:root {
    --primary-blue: #007bff;
    --secondary-blue: #0056b3;
    --light-blue: #f0f7ff;
    --white: #ffffff;
    --text-dark: #343a40;
    --text-light: #6c757d;
    --border-color: #dee2e6;
    --shadow: 0 4px 15px rgba(0, 0, 0, 0.07);
}

body {
    background-color: var(--light-blue);
    font-family: 'Poppins', sans-serif;
    color: var(--text-dark);
}

.chat-container {
    max-width: 1200px;
    height: calc(100vh - 120px);
    margin: 20px auto;
    background: var(--white);
    border-radius: 16px;
    box-shadow: var(--shadow);
    display: flex;
    overflow: hidden;
}

.conversations-sidebar {
    width: 340px;
    background-color: #fcfdff;
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
}

.sidebar-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.sidebar-header h2 {
    font-size: 1.5rem;
    color: var(--text-dark);
    font-weight: 600;
    margin: 0;
}

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

.conversation-item {
    display: flex;
    align-items: center;
    padding: 1rem 1.5rem;
    cursor: pointer;
    transition: background-color 0.2s;
    border-bottom: 1px solid var(--border-color);
}

.conversation-item:hover, .conversation-item.active {
    background-color: var(--light-blue);
}

.conversation-item .profile-pic {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    object-fit: cover;
    margin-right: 15px;
}

.conversation-info .user-name {
    font-weight: 600;
    color: var(--text-dark);
    margin: 0 0 4px 0;
}

.conversation-info .last-message {
    font-size: 0.9em;
    color: var(--text-light);
    margin: 0;
}

.chat-main {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

.chat-window {
    display: flex;
    flex-direction: column;
    height: 100%;
}

#chat-welcome-screen .welcome-message {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    color: var(--text-light);
    padding: 2rem;
}

#chat-welcome-screen h3 {
    font-size: 1.8rem;
    font-weight: 600;
    color: var(--text-dark);
    margin: 0 0 10px 0;
}

.chat-header {
    display: flex;
    align-items: center;
    padding: 1rem 1.5rem;
    background-color: var(--white);
    border-bottom: 1px solid var(--border-color);
}

.chat-header .profile-pic {
    width: 45px;
    height: 45px;
    border-radius: 50%;
    margin-right: 15px;
}

.chat-header h3 {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-dark);
    flex-grow: 1;
    margin: 0;
}

.view-profile-btn {
    text-decoration: none;
    font-weight: 500;
    color: var(--primary-blue);
    transition: color 0.2s;
}
.view-profile-btn:hover {
    color: var(--secondary-blue);
}

.messages-container {
    flex-grow: 1;
    overflow-y: auto;
    padding: 1.5rem;
    background-color: #f7f9fc;
    display: flex;
    flex-direction: column;
}

.message {
    max-width: 70%;
    padding: 10px 15px;
    border-radius: 18px;
    margin-bottom: 10px;
    line-height: 1.4;
    word-wrap: break-word;
}

.message.sent {
    background-color: var(--primary-blue);
    color: var(--white);
    border-bottom-right-radius: 4px;
    align-self: flex-end;
}

.message.received {
    background-color: var(--white);
    color: var(--text-dark);
    border: 1px solid var(--border-color);
    border-bottom-left-radius: 4px;
    align-self: flex-start;
}

.message-input-area {
    display: flex;
    align-items: center;
    padding: 1rem 1.5rem;
    border-top: 1px solid var(--border-color);
    background: var(--white);
}

#message-input {
    flex-grow: 1;
    border: 1px solid var(--border-color);
    border-radius: 50px;
    padding: 12px 20px;
    font-size: 1rem;
    outline: none;
    transition: border-color 0.2s;
}

#message-input:focus {
    border-color: var(--primary-blue);
}

#send-button {
    background-color: var(--primary-blue);
    color: white;
    border: none;
    border-radius: 50px;
    padding: 0 25px;
    height: 48px;
    margin-left: 10px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: background-color 0.2s;
}

#send-button:hover {
    background-color: var(--secondary-blue);
}

.loading-text, .empty-text {
    text-align: center;
    padding: 2rem;
    color: var(--text-light);
}