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

:root {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    --border-color: #e2e8f0;
    --sent-message-bg: #6366f1;
    --sent-message-text: #ffffff;
    --received-message-bg: #f1f5f9;
    --received-message-text: #1e293b;
    --online-color: #22c55e;
    --away-color: #f59e0b;
    --offline-color: #94a3b8;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-full: 9999px;
    --transition: all 0.2s ease;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.app-container {
    width: 100%;
    max-width: 1200px;
    height: 85vh;
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    display: flex;
    overflow: hidden;
}

/* Sidebar Styles */
.sidebar {
    width: 360px;
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    flex-shrink: 0;
}

.sidebar-header {
    padding: 20px 20px 16px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-bottom: 1px solid var(--border-color);
}

.sidebar-header h2 {
    font-size: 24px;
    font-weight: 700;
    color: var(--text-primary);
}

.new-chat-btn {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-full);
    border: none;
    background: var(--primary-color);
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.new-chat-btn:hover {
    background: var(--primary-hover);
    transform: scale(1.05);
}

.search-bar {
    padding: 16px 20px;
    display: flex;
    align-items: center;
    gap: 12px;
    background: var(--bg-primary);
    margin: 16px 16px 8px;
    border-radius: var(--radius-full);
    border: 1px solid var(--border-color);
}

.search-bar:focus-within {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.search-bar i {
    color: var(--text-muted);
}

.search-bar input {
    flex: 1;
    border: none;
    outline: none;
    font-size: 14px;
    color: var(--text-primary);
    background: transparent;
}

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

.contacts-list {
    flex: 1;
    overflow-y: auto;
    padding: 8px;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition);
}

.contact-item:hover {
    background: var(--bg-tertiary);
}

.contact-item.active {
    background: rgba(99, 102, 241, 0.1);
}

.contact-item.active .contact-name {
    color: var(--primary-color);
}

.avatar-container {
    position: relative;
    flex-shrink: 0;
}

.contact-avatar {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-full);
    object-fit: cover;
}

.online-indicator {
    width: 12px;
    height: 12px;
    border-radius: var(--radius-full);
    position: absolute;
    bottom: 2px;
    right: 2px;
    border: 2px solid var(--bg-secondary);
}

.online-indicator.online {
    background: var(--online-color);
}

.online-indicator.away {
    background: var(--away-color);
}

.online-indicator.offline {
    background: var(--offline-color);
}

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

.contact-name {
    font-size: 15px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.contact-preview {
    font-size: 13px;
    color: var(--text-secondary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.contact-meta {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 4px;
}

.contact-time {
    font-size: 12px;
    color: var(--text-muted);
}

.unread-badge {
    background: var(--primary-color);
    color: white;
    font-size: 11px;
    font-weight: 600;
    padding: 2px 8px;
    border-radius: var(--radius-full);
    min-width: 20px;
    text-align: center;
}

/* Chat Area Styles */
.chat-area {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--bg-primary);
}

.chat-header {
    padding: 16px 24px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.chat-header-info {
    display: flex;
    align-items: center;
    gap: 12px;
}

.chat-header .avatar-container .contact-avatar {
    width: 44px;
    height: 44px;
}

.chat-header .online-indicator {
    border-color: var(--bg-primary);
}

.chat-header-text h3 {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
}

.chat-header-text span {
    font-size: 13px;
    color: var(--text-secondary);
}

.chat-header-actions {
    display: flex;
    gap: 8px;
}

.chat-header-actions button {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-full);
    border: none;
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.chat-header-actions button:hover {
    background: var(--border-color);
    color: var(--text-primary);
}

/* Messages Container */
.messages-container {
    flex: 1;
    overflow-y: auto;
    padding: 24px;
    display: flex;
    flex-direction: column;
    gap: 16px;
    background: var(--bg-primary);
}

.no-chat-selected {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    gap: 12px;
}

.no-chat-selected i {
    font-size: 48px;
    opacity: 0.5;
}

.message-wrapper {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.message-wrapper.sent {
    align-items: flex-end;
}

.message-wrapper.received {
    align-items: flex-start;
}

.message-bubble {
    max-width: 70%;
    padding: 12px 16px;
    border-radius: var(--radius-lg);
    font-size: 14px;
    line-height: 1.5;
    word-wrap: break-word;
}

.message-wrapper.sent .message-bubble {
    background: var(--sent-message-bg);
    color: var(--sent-message-text);
    border-bottom-right-radius: 4px;
}

.message-wrapper.received .message-bubble {
    background: var(--received-message-bg);
    color: var(--received-message-text);
   : 4px border-bottom-left-radius;
}

.message-time {
    font-size: 11px;
    color: var(--text-muted);
    padding: 0 4px;
    margin-top: 4px;
}

.message-wrapper.sent .message-time {
    text-align: right;
}

.message-image {
    max-width: 250px;
    border-radius: var(--radius-md);
    margin-bottom: 4px;
}

/* Message Input Area */
.message-input-area {
    padding: 16px 24px;
    border-top: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 12px;
    background: var(--bg-primary);
}

.message-input-area.hidden {
    display: none;
}

.message-input-area button {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-full);
    border: none;
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.message-input-area button:hover {
    background: var(--border-color);
    color: var(--text-primary);
}

.message-input-area .attach-btn:hover,
.message-input-area .emoji-btn:hover {
    color: var(--primary-color);
}

.message-input-area input {
    flex: 1;
    padding: 12px 20px;
    border-radius: var(--radius-full);
    border: 1px solid var(--border-color);
    font-size: 14px;
    color: var(--text-primary);
    background: var(--bg-tertiary);
    transition: var(--transition);
}

.message-input-area input:focus {
    outline: none;
    border-color: var(--primary-color);
    background: var(--bg-primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

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

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

.send-btn:hover {
    background: var(--primary-hover) !important;
    color: white !important;
    transform: scale(1.05);
}

/* Date Separator */
.date-separator {
    text-align: center;
    padding: 8px 0;
}

.date-separator span {
    background: var(--bg-tertiary);
    color: var(--text-muted);
    font-size: 12px;
    padding: 6px 16px;
    border-radius: var(--radius-full);
}

/* Typing Indicator */
.typing-indicator {
    display: flex;
    align-items: center;
    gap: 4px;
    padding: 12px 16px;
    background: var(--received-message-bg);
    border-radius: var(--radius-lg);
    width: fit-content;
}

.typing-indicator span {
    width: 8px;
    height: 8px;
    background: var(--text-muted);
    border-radius: var(--radius-full);
    animation: typing 1.4s infinite ease-in-out;
}

.typing-indicator span:nth-child(1) {
    animation-delay: 0s;
}

.typing-indicator span:nth-child(2) {
    animation-delay: 0.2s;
}

.typing-indicator span:nth-child(3) {
    animation-delay: 0.4s;
}

@keyframes typing {
    0%, 60%, 100% {
        transform: translateY(0);
    }
    30% {
        transform: translateY(-6px);
    }
}

/* Scrollbar Styles */
.messages-container::-webkit-scrollbar,
.contacts-list::-webkit-scrollbar {
    width: 6px;
}

.messages-container::-webkit-scrollbar-track,
.contacts-list::-webkit-scrollbar-track {
    background: transparent;
}

.messages-container::-webkit-scrollbar-thumb,
.contacts-list::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 3px;
}

.messages-container::-webkit-scrollbar-thumb:hover,
.contacts-list::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
}

/* Responsive */
@media (max-width: 768px) {
    .app-container {
        height: 100vh;
        border-radius: 0;
    }
    
    .sidebar {
        width: 100%;
        position: absolute;
        left: 0;
        top: 0;
        bottom: 0;
        z-index: 10;
    }
    
    .sidebar.hidden {
        display: none;
    }
    
    .chat-area {
        width: 100%;
    }
}