/* ==========================================================================
   LMS · 课件与作业管理系统
   独立前端，与主站（os.css）共享设计变量，代码完全分离
   部署路径：lms.sakura-project.cn
   ========================================================================== */

/* ---------- 设计变量（与主站同步） ---------- */
:root {
  --bg: #fef9f5;
  --bg-alt: #ffffff;
  --surface: #ffffff;
  --surface-alt: #fef5fa;

  --primary: #d55b91;
  --primary-hover: #bf3f7a;
  --primary-soft: #f0dce8;
  --primary-ghost: #fce8f2;

  --accent: #f5c6a0;

  --text: #2a1e2a;
  --text-secondary: #7a5a6a;
  --text-muted: #a88a9a;

  --border: #f0dce8;
  --border-strong: #e0c0d8;

  --shadow-sm: 0 2px 8px rgba(213, 91, 145, 0.05);
  --shadow-md: 0 4px 20px rgba(213, 91, 145, 0.08);
  --shadow-lg: 0 12px 40px rgba(213, 91, 145, 0.10);

  --font-sans: system-ui, -apple-system, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", "Cascadia Mono", Consolas, "SF Mono", Menlo, monospace;

  --maxw: 1120px;
  --radius: 14px;
  --radius-sm: 8px;

  --ok: #4caf7a;
  --warn: var(--accent);
  --err: #e0667a;
}

/* ---------- 重置 ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
  html { scroll-behavior: auto; }
}

/* ---------- 页面主体 ---------- */
body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 15px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  position: relative;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background:
    radial-gradient(58% 44% at 82% -6%, rgba(213, 91, 145, 0.08), transparent 62%),
    radial-gradient(44% 44% at 6% 8%, rgba(245, 198, 160, 0.06), transparent 58%);
}

::selection { background: var(--primary-soft); color: var(--text); }

a { color: var(--primary); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--primary-hover); }

/* ---------- 版心 ---------- */
.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 clamp(18px, 4.5vw, 56px); }

.hairline {
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--border), transparent);
  border: 0;
  margin: 0;
}

/* ---------- 页头 ---------- */
.site-head {
  position: sticky;
  top: 0;
  z-index: 60;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px) saturate(120%);
  -webkit-backdrop-filter: blur(12px) saturate(120%);
  border-bottom: 1px solid var(--border);
}

.site-head .inner {
  display: flex;
  align-items: center;
  gap: 20px;
  height: 60px;
}

.brand { display: flex; align-items: center; gap: 12px; flex-shrink: 0; text-decoration: none; }

.brand .mark {
  width: 32px; height: 32px;
  display: grid; place-items: center;
  border-radius: 9px;
  font-size: 16px;
  font-weight: 500;
  color: var(--primary);
  background: var(--primary-ghost);
  border: 1px solid var(--primary-soft);
}

.brand .name {
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--text);
}
.brand .name em { font-style: normal; color: var(--primary); }
.brand .tag { display: block; font-size: 10px; letter-spacing: 0.24em; color: var(--text-muted); margin-top: 1px; }

.site-nav { margin-left: auto; display: flex; align-items: center; gap: 2px; flex-wrap: nowrap; }

.site-nav a {
  font-size: 13.5px;
  color: var(--text-secondary);
  padding: 8px 13px;
  border-radius: 7px;
  letter-spacing: 0.02em;
  transition: color 0.2s, background 0.2s;
  white-space: nowrap;
}
.site-nav a:hover { color: var(--text); background: var(--primary-ghost); }
.site-nav a.on { color: var(--primary); background: var(--primary-ghost); font-weight: 600; }

.nav-toggle {
  display: none;
  margin-left: auto;
  background: none;
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 7px;
  padding: 7px 11px;
  font-family: var(--font-sans);
  font-size: 14px;
  cursor: pointer;
}

/* ---------- 排版 ---------- */
.eyebrow {
  display: inline-flex;
  align-items: center;
  font-size: 11px;
  letter-spacing: 0.28em;
  text-transform: uppercase;
  color: var(--primary);
  font-weight: 600;
}

h1.display {
  font-size: clamp(34px, 6.2vw, 64px);
  line-height: 1.08;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin: 16px 0 14px;
  color: var(--text);
}

.grad {
  background: linear-gradient(110deg, var(--primary) 10%, #f28aab 55%, var(--accent) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

h2.sec {
  font-size: clamp(24px, 3.4vw, 36px);
  font-weight: 800;
  letter-spacing: -0.01em;
  line-height: 1.2;
  margin: 10px 0 8px;
  color: var(--text);
}

.lede { color: var(--text-secondary); font-size: 15.5px; max-width: 660px; }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  font-family: var(--font-sans);
  font-size: 13.5px;
  font-weight: 500;
  letter-spacing: 0.02em;
  padding: 11px 20px;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.2s, background 0.2s, border-color 0.2s, color 0.2s, box-shadow 0.2s;
  text-decoration: none;
}

.btn-primary {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
  box-shadow: 0 6px 20px -8px rgba(213, 91, 145, 0.5);
}
.btn-primary:hover {
  background: var(--primary-hover);
  border-color: var(--primary-hover);
  color: #fff;
  transform: translateY(-2px);
  box-shadow: 0 10px 28px -8px rgba(213, 91, 145, 0.6);
}

.btn-outline {
  background: transparent;
  border-color: var(--primary);
  color: var(--primary);
}
.btn-outline:hover {
  background: var(--primary-ghost);
  color: var(--primary-hover);
  border-color: var(--primary-hover);
  transform: translateY(-2px);
}

.btn-ghost {
  background: transparent;
  border-color: var(--border);
  color: var(--text-muted);
}
.btn-ghost:hover {
  border-color: var(--border-strong);
  color: var(--text);
  background: var(--primary-ghost);
  transform: translateY(-2px);
}

.btn-sm { padding: 8px 14px; font-size: 12.5px; }
.btn[disabled] { opacity: 0.45; cursor: not-allowed; transform: none; box-shadow: none; }

/* ---------- 卡片 ---------- */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  position: relative;
  box-shadow: var(--shadow-sm);
  transition: transform 0.28s, box-shadow 0.28s, border-color 0.28s;
}
.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-strong);
}

.grid-2 { display: grid; gap: 22px; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); }
.grid-3 { display: grid; gap: 18px; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }

.card h3 { font-size: 16.5px; font-weight: 700; margin-bottom: 8px; letter-spacing: 0.01em; color: var(--text); }
.card p { color: var(--text-secondary); font-size: 13.5px; }

/* ---------- 统计条 ---------- */
.stats {
  display: grid;
  gap: 1px;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}
.stat { background: var(--surface); padding: 22px 18px; }
.stat b {
  display: block;
  font-size: clamp(22px, 2.8vw, 30px);
  font-weight: 800;
  color: var(--text);
  letter-spacing: -0.01em;
}
.stat b i { font-style: normal; color: var(--primary); }
.stat small {
  display: block;
  color: var(--text-muted);
  font-size: 11.5px;
  letter-spacing: 0.12em;
  margin-top: 4px;
  text-transform: uppercase;
}

/* ---------- 步骤 ---------- */
.steps { display: grid; gap: 16px; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); counter-reset: s; }
.step {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  counter-increment: s;
  box-shadow: var(--shadow-sm);
  transition: transform 0.28s, box-shadow 0.28s, border-color 0.28s;
}
.step:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); border-color: var(--border-strong); }
.step::before {
  content: "0" counter(s);
  display: inline-grid;
  place-items: center;
  width: 34px; height: 34px;
  border-radius: 50%;
  background: var(--primary-ghost);
  border: 1px solid var(--primary-soft);
  font-size: 13px;
  font-weight: 800;
  color: var(--primary);
  margin-bottom: 12px;
}
.step b { display: block; font-size: 15px; margin-bottom: 6px; color: var(--text); font-weight: 700; }
.step p { color: var(--text-secondary); font-size: 13px; }

/* ---------- 章节间距 ---------- */
.section { padding: clamp(52px, 8vw, 96px) 0; position: relative; z-index: 1; }
.section-head { margin-bottom: 34px; }

/* ---------- 表格 ---------- */
table.spec { width: 100%; border-collapse: collapse; font-size: 13.5px; }
table.spec th, table.spec td { text-align: left; padding: 11px 13px; border-bottom: 1px solid var(--border); vertical-align: top; }
table.spec th {
  color: var(--text-muted);
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  font-weight: 700;
}
table.spec td b { color: var(--text); }
table.spec td { color: var(--text-secondary); }
table.spec tr:last-child td { border-bottom: 0; }

/* ---------- 提示条 ---------- */
.notice {
  display: flex; gap: 12px; align-items: flex-start;
  border: 1px solid rgba(245, 198, 160, 0.5);
  border-left: 3px solid var(--accent);
  background: #fdf8f0;
  border-radius: var(--radius-sm);
  padding: 13px 16px;
  font-size: 13.5px;
  color: var(--text-secondary);
  margin: 18px 0;
}
.notice b { color: #c98a3a; font-size: 12px; letter-spacing: 0.08em; flex-shrink: 0; font-weight: 700; }

/* ---------- 代码块 ---------- */
pre.code {
  background: #f8f4f8;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 15px 17px;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 12.5px;
  line-height: 1.75;
  color: var(--text-secondary);
}
code.inline {
  font-family: var(--font-mono);
  font-size: 12.5px;
  background: var(--primary-ghost);
  border: 1px solid var(--primary-soft);
  border-radius: 5px;
  padding: 1px 6px;
  color: var(--primary);
}

/* ---------- 徽章 ---------- */
.badge {
  font-size: 10.5px;
  font-weight: 600;
  letter-spacing: 0.1em;
  padding: 3px 10px;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--text-secondary);
  text-transform: uppercase;
  background: var(--surface);
}
.badge.latest { color: #fff; background: var(--primary); border-color: var(--primary); }
.badge.ok { color: #1f6d42; background: #e6f5ec; border-color: rgba(76, 175, 122, 0.5); }
.badge.err { color: #a83244; background: #fde8ec; border-color: rgba(224, 102, 122, 0.5); }

/* ---------- 页脚 ---------- */
.site-foot {
  position: relative; z-index: 1;
  border-top: 1px solid var(--border);
  padding: 42px 0 56px;
  color: var(--text-muted);
  font-size: 12.5px;
  background: var(--surface-alt);
}
.site-foot .cols { display: flex; gap: 40px; flex-wrap: wrap; justify-content: space-between; }
.site-foot h4 {
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-secondary);
  margin-bottom: 10px;
  font-weight: 700;
}
.site-foot a { color: var(--text-muted); }
.site-foot a:hover { color: var(--primary); }
.site-foot ul { list-style: none; }
.site-foot li { margin: 5px 0; }
.site-foot .legal { margin-top: 30px; padding-top: 20px; border-top: 1px solid var(--border); line-height: 2; }

/* ---------- 滚动揭示 ---------- */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity 0.65s cubic-bezier(0.2, 0.7, 0.2, 1), transform 0.65s cubic-bezier(0.2, 0.7, 0.2, 1); }
.reveal.in { opacity: 1; transform: none; }

/* ---------- 表单字段 ---------- */
.form-field { margin-bottom: 18px; }
.form-field label {
  display: block;
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 7px;
}
.form-field input,
.form-field textarea {
  width: 100%;
  padding: 11px 14px;
  font-family: var(--font-sans);
  font-size: 14px;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  transition: border-color 0.2s, box-shadow 0.2s;
  -webkit-appearance: none;
  appearance: none;
}
.form-field input:focus,
.form-field textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(213, 91, 145, 0.10);
}
.form-field input[disabled] {
  background: var(--surface-alt);
  color: var(--text-muted);
  cursor: not-allowed;
}
.form-field textarea {
  resize: vertical;
  min-height: 100px;
}
.form-field input[type="date"] {
  min-height: 42px;
}

/* ---------- 筛选栏 ---------- */
.filter-bar {
  display: flex;
  align-items: flex-end;
  gap: 14px;
  flex-wrap: wrap;
  padding: 16px 20px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  margin-bottom: 22px;
}
.filter-group {
  display: flex;
  flex-direction: column;
  gap: 5px;
}
.filter-group label {
  font-size: 10.5px;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--text-muted);
}
.filter-group select {
  padding: 8px 12px;
  font-family: var(--font-sans);
  font-size: 13px;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  min-width: 120px;
  transition: border-color 0.2s;
  -webkit-appearance: none;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg width='10' height='6' viewBox='0 0 10 6' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M1 1l4 4 4-4' stroke='%23a88a9a' stroke-width='1.5' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 10px center;
  padding-right: 28px;
}
.filter-group select:focus {
  outline: none;
  border-color: var(--primary);
}
.filter-bar .btn { margin-bottom: 1px; }

/* ---------- 教师操作栏 ---------- */
.teacher-bar {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 20px;
  box-shadow: var(--shadow-sm);
}

/* ---------- 作业列表 ---------- */
.assignment-list { display: flex; flex-direction: column; }

/* ---------- 作业卡片 ---------- */
.assignment-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 22px;
  box-shadow: var(--shadow-sm);
  transition: transform 0.25s, box-shadow 0.25s, border-color 0.25s;
  opacity: 0;
  transform: translateY(14px);
}
.assignment-card.in {
  opacity: 1;
  transform: none;
}
.assignment-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-strong);
}
.ac-head {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}
.ac-head .badge { font-size: 10px; letter-spacing: 0.06em; }
.ac-date {
  font-size: 12px;
  color: var(--text-muted);
  letter-spacing: 0.04em;
  margin-left: auto;
  white-space: nowrap;
}
.ac-del { margin-left: 0; }
.ac-body {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: 12px;
  white-space: pre-wrap;
  word-break: break-word;
}
.ac-foot {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
  padding-top: 12px;
}

/* ---------- 空状态 ---------- */
.empty {
  text-align: center;
  padding: 48px 20px;
  color: var(--text-muted);
  font-size: 14px;
  border: 1px dashed var(--border-strong);
  border-radius: var(--radius);
  margin-top: 12px;
}

/* ---------- 响应式补充 ---------- */
@media (max-width: 860px) {
  .filter-bar { flex-direction: column; align-items: stretch; gap: 10px; }
  .filter-group { width: 100%; }
  .filter-group select { width: 100%; min-width: 0; }
  .filter-bar .btn { width: 100%; justify-content: center; }
}
@media (max-width: 480px) {
  .ac-date { margin-left: 0; width: 100%; text-align: left; }
  .ac-foot { flex-wrap: wrap; }
}

/* ---------- 响应式 ---------- */
@media (max-width: 860px) {
  .site-head .inner { height: 56px; }
  .site-nav {
    display: none;
    position: absolute;
    top: 56px; left: 0; right: 0;
    flex-direction: column;
    align-items: stretch;
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow-md);
    padding: 10px 18px 16px;
    gap: 2px;
  }
  .site-nav.open { display: flex; }
  .site-nav a { padding: 11px 12px; }
  .nav-toggle { display: block; }
  .brand .tag { display: none; }

  .grid-2, .grid-3 { grid-template-columns: 1fr; gap: 16px; }
  .stats { grid-template-columns: repeat(2, 1fr); }
  .section { padding: clamp(40px, 6vw, 64px) 0; }
}

@media (max-width: 480px) {
  .stats { grid-template-columns: 1fr; }
  .site-foot .cols { flex-direction: column; gap: 24px; }
}