fix: simplify preference controls

index.html

@@ -284,9 +284,10 @@
         .preference-trigger {
             display: inline-flex;
             align-items: center;
-            gap: 8px;
+            justify-content: center;
+            width: 38px;
             min-height: 38px;
-            padding: 0 11px;
+            padding: 0;
             border: 1px solid var(--line);
             border-radius: 9px;
             background: rgba(255, 255, 255, .025);
@@ -310,8 +311,6 @@
             font: 500 17px/1 "Segoe UI Symbol", "Noto Sans Symbols", sans-serif;
         }
         .preference-icon--globe { font-size: 16px; }
-        .preference-chevron { color: var(--text-faint); font: 700 13px/1 var(--mono); transition: transform .2s ease; }
-        .preference-menu.open .preference-chevron { transform: rotate(180deg); }
         .preference-popover {
             position: absolute;
             top: calc(100% + 10px);
@@ -707,7 +706,13 @@
         .solution-group-code { display: block; margin-bottom: 28px; color: var(--solution-accent, var(--cyan)); font: 650 10px/1 var(--mono); letter-spacing: .12em; }
         .solution-group h3 { margin-bottom: 12px; color: var(--white); font-size: 34px; line-height: 1.2; letter-spacing: -.04em; }
         .solution-group-desc { margin-bottom: 0; color: var(--text-soft); font-size: 14px; line-height: 1.7; }
-        .solution-items { display: grid; gap: 10px; margin-top: auto; }
+        .solution-items {
+            display: grid;
+            flex: 1;
+            grid-template-rows: repeat(3, minmax(min-content, 1fr));
+            gap: 10px;
+            margin-top: auto;
+        }
         .solution-item { padding: 17px 18px 18px; border: 1px solid var(--line); border-radius: var(--radius-md); background: rgba(0, 0, 0, .13); transition: transform .25s var(--ease), border-color .25s ease, background .25s ease; }
         .solution-item:hover { transform: translateX(4px); border-color: color-mix(in srgb, var(--solution-accent, var(--cyan)) 42%, transparent); background: rgba(255, 255, 255, .045); }
         .solution-item-code { display: block; margin-bottom: 15px; color: var(--solution-accent, var(--cyan)); font: 700 10px/1 var(--mono); letter-spacing: .12em; }
@@ -975,6 +980,7 @@
             .services-layout { grid-template-columns: 1fr; }
             .solution-group { min-height: 0; padding: 24px; }
             .solution-group-head { min-height: 0; margin-bottom: 28px; }
+            .solution-items { flex: none; grid-template-rows: none; }
             .solution-group-code { margin-bottom: 20px; }
             .solution-group h3 { font-size: 29px; }
             .proof-grid { grid-template-columns: 1fr; }
@@ -1030,8 +1036,6 @@
                     <div class="preference-menu" id="themeSwitch">
                         <button class="preference-trigger" type="button" aria-haspopup="menu" aria-expanded="false" aria-label="外观模式" data-i18n-aria="theme_label">
                             <span class="preference-icon" data-theme-current-icon aria-hidden="true">◐</span>
-                            <span class="preference-trigger-label" data-theme-current>Auto</span>
-                            <span class="preference-chevron" aria-hidden="true">⌄</span>
                         </button>
                         <div class="preference-popover" role="menu">
                             <button class="preference-item" type="button" role="menuitemradio" aria-checked="true" data-theme-option="system" aria-label="跟随系统" data-i18n-aria="theme_system">
@@ -1048,8 +1052,6 @@
                     <div class="preference-menu" id="langSwitch">
                         <button class="preference-trigger" type="button" aria-haspopup="menu" aria-expanded="false" aria-label="语言切换" data-i18n-aria="lang_label">
                             <span class="preference-icon preference-icon--globe" aria-hidden="true">◎</span>
-                            <span class="preference-trigger-label" data-language-current>简体中文</span>
-                            <span class="preference-chevron" aria-hidden="true">⌄</span>
                         </button>
                         <div class="preference-popover" role="menu">
                             <button class="preference-item" type="button" role="menuitemradio" aria-checked="true" data-lang="zh">