/* style.css — flat, DeepSeek-like theme. Flexbox only, no CSS Grid.
   Light + dark via variables on <html>. Targeted at iOS 12 Safari, which does
   NOT support flexbox `gap`, so spacing is done with margins throughout. */

* { -webkit-box-sizing: border-box; box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  width: 100%;
  overflow: hidden;
  -webkit-text-size-adjust: 100%;
  -webkit-tap-highlight-color: transparent;
}

/* ---------- Theme variables ---------- */

html.theme-light {
  --bg: #ffffff;
  --bg-soft: #f7f8fa;
  --bg-elev: #ffffff;
  --text: #16181d;
  --text-soft: #6b7280;
  --border: #eceef2;
  --border-strong: #dcdfe5;
  --hover: rgba(16, 20, 30, .05);
  --accent: #4d6bfe;
  --accent-hover: #3f5cf0;
  --accent-soft: rgba(77, 107, 254, .10);
  --bubble: #eef1ff;
  --bubble-text: #1b2559;
  --danger: #e5484d;
  --shadow: 0 10px 34px rgba(15, 18, 26, .14);
  --hl-comment: #7a8291;
  --hl-keyword: #cf222e;
  --hl-string: #0a3069;
  --hl-number: #0550ae;
  --hl-title: #8250df;
  --hl-attr: #953800;
}

html.theme-dark {
  --bg: #16171a;
  --bg-soft: #1c1d21;
  --bg-elev: #202126;
  --text: #e9eaee;
  --text-soft: #9aa0aa;
  --border: #2a2c31;
  --border-strong: #383b42;
  --hover: rgba(255, 255, 255, .06);
  --accent: #5b78ff;
  --accent-hover: #6d87ff;
  --accent-soft: rgba(91, 120, 255, .16);
  --bubble: #262c44;
  --bubble-text: #dfe4ff;
  --danger: #ff6b6b;
  --shadow: 0 10px 34px rgba(0, 0, 0, .5);
  --hl-comment: #8b949e;
  --hl-keyword: #ff7b72;
  --hl-string: #a5d6ff;
  --hl-number: #79c0ff;
  --hl-title: #d2a8ff;
  --hl-attr: #ffa657;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
               "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 15px;
  line-height: 1.65;
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
}

button { font-family: inherit; }

/* Icons: sized by class, coloured by the theme via currentColor. */
.ic { width: 20px; height: 20px; display: block; -ms-flex-negative: 0; flex: none; }
.app-logo { display: block; }

/* ---------- App shell ---------- */

.app { display: -webkit-box; display: -ms-flexbox; display: flex;
       -webkit-box-orient: vertical; -webkit-flex-direction: column; flex-direction: column;
       height: 100%; width: 100%; }

.topbar {
  display: -webkit-box; display: -ms-flexbox; display: flex;
  -webkit-box-align: center; align-items: center;
  height: 56px; min-height: 56px; padding: 0 10px;
  background: var(--bg); border-bottom: 1px solid var(--border);
  position: relative; z-index: 30;
}
.brand {
  -webkit-box-flex: 1; flex: 1;
  display: -webkit-box; display: -ms-flexbox; display: flex;
  -webkit-box-align: center; align-items: center; -webkit-box-pack: center; justify-content: center;
  font-weight: 700; letter-spacing: .01em; font-size: 16px;
}
.brand .app-logo { width: 20px; height: 20px; color: var(--accent); margin-right: 8px; }

.iconbtn {
  -webkit-appearance: none; appearance: none;
  border: none; background: transparent; color: var(--text-soft);
  width: 40px; height: 40px; border-radius: 10px;
  display: -webkit-inline-box; display: inline-flex;
  -webkit-box-align: center; align-items: center; -webkit-box-pack: center; justify-content: center;
  cursor: pointer; padding: 0;
}
.iconbtn .ic { width: 22px; height: 22px; }
.iconbtn:hover, .iconbtn:active { background: var(--hover); color: var(--text); }
.topbar .iconbtn { margin-left: 2px; }

.body { display: -webkit-box; display: -ms-flexbox; display: flex;
        -webkit-box-flex: 1; flex: 1; min-height: 0; position: relative; }

/* ---------- Sidebar ---------- */

.sidebar {
  width: 268px; min-width: 268px;
  display: -webkit-box; display: -ms-flexbox; display: flex;
  -webkit-box-orient: vertical; -webkit-flex-direction: column; flex-direction: column;
  background: var(--bg-soft); border-right: 1px solid var(--border);
}
.sidebar-head { padding: 16px 16px 8px; font-size: 11px; letter-spacing: .1em;
                color: var(--text-soft); text-transform: uppercase; font-weight: 600; }
.sidebar-search-wrap { padding: 0 12px 10px; }
.sidebar-search {
  width: 100%; padding: 9px 12px; border: 1px solid var(--border-strong);
  border-radius: 10px; background: var(--bg); color: var(--text); font-size: 14px;
  -webkit-appearance: none; outline: none;
}
.sidebar-search:focus { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }

.conv-list { list-style: none; margin: 0; padding: 0 8px 8px; overflow-y: auto;
             -webkit-box-flex: 1; flex: 1; -webkit-overflow-scrolling: touch; }
.conv-item {
  position: relative; padding: 10px 34px 10px 12px; border-radius: 10px;
  font-size: 14px; color: var(--text); cursor: pointer;
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.conv-item + .conv-item { margin-top: 2px; }
.conv-item:hover, .conv-item:active { background: var(--hover); }
.conv-item.active { background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.conv-item .del {
  position: absolute; right: 8px; top: 50%; -webkit-transform: translateY(-50%); transform: translateY(-50%);
  width: 24px; height: 24px; border-radius: 8px;
  display: -webkit-box; display: flex; -webkit-box-align: center; align-items: center;
  -webkit-box-pack: center; justify-content: center;
  color: var(--text-soft); opacity: .6;
}
.conv-item .del .ic { width: 15px; height: 15px; }
.conv-item .del:hover { opacity: 1; }
.conv-item .del:active { background: var(--hover); color: var(--danger); }

.sidebar-foot { padding: 10px 14px; border-top: 1px solid var(--border); }
.linkbtn { background: none; border: none; color: var(--text-soft); font-size: 13px;
           cursor: pointer; padding: 4px 0; }
.linkbtn:active { color: var(--danger); }

.backdrop { display: none; }

/* ---------- Main / messages ---------- */

.main { display: -webkit-box; display: -ms-flexbox; display: flex;
        -webkit-box-orient: vertical; -webkit-flex-direction: column; flex-direction: column;
        -webkit-box-flex: 1; flex: 1; min-width: 0; background: var(--bg); position: relative; }
.main.dragging::after {
  content: ''; position: absolute; left: 0; right: 0; top: 0; bottom: 0;
  border: 2px dashed var(--accent); border-radius: 12px; margin: 10px;
  pointer-events: none; z-index: 5; background: var(--accent-soft);
}

.messages { -webkit-box-flex: 1; flex: 1; overflow-y: auto; -webkit-overflow-scrolling: touch;
            padding: 24px 16px 12px; }

.empty { max-width: 780px; margin: 15vh auto 0; text-align: center; color: var(--text-soft); }
.empty-logo {
  width: 58px; height: 58px; margin: 0 auto 18px; border-radius: 17px;
  background: var(--accent-soft); color: var(--accent);
  display: -webkit-box; display: flex; -webkit-box-align: center; align-items: center;
  -webkit-box-pack: center; justify-content: center;
}
.empty-logo .app-logo { width: 30px; height: 30px; }
.empty-title { font-size: 20px; font-weight: 700; color: var(--text); margin-bottom: 8px; }
.empty-hint { font-size: 14px; margin: 4px 0; }

.msg { display: -webkit-box; display: -ms-flexbox; display: flex;
       max-width: 780px; margin: 0 auto 22px; }
.msg.user { -webkit-box-pack: end; justify-content: flex-end; }
.msg.assistant { -webkit-box-align: start; align-items: flex-start; }
.msg.assistant > .avatar { margin-right: 12px; }

.avatar {
  width: 30px; height: 30px; border-radius: 9px; background: var(--accent); color: #fff;
  display: -webkit-box; display: flex; -webkit-box-align: center; align-items: center;
  -webkit-box-pack: center; justify-content: center; -ms-flex-negative: 0; flex: none; margin-top: 2px;
}
.avatar .app-logo { width: 18px; height: 18px; }

.bubble { min-width: 0; word-wrap: break-word; overflow-wrap: break-word; }
.msg.assistant .bubble { -webkit-box-flex: 1; flex: 1; min-width: 0; }
.msg.user .bubble {
  max-width: 78%; background: var(--bubble); color: var(--bubble-text);
  border-radius: 18px 18px 5px 18px; padding: 10px 14px;
}
.msg.error .bubble {
  background: transparent; color: var(--danger);
  border: 1px solid var(--danger); border-radius: 14px; padding: 10px 14px;
}

.msg-actions { display: -webkit-box; display: -ms-flexbox; display: flex;
               -webkit-box-align: center; align-items: center; margin-top: 8px; }
.msg-actions > * + * { margin-left: 4px; }
.msg.user .msg-actions { -webkit-box-pack: end; justify-content: flex-end; }
.msg-btn {
  display: -webkit-inline-box; display: inline-flex;
  -webkit-box-align: center; align-items: center;
  border: none; background: transparent; color: var(--text-soft);
  border-radius: 8px; padding: 4px 8px; font-size: 12.5px; cursor: pointer;
}
.msg-btn .ic { width: 15px; height: 15px; }
.msg-btn .btn-label { margin-left: 5px; }
.msg-btn:hover, .msg-btn:active { background: var(--hover); color: var(--text); }
.msg-btn.done { color: var(--accent); }
.msg.streaming .msg-actions { visibility: hidden; }

/* Reasoning / thinking block */
.reasoning {
  margin: 0 0 10px; border: 1px solid var(--border); border-radius: 12px;
  background: var(--bg-soft); font-size: 13.5px; color: var(--text-soft); overflow: hidden;
}
.reasoning summary { cursor: pointer; padding: 9px 12px; font-weight: 600; outline: none; }
.reasoning summary::-webkit-details-marker { display: none; }
.reasoning-content { white-space: pre-wrap; padding: 0 12px 10px; max-height: 300px; overflow: auto; }

/* Inline message editor */
.msg-editor { min-width: 240px; }
.msg-editor-input {
  width: 100%; border: 1px solid var(--border-strong); border-radius: 12px; padding: 9px 11px;
  font: inherit; font-size: 14px; resize: vertical; background: var(--bg); color: var(--text); outline: none;
}
.msg-editor-input:focus { border-color: var(--accent); }

/* ---------- Attachments ---------- */

.att-preview { display: -webkit-box; display: -ms-flexbox; display: flex;
               -ms-flex-wrap: wrap; flex-wrap: wrap; margin-bottom: 4px; }
.att-item { position: relative; margin: 4px 8px 4px 0; }
.att-thumb {
  width: 68px; height: 68px; object-fit: cover; border-radius: 10px;
  border: 1px solid var(--border-strong); display: block; background: var(--bg-soft);
}
.att-chip {
  display: -webkit-inline-box; display: inline-flex; -webkit-box-align: center; align-items: center;
  border: 1px solid var(--border-strong); border-radius: 9px; padding: 7px 11px;
  font-size: 12.5px; color: var(--text-soft); background: var(--bg-elev);
  max-width: 170px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.att-remove {
  position: absolute; top: -7px; right: -7px; width: 22px; height: 22px; border-radius: 50%;
  border: none; background: var(--danger); color: #fff; cursor: pointer; padding: 0;
  display: -webkit-box; display: flex; -webkit-box-align: center; align-items: center;
  -webkit-box-pack: center; justify-content: center; box-shadow: 0 1px 3px rgba(0,0,0,.25);
}
.att-remove .ic { width: 12px; height: 12px; }

/* ---------- Composer ---------- */

.composer { padding: 8px 16px 16px; background: var(--bg); }
.composer-row {
  display: -webkit-box; display: -ms-flexbox; display: flex;
  -webkit-box-align: end; align-items: flex-end;
  border: 1px solid var(--border-strong); border-radius: 16px; padding: 6px;
  background: var(--bg-elev);
}
.composer-row:focus-within { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
.composer-row > * + * { margin-left: 6px; }
.attach-btn { width: 36px; height: 36px; border-radius: 10px; }
.attach-btn .ic { width: 20px; height: 20px; }
.input {
  -webkit-box-flex: 1; flex: 1; min-width: 0; resize: none; max-height: 180px;
  border: none; outline: none; background: transparent; color: var(--text);
  padding: 8px 4px; font: inherit; font-size: 15px; line-height: 1.5; overflow-y: auto;
}
.sendbtn {
  display: -webkit-inline-box; display: inline-flex;
  -webkit-box-align: center; align-items: center;
  border: none; background: var(--accent); color: #fff;
  border-radius: 12px; height: 36px; padding: 0 14px;
  font-size: 14px; font-weight: 600; cursor: pointer; white-space: nowrap;
}
.sendbtn .ic { width: 17px; height: 17px; }
.sendbtn .send-label { margin-left: 6px; }
.sendbtn .ic-stop { display: none; }
.sendbtn.stop { background: var(--danger); }
.sendbtn.stop .ic-send { display: none; }
.sendbtn.stop .ic-stop { display: block; }
.sendbtn:hover { background: var(--accent-hover); }
.sendbtn.stop:hover { background: var(--danger); }

.scroll-bottom-btn {
  position: absolute; right: 18px; bottom: 96px; width: 40px; height: 40px; border-radius: 50%;
  border: 1px solid var(--border-strong); background: var(--bg-elev); color: var(--text-soft);
  box-shadow: var(--shadow); cursor: pointer; z-index: 10; padding: 0; display: none;
  -webkit-box-align: center; align-items: center; -webkit-box-pack: center; justify-content: center;
}
.scroll-bottom-btn .ic { width: 20px; height: 20px; }
.scroll-bottom-btn.visible { display: -webkit-box; display: flex; }

/* ---------- Content typography ---------- */

.content > :first-child { margin-top: 0; }
.content > :last-child { margin-bottom: 0; }
.content p { margin: 0 0 12px; }
.content h1, .content h2, .content h3, .content h4 { margin: 20px 0 10px; line-height: 1.35; font-weight: 700; }
.content h1 { font-size: 1.4em; } .content h2 { font-size: 1.24em; }
.content h3 { font-size: 1.1em; } .content h4 { font-size: 1em; }
.content ul, .content ol { margin: 0 0 12px; padding-left: 22px; }
.content li { margin: 4px 0; }
.content a { color: var(--accent); text-decoration: none; }
.content a:hover { text-decoration: underline; }
.msg.user .content a { color: var(--bubble-text); text-decoration: underline; }
.content blockquote {
  margin: 12px 0; padding: 6px 14px; border-left: 3px solid var(--border-strong); color: var(--text-soft);
}
.content hr { border: none; border-top: 1px solid var(--border); margin: 16px 0; }
.content img { max-width: 100%; border-radius: 10px; }

.content :not(pre) > code {
  font-family: "SF Mono", "Menlo", "Consolas", "Monaco", monospace;
  font-size: .88em; background: var(--bg-soft); border: 1px solid var(--border);
  border-radius: 6px; padding: 1px 5px;
}
.msg.user .content :not(pre) > code { background: rgba(255,255,255,.35); border-color: transparent; }

.content table { border-collapse: collapse; width: 100%; margin: 12px 0; font-size: .95em;
                 display: block; overflow-x: auto; -webkit-overflow-scrolling: touch; }
.content th, .content td { border: 1px solid var(--border-strong); padding: 7px 11px; text-align: left; }
.content th { background: var(--bg-soft); font-weight: 600; }
.content tbody tr:nth-child(even) { background: rgba(127,127,127,.05); }

/* Code block card */
.code-block {
  border: 1px solid var(--border); border-radius: 12px; overflow: hidden;
  margin: 12px 0; background: var(--bg-soft);
}
.code-head {
  display: -webkit-box; display: -ms-flexbox; display: flex;
  -webkit-box-align: center; align-items: center; -webkit-box-pack: justify; justify-content: space-between;
  padding: 6px 10px 6px 12px; background: transparent;
  border-bottom: 1px solid var(--border); font-size: 12px; color: var(--text-soft);
}
.code-lang { font-family: "SF Mono", Menlo, Consolas, monospace; letter-spacing: .03em; }
.code-copy {
  display: -webkit-inline-box; display: inline-flex;
  -webkit-box-align: center; align-items: center;
  border: none; background: transparent; color: var(--text-soft);
  border-radius: 7px; padding: 3px 8px; font-size: 12px; cursor: pointer;
}
.code-copy .ic { width: 13px; height: 13px; }
.code-copy .btn-label { margin-left: 5px; }
.code-copy:hover, .code-copy:active { background: var(--hover); color: var(--text); }
.code-copy.done { color: var(--accent); }
.code-block pre { margin: 0; padding: 12px 14px; overflow-x: auto; -webkit-overflow-scrolling: touch; }
.code-block pre code {
  font-family: "SF Mono", Menlo, Consolas, Monaco, monospace;
  font-size: 13px; line-height: 1.6; display: block; white-space: pre; color: var(--text);
}

/* highlight.js tokens (theme-aware; no external theme file) */
.hljs-comment, .hljs-quote { color: var(--hl-comment); font-style: italic; }
.hljs-keyword, .hljs-selector-tag, .hljs-literal, .hljs-section, .hljs-doctag, .hljs-type, .hljs-name, .hljs-strong { color: var(--hl-keyword); }
.hljs-string, .hljs-regexp, .hljs-addition, .hljs-attribute, .hljs-meta .hljs-string { color: var(--hl-string); }
.hljs-number, .hljs-symbol, .hljs-bullet, .hljs-link, .hljs-meta, .hljs-deletion { color: var(--hl-number); }
.hljs-title, .hljs-title.function_, .hljs-section .hljs-title, .hljs-built_in { color: var(--hl-title); }
.hljs-attr, .hljs-variable, .hljs-template-variable, .hljs-selector-attr, .hljs-selector-pseudo, .hljs-params { color: var(--hl-attr); }
.hljs-emphasis { font-style: italic; }
.hljs-strong { font-weight: 700; }

/* kbd, sup/sub, footnotes */
.content kbd {
  font-family: "SF Mono", Menlo, Consolas, monospace; font-size: .8em;
  background: var(--bg-soft); border: 1px solid var(--border-strong);
  border-bottom-width: 2px; border-radius: 6px; padding: 1px 6px; color: var(--text);
}
.content sup, .content sub { font-size: .75em; }
.content .fn-ref { color: var(--accent); }
.footnotes { margin-top: 16px; padding-top: 12px; border-top: 1px solid var(--border);
             font-size: .9em; color: var(--text-soft); }
.footnotes ol { margin: 0; padding-left: 20px; }
.footnotes a { color: var(--accent); }

.katex-display { overflow-x: auto; overflow-y: hidden; padding: 6px 0; }
.katex { font-size: 1.02em; }

/* ---------- Modals ---------- */

.modal { display: none; position: fixed; left: 0; top: 0; right: 0; bottom: 0;
         background: rgba(9, 11, 16, .5); z-index: 50;
         -webkit-box-align: center; align-items: center; -webkit-box-pack: center; justify-content: center;
         padding: 16px; }
.modal.open { display: -webkit-box; display: -ms-flexbox; display: flex; }
.modal-card {
  background: var(--bg-elev); border: 1px solid var(--border); border-radius: 18px;
  width: 100%; max-width: 480px; max-height: 90vh;
  display: -webkit-box; display: -ms-flexbox; display: flex;
  -webkit-box-orient: vertical; -webkit-flex-direction: column; flex-direction: column;
  box-shadow: var(--shadow); overflow: hidden;
}
.modal-head {
  display: -webkit-box; display: -ms-flexbox; display: flex;
  -webkit-box-align: center; align-items: center; -webkit-box-pack: justify; justify-content: space-between;
  padding: 14px 12px 14px 16px; font-weight: 700; font-size: 15px;
  border-bottom: 1px solid var(--border);
}
.modal-head .iconbtn { width: 34px; height: 34px; }
.modal-head .iconbtn .ic { width: 18px; height: 18px; }
.modal-body { padding: 8px 16px 14px; overflow-y: auto; -webkit-overflow-scrolling: touch; }
.modal-foot { padding: 12px 16px; border-top: 1px solid var(--border); text-align: right; }
.modal-actions { display: -webkit-box; display: -ms-flexbox; display: flex;
                 -webkit-box-align: center; align-items: center; margin: 14px 0 4px; }
.modal-actions > * + * { margin-left: 8px; }

.row { display: -webkit-box; display: -ms-flexbox; display: flex;
       -webkit-box-align: center; align-items: center; padding: 9px 0; }
.row > * + * { margin-left: 12px; }
.row-textarea { -webkit-box-align: start; align-items: flex-start;
                -webkit-box-orient: vertical; -webkit-flex-direction: column; flex-direction: column; }
.row-textarea > * + * { margin-left: 0; margin-top: 7px; }
.row-label { min-width: 96px; font-size: 13.5px; color: var(--text-soft); }
.row-input {
  -webkit-box-flex: 1; flex: 1; min-width: 0; width: 100%;
  border: 1px solid var(--border-strong); border-radius: 10px; padding: 9px 11px;
  font: inherit; font-size: 14px; background: var(--bg); color: var(--text);
  -webkit-appearance: none; outline: none;
}
.row-input.code { font-family: "SF Mono", Menlo, Consolas, monospace; font-size: 13px; }
.row-input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
.row-input.invalid { border-color: var(--danger); box-shadow: 0 0 0 3px rgba(229,72,77,.12); }
.row-textarea-input { resize: vertical; }
.row-suffix { font-size: 13px; color: var(--text-soft); min-width: 34px; text-align: right; }
.row-checkbox-wrap { -webkit-box-flex: 1; flex: 1; }
.row-checkbox { width: 18px; height: 18px; }
.row-hint { font-size: 12.5px; color: var(--text-soft); margin: 0 0 10px; line-height: 1.5; }
.row-hint.invalid { color: var(--danger); }

.primarybtn { border: none; background: var(--accent); color: #fff; border-radius: 10px;
              padding: 10px 20px; font-size: 14px; font-weight: 600; cursor: pointer; }
.primarybtn:hover { background: var(--accent-hover); }
.ghostbtn { border: 1px solid var(--border-strong); background: transparent; color: var(--text);
            border-radius: 10px; padding: 10px 16px; font-size: 14px; cursor: pointer; }
.ghostbtn:hover, .ghostbtn:active { background: var(--hover); }

/* ---------- Responsive ---------- */

@media (max-width: 720px) {
  .sidebar {
    position: absolute; left: 0; top: 0; bottom: 0; z-index: 40;
    -webkit-transform: translateX(-100%); transform: translateX(-100%);
    transition: -webkit-transform .22s ease, transform .22s ease;
    box-shadow: var(--shadow);
  }
  .sidebar.open { -webkit-transform: translateX(0); transform: translateX(0); }
  .backdrop { display: block; position: absolute; left: 0; top: 0; right: 0; bottom: 0;
              background: rgba(9, 11, 16, .4); z-index: 35; opacity: 0; visibility: hidden;
              transition: opacity .22s ease; }
  .backdrop.open { opacity: 1; visibility: visible; }
  .messages { padding: 18px 12px 8px; }
  .msg.user .bubble { max-width: 84%; }
  .composer { padding: 8px 12px 14px; }
  .sendbtn .send-label { display: none; }
  .sendbtn { padding: 0 11px; }
}