/* 教师后台使用同名皮肤，阅读与批阅区域保持清晰的浅底。 */
:root[data-skin="cosmic"] { --primary:#6352d6; --primary-strong:#4435a8; --teal:#3f7f9e; --ink:#202641; --muted:#626b84; --line:#e2e4f2; --surface:#fff; --canvas:#f1f2fa; --sidebar:#252650; --sidebar-soft:#34366b; --shadow:0 8px 28px rgba(38,32,85,.06); --skin-soft:#eeebff; --skin-end:#7574e8; }
:root[data-skin="aurora"] { --primary:#087c70; --primary-strong:#065a52; --teal:#28768c; --ink:#163934; --muted:#526f69; --line:#d9e9e3; --surface:#fff; --canvas:#eff7f3; --sidebar:#124e48; --sidebar-soft:#20685d; --shadow:0 8px 28px rgba(22,82,65,.06); --skin-soft:#dff4eb; --skin-end:#4aaf99; }
:root[data-skin="sunrise"] { --primary:#a43d70; --primary-strong:#7d2855; --teal:#b2592e; --ink:#42263c; --muted:#7b6071; --line:#eddfdf; --surface:#fff; --canvas:#fcf3ed; --sidebar:#672b55; --sidebar-soft:#803a6b; --shadow:0 8px 28px rgba(94,44,70,.06); --skin-soft:#fae9e8; --skin-end:#dc8247; }
:root[data-skin] .panel,:root[data-skin] .card,:root[data-skin] .stat-card { border:1px solid var(--line); border-radius:18px; box-shadow:var(--shadow); }
:root[data-skin] .topbar { background:var(--surface); border-bottom:1px solid var(--line); }
:root[data-skin] .button:not(.secondary):not(.danger) { background:linear-gradient(120deg,var(--primary),var(--primary-strong)); }
:root[data-skin] .stat-card::after { background:var(--skin-soft); }
:root[data-skin] .theme-switch button.on { background:var(--skin-soft); color:var(--primary); border-color:var(--primary); }
:root[data-skin] .theme-switch { flex-wrap:wrap; max-width:340px; }
:root[data-skin] .sidebar { background:radial-gradient(ellipse at 100% 0,rgba(255,255,255,.1),transparent 60%),var(--sidebar); }
:root[data-skin] .login-panel { border:1px solid var(--line); border-radius:26px; box-shadow:var(--shadow); }
:root[data-skin] .login-art { background:linear-gradient(135deg,var(--sidebar),var(--primary)); }
:root[data-skin] .rich-editor { background:#fff; color:var(--ink); }
@media(max-width:700px) { .theme-switch { flex-wrap:wrap; max-width:260px; }.theme-switch button { font-size:11px; padding:5px 7px; } }
@media(prefers-reduced-motion:reduce) { :root[data-skin] *, :root[data-skin] *::before, :root[data-skin] *::after { animation:none!important; transition:none!important; } }

:root[data-skin="starry"] {--primary:#3858b8;--ink:#1c2944;--muted:#586987;--line:#dbe3f2;--primary-strong:#09152f;--teal:#3858b8;--surface:#fff;--canvas:#eef2fa;--sidebar:#09152f;--sidebar-soft:#173366;--skin-soft:#e8efff;--skin-end:#426ca6;}

:root[data-skin="starwars"] {--primary:#886018;--ink:#292b33;--muted:#6e6758;--line:#e4ddce;--primary-strong:#11151f;--teal:#886018;--surface:#fff;--canvas:#f5f2eb;--sidebar:#11151f;--sidebar-soft:#2e3039;--skin-soft:#f7efdb;--skin-end:#68502c;}
:root[data-skin="starry"] .sidebar,:root[data-skin="starry"] .login-art { background:radial-gradient(circle at 17px 23px,#d6f4ff88 1px,transparent 1.5px) 0 0/73px 67px,radial-gradient(ellipse at 90% 0,#426ca6,transparent 55%),#09152f; }
:root[data-skin="starwars"] .sidebar,:root[data-skin="starwars"] .login-art { background:repeating-linear-gradient(118deg,transparent 0 67px,#ffe29a14 68px 69px,transparent 70px 124px),linear-gradient(120deg,#11151f,#2e3039); border-right:1px solid #9b783a; }