/* Improved CSS */

:root {
    --header-bg: #444;
    --footer-bg: #000;
    --footer-text: #fff;
    --main-bg: #fff;
    --chatbot-bg: #f5f5f5;
}

html {
    box-sizing: border-box;
}

*, *:before, *:after {
    box-sizing: inherit;
}

body.tank {
    background: url("images/classes.jpg") no-repeat top center fixed;
    background-size: cover;
    font-family: Verdana, Arial, sans-serif;
    color: #111;
    margin: 0;
    padding: 0;
    font-size: 15px;
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

header {
    box-shadow: 0 3px 3px rgba(0,0,0,0.2);
    margin-bottom: 20px;
    width: 100%;
    padding: 0 0 10px 0;
    border-bottom: 1px solid #222;
    background-color: var(--header-bg);
    color: #fff;
}

h1, h2 {
    margin: 0.5em 0;
}

div.chatbot-container {
    background-color: var(--chatbot-bg);
}

main.chat-container {
    background-color: var(--main-bg);
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 1em;
    margin: 2em auto;
    min-width: 0;
    max-width: 100vw;
    min-height: 0;
    max-height: 100vh;
    width: 100vw;
    height: 100%;
}

iframe {
    width: 100%;
    height: 80vh;
    min-width: 0;
    min-height: 0;
    max-width: 1200px;
    max-height: 90vh;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.08);
    display: block;
    margin: 0 auto;
    background: #fff;
    border: none;
}

@media (max-width: 600px) {
    iframe {
        height: 60vh;
        max-width: 100vw;
    }
}

img.loger {
    max-height: 115px;
    max-width: 121px;
    float: left;
    border: 1.5px solid #222;
    background: #fff;
    border-radius: 8px;
    margin-right: 1em;
}

h1.liner {
    text-align: center;
}

footer {
    box-shadow: 0 3px 3px rgba(0,0,0,0.2);
    min-height: 10vh;
    width: 100%;
    padding: 10px 0;
    margin-top: 0.5vh;
    text-align: center;
    background-color: var(--footer-bg);
    color: var(--footer-text);
}

div.copier {
    background-color: var(--footer-bg);
    color: var(--footer-text);
    text-align: center;
    font-size: 3.5vh;
    margin-top: 10vh;
    padding-bottom: 20px;
}