* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

body {
    background-color: #ececec;
    height: 100vh;
    height: 100dvh; /* Fix for mobile browsers */
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
}

.app-container {
    width: 100%;
    height: 100%;
    max-width: 1200px; /* Optional: limit max width for desktop feel */
    max-height: 850px; /* Optional: limit max height */
    background-color: #fff;
    display: flex;
    box-shadow: 0 0 20px rgba(0,0,0,0.1);
    border-radius: 4px;
    overflow: hidden;
}

/* Sidebar */
.sidebar {
    width: 60px;
    background-color: #2e2e2e;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding-top: 20px;
    padding-bottom: 20px;
    flex-shrink: 0;
}

.user-avatar img {
    width: 36px;
    height: 36px;
    border-radius: 4px;
    margin-bottom: 20px;
    cursor: pointer;
}

.nav-icons {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.nav-item {
    color: #969696;
    font-size: 20px;
    cursor: pointer;
    text-align: center;
    width: 100%;
    padding: 5px 0;
}

.nav-item:hover {
    color: #d6d6d6;
}

.nav-item.active {
    color: #07c160;
}

/* List Panel */
.list-panel {
    width: 250px;
    background-color: #ebebeb;
    border-right: 1px solid #d6d6d6;
    display: flex;
    flex-direction: column;
    flex-shrink: 0;
}

.search-bar {
    padding: 25px 12px 10px 12px;
    background-color: #f7f7f7;
    display: flex;
    align-items: center;
    gap: 10px;
}

.search-input-wrapper {
    background-color: #e2e2e2;
    border-radius: 4px;
    padding: 4px 8px;
    display: flex;
    align-items: center;
    flex: 1;
    font-size: 12px;
}

.search-input-wrapper i {
    color: #999;
    margin-right: 5px;
}

.search-input-wrapper input {
    border: none;
    background: transparent;
    outline: none;
    width: 100%;
    font-size: 12px;
}

.add-btn {
    background-color: #e2e2e2;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 4px;
    cursor: pointer;
    color: #666;
    font-size: 12px;
}

.list-content {
    flex: 1;
    overflow-y: auto;
}

.list-content::-webkit-scrollbar {
    width: 6px;
}

.list-content::-webkit-scrollbar-thumb {
    background-color: #dcdcdc;
    border-radius: 3px;
}

/* Chat List Item */
.chat-item {
    display: flex;
    padding: 12px;
    cursor: pointer;
    position: relative;
}

.chat-item:hover {
    background-color: #dcdcdc;
}

.chat-item.active {
    background-color: #c6c6c6;
}

.chat-item .avatar {
    width: 40px;
    height: 40px;
    border-radius: 4px;
    margin-right: 10px;
    flex-shrink: 0;
}

.chat-item .info {
    flex: 1;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.chat-item .top-row {
    display: flex;
    justify-content: space-between;
    margin-bottom: 4px;
}

.chat-item .name {
    font-size: 14px;
    color: #000;
    font-weight: 500;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.chat-item .time {
    font-size: 10px;
    color: #999;
}

.chat-item .message-preview {
    font-size: 12px;
    color: #999;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* Contact List Item */
.list-section-header {
    padding: 4px 12px;
    font-size: 12px;
    color: #999;
    background-color: #dedede;
}

.contact-item {
    display: flex;
    align-items: center;
    padding: 10px 12px;
    cursor: pointer;
    border-bottom: 1px solid #e7e7e7;
}

.contact-item:hover {
    background-color: #dcdcdc;
}

.contact-item .avatar {
    width: 36px;
    height: 36px;
    border-radius: 4px;
    margin-right: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.contact-item .avatar img {
    width: 100%;
    height: 100%;
    border-radius: 4px;
}

.contact-item .icon-bg {
    color: #fff;
}

.contact-item .icon-bg.orange { background-color: #fa9d3b; }
.contact-item .icon-bg.green { background-color: #07c160; }

.contact-item .name {
    font-size: 14px;
    color: #000;
}

/* Chat Panel */
.chat-panel {
    flex: 1;
    display: flex;
    flex-direction: column;
    background-color: #f5f5f5;
    position: relative;
}

.chat-header {
    height: 60px;
    border-bottom: 1px solid #e7e7e7;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 20px;
    flex-shrink: 0;
}

.chat-title {
    font-size: 18px;
    font-weight: 500;
    cursor: pointer;
}

.chat-options {
    color: #999;
    cursor: pointer;
    font-size: 18px;
}

.chat-options:hover {
    color: #333;
}

.chat-messages {
    flex: 1;
    padding: 20px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.chat-messages::-webkit-scrollbar {
    width: 6px;
}

.chat-messages::-webkit-scrollbar-thumb {
    background-color: #dcdcdc;
    border-radius: 3px;
}

.message {
    display: flex;
    align-items: flex-start;
    max-width: 80%;
}

.message.self {
    align-self: flex-end;
    flex-direction: row-reverse;
}

.message .avatar {
    width: 36px;
    height: 36px;
    border-radius: 4px;
    margin: 0 10px;
    flex-shrink: 0;
}

.message .content {
    background-color: #fff;
    padding: 9px 13px;
    border-radius: 4px;
    font-size: 14px;
    line-height: 1.5;
    position: relative;
    word-wrap: break-word;
    box-shadow: 0 1px 2px rgba(0,0,0,0.05);
}

.message.self .content {
    background-color: #95ec69;
}

/* Triangles for bubbles */
.message .content::before {
    content: "";
    position: absolute;
    top: 12px;
    border: 6px solid transparent;
}

.message:not(.self) .content::before {
    left: -11px;
    border-right-color: #fff;
}

.message.self .content::before {
    right: -11px;
    border-left-color: #95ec69;
}

.chat-input-area {
    height: 160px;
    border-top: 1px solid #e7e7e7;
    display: flex;
    flex-direction: column;
    background-color: #f5f5f5;
    flex-shrink: 0;
}

.toolbar {
    padding: 10px 20px;
    display: flex;
    gap: 15px;
    color: #666;
    font-size: 18px;
}

.toolbar i {
    cursor: pointer;
}

.toolbar i:hover {
    color: #333;
}

.input-box {
    flex: 1;
    padding: 0 20px;
}

.input-box textarea {
    width: 100%;
    height: 100%;
    border: none;
    background: transparent;
    resize: none;
    outline: none;
    font-size: 14px;
    line-height: 1.5;
}

.action-bar {
    padding: 10px 20px;
    display: flex;
    justify-content: flex-end;
    align-items: center;
    gap: 10px;
}

.tip {
    font-size: 12px;
    color: #999;
}

.send-btn {
    background-color: #e9e9e9;
    color: #07c160; /* Disabled look initially */
    border: 1px solid #e7e7e7;
    padding: 6px 20px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 14px;
    transition: all 0.2s;
}

.send-btn:hover {
    background-color: #d2d2d2;
}

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

.empty-state {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: #f5f5f5;
    color: #e0e0e0;
    font-size: 100px;
}

/* Mobile Responsiveness */
.mobile-back-btn {
    display: none;
}

@media (max-width: 768px) {
    body {
        background-color: #fff;
    }

    .app-container {
        max-width: 100%;
        max-height: 100%;
        border-radius: 0;
        box-shadow: none;
        flex-direction: column-reverse; /* Sidebar at bottom */
    }

    /* Sidebar becomes Bottom Tab Bar */
    .sidebar {
        width: 100%;
        height: calc(55px + env(safe-area-inset-bottom));
        padding-bottom: env(safe-area-inset-bottom);
        flex-direction: row;
        padding-top: 0;
        padding-left: 0;
        padding-right: 0;
        justify-content: space-around;
        border-top: 1px solid #e7e7e7;
        background: #f7f7f7;
        flex-shrink: 0;
    }

    .nav-icons {
        flex-direction: row;
        width: 100%;
        justify-content: space-around;
        gap: 0;
        align-items: center;
    }

    .nav-item {
        padding: 0;
        display: flex;
        align-items: center;
        justify-content: center;
        height: 100%;
    }

    .user-avatar, .nav-bottom {
        display: none;
    }

    /* List Panel takes full space */
    .list-panel {
        width: 100%;
        flex: 1;
        border-right: none;
    }

    /* Chat Panel - Full Screen Overlay */
    .chat-panel {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        z-index: 100;
        transform: translateX(100%); /* Hidden by default */
        transition: transform 0.3s ease;
        background-color: #f5f5f5;
    }

    .app-container.mobile-chat-active .chat-panel {
        transform: translateX(0);
    }

    .mobile-back-btn {
        display: block;
        margin-right: 15px;
        font-size: 18px;
        cursor: pointer;
    }
    
    /* Adjust Chat Input for Mobile */
    .chat-input-area {
        height: auto;
        min-height: 50px;
        padding-bottom: 10px;
    }
    
    .toolbar {
        padding: 10px;
    }
    
    .input-box {
        padding: 0 10px;
        height: 40px;
    }
    
    .action-bar {
        padding: 5px 10px;
    }
    
    .tip {
        display: none; /* Hide tip on mobile */
    }
}