```css
* {
    box-sizing: border-box;
}

:root {
    --bg: #0b0d10;
    --panel: rgba(18, 21, 27, 0.82);
    --panel-solid: #12151b;
    --border: rgba(255, 255, 255, 0.08);
    --text: #f5f7fa;
    --muted: #8b93a1;
    --user: #252a33;
    --input: #171b22;
    --accent: #ffffff;
}

html,
body {
    margin: 0;
    width: 100%;
    height: 100%;
}

body {
    font-family:
        Inter,
        -apple-system,
        BlinkMacSystemFont,
        "Segoe UI",
        Roboto,
        Helvetica,
        Arial,
        sans-serif;

    background:
        radial-gradient(
            circle at 50% -20%,
            rgba(120, 130, 160, 0.16),
            transparent 40%
        ),
        var(--bg);

    color: var(--text);
    overflow: hidden;
}

/* Main application */

.chat-container {
    width: 100%;
    max-width: 900px;
    height: 100vh;
    height: 100dvh;

    margin: 0 auto;

    display: flex;
    flex-direction: column;

    padding: 0 22px;
}

/* Header */

h1 {
    margin: 0;
    padding: 24px 0 20px;

    font-size: 19px;
    font-weight: 600;
    letter-spacing: -0.3px;

    text-align: center;

    color: var(--text);
}

/* Chat area */

#chat {
    flex: 1;

    overflow-y: auto;

    padding: 20px 4px 30px;

    scroll-behavior: smooth;

    scrollbar-width: thin;
    scrollbar-color: rgba(255, 255, 255, 0.12) transparent;
}

#chat::-webkit-scrollbar {
    width: 6px;
}

#chat::-webkit-scrollbar-track {
    background: transparent;
}

#chat::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.12);
    border-radius: 10px;
}

/* Messages */

.message {
    max-width: 78%;

    padding: 13px 17px;
    margin: 12px 0;

    border-radius: 18px;

    font-size: 15px;
    line-height: 1.6;

    white-space: pre-wrap;
    word-wrap: break-word;

    animation: messageIn 0.25s ease-out;
}

.user {
    margin-left: auto;

    background: var(--user);

    border: 1px solid rgba(255, 255, 255, 0.05);

    border-bottom-right-radius: 6px;
}

.ai {
    margin-right: auto;

    background: transparent;

    border-bottom-left-radius: 6px;

    color: #e5e7eb;
}

/* Input area */

.input-area {
    width: 100%;

    display: flex;
    align-items: center;

    gap: 10px;

    margin: 0 auto 22px;

    padding: 7px;

    background: rgba(23, 27, 34, 0.9);

    border: 1px solid var(--border);

    border-radius: 18px;

    box-shadow:
        0 10px 40px rgba(0, 0, 0, 0.35),
        inset 0 1px 0 rgba(255, 255, 255, 0.025);

    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);

    transition:
        border-color 0.2s ease,
        box-shadow 0.2s ease;
}

.input-area:focus-within {
    border-color: rgba(255, 255, 255, 0.16);

    box-shadow:
        0 10px 40px rgba(0, 0, 0, 0.4),
        0 0 0 3px rgba(255, 255, 255, 0.025);
}

/* Text input */

input {
    flex: 1;

    min-width: 0;

    padding: 13px 15px;

    background: transparent;

    border: none;
    outline: none;

    color: var(--text);

    font-family: inherit;
    font-size: 15px;
}

input::placeholder {
    color: v
```