body {
    font-family: Arial, sans-serif;
    margin: 0;
}

#app-layout {
    height: 100vh;
    display: flex;
    overflow: hidden;
}

#left-panel {
    width: 430px;
    min-width: 300px;
    max-width: 680px;
    background-color: #f8f9fa;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

#resize-handle {
    width: 8px;
    cursor: col-resize;
    background: linear-gradient(to right, #e5e7eb, #d1d5db, #e5e7eb);
}

#chat {
    flex: 1;
    min-width: 360px;
    height: 100vh;
    display: flex;
    flex-direction: column;
    padding: 0 16px;
}

#chat-messages {
    flex-grow: 1;
    padding: 10px;
    background-color: #ffffff;
    border: 1px solid #dee2e6;
}

.sidebar-list {
    overflow-y: auto;
}

#conversations-list {
    max-height: 38vh;
}

#contacts-list {
    flex: 1;
}

.conversation-item,
.contact-item {
    padding: 12px;
    border-bottom: 1px solid #e6e6e6;
    cursor: pointer;
}

.conversation-item:hover,
.contact-item:hover {
    background-color: #eef2f7;
}

.conversation-item.active,
.contact-item.active {
    background-color: #dde8f8;
}

.message-row {
    margin-bottom: 10px;
}

.message-bubble {
    display: inline-block;
    padding: 8px 12px;
    border-radius: 10px;
    max-width: 75%;
}

.message-outbound .message-bubble {
    background-color: #d7f8c4;
}

.message-inbound .message-bubble {
    background-color: #f0f2f5;
}

.login-page {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: #f3f5f7;
}

.login-card {
    width: 100%;
    max-width: 420px;
}

@media (max-width: 900px) {
    #left-panel {
        width: 320px;
        min-width: 260px;
    }

    #chat {
        min-width: 280px;
        padding: 0 8px;
    }
}