: flex;
    animation: modalFadeIn 0.3s ease forwards;
}

@keyframes modalFadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.modal-content {
    width: 100%;
    max-width: 500px;
    border-radius: var(--border-radius);
    padding: 2rem;
    transform: translateY(20px);
    transition: transform 0.3s ease;
}

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

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

.modal-header h2 {
    font-size: 1.25rem;
    font-weight: 600;
}

.close-btn {
    background: transparent;
    color: var(--text-secondary);
    font-size: 1.25rem;
}

.close-btn:hover {
    color: var(--danger-color);
}

.form-group {
    margin-bottom: 1.25rem;
}

.form-row {
    display: flex;
    gap: 1rem;
}

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

label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

input[type="text"],
input[type="date"],
textarea,
select {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid var(--surface-border);
    border-radius: var(--border-radius-sm);
    background: var(--card-bg);
    color: var(--text-primary);
    font-family: inherit;
    font-size: 0.95rem;
    transition: var(--transition);
}

input:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

textarea {
    resize: vertical;
}

.form-actions {
    display: flex;
    justify-content: flex-end;
    gap: 1rem;
    margin-top: 2rem;
}

/* Responsive */
@media (max-width: 768px) {
    .board-container {
        flex-direction: column;
        overflow-y: auto;
    }
    .board-column {
        min-height: 400px;
    }
    .app-header {
        flex-direction: column;
        gap: 1rem;
        align-items: flex-start;
    }
    .header-actions {
        width: 100%;
        justify-content: space-between;
    }
    #searchInput {
        width: 100%;
    }
    #searchInput:focus {
        width: 100%;
    }
    .search-container {
        flex: 1;
    }
}