:root {
    --bg-dark: #1a2332;
    --bg-panel: #2a3f5f;
    --bg-card: #3d5a80;
    --text-light: #ffffff;
    --accent: #4fc3f7;
    --primary: #2196f3;
    --secondary: #00bcd4;
    --radius: 10px;
    --shadow: 0 8px 25px rgba(0, 0, 0, 0.3);
}
body {
    font-family: Arial, sans-serif;
    background: #f5f5f5;
    margin: 0;
    padding: 0;
}
.container {
    width: 95%;
    margin: 40px auto;
    background: var(--bg-panel);
    border-radius: 18px;
    box-shadow: var(--shadow);
    padding: 18px 18px 24px 18px;
    color: var(--text-light);
    max-width: 1400px;
}

.container a {
    color: var(--secondary);
    font-weight: 700;
    text-decoration: none;
}
.container a:hover { opacity: 0.9; }
h3 {
    color: var(--accent);
    text-align: center;
    margin-bottom: 18px;
    font-size: 1.5rem;
    letter-spacing: 1px;
}
.chat-box {
    height: 350px;
    overflow-y: auto;
    background: #e8f4f8;
    border: 1px solid var(--secondary);
    border-radius: var(--radius);
    padding: 18px 12px;
    display: flex;
    flex-direction: column;
    margin-bottom: 18px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.15);
}
.message {
    margin: 10px 0;
    padding: 12px 16px;
    border-radius: var(--radius);
    max-width: 80%;
    font-size: 1.04rem;
    line-height: 1.6;
    word-break: break-word;
    box-shadow: 0 2px 8px #0002;
}
.user {
    background: linear-gradient(135deg, #2196f3 0%, #1976d2 100%);
    color: var(--text-light);
    align-self: flex-end;
    text-align: right;
    border-bottom-right-radius: 2px;
    border-top-right-radius: 18px;
    border-top-left-radius: 18px;
    margin-left: auto;
}
.assistant {
    background: linear-gradient(135deg, #00bcd4 0%, #0097a7 100%);
    color: #ffffff;
    align-self: flex-start;
    border-bottom-left-radius: 2px;
    border-top-left-radius: 18px;
    border-top-right-radius: 18px;
}
.error {
    background: #f8d7da;
    color: #842029;
    text-align: center;
    border: 1px solid #f5c2c7;
}
.warning {
    background: #fff3cd;
    color: #856404;
    text-align: center;
    border: 1px solid #ffeeba;
}
.chat-form-row {
    display: flex;
    align-items: stretch;
    gap: 0;
}
#user-message {
    background: #ffffff;
    color: #1a2332;
    border: 2px solid var(--secondary);
    border-right: none;
    border-radius: 10px 0 0 10px;
    padding: 12px;
    font-size: 1.05rem;
    height: 48px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    flex: 1 1 auto;
    box-sizing: border-box;
}
#user-message::placeholder { color: #90a4ae; }
.btn-primary {
    background: linear-gradient(135deg, var(--secondary) 0%, var(--primary) 100%);
    color: #ffffff;
    border: none;
    border-radius: 0 10px 10px 0;
    padding: 0 18px;
    font-size: 1.08rem;
    font-weight: bold;
    cursor: pointer;
    transition: transform 0.18s, box-shadow 0.18s;
    box-shadow: 0 2px 8px rgba(33, 150, 243, 0.3);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    height: 48px;
    min-width: 52px;
    flex-shrink: 0;
    box-sizing: border-box;
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 4px 12px rgba(33, 150, 243, 0.5); }
@media (max-width:600px){
    .container { width: 95% !important; max-width: 95%; padding:16px 12px; margin: 20px auto; }
    .chat-box { height:220px; padding:10px 4px; }
    #user-message { font-size:1rem; height: 44px; }
    .btn-primary { height:44px; font-size:1rem; min-width: 44px; }
}