/* 逐题辅导：固定上下区域，只滚动对话内容。 */
.xp-side {
 width: var(--ai-panel-width, clamp(420px, 31vw, 520px));
 height: calc(100dvh - 108px); min-height: 0; position: sticky; top: 90px;
}
.xp-body.zl-mode .xp-side { width: var(--ai-panel-width, 420px); }
.xp-ai { padding: 0; overflow: hidden; background: var(--card-bg, #fffdf8); border-radius: 16px; }
.xp-ai [hidden] { display: none !important; }
.xp-ai-head { padding: 18px 18px 8px; flex: none; }
.xp-ai-head .t { gap: 8px; white-space: nowrap; }
.xp-ai-head .t::before { display: none; }
.xp-ai-spark { color: var(--gold-deep, #a8802f); }
.xp-ai-head-actions { display: flex; align-items: center; gap: 10px; }
.xp-ai-mode { padding: 4px 9px; border: 1px solid #e6d6b8; border-radius: 7px; font-size: 11px; color: #89652c; background: #fff9ef; }
.xp-ai-toggle { width: 28px; height: 28px; border-radius: 50%; border: 1px solid var(--card-border); color: var(--ink); background: transparent; font-size: 20px; cursor: pointer; }
.xp-ai-sub { padding: 0 18px; color: var(--text-secondary); font-size: 12px; line-height: 1.6; flex: none; }
.xp-ai-tabs { flex: none; flex-wrap: nowrap; overflow-x: auto; margin: 10px 18px 0; padding-bottom: 4px; }
.xp-ai-tabs .xp-ai-tab { flex: none; }
.xp-ai-steps { list-style: none; display: flex; padding: 16px 18px; gap: 8px; flex: none; border-bottom: 1px solid var(--card-border); }
.xp-ai-steps li { display: flex; align-items: center; gap: 6px; font-size: 11px; color: var(--text-secondary); white-space: nowrap; flex: 1; }
.xp-ai-steps li:not(:last-child)::after { content: ''; flex: 1; height: 1px; background: var(--card-border); margin-left: 2px; }
.xp-ai-steps li:last-child { flex: 0 0 auto; }
.xp-ai-steps li > span { width: 25px; height: 25px; display: grid; place-items: center; border: 1px solid var(--card-border); border-radius: 50%; }
.xp-ai-steps li.is-active { color: var(--ink); font-weight: 600; }
.xp-ai-steps li.is-active > span { background: var(--ink); color: #fff; border-color: #b58b42; }
.xp-ai-steps li.is-done > span { background: #edf4ef; border-color: #b8d4c4; color: #23724f; }
.xp-ai-stream-wrap { position: relative; flex: 1 1 auto; display: flex; min-height: 0; overflow: hidden; }
.xp-ai-stream { margin: 0; padding: 18px 16px; min-height: 0; max-height: none; gap: 18px; overscroll-behavior: contain; overflow-anchor: none; scrollbar-gutter: stable; }
.xp-ai-empty { padding: 16px 4px; }
.xp-ai-msg { flex: none; align-items: flex-start; gap: 9px; min-width: 0; }
.xp-ai-avatar { flex: 0 0 27px; width: 27px; height: 27px; display: grid; place-items: center; color: #52749b; background: #eaf1f8; border-radius: 10px; font-size: 15px; }
.xp-ai-bubble { min-width: 0; max-width: 100%; padding: 0; background: transparent; border: 0; border-radius: 0; color: var(--text-primary); flex: 1; }
.xp-ai-msg.student .xp-ai-bubble { flex: 0 1 auto; max-width: 88%; border-radius: 12px 12px 3px 12px; padding: 9px 13px; }
.xp-ai-bubble p { margin-bottom: 12px; }
.xp-ai-bubble h4 { font-weight: 650; margin: 16px 0 8px; }
.xp-ai-bubble h4:first-child { margin-top: 0; }
.xp-ai-bubble ul, .xp-ai-bubble ol { padding-left: 1.35em; margin: 8px 0 12px; }
.xp-ai-bubble li + li { margin-top: 6px; }
.xp-ai-bubble code { background: rgba(82,116,155,.08); padding: 2px 5px; border-radius: 4px; white-space: pre-wrap; }
.xp-ai-bubble hr { border: 0; border-top: 1px solid var(--card-border); margin: 14px 0; }
.xp-condition-card { margin: 12px 0; padding: 12px 14px; border: 1px solid #e9d8b6; border-radius: 10px; background: #fffcf5; }
.xp-condition-card > :last-child { margin-bottom: 0; }
.xp-condition-card p + p { padding: 9px 11px; background: #edf4fb; color: #294a71; border-radius: 7px; }
.xp-md-cards { display: grid; gap: 10px; margin: 12px 0; }
.xp-md-card { border: 1px solid var(--card-border); border-radius: 10px; padding: 12px; background: var(--input-bg, #fff); }
.xp-md-card dt { color: var(--text-secondary); font-size: .85em; margin-bottom: 3px; }
.xp-md-card dd { margin: 0; overflow-wrap: anywhere; }
.xp-md-card dd + dt { margin-top: 10px; }
.xp-md-card dd:last-child:not(:first-child) { background: #edf4fb; color: #294a71; padding: 7px 9px; border-radius: 6px; }
.xp-choice { margin-top: 14px; padding-top: 12px; border-top: 1px solid var(--card-border); }
.xp-choice .q { font-weight: 600; margin-bottom: 10px; color: var(--text-primary); }
.xp-choice .opts { display: grid; gap: 8px; }
.xp-opt { display: flex; align-items: baseline; gap: 10px; border-radius: 9px; padding: 10px 12px; width: 100%; font-size: 1em; line-height: 1.6; background: var(--input-bg, #fff); }
.xp-opt-letter { font-weight: 600; color: #5d6d84; }
.xp-opt:hover:enabled { background: #f1f5fa; color: var(--ink); border-color: #778ba5; }
.xp-opt:disabled { opacity: .65; }
.xp-opt.is-picked { border-color: #778ba5; background: #edf3fa; opacity: 1; }
.xp-choice-hint { color: var(--text-secondary); margin-top: 8px; }
.xp-ai-composer { padding: 12px 16px 10px; flex: none; border-top: 1px solid var(--card-border); background: var(--card-bg); }
.xp-ai-links { gap: 8px; margin: 0 0 10px; flex-wrap: wrap; }
.xp-ai-link { padding: 6px 11px; border: 1px solid var(--input-border, #d8dbe0); border-radius: 7px; font-family: inherit; background: var(--input-bg, #fff); }
.xp-ai-link:hover:enabled { background: #f1f4f8; border-color: #8c99ab; }
.xp-ai-link:disabled { opacity: .5; cursor: default; }
.xp-ai-foot { margin: 0; padding: 0; border: 1px solid var(--input-border, #d8dbe0); border-radius: 11px; background: var(--input-bg, #fff); gap: 0; overflow: hidden; }
.xp-ai-foot:focus-within { border-color: #8799b3; box-shadow: 0 0 0 3px rgba(82,116,155,.08); }
.xp-ai-input { min-width: 0; min-height: 68px; max-height: 144px; padding: 10px 12px; border: 0; background: transparent; border-radius: 0; }
.xp-ai-input:focus { border: 0; }
.xp-ai-send { width: 36px; height: 36px; margin: 0 9px 9px 0; }
.xp-ai-send svg { width: 18px; height: 18px; }
.xp-ai-keyhint { text-align: right; color: var(--text-muted); font-size: 10px; margin-top: 6px; }
.xp-ai-note { margin: 7px 0 0; line-height: 1.5; }
.xp-ai-new { position: absolute; bottom: 10px; left: 50%; transform: translateX(-50%); border: 1px solid var(--card-border); border-radius: 20px; background: var(--input-bg, #fff); padding: 6px 13px; color: var(--ink); box-shadow: 0 3px 12px #17203315; cursor: pointer; }
.xp-ai-resize { position: absolute; top: 0; bottom: 0; left: -14px; width: 10px; cursor: col-resize; touch-action: none; }
.xp-ai-resize::after { content: '⋮'; position: absolute; top: 42%; left: 0; width: 10px; padding: 10px 0; text-align: center; color: #8c99ab; background: #e7e9ed; border-radius: 8px; }
.xp-side.is-collapsed { width: 190px !important; height: auto; }
.xp-side.is-collapsed .xp-ai > :not(.xp-ai-head), .xp-side.is-collapsed .xp-ai-mode, .xp-side.is-collapsed .xp-ai-resize { display: none !important; }
.xp-side.is-collapsed .xp-ai-head { padding: 14px; }
html.xp-ai-resizing, html.xp-ai-resizing * { cursor: col-resize !important; user-select: none !important; }
.xp-ai :is(button, textarea):focus-visible, .xp-ai-resize:focus-visible { outline: 2px solid #8799b3; outline-offset: 3px; }
@media (max-width: 1380px) and (min-width: 1181px) {
 .xp-side, .xp-body.zl-mode .xp-side { width: var(--ai-panel-width, 380px); }
}
@media (max-width: 1180px) {
 .xp-side, .xp-body.zl-mode .xp-side { width: 100%; position: static; height: min(780px, calc(100dvh - 80px)); min-height: 480px; max-height: none; }
 .xp-ai-resize { display: none; }
 .xp-side.is-collapsed { width: 100% !important; min-height: 0; }
}
@media (max-width: 600px) {
 .xp-side, .xp-body.zl-mode .xp-side { height: calc(100dvh - 80px); min-height: 420px; }
 .xp-ai-head { padding: 14px 12px 8px; }
 .xp-ai-sub { padding: 0 12px; }
 .xp-ai-tabs { margin-left: 12px; margin-right: 12px; }
 .xp-ai-steps { padding: 12px; gap: 5px; }
 .xp-ai-steps li { font-size: 10px; gap: 4px; }
 .xp-ai-steps li > span { width: 22px; height: 22px; }
 .xp-ai-stream { padding: 14px 10px; }
 .xp-ai-avatar { display: none; }
 .xp-ai-composer { padding: 10px; }
 .xp-ai-keyhint { display: none; }
}
@media (prefers-reduced-motion: reduce) { .xp-ai .caret { animation: none; } }