:root {
    --bg-color: #fff;
    --text-color: #333;
    --sidebar-bg: #f7f7f7;
    --border-color: #ddd;
    --input-bg: #fff;
    --message-user-bg: #007bff;
    --message-user-text: #fff;
    --message-model-bg: #e9e9eb;
    --message-model-text: #000;
    --button-bg: #007bff;
    --button-text: #fff;
    --hover-bg: #f0f0f0;
    --active-bg: #e0e0e0;
    --arrow-down-icon: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="%23333" viewBox="0 0 16 16"><path d="M7.247 11.14 2.451 5.658C1.885 5.013 2.345 4 3.204 4h9.592a1 1 0 0 1 .753 1.659l-4.796 5.48a1 1 0 0 1-1.506 0z"/></svg>');
}

body.dark-mode {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --sidebar-bg: #1e1e1e;
    --border-color: #333;
    --input-bg: #2c2c2c;
    --message-user-bg: #0056b3;
    --message-user-text: #e0e0e0;
    --message-model-bg: #2c2c2c;
    --message-model-text: #e0e0e0;
    --button-bg: #0056b3;
    --button-text: #e0e0e0;
    --hover-bg: #333;
    --active-bg: #444;
    --arrow-down-icon: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="%23e0e0e0" viewBox="0 0 16 16"><path d="M7.247 11.14 2.451 5.658C1.885 5.013 2.345 4 3.204 4h9.592a1 1 0 0 1 .753 1.659l-4.796 5.48a1 1 0 0 1-1.506 0z"/></svg>');
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    margin: 0;
    height: 100%;
    background-color: var(--bg-color);
    color: var(--text-color);
    overflow: hidden; /* Prevent scrolling of the body */
}

.container {
    display: flex;
    height: 100vh;
    position: relative;
}

.sidebar {
    width: 250px;
    background-color: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    padding: 20px;
    box-sizing: border-box;
    display: flex;
    flex-direction: column;
    z-index: 200;
}

.sidebar-header {
    margin-bottom: 10px;
}

.sidebar h2 {
    margin-top: 0;
    font-size: 1.2em;
    color: var(--text-color);
    margin-bottom: 10px;
}

#new-chat-btn {
    width: 100%;
    padding: 10px;
    background-color: var(--button-bg);
    color: var(--button-text);
    border: none;
    border-radius: 5px;
    cursor: pointer;
    margin-bottom: 20px;
    font-size: 1em;
}

#conversation-list {
    list-style: none;
    padding: 0;
    margin: 0;
    overflow-y: auto;
}

#conversation-list li {
    padding: 10px;
    cursor: pointer;
    border-radius: 5px;
    margin-bottom: 5px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    position: relative;
}

.delete-btn {
    position: absolute;
    right: 10px;
    top: 50%;
    transform: translateY(-50%);
    display: none;
    cursor: pointer;
    border: none;
    background: none;
    font-size: 1.2em;
    color: #999;
}

#conversation-list li:hover .delete-btn {
    display: block;
}

#conversation-list li:hover {
    background-color: var(--hover-bg);
}

#conversation-list li.active {
    background-color: var(--active-bg);
    font-weight: bold;
}

.chat-area {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    height: 100vh;
}

.chat-header {
    padding: 10px 20px;
    border-bottom: 1px solid var(--border-color);
    background-color: var(--bg-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

#theme-toggle-btn {
    background: none;
    border: none;
    font-size: 1.5em;
    cursor: pointer;
    color: var(--text-color);
}

.model-selector {
    display: flex;
    align-items: center;
}

.model-selector label {
    margin-right: 10px;
    font-size: 0.9em;
}

#model {
    background-color: var(--input-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    border-radius: 5px;
    padding: 5px 30px 5px 10px;
    font-size: 0.9em;
    cursor: pointer;
    -webkit-appearance: none;
    appearance: none;
    background-image: var(--arrow-down-icon);
    background-repeat: no-repeat;
    background-position: right 10px center;
    background-size: 1em;
}

#chat-window {
    flex-grow: 1;
    padding: 20px;
    overflow-y: auto;
    background-color: var(--bg-color);
}

.message {
    margin-bottom: 15px;
    padding: 10px 15px;
    border-radius: 18px;
    max-width: 80%;
    line-height: 1.5;
}

.user-message {
    background-color: var(--message-user-bg);
    color: var(--message-user-text);
    align-self: flex-end;
    margin-left: auto;
}

.model-message {
    background-color: var(--message-model-bg);
    color: var(--message-model-text);
    align-self: flex-start;
}

.error-message {
    background-color: #ffcccc;
    color: #a00;
    align-self: flex-start;
}

.chat-input {
    display: flex;
    padding: 20px;
    border-top: 1px solid var(--border-color);
    background-color: var(--bg-color);
}

#message-input {
    flex-grow: 1;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    margin-right: 10px;
    background-color: var(--input-bg);
    color: var(--text-color);
}

#send-btn {
    padding: 10px 20px;
    background-color: var(--button-bg);
    color: var(--button-text);
    border: none;
    border-radius: 5px;
    cursor: pointer;
}

#overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 100;
}

/* --- Button Styles --- */

#sidebar-toggle-btn {
    width: 24px;
    height: 24px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0;
    display: flex;
    flex-direction: column;
    justify-content: space-around;
}

#sidebar-toggle-btn span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--text-color);
    border-radius: 1px;
    transition: all 0.3s ease-in-out;
}

.container.sidebar-open #sidebar-toggle-btn span:nth-child(1) {
    transform: translateY(8px) rotate(45deg);
}

.container.sidebar-open #sidebar-toggle-btn span:nth-child(2) {
    opacity: 0;
}

.container.sidebar-open #sidebar-toggle-btn span:nth-child(3) {
    transform: translateY(-8px) rotate(-45deg);
}

/* --- Responsive Design --- */

/* Mobile styles */
@media (max-width: 768px) {
    .sidebar {
        position: absolute;
        transform: translateX(-100%);
        height: 100%;
        transition: transform 0.3s ease-in-out;
    }

    .container.sidebar-open .sidebar {
        transform: translateX(0);
    }

    .container.sidebar-open #overlay {
        display: block;
    }

    #desktop-sidebar-toggle-btn {
        display: none;
    }
}

/* Desktop styles */
@media (min-width: 769px) {
    #sidebar-toggle-btn {
        display: none; /* Hide hamburger on desktop */
    }

    .sidebar {
        transition: width 0.3s, padding 0.3s;
        overflow-x: hidden;
    }

    .container.sidebar-collapsed .sidebar {
        width: 0;
        padding: 20px 0;
    }

    #desktop-sidebar-toggle-btn {
        position: absolute;
        top: 50%;
        left: 250px;
        transform: translate(-50%, -50%);
        z-index: 100;
        width: 24px;
        height: 24px;
        background: var(--bg-color);
        border: 1px solid var(--border-color);
        border-radius: 50%;
        display: flex;
        align-items: center;
        justify-content: center;
        transition: left 0.3s;
        font-size: 1.2em;
        color: var(--text-color);
    }

    .container.sidebar-collapsed #desktop-sidebar-toggle-btn {
        left: 0;
    }
}