/* ========================================
   CSS Variables & Reset
======================================== */
:root {
    /* Colors */
    --bg-primary: #0a0a0f;
    --bg-secondary: #12121a;
    --bg-tertiary: #1a1a25;
    --bg-glass: rgba(26, 26, 37, 0.8);
    
    --accent-primary: #6366f1;
    --accent-secondary: #8b5cf6;
    --accent-gradient: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #a855f7 100%);
    --accent-glow: rgba(99, 102, 241, 0.3);
    
    --text-primary: #ffffff;
    --text-secondary: #a1a1aa;
    --text-muted: #71717a;
    
    --success: #22c55e;
    --warning: #f59e0b;
    --danger: #ef4444;
    
    --border-color: rgba(255, 255, 255, 0.08);
    --border-light: rgba(255, 255, 255, 0.12);
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.2);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4);
    --shadow-glow: 0 0 20px var(--accent-glow);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 200ms ease;
    --transition-slow: 300ms ease;
}

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

html {
    font-size: 16px;
}

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;
    overflow-x: hidden;
}

/* ========================================
   App Container & Layout
======================================== */
.app-container {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    background: 
        radial-gradient(ellipse at 20% 0%, rgba(99, 102, 241, 0.15) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 100%, rgba(139, 92, 246, 0.1) 0%, transparent 50%),
        var(--bg-primary);
}

/* ========================================
   Header
======================================== */
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-xl);
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

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

.logo-icon {
    width: 36px;
    height: 36px;
    background: var(--accent-gradient);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-glow);
}

.logo-icon svg {
    width: 20px;
    height: 20px;
    color: white;
}

.logo-text {
    font-size: 1.25rem;
    font-weight: 700;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.user-info {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
}

.username-input {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--text-primary);
    font-size: 0.875rem;
    width: 150px;
    transition: var(--transition-base);
}

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

.connection-status {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
}

.status-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--warning);
    animation: pulse 2s infinite;
}

.status-dot.connected {
    background: var(--success);
    animation: none;
}

.status-dot.error {
    background: var(--danger);
    animation: none;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

/* ========================================
   Main Content Layout
======================================== */
.main-content {
    display: flex;
    flex: 1;
    gap: var(--spacing-xl);
    padding: var(--spacing-xl);
    max-width: 1600px;
    margin: 0 auto;
    width: 100%;
}

/* ========================================
   Sidebar
======================================== */
.sidebar {
    width: 320px;
    flex-shrink: 0;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.panel {
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    overflow: hidden;
}

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

.panel-header h2 {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 0.9rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
}

.panel-header h2 svg {
    width: 18px;
    height: 18px;
}

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

.badge {
    background: var(--accent-primary);
    color: white;
    font-size: 0.75rem;
    font-weight: 600;
    padding: 0.125rem 0.5rem;
    border-radius: var(--radius-sm);
    min-width: 24px;
    text-align: center;
}

/* Peers List */
.peers-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    max-height: 300px;
    overflow-y: auto;
}

.peer-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--bg-tertiary);
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: var(--transition-base);
    border: 1px solid transparent;
}

.peer-item:hover {
    background: rgba(99, 102, 241, 0.1);
    border-color: var(--accent-primary);
}

.peer-item .avatar {
    width: 40px;
    height: 40px;
    background: var(--accent-gradient);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
}

.peer-item .avatar svg {
    width: 20px;
    height: 20px;
    color: white;
}

.peer-item .info {
    flex: 1;
}

.peer-item .name {
    font-weight: 500;
    font-size: 0.9rem;
}

.peer-item .status {
    font-size: 0.75rem;
    color: var(--text-muted);
}

.empty-state {
    text-align: center;
    padding: var(--spacing-xl);
    color: var(--text-muted);
}

.empty-state svg {
    width: 48px;
    height: 48px;
    margin-bottom: var(--spacing-md);
    opacity: 0.5;
}

.empty-state p {
    font-size: 0.9rem;
    margin-bottom: var(--spacing-xs);
}

.empty-state span {
    font-size: 0.8rem;
}

/* Invite Panel */
.invite-description {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

.divider {
    display: flex;
    align-items: center;
    margin: var(--spacing-lg) 0;
    color: var(--text-muted);
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

.divider::before,
.divider::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--border-color);
}

.divider span {
    padding: 0 var(--spacing-md);
}

.input-group {
    display: flex;
    gap: var(--spacing-sm);
}

.input-group .input {
    flex: 1;
}

/* ========================================
   Content Area
======================================== */
.content-area {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

/* Connected Peer Panel */
.connected-peer-panel {
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border: 1px solid var(--success);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
}

.connected-peer-info {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
}

.peer-avatar {
    width: 48px;
    height: 48px;
    background: var(--accent-gradient);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
}

.peer-avatar svg {
    width: 24px;
    height: 24px;
    color: white;
}

.peer-details {
    flex: 1;
}

.peer-name {
    display: block;
    font-weight: 600;
    font-size: 1.1rem;
}

.peer-status {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 0.8rem;
    color: var(--success);
}

/* Drop Zone */
.drop-zone {
    flex: 1;
    min-height: 300px;
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border: 2px dashed var(--border-light);
    border-radius: var(--radius-xl);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-base);
    position: relative;
    cursor: pointer;
}

.drop-zone:hover {
    border-color: var(--accent-primary);
    background: rgba(99, 102, 241, 0.05);
}

.drop-zone.dragover {
    border-color: var(--accent-primary);
    background: rgba(99, 102, 241, 0.1);
    border-style: solid;
}

.drop-zone-content {
    text-align: center;
    padding: var(--spacing-2xl);
}

.drop-zone.dragover .drop-zone-content {
    display: none;
}

.drop-zone-active {
    display: none;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
    color: var(--accent-primary);
}

.drop-zone.dragover .drop-zone-active {
    display: flex;
}

.drop-zone-active svg {
    width: 64px;
    height: 64px;
    animation: bounce 1s infinite;
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

.drop-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto var(--spacing-lg);
    background: var(--bg-tertiary);
    border-radius: var(--radius-xl);
    display: flex;
    align-items: center;
    justify-content: center;
}

.drop-icon svg {
    width: 40px;
    height: 40px;
    color: var(--text-muted);
}

.drop-zone-content h3 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-xs);
}

.drop-zone-content p {
    color: var(--text-muted);
    margin-bottom: var(--spacing-lg);
}

/* Files Queue */
.files-queue {
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    overflow: hidden;
}

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

.queue-header h3 {
    font-size: 1rem;
    font-weight: 600;
}

.queue-list {
    padding: var(--spacing-md);
    max-height: 200px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.queue-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
}

.queue-item .file-icon {
    width: 40px;
    height: 40px;
    background: var(--accent-gradient);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
}

.queue-item .file-icon svg {
    width: 20px;
    height: 20px;
    color: white;
}

.queue-item .file-info {
    flex: 1;
    min-width: 0;
}

.queue-item .file-name {
    font-weight: 500;
    font-size: 0.9rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.queue-item .file-size {
    font-size: 0.75rem;
    color: var(--text-muted);
}

.queue-item .remove-btn {
    width: 32px;
    height: 32px;
    background: transparent;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-fast);
}

.queue-item .remove-btn:hover {
    background: rgba(239, 68, 68, 0.1);
    color: var(--danger);
}

.queue-actions {
    padding: var(--spacing-md) var(--spacing-lg);
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: flex-end;
}

/* Transfers Panel */
.transfers-panel {
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    overflow: hidden;
}

.transfers-list {
    padding: var(--spacing-md);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.transfer-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--bg-tertiary);
    border-radius: var(--radius-lg);
}

.transfer-item .file-icon {
    width: 44px;
    height: 44px;
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
}

.transfer-item .file-icon svg {
    width: 22px;
    height: 22px;
    color: var(--accent-primary);
}

.transfer-item .transfer-info {
    flex: 1;
    min-width: 0;
}

.transfer-item .file-name {
    font-weight: 500;
    font-size: 0.9rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    margin-bottom: var(--spacing-xs);
}

.transfer-item .progress-bar {
    height: 6px;
    background: var(--bg-secondary);
    border-radius: 3px;
    overflow: hidden;
    margin-bottom: var(--spacing-xs);
}

.transfer-item .progress-fill {
    height: 100%;
    background: var(--accent-gradient);
    border-radius: 3px;
    transition: width 0.3s ease;
}

.transfer-item .transfer-status {
    display: flex;
    justify-content: space-between;
    font-size: 0.75rem;
    color: var(--text-muted);
}

.transfer-item .transfer-direction {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.transfer-item .transfer-direction svg {
    width: 14px;
    height: 14px;
}

.transfer-item .transfer-direction.upload svg {
    color: var(--accent-primary);
}

.transfer-item .transfer-direction.download svg {
    color: var(--success);
}

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

.transfer-item.completed .progress-fill {
    background: var(--success);
}

/* ========================================
   Buttons
======================================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: 0.875rem;
    font-weight: 500;
    border-radius: var(--radius-md);
    border: none;
    cursor: pointer;
    transition: var(--transition-base);
    text-decoration: none;
    white-space: nowrap;
}

.btn svg {
    width: 18px;
    height: 18px;
}

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

.btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: 0 0 30px var(--accent-glow);
}

.btn-primary:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.btn-secondary {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

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

.btn-outline {
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
}

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

.btn-danger {
    background: rgba(239, 68, 68, 0.1);
    color: var(--danger);
    border: 1px solid rgba(239, 68, 68, 0.2);
}

.btn-danger:hover {
    background: rgba(239, 68, 68, 0.2);
}

.btn-block {
    width: 100%;
}

.btn-sm {
    padding: var(--spacing-xs) var(--spacing-md);
    font-size: 0.8rem;
}

.btn-lg {
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: 1rem;
}

/* ========================================
   Inputs
======================================== */
.input {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--text-primary);
    font-size: 0.875rem;
    width: 100%;
    transition: var(--transition-base);
}

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

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

/* ========================================
   Modal
======================================== */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    padding: var(--spacing-lg);
}

.modal {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    width: 100%;
    max-width: 480px;
    overflow: hidden;
    animation: modalIn 0.2s ease;
}

@keyframes modalIn {
    from {
        opacity: 0;
        transform: scale(0.95) translateY(-10px);
    }
    to {
        opacity: 1;
        transform: scale(1) translateY(0);
    }
}

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

.modal-header h3 {
    font-size: 1.1rem;
    font-weight: 600;
}

.modal-close {
    width: 32px;
    height: 32px;
    background: transparent;
    border: none;
    color: var(--text-muted);
    font-size: 1.5rem;
    cursor: pointer;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-fast);
}

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

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

.modal-body p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

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

.invite-link-box {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.invite-link-box .input {
    flex: 1;
}

.invite-note {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 0.85rem;
    color: var(--text-muted);
}

.invite-note svg {
    width: 16px;
    height: 16px;
    flex-shrink: 0;
}

.connection-request-content {
    text-align: center;
    padding: var(--spacing-lg) 0;
}

.requester-avatar {
    width: 72px;
    height: 72px;
    background: var(--accent-gradient);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto var(--spacing-lg);
}

.requester-avatar svg {
    width: 36px;
    height: 36px;
    color: white;
}

.request-note {
    font-size: 0.85rem !important;
    color: var(--text-muted) !important;
}

/* ========================================
   Toast Notifications
======================================== */
.toast-container {
    position: fixed;
    bottom: var(--spacing-xl);
    right: var(--spacing-xl);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    z-index: 1100;
}

.toast {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    animation: toastIn 0.3s ease;
    max-width: 400px;
}

.toast.success {
    border-color: var(--success);
}

.toast.error {
    border-color: var(--danger);
}

.toast.info {
    border-color: var(--accent-primary);
}

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

.toast-icon {
    width: 24px;
    height: 24px;
    flex-shrink: 0;
}

.toast.success .toast-icon {
    color: var(--success);
}

.toast.error .toast-icon {
    color: var(--danger);
}

.toast.info .toast-icon {
    color: var(--accent-primary);
}

.toast-message {
    font-size: 0.9rem;
}

/* ========================================
   Scrollbar
======================================== */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: var(--border-light);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
}

/* ========================================
   Responsive
======================================== */
@media (max-width: 1024px) {
    .main-content {
        flex-direction: column;
    }
    
    .sidebar {
        width: 100%;
        flex-direction: row;
        flex-wrap: wrap;
    }
    
    .sidebar .panel {
        flex: 1;
        min-width: 280px;
    }
}

@media (max-width: 640px) {
    .header {
        flex-direction: column;
        gap: var(--spacing-md);
        padding: var(--spacing-md);
    }
    
    .user-info {
        width: 100%;
        justify-content: space-between;
    }
    
    .username-input {
        flex: 1;
    }
    
    .main-content {
        padding: var(--spacing-md);
    }
    
    .sidebar .panel {
        min-width: 100%;
    }
    
    .toast-container {
        left: var(--spacing-md);
        right: var(--spacing-md);
    }
    
    .toast {
        max-width: 100%;
    }
}