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

:root {
    --bg-primary: #0a0e27;
    --bg-secondary: #151932;
    --bg-tertiary: #1e2442;
    --bg-card: rgba(30, 36, 66, 0.6);
    --bg-hover: rgba(99, 102, 241, 0.1);
    
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    
    --accent-primary: #6366f1;
    --accent-secondary: #8b5cf6;
    --accent-success: #10b981;
    --accent-danger: #ef4444;
    --accent-warning: #f59e0b;
    
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-success: linear-gradient(135deg, #10b981 0%, #059669 100%);
    --gradient-danger: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
    
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.3);
    --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.3);
    
    --border-radius-sm: 8px;
    --border-radius-md: 12px;
    --border-radius-lg: 16px;
    
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    background-image: 
        radial-gradient(at 0% 0%, rgba(99, 102, 241, 0.15) 0px, transparent 50%),
        radial-gradient(at 100% 100%, rgba(139, 92, 246, 0.15) 0px, transparent 50%);
    background-attachment: fixed;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 10px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--accent-primary);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-secondary);
}

/* Container */
.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 2rem 1rem;
    animation: fadeIn 0.6s ease;
}

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

/* Header */
.header {
    text-align: center;
    margin-bottom: 3rem;
    animation: slideDown 0.6s ease;
}

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

.title {
    font-size: 3rem;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
}

.title-icon {
    font-size: 2.5rem;
    filter: drop-shadow(0 0 10px rgba(99, 102, 241, 0.5));
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
    font-weight: 400;
}

/* Main Content */
.main-content {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

/* Add Todo Section */
.add-todo-section {
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: var(--border-radius-lg);
    padding: 2rem;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
}

.add-todo-section:hover {
    box-shadow: var(--shadow-glow);
    border-color: rgba(99, 102, 241, 0.4);
}

.todo-form {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-label {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
}

.form-input,
.form-textarea {
    background: var(--bg-tertiary);
    border: 2px solid transparent;
    border-radius: var(--border-radius-md);
    padding: 0.875rem 1.25rem;
    color: var(--text-primary);
    font-size: 1rem;
    font-family: inherit;
    transition: all var(--transition-fast);
    outline: none;
}

.form-input:focus,
.form-textarea:focus {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.form-input::placeholder,
.form-textarea::placeholder {
    color: var(--text-muted);
}

.form-textarea {
    resize: vertical;
    min-height: 80px;
}

/* Buttons */
.btn {
    padding: 0.875rem 1.75rem;
    border: none;
    border-radius: var(--border-radius-md);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    font-family: inherit;
    outline: none;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-sm);
}

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

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

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

.btn-icon {
    font-size: 1.25rem;
    line-height: 1;
}

/* Stats Section */
.stats-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
    animation: fadeInUp 0.6s ease 0.2s both;
}

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

.stat-card {
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: var(--border-radius-md);
    padding: 1.5rem;
    text-align: center;
    transition: all var(--transition-normal);
}

.stat-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-glow);
    border-color: rgba(99, 102, 241, 0.4);
}

.stat-value {
    font-size: 2.5rem;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 0.25rem;
}

.stat-label {
    color: var(--text-secondary);
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* Todos Section */
.todos-section {
    animation: fadeInUp 0.6s ease 0.3s both;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.section-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

.filter-buttons {
    display: flex;
    gap: 0.5rem;
    background: var(--bg-card);
    padding: 0.25rem;
    border-radius: var(--border-radius-md);
    border: 1px solid rgba(99, 102, 241, 0.2);
}

.filter-btn {
    padding: 0.5rem 1rem;
    background: transparent;
    border: none;
    border-radius: var(--border-radius-sm);
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-fast);
    font-family: inherit;
}

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

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

/* Todos Container */
.todos-container {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 4rem 2rem;
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    border: 2px dashed rgba(99, 102, 241, 0.3);
    border-radius: var(--border-radius-lg);
}

.empty-icon {
    font-size: 4rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

.empty-text {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.empty-subtext {
    color: var(--text-muted);
    font-size: 0.95rem;
}

/* Todo Item */
.todo-item {
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: var(--border-radius-md);
    padding: 1.5rem;
    display: flex;
    gap: 1rem;
    align-items: flex-start;
    transition: all var(--transition-normal);
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.todo-item:hover {
    border-color: rgba(99, 102, 241, 0.4);
    box-shadow: var(--shadow-md);
    transform: translateX(4px);
}

.todo-item.completed {
    opacity: 0.6;
}

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

.todo-checkbox {
    width: 24px;
    height: 24px;
    border: 2px solid var(--accent-primary);
    border-radius: 6px;
    cursor: pointer;
    flex-shrink: 0;
    margin-top: 2px;
    position: relative;
    transition: all var(--transition-fast);
}

.todo-checkbox:hover {
    background: var(--bg-hover);
    transform: scale(1.1);
}

.todo-checkbox.checked {
    background: var(--gradient-success);
    border-color: var(--accent-success);
}

.todo-checkbox.checked::after {
    content: '✓';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: white;
    font-size: 14px;
    font-weight: bold;
}

.todo-content {
    flex: 1;
    min-width: 0;
}

.todo-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
    word-wrap: break-word;
}

.todo-description {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 0.5rem;
    line-height: 1.5;
    word-wrap: break-word;
}

.todo-meta {
    display: flex;
    gap: 1rem;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.todo-actions {
    display: flex;
    gap: 0.5rem;
    flex-shrink: 0;
}

.action-btn {
    width: 36px;
    height: 36px;
    border: none;
    border-radius: var(--border-radius-sm);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    transition: all var(--transition-fast);
    background: var(--bg-tertiary);
}

.action-btn:hover {
    transform: scale(1.1);
}

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

.delete-btn:hover {
    background: var(--accent-danger);
    color: white;
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(10, 14, 39, 0.8);
    backdrop-filter: blur(8px);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    animation: fadeIn 0.3s ease;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--bg-secondary);
    border: 1px solid rgba(99, 102, 241, 0.3);
    border-radius: var(--border-radius-lg);
    padding: 2rem;
    max-width: 500px;
    width: 90%;
    box-shadow: var(--shadow-lg);
    animation: scaleIn 0.3s ease;
}

@keyframes scaleIn {
    from {
        opacity: 0;
        transform: scale(0.9);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

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

.modal-title {
    font-size: 1.5rem;
    font-weight: 600;
}

.modal-close {
    background: none;
    border: none;
    font-size: 2rem;
    color: var(--text-secondary);
    cursor: pointer;
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--border-radius-sm);
    transition: all var(--transition-fast);
}

.modal-close:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}

.modal-form {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.modal-actions {
    display: flex;
    gap: 1rem;
    margin-top: 0.5rem;
}

.modal-actions .btn {
    flex: 1;
}

/* Footer */
.footer {
    text-align: center;
    margin-top: 4rem;
    padding: 2rem 0;
    color: var(--text-muted);
    font-size: 0.9rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .title {
        font-size: 2rem;
    }
    
    .section-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .filter-buttons {
        width: 100%;
    }
    
    .filter-btn {
        flex: 1;
    }
    
    .todo-item {
        flex-direction: column;
    }
    
    .todo-actions {
        width: 100%;
        justify-content: flex-end;
    }
    
    .modal-content {
        width: 95%;
        padding: 1.5rem;
    }
}

/* Loading State */
.loading {
    text-align: center;
    padding: 2rem;
    color: var(--text-secondary);
}

.loading::after {
    content: '...';
    animation: dots 1.5s steps(4, end) infinite;
}

@keyframes dots {
    0%, 20% {
        content: '.';
    }
    40% {
        content: '..';
    }
    60%, 100% {
        content: '...';
    }
}

/* Hidden */
.hidden {
    display: none !important;
}