body {
    font-family: 'Inter', sans-serif;
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    background-color: var(--background-color);
    color: var(--text-color);
    transition: background-color 0.3s, color 0.3s;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
    background-color: var(--header-background-color);
    color: var(--header-text-color);
}

header .logo {
    display: flex;
    align-items: center;
    gap: 10px;
}

header .logo img {
    width: 40px;
    height: 40px;
    border-radius: 50%;
}

nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    gap: 20px;
}

nav ul li a {
    text-decoration: none;
    color: var(--header-link-color);
    font-weight: bold;
    transition: color 0.3s;
}

nav ul li a:hover {
    color: var(--header-link-hover-color);
}

nav ul li a.active {
    text-decoration: underline;
    color: var(--header-link-hover-color);
}

main {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 80vh;
    padding: 20px;
    background-color: var(--background-color);
}

#chat-container {
    width: 90%;
    max-width: 500px;
    height: 70vh;
    max-height: 600px;
    background-color: var(--container-background-color);
    border-radius: 8px;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    transition: background-color 0.3s, box-shadow 0.3s;
}

#chat-log {
    flex: 1;
    padding: 10px;
    overflow-y: auto;
    border-bottom: 1px solid var(--divider-color);
    font-size: 14px;
    line-height: 1.5;
    color: var(--text-secondary-color);
    word-wrap: break-word;
}

#chat-input-container {
    display: flex;
    border-top: 1px solid var(--divider-color);
    padding: 10px;
    gap: 10px;
    align-items: center;
}

#chat-input {
    flex: 1;
    padding: 8px;
    font-size: 14px;
    border: 1px solid var(--input-border-color);
    border-radius: 5px;
    outline: none;
    resize: none;
    overflow-y: hidden;
    height: auto;
    min-height: 25px;
    max-height: 100px;
    transition: border-color 0.3s, height 0.2s;
    white-space: pre-wrap;
    background-color: var(--input-background-color);
    color: var(--text-color);
}

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

#send-button {
    padding: 8px 15px;
    background-color: var(--primary-color);
    color: var(--button-text-color);
    border: none;
    border-radius: 5px;
    font-size: 14px;
    font-weight: bold;
    cursor: pointer;
    transition: background-color 0.3s, transform 0.2s;
}

#send-button:hover {
    background-color: var(--primary-hover-color);
    transform: scale(1.05);
}

#send-button:active {
    transform: scale(0.95);
}

footer {
    text-align: center;
    padding: 10px 0;
    background-color: var(--footer-background-color);
    color: var(--footer-text-color);
    font-size: 12px;
}

/* Scrollbar Styling for Chat Log */
#chat-log::-webkit-scrollbar {
    width: 6px;
}

#chat-log::-webkit-scrollbar-thumb {
    background-color: var(--primary-color);
    border-radius: 3px;
}

#chat-log::-webkit-scrollbar-thumb:hover {
    background-color: var(--primary-hover-color);
}

/* Responsive Design */
@media (max-width: 768px) {
    header {
        flex-direction: column;
        text-align: center;
    }

    nav ul {
        flex-direction: column;
        gap: 15px;
    }

    #chat-container {
        width: 95%;
        height: 75vh;
    }

    #chat-input {
        font-size: 12px;
    }

    #send-button {
        font-size: 12px;
    }
}

@media (max-width: 480px) {
    header h1 {
        font-size: 18px;
    }

    #chat-container {
        height: 80vh;
    }

    #chat-log {
        font-size: 12px;
    }

    #chat-input {
        font-size: 12px;
        min-height: 25px;
    }
}

/* Light Theme Variables */
:root {
    --background-color: #f9f9f9;
    --text-color: #333;
    --text-secondary-color: #555;
    --primary-color: #6c63ff;
    --primary-hover-color: #574bdf;
    --header-background-color: #6c63ff;
    --header-text-color: #fff;
    --header-link-color: #fff;
    --header-link-hover-color: #d1cfff;
    --container-background-color: #fff;
    --input-background-color: #fff;
    --input-border-color: #ddd;
    --button-text-color: #fff;
    --footer-background-color: #333;
    --footer-text-color: #fff;
    --divider-color: #ddd;
}

[data-theme="dark"] {
    --background-color: #121212;
    --text-color: #e0e0e0;
    --text-secondary-color: #bdbdbd;
    --primary-color: #81c784;
    --primary-hover-color: #66bb6a;
    --header-background-color: #2e7d32;
    --header-text-color: #fff;
    --header-link-color: #fff;
    --header-link-hover-color: #aed581;
    --container-background-color: #1e1e1e;
    --input-background-color: #2a2a2a;
    --input-border-color: #3a3a3a;
    --button-text-color: #000;
    --footer-background-color: #1c1c1c;
    --footer-text-color: #fff;
    --divider-color: #3a3a3a;
}