:root {
    color-scheme: light;
    --blue: #2563eb;
    --blue-dark: #1d4ed8;
    --surface: #ffffff;
    --page: #eef2f7;
    --muted: #64748b;
    --line: #dbe3ef;
    --bot: #eef2f7;
}

* { box-sizing: border-box; }

html, body {
    width: 100%;
    min-height: 100%;
    margin: 0;
    overflow-x: hidden;
}

body {
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: var(--page);
    color: #0f172a;
    font-family: Arial, Helvetica, sans-serif;
}

button, input { font: inherit; }
button { -webkit-tap-highlight-color: transparent; }

.chat-container {
    width: min(100%, 760px);
    height: min(860px, 100dvh);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    background: var(--surface);
    border-radius: 20px;
    box-shadow: 0 14px 40px rgba(15, 23, 42, .16);
}

header {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 12px;
    padding: 19px 22px;
    color: #fff;
    text-align: center;
    background: linear-gradient(135deg, var(--blue), #1746b4);
}

.brand-logo {
    width: 58px;
    height: 58px;
    display: block;
    flex: 0 0 auto;
    border: 2px solid rgba(255,255,255,.72);
    border-radius: 50%;
    background: #fff;
    object-fit: cover;
}

header h1 { margin: 0 0 3px; font-size: 25px; }
header p { margin: 0; opacity: .92; font-size: 14px; }

.chat-box {
    flex: 1;
    min-height: 0;
    display: flex;
    flex-direction: column;
    gap: 14px;
    padding: 18px;
    overflow-y: auto;
    overflow-x: hidden;
    scroll-behavior: smooth;
}

.message {
    width: fit-content;
    max-width: 86%;
    padding: 12px 15px;
    border-radius: 16px;
    line-height: 1.58;
    overflow-wrap: anywhere;
}

.message.bot { align-self: flex-start; background: var(--bot); border-bottom-left-radius: 5px; }
.message.user { align-self: flex-end; color: #fff; background: var(--blue); border-bottom-right-radius: 5px; }
.message.waiting { color: var(--muted); animation: pulse 1.4s infinite; }

@keyframes pulse { 50% { opacity: .55; } }

.response-content p { margin: 0 0 10px; }
.response-content p:last-child { margin-bottom: 0; }
.response-content ul, .response-content ol { margin: 8px 0; padding-left: 24px; }
.response-content mjx-container[display="true"] {
    display: block !important;
    max-width: 100% !important;
    overflow-x: auto !important;
    overflow-y: hidden;
    padding: 5px 0;
}

.message-attachment {
    margin-bottom: 7px;
    font-weight: 700;
}

.composer {
    flex: 0 0 auto;
    padding: 10px 14px max(10px, env(safe-area-inset-bottom));
    border-top: 1px solid var(--line);
    background: #fff;
}

.attachment-preview {
    position: relative;
    width: min(100%, 430px);
    min-height: 60px;
    display: flex;
    align-items: center;
    gap: 10px;
    margin: 0 0 9px;
    padding: 8px 40px 8px 9px;
    border: 1px solid #bfdbfe;
    border-radius: 12px;
    background: #eff6ff;
}
.attachment-preview[hidden] { display: none; }
.attachment-preview img { width: 52px; height: 52px; object-fit: cover; border-radius: 8px; }
.file-icon { font-size: 30px; }
.file-meta { min-width: 0; display: flex; flex-direction: column; gap: 3px; }
.file-meta strong { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.file-meta span { color: var(--muted); font-size: 12px; }
.remove-file {
    position: absolute;
    top: 7px;
    right: 8px;
    width: 28px;
    height: 28px;
    border: 0;
    border-radius: 50%;
    color: #475569;
    background: #dbeafe;
    cursor: pointer;
    font-size: 21px;
    line-height: 1;
}

.input-area { display: flex; gap: 8px; align-items: center; }
#user-input {
    min-width: 0;
    flex: 1;
    padding: 12px 14px;
    border: 1px solid #cbd5e1;
    border-radius: 12px;
    outline: 0;
}
#user-input:focus { border-color: var(--blue); box-shadow: 0 0 0 3px rgba(37,99,235,.12); }

.icon-btn, #send-btn, .latex-button, .copy-latex-button {
    border: 0;
    border-radius: 10px;
    cursor: pointer;
    font-weight: 700;
}
.icon-btn { width: 45px; height: 45px; flex: 0 0 auto; background: #e2e8f0; font-size: 21px; }
#send-btn { padding: 12px 18px; color: #fff; background: var(--blue); }
#send-btn:hover { background: var(--blue-dark); }
button:disabled { cursor: wait; opacity: .62; }
.upload-help { margin: 7px 0 0 53px; color: var(--muted); font-size: 11px; }

.latex-container { margin-top: 12px; }
.latex-button, .copy-latex-button { padding: 8px 11px; color: #fff; background: #334155; font-size: 12px; }
.copy-latex-button { margin-top: 7px; background: var(--blue); }
.latex-code-container pre {
    max-width: 100%;
    margin: 8px 0 0;
    padding: 12px;
    overflow-x: auto;
    white-space: pre-wrap;
    border-radius: 8px;
    color: #e2e8f0;
    background: #0f172a;
    font: 12px/1.5 Consolas, monospace;
}

@media (max-width: 600px) {
    body { align-items: stretch; }
    .chat-container { width: 100%; height: 100dvh; border-radius: 0; box-shadow: none; }
    header { padding: 13px 16px; }
    .brand-logo { width: 50px; height: 50px; }
    header h1 { font-size: 21px; }
    .chat-box { padding: 12px; }
    .message { max-width: 94%; font-size: 15px; }
    .message.user { max-width: 88%; }
    .composer { position: sticky; bottom: 0; padding-inline: 9px; }
    .input-area { gap: 6px; }
    .icon-btn { width: 42px; height: 42px; }
    #user-input { padding: 11px; font-size: 16px; }
    #send-btn { padding: 11px 12px; font-size: 14px; }
    .upload-help { margin-left: 48px; }
}