:root {
    --bg-color: #f0f2f5;
    --text-color: #1c1e21;
    --primary: #0084ff;
    --bubble-sent: #dcf8c6;
    --bubble-received: #ffffff;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 20px;
    display: flex;
    justify-content: center;
}

.container {
    background: white;
    max-width: 600px;
    width: 100%;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

header h1 {
    margin-top: 0;
    font-size: 1.5rem;
    text-align: center;
}

.hidden {
    display: none;
}

.file-label, button {
    display: block;
    width: 100%;
    padding: 12px;
    background: var(--primary);
    color: white;
    text-align: center;
    border-radius: 8px;
    cursor: pointer;
    border: none;
    font-size: 1rem;
    box-sizing: border-box;
}

input[type="file"] {
    display: none;
}

.config-group {
    margin: 20px 0;
}

.config-group h3 {
    font-size: 1rem;
    margin-bottom: 10px;
}

#participants-list label {
    display: block;
    margin-bottom: 5px;
}

.chat-window {
    margin-top: 20px;
    padding: 20px;
    background: #e5ddd5;
    border-radius: 8px;
    min-height: 200px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.message {
    max-width: 80%;
    padding: 10px 14px;
    border-radius: 16px;
    font-size: 0.95rem;
    line-height: 1.4;
    position: relative;
}

.message .sender {
    font-size: 0.75rem;
    font-weight: bold;
    margin-bottom: 4px;
    color: #555;
}

.msg-received {
    align-self: flex-start;
    background-color: var(--bubble-received);
    border-top-left-radius: 4px;
}

.msg-sent {
    align-self: flex-end;
    background-color: var(--bubble-sent);
    border-top-right-radius: 4px;
}

/* Guide and Footer Styling */
.guide {
    font-size: 0.9rem;
    color: #65676b;
    text-align: center;
    line-height: 1.4;
    margin-bottom: 20px;
    background: #f7f8fa;
    padding: 10px;
    border-radius: 6px;
}

code {
    background: #e4e6eb;
    padding: 2px 4px;
    border-radius: 4px;
    font-family: monospace;
}

footer {
    text-align: center;
    margin-top: 30px;
    padding-top: 15px;
    border-top: 1px solid #e4e6eb;
    font-size: 0.85rem;
    color: #888;
}

footer a {
    color: var(--primary);
    text-decoration: none;
    font-weight: 500;
}

footer a:hover {
    text-decoration: underline;
}