* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: Arial, sans-serif;
    background: #0f1220;
    color: #e8ebff;
}

.app {
    width: min(860px, 100%);
    margin: 0 auto;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    padding: 20px;
    gap: 16px;
}

.topbar h1 {
    margin: 0;
    font-size: 26px;
}

.topbar p {
    margin: 6px 0 0;
    color: #9aa3d7;
}

.chat {
    flex: 1;
    background: #151a2d;
    border: 1px solid #2a335f;
    border-radius: 14px;
    padding: 16px;
    overflow-y: auto;
    max-height: 68vh;
}

.message {
    max-width: 82%;
    margin-bottom: 12px;
    padding: 10px 12px;
    border-radius: 10px;
    line-height: 1.35;
}

.message.user {
    margin-left: auto;
    background: #3047c9;
}

.message.bot {
    background: #1f2747;
}

.composer {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 10px;
}

.composer input {
    width: 100%;
    background: #141a30;
    color: #fff;
    border: 1px solid #2d3767;
    border-radius: 10px;
    padding: 12px;
    font-size: 15px;
}

.composer button {
    border: 0;
    border-radius: 10px;
    padding: 0 18px;
    background: #5f75ff;
    color: #fff;
    cursor: pointer;
    font-weight: 600;
}