:root {
    /* Colors */
    --primary: #0084FF;
    --primary-dark: #0074E4;
    --primary-light: #E7F3FF;
    --secondary: #10B981;
    --accent: #8B5CF6;
    
    /* Background Colors */
    --bg-primary: #FFFFFF;
    --bg-secondary: #F7F9FC;
    --bg-tertiary: #F0F2F5;
    --bg-sidebar: #FFFFFF;
    --bg-message-sent: #0084FF;
    --bg-message-received: #F0F2F5;
    
    /* Text Colors */
    --text-primary: #050505;
    --text-secondary: #65676B;
    --text-tertiary: #8A8D91;
    --text-white: #FFFFFF;
    
    /* Border Colors */
    --border-color: #E4E6EB;
    --border-hover: #D0D3D8;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-xl: 0 8px 32px rgba(0, 0, 0, 0.16);
    
    /* Spacing */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    
    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-full: 9999px;
    
    /* Transitions */
    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    
    /* Font */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
}

/*RESET & BASE*/
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-family);
    background: var(--bg-secondary);
    color: var(--text-primary);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow: hidden;
}

/* ===================================
   LAYOUT
   =================================== */
.chat-container {
    display: grid;
    grid-template-columns: 360px 1fr;
    height: 100vh;
    max-width: 1600px;
    margin: 0 auto;
    background: var(--bg-primary);
    box-shadow: var(--shadow-xl);
}

/* ===================================
   SIDEBAR
   =================================== */
.sidebar {
    background: var(--bg-sidebar);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    height: 100vh;
}

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

.user-profile {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    flex: 1;
}

.user-info {
    flex: 1;
}

.user-name {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
}

.user-status {
    font-size: 0.8125rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 6px;
    margin-top: 2px;
}

.status-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    display: inline-block;
}

.status-online {
    background: var(--secondary);
}

.status-away {
    background: #F59E0B;
}

.status-offline {
    background: var(--text-tertiary);
}

.sidebar-actions {
    display: flex;
    gap: var(--spacing-sm);
}

/* Search Bar */
.search-container {
    padding: var(--spacing-md) var(--spacing-lg);
    position: relative;
}

.search-icon {
    position: absolute;
    left: calc(var(--spacing-lg) + var(--spacing-md));
    top: 50%;
    transform: translateY(-50%);
    width: 18px;
    height: 18px;
    color: var(--text-tertiary);
    pointer-events: none;
}

.search-input {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md) var(--spacing-sm) 42px;
    background: var(--bg-tertiary);
    border: none;
    border-radius: var(--radius-full);
    font-family: var(--font-family);
    font-size: 0.9375rem;
    color: var(--text-primary);
    outline: none;
    transition: var(--transition);
}

.search-input:focus {
    background: var(--bg-secondary);
    box-shadow: 0 0 0 2px var(--primary-light);
}

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

/* Conversations List */
.conversations-list {
    flex: 1;
    overflow-y: auto;
    padding: var(--spacing-sm) 0;
}

.conversation-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md) var(--spacing-lg);
    cursor: pointer;
    transition: var(--transition);
    position: relative;
}

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

.conversation-item.active {
    background: var(--primary-light);
}

.conversation-item.active::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 4px;
    background: var(--primary);
    border-radius: 0 4px 4px 0;
}

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

.conversation-header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    margin-bottom: 4px;
}

.conversation-name {
    font-size: 0.9375rem;
    font-weight: 600;
    color: var(--text-primary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.conversation-time {
    font-size: 0.75rem;
    color: var(--text-tertiary);
    flex-shrink: 0;
    margin-left: var(--spacing-sm);
}

.conversation-preview {
    font-size: 0.875rem;
    color: var(--text-secondary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    display: flex;
    align-items: center;
    gap: 6px;
}

.unread-badge {
    background: var(--primary);
    color: var(--text-white);
    font-size: 0.6875rem;
    font-weight: 700;
    padding: 2px 6px;
    border-radius: var(--radius-full);
    min-width: 18px;
    text-align: center;
}

.read-receipt {
    width: 14px;
    height: 14px;
    flex-shrink: 0;
}

.read-receipt.sent {
    color: var(--text-tertiary);
}

.read-receipt.delivered {
    color: var(--text-tertiary);
}

.read-receipt.read {
    color: var(--primary);
}

/* ===================================
   AVATAR
   =================================== */
.avatar {
    position: relative;
    flex-shrink: 0;
}

.avatar-user {
    width: 40px;
    height: 40px;
}

.avatar-contact {
    width: 40px;
    height: 40px;
}

.avatar-small {
    width: 48px;
    height: 48px;
}

.avatar img {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    object-fit: cover;
}

.avatar-status {
    position: absolute;
    bottom: 0;
    right: 0;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    border: 2px solid var(--bg-primary);
}

/* ===================================
   CHAT MAIN
   =================================== */
.chat-main {
    display: flex;
    flex-direction: column;
    height: 100vh;
    background: var(--bg-primary);
}

/* Chat Header */
.chat-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--bg-primary);
    z-index: 10;
}

.chat-contact-info {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.contact-details {
    flex: 1;
}

.contact-name {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
}

.contact-status {
    font-size: 0.8125rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 6px;
    margin-top: 2px;
}

.typing-indicator {
    display: flex;
    align-items: center;
    gap: 4px;
    color: var(--primary);
}

.typing-indicator span {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: currentColor;
    animation: typing 1.4s ease-in-out infinite;
}

.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% {
        opacity: 0.3;
        transform: translateY(0);
    }
    30% {
        opacity: 1;
        transform: translateY(-6px);
    }
}

.chat-actions {
    display: flex;
    gap: var(--spacing-sm);
}

/* ===================================
   MESSAGES CONTAINER
   =================================== */
.messages-container {
    flex: 1;
    overflow-y: auto;
    padding: var(--spacing-lg);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    background: var(--bg-primary);
}

.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    color: var(--text-tertiary);
    text-align: center;
    padding: var(--spacing-xl);
}

.empty-icon {
    width: 80px;
    height: 80px;
    margin-bottom: var(--spacing-lg);
    opacity: 0.3;
}

.empty-state h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
}

.empty-state p {
    font-size: 0.9375rem;
    max-width: 400px;
}

/* Date Separator */
.date-separator {
    display: flex;
    align-items: center;
    justify-content: center;
    margin: var(--spacing-lg) 0;
}

.date-separator span {
    background: var(--bg-tertiary);
    padding: 6px 16px;
    border-radius: var(--radius-full);
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--text-secondary);
}

/* Message Group */
.message-group {
    display: flex;
    gap: var(--spacing-sm);
    align-items: flex-end;
}

.message-group.sent {
    flex-direction: row-reverse;
}

.message-group.received {
    flex-direction: row;
}

.message-group-avatar {
    width: 28px;
    height: 28px;
    flex-shrink: 0;
}

.message-group-avatar img {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    object-fit: cover;
}

.message-group-content {
    display: flex;
    flex-direction: column;
    gap: 2px;
    max-width: 65%;
}

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

/* Message Bubble */
.message-bubble {
    padding: 10px 16px;
    border-radius: var(--radius-lg);
    font-size: 0.9375rem;
    line-height: 1.5;
    word-wrap: break-word;
    position: relative;
    animation: messageIn 0.2s ease;
}

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

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

.message-time {
    font-size: 0.6875rem;
    color: var(--text-tertiary);
    margin-top: 4px;
    display: flex;
    align-items: center;
    gap: 4px;
}

.message-group.sent .message-time {
    color: rgba(255, 255, 255, 0.8);
}

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

/* ===================================
   MESSAGE INPUT
   =================================== */
.message-input-container {
    padding: var(--spacing-lg);
    border-top: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    background: var(--bg-primary);
}

.input-wrapper {
    flex: 1;
    position: relative;
}

.message-input {
    width: 100%;
    padding: 12px 20px;
    background: var(--bg-tertiary);
    border: none;
    border-radius: var(--radius-full);
    font-family: var(--font-family);
    font-size: 0.9375rem;
    color: var(--text-primary);
    outline: none;
    transition: var(--transition);
}

.message-input:focus {
    background: var(--bg-secondary);
    box-shadow: 0 0 0 2px var(--primary-light);
}

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

/* ===================================
   BUTTONS
   =================================== */
.icon-btn {
    width: 40px;
    height: 40px;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
}

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

.icon-btn:active {
    transform: scale(0.95);
}

.icon-btn svg {
    width: 20px;
    height: 20px;
}

.send-btn {
    width: 40px;
    height: 40px;
    border: none;
    background: var(--primary);
    color: var(--text-white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
}

.send-btn:hover:not(:disabled) {
    background: var(--primary-dark);
    transform: scale(1.05);
}

.send-btn:active:not(:disabled) {
    transform: scale(0.95);
}

.send-btn:disabled {
    background: var(--bg-tertiary);
    color: var(--text-tertiary);
    cursor: not-allowed;
}

.send-btn svg {
    width: 20px;
    height: 20px;
}

/* ===================================
   EMOJI PICKER
   =================================== */
.emoji-picker {
    position: absolute;
    bottom: 100%;
    right: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    padding: var(--spacing-md);
    max-width: 320px;
    animation: fadeIn 0.2s ease;
}

.emoji-grid {
    display: grid;
    grid-template-columns: repeat(8, 1fr);
    gap: 4px;
    max-height: 280px;
    overflow-y: auto;
}

.emoji-item {
    width: 36px;
    height: 36px;
    border: none;
    background: transparent;
    font-size: 1.5rem;
    cursor: pointer;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.emoji-item:hover {
    background: var(--bg-tertiary);
    transform: scale(1.2);
}

/* ===================================
   TOAST NOTIFICATIONS
   =================================== */
.toast-container {
    position: fixed;
    top: var(--spacing-lg);
    right: var(--spacing-lg);
    z-index: 1000;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.toast {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-md) var(--spacing-lg);
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    min-width: 300px;
    animation: slideIn 0.3s ease;
}

.toast-icon {
    width: 20px;
    height: 20px;
    flex-shrink: 0;
}

.toast-message {
    flex: 1;
    font-size: 0.875rem;
    color: var(--text-primary);
}

@keyframes slideIn {
    from {
        transform: translateX(400px);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

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

/* ===================================
   SCROLLBAR
   =================================== */
.conversations-list::-webkit-scrollbar,
.messages-container::-webkit-scrollbar,
.emoji-grid::-webkit-scrollbar {
    width: 6px;
}

.conversations-list::-webkit-scrollbar-track,
.messages-container::-webkit-scrollbar-track,
.emoji-grid::-webkit-scrollbar-track {
    background: transparent;
}

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

.conversations-list::-webkit-scrollbar-thumb:hover,
.messages-container::-webkit-scrollbar-thumb:hover,
.emoji-grid::-webkit-scrollbar-thumb:hover {
    background: var(--border-hover);
}

/* ===================================
   RESPONSIVE DESIGN
   =================================== */
@media (max-width: 1024px) {
    .chat-container {
        grid-template-columns: 320px 1fr;
    }
}

@media (max-width: 768px) {
    .chat-container {
        grid-template-columns: 1fr;
    }
    
    .sidebar {
        display: none;
    }
    
    .sidebar.active {
        display: flex;
        position: fixed;
        left: 0;
        top: 0;
        width: 320px;
        height: 100vh;
        z-index: 100;
        box-shadow: var(--shadow-xl);
    }
    
    .message-group-content {
        max-width: 85%;
    }
}

@media (max-width: 480px) {
    .message-input-container {
        padding: var(--spacing-md);
    }
    
    .chat-header {
        padding: var(--spacing-md);
    }
    
    .messages-container {
        padding: var(--spacing-md);
    }
}