/* ==========================================
   bank.css - 题库页面专属样式 v5.0
   前缀：bk-
   设计语言：玻璃质感 + 动态渐变 + 3D悬浮 + 流光动效
   ========================================== */

/* ===== CSS 变量 ===== */
:root {
  --bk-primary: #4f46e5;
  --bk-primary-light: #6366f1;
  --bk-accent: #f59e0b;
  --bk-surface: #ffffff;
  --bk-surface-alt: #f8fafc;
  --bk-border: #e2e8f0;
  --bk-text: #1e293b;
  --bk-text-muted: #94a3b8;
  --bk-radius: 20px;
  --bk-radius-sm: 14px;
  --bk-shadow-sm: 0 1px 3px rgba(0,0,0,.04), 0 1px 2px rgba(0,0,0,.06);
  --bk-shadow: 0 4px 24px rgba(79,70,229,.06), 0 1px 4px rgba(0,0,0,.04);
  --bk-shadow-lg: 0 20px 48px rgba(79,70,229,.1), 0 8px 16px rgba(0,0,0,.06);
  --bk-shadow-xl: 0 32px 64px rgba(79,70,229,.12), 0 8px 24px rgba(0,0,0,.08);
  --bk-transition: .35s cubic-bezier(.16,1,.3,1);
  --bk-transition-spring: .5s cubic-bezier(.34,1.56,.64,1);
}

/* ========================================
   Hero 区域 v5.0 - 动态渐变网格背景
   ======================================== */
.bk-hero {
  position: relative;
  overflow: hidden;
  isolation: isolate;
  background: linear-gradient(
    160deg,
    #eef2ff 0%,
    #f0f9ff 20%,
    #faf5ff 45%,
    #f0fdf4 65%,
    #fefce8 85%,
    #f8fafc 100%
  );
}
.bk-hero::before {
  content: '';
  position: absolute;
  inset: -50%;
  z-index: 0;
  background:
    /* 三层流动光斑 */
    radial-gradient(ellipse 900px 650px at 15% 30%, rgba(99,102,241,.07), transparent 70%),
    radial-gradient(ellipse 750px 550px at 80% 10%, rgba(59,130,246,.06), transparent 70%),
    radial-gradient(ellipse 650px 450px at 55% 80%, rgba(139,92,246,.05), transparent 70%),
    radial-gradient(ellipse 500px 350px at 30% 65%, rgba(16,185,129,.05), transparent 70%);
  animation: bkHeroDrift 18s ease-in-out infinite;
}
@keyframes bkHeroDrift {
  0%, 100% { transform: translate(0, 0) rotate(0deg); }
  33% { transform: translate(2%, -1%) rotate(1deg); }
  66% { transform: translate(-1%, 1%) rotate(-1deg); }
}
/* 装饰网格线 */
.bk-hero::after {
  content: '';
  position: absolute;
  inset: 0;
  z-index: 0;
  opacity: .18;
  background-image:
    linear-gradient(rgba(99,102,241,.1) 1px, transparent 1px),
    linear-gradient(90deg, rgba(99,102,241,.1) 1px, transparent 1px);
  background-size: 60px 60px;
  mask-image: radial-gradient(ellipse 80% 60% at 50% 40%, black 30%, transparent 70%);
  -webkit-mask-image: radial-gradient(ellipse 80% 60% at 50% 40%, black 30%, transparent 70%);
}

.bk-hero-bg {
  position: absolute; inset: 0; pointer-events: none; z-index: 0;
}

/* Hero 波浪 */
.bk-hero-wave {
  position: absolute; bottom: -1px; left: 0; right: 0; height: 64px; z-index: 5;
}
.bk-hero-wave svg { width: 100%; height: 100%; display: block; }

/* Hero 标题 */
.bk-hero-title {
  font-size: clamp(1.8rem, 4.5vw, 3rem);
  font-weight: 900;
  font-family: 'Noto Sans SC', 'PingFang SC', sans-serif;
  margin-bottom: 12px;
  letter-spacing: -.02em;
  line-height: 1.2;
}
.bk-hero-desc {
  color: #64748b;
  font-size: .92rem;
  max-width: 640px;
  margin: 0 auto;
  line-height: 1.6;
}

/* 实时状态徽章 */
.bk-hero .inline-flex.items-center.gap-2 {
  box-shadow: 0 2px 12px rgba(79,70,229,.06);
  border-color: rgba(99,102,241,.15);
  color: #6366f1;
  font-weight: 700;
}

/* ========================================
   统计卡片 v5.0 - 玻璃质感 + 发光边框
   ======================================== */
.bk-stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
  max-width: 800px;
  margin: 28px auto 0;
}
@media (min-width: 640px) { .bk-stats { grid-template-columns: repeat(3, 1fr); } }
@media (min-width: 1024px) { .bk-stats { grid-template-columns: repeat(6, 1fr); } }

.bk-stat-card {
  position: relative;
  overflow: hidden;
  background: rgba(255,255,255,.82);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid rgba(226,232,240,.7);
  border-radius: 18px;
  padding: 16px;
  text-align: center;
  transition: var(--bk-transition-spring);
}
.bk-stat-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: 18px;
  padding: 1px;
  background: linear-gradient(135deg, rgba(99,102,241,.12), rgba(236,72,153,.06), rgba(16,185,129,.08));
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
  opacity: 0;
  transition: opacity .4s;
}
.bk-stat-card:hover::before { opacity: 1; }
.bk-stat-card:hover {
  transform: translateY(-4px) scale(1.02);
  box-shadow: var(--bk-shadow-lg);
  background: rgba(255,255,255,.94);
  border-color: rgba(99,102,241,.18);
}

.bk-stat-val {
  font-size: 1.6rem;
  font-weight: 900;
  background: linear-gradient(135deg, #4f46e5, #8b5cf6);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1.2;
  font-family: 'JetBrains Mono', 'SF Mono', monospace;
  letter-spacing: -.02em;
}
.bk-stat-clr {
  background: linear-gradient(135deg, var(--clr), color-mix(in srgb, var(--clr) 80%, #fff));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.bk-stat-lbl {
  font-size: .66rem;
  color: #94a3b8;
  font-weight: 700;
  margin-top: 3px;
  letter-spacing: .03em;
  text-transform: uppercase;
}
.bk-stat-bar {
  height: 5px;
  border-radius: 3px;
  margin-top: 10px;
  width: 100%;
  background: #f1f5f9;
  overflow: hidden;
}
.bk-stat-fill {
  height: 100%;
  border-radius: 3px;
  transition: width 1.4s cubic-bezier(.16,1,.3,1);
  position: relative;
}
.bk-stat-fill::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,.35), transparent);
  animation: bkShine 2s ease-in-out infinite;
}
@keyframes bkShine {
  0% { transform: translateX(-100%); }
  60%, 100% { transform: translateX(200%); }
}

/* ========================================
   筛选栏 v5.0 - 浮动玻璃面板
   ======================================== */
.bk-filter {
  background: rgba(255,255,255,.88);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border: 1px solid rgba(226,232,240,.55);
  border-radius: var(--bk-radius);
  padding: 18px 20px;
  margin-bottom: 20px;
  box-shadow: var(--bk-shadow-sm);
  transition: var(--bk-transition);
}
.bk-filter:focus-within {
  box-shadow: 0 4px 28px rgba(79,70,229,.1);
  border-color: rgba(165,180,252,.5);
  transform: translateY(-1px);
}

.bk-filter-row {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 16px;
}
@media (min-width: 640px) { .bk-filter-row { flex-direction: row; } }

.bk-search-wrap { flex: 1; position: relative; }
.bk-search-icon {
  position: absolute; left: 15px; top: 50%;
  transform: translateY(-50%);
  color: #94a3b8;
  pointer-events: none;
  transition: color .3s;
}
.bk-search-input:focus ~ .bk-search-icon,
.bk-search-input:focus + .bk-search-icon { color: #6366f1; }

.bk-search-input {
  background: #f8fafc;
  border: 2px solid #e2e8f0;
  border-radius: 14px;
  padding: 12px 16px 12px 44px;
  font-size: .88rem;
  width: 100%;
  transition: all .3s;
  outline: none;
  color: #334155;
  font-family: inherit;
}
.bk-search-input:focus {
  border-color: #a5b4fc;
  background: #fff;
  box-shadow: 0 0 0 5px rgba(99,102,241,.06);
}
.bk-search-input::placeholder { color: #94a3b8; font-weight: 400; }

.bk-filter-actions {
  display: flex; gap: 8px; align-items: center; flex-shrink: 0;
}

/* 筛选药丸 */
.bk-filter-pills {
  display: flex; flex-wrap: wrap; align-items: center; gap: 8px;
}
.bk-filter-label {
  font-size: .7rem; font-weight: 700; color: #94a3b8;
  margin-right: 2px; letter-spacing: .04em;
}
.bk-filter-divider {
  width: 1px; height: 22px; background: linear-gradient(transparent, #e2e8f0, transparent);
  margin: 0 8px;
}

.bk-pill {
  display: inline-flex; align-items: center; gap: 5px;
  padding: 6px 14px; border-radius: 9999px; font-size: .73rem;
  font-weight: 700; cursor: pointer;
  transition: all .3s cubic-bezier(.25,.8,.25,1.2);
  border: 2px solid #e2e8f0;
  background: #fff;
  color: #64748b;
  white-space: nowrap; user-select: none; text-decoration: none;
  position: relative;
  overflow: hidden;
}
.bk-pill::after {
  content: '';
  position: absolute; inset: 0; border-radius: 9999px;
  background: linear-gradient(135deg, rgba(99,102,241,.08), rgba(139,92,246,.05));
  opacity: 0; transition: opacity .3s;
}
.bk-pill:hover::after { opacity: 1; }
.bk-pill:hover { border-color: #a5b4fc; color: #4f46e5; transform: translateY(-2px); box-shadow: 0 4px 16px rgba(99,102,241,.1); }
.bk-pill.active {
  border-color: transparent; color: #fff;
  box-shadow: 0 4px 18px rgba(99,102,241,.3);
  background: linear-gradient(135deg, #6366f1, #4f46e5);
  transform: translateY(-1px);
}
.bk-pill.active.beginner  { background: linear-gradient(135deg,#10b981,#059669); box-shadow: 0 4px 18px rgba(16,185,129,.35); }
.bk-pill.active.basic     { background: linear-gradient(135deg,#3b82f6,#2563eb); box-shadow: 0 4px 18px rgba(59,130,246,.35); }
.bk-pill.active.medium    { background: linear-gradient(135deg,#f59e0b,#d97706); box-shadow: 0 4px 18px rgba(245,158,11,.35); }
.bk-pill.active.advanced  { background: linear-gradient(135deg,#f97316,#ea580c); box-shadow: 0 4px 18px rgba(249,115,22,.35); }
.bk-pill.active.real_exam { background: linear-gradient(135deg,#ef4444,#dc2626); box-shadow: 0 4px 18px rgba(239,68,68,.35); }
.bk-pill-cnt { opacity: .65; font-size: .64rem; margin-left: 3px; font-weight: 600; }
.bk-pill.active .bk-pill-cnt { opacity: .9; }

/* ========================================
   按钮系统 v5.0
   ======================================== */
.bk-btn-search {
  padding: 11px 22px;
  background: linear-gradient(135deg, #4f46e5, #6366f1);
  color: #fff; font-weight: 700; border-radius: 14px;
  font-size: .85rem; border: none; cursor: pointer;
  white-space: nowrap;
  transition: all .3s;
  box-shadow: 0 2px 12px rgba(79,70,229,.25);
  position: relative; overflow: hidden;
}
.bk-btn-search::after {
  content: '';
  position: absolute; inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,.2), transparent);
  opacity: 0; transition: opacity .3s;
}
.bk-btn-search:hover::after { opacity: 1; }
.bk-btn-search:hover { box-shadow: 0 6px 24px rgba(79,70,229,.4); transform: translateY(-2px); }
.bk-btn-search:active { transform: scale(.96); }

.bk-btn-clear {
  padding: 11px 18px; background: #f8fafc; color: #64748b;
  font-weight: 700; border-radius: 14px; font-size: .85rem;
  border: 1.5px solid #e2e8f0; text-decoration: none;
  display: inline-flex; align-items: center; white-space: nowrap;
  transition: all .25s;
}
.bk-btn-clear:hover { background: #fee2e2; color: #ef4444; border-color: #fecaca; }

.bk-btn-primary {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 13px 30px; border-radius: 14px; font-size: .85rem; font-weight: 700;
  background: linear-gradient(135deg, #4f46e5, #7c3aed); color: #fff;
  text-decoration: none;
  box-shadow: 0 4px 20px rgba(79,70,229,.35);
  transition: all .3s;
  position: relative; overflow: hidden;
}
.bk-btn-primary::after {
  content: '';
  position: absolute; inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,.15), transparent 60%);
  opacity: 0; transition: opacity .3s;
}
.bk-btn-primary:hover::after { opacity: 1; }
.bk-btn-primary:hover { box-shadow: 0 8px 28px rgba(79,70,229,.5); transform: translateY(-2px); }

.bk-btn-vip {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 13px 30px; border-radius: 14px; font-size: .85rem; font-weight: 700;
  background: linear-gradient(135deg, #f59e0b, #ea580c); color: #fff;
  text-decoration: none;
  box-shadow: 0 4px 20px rgba(245,158,11,.35);
  transition: all .3s;
  position: relative; overflow: hidden;
}
.bk-btn-vip::after {
  content: '';
  position: absolute; inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,.15), transparent 60%);
  opacity: 0; transition: opacity .3s;
}
.bk-btn-vip:hover::after { opacity: 1; }
.bk-btn-vip:hover { box-shadow: 0 8px 28px rgba(245,158,11,.5); transform: translateY(-2px); }

.bk-btn-ghost {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 12px 24px; border-radius: 14px; font-size: .85rem; font-weight: 600;
  background: #f8fafc; color: #64748b;
  border: 1px solid #e2e8f0; cursor: pointer;
  transition: all .25s;
}
.bk-btn-ghost:hover { background: #e2e8f0; color: #475569; }

.bk-btn-copy-sm {
  display: inline-flex; align-items: center; gap: 4px;
  padding: 7px 16px; border-radius: 10px; font-size: .72rem;
  font-weight: 700; background: #f1f5f9; color: #475569;
  border: 1px solid #e2e8f0; cursor: pointer;
  transition: all .25s;
}
.bk-btn-copy-sm:hover { background: #ede9fe; color: #6d28d9; border-color: #c4b5fd; }

/* ========================================
   工具栏 v5.0
   ======================================== */
.bk-toolbar {
  display: flex; flex-wrap: wrap; align-items: center;
  justify-content: space-between; gap: 14px; margin-bottom: 20px;
}
.bk-toolbar-left { display: flex; align-items: center; gap: 12px; }
.bk-toolbar-right { display: flex; align-items: center; gap: 10px; }
.bk-toolbar-count {
  font-size: .88rem; font-weight: 700; color: #475569;
}
.bk-toolbar-tag {
  font-size: .68rem;
  background: linear-gradient(135deg, #ede9fe, #eff6ff);
  color: #6366f1;
  padding: 4px 12px; border-radius: 9999px;
  font-weight: 700; border: 1px solid #c4b5fd;
}

.bk-toolbar-btn {
  display: inline-flex; align-items: center; gap: 5px;
  padding: 8px 16px; border-radius: 10px; font-size: .78rem; font-weight: 600;
  cursor: pointer; transition: all .25s;
  border: 1.5px solid #e2e8f0; background: #fff; color: #64748b;
}
.bk-toolbar-btn:hover { background: #f8fafc; border-color: #cbd5e1; color: #334155; }
.bk-toolbar-btn.active {
  background: linear-gradient(135deg, #ede9fe, #eff6ff);
  border-color: #a5b4fc; color: #4f46e5;
  box-shadow: 0 2px 8px rgba(99,102,241,.12);
}

.bk-sort-select {
  padding: 8px 36px 8px 14px; border-radius: 10px; font-size: .78rem;
  font-weight: 600; border: 1.5px solid #e2e8f0; background: #fff;
  color: #64748b; cursor: pointer; appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg width='10' height='6' viewBox='0 0 10 6' fill='none'%3E%3Cpath d='M1 1l4 4 4-4' stroke='%2394a3b8' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-position: right 12px center;
  transition: all .25s; outline: none;
}
.bk-sort-select:focus { border-color: #a5b4fc; box-shadow: 0 0 0 3px rgba(99,102,241,.06); }

/* ========================================
   题卡网格 v5.0
   ======================================== */
.bk-grid {
  display: grid;
  grid-template-columns: repeat(1, 1fr);
  gap: 20px;
}
@media (min-width: 640px) { .bk-grid { grid-template-columns: repeat(2, 1fr); } }
@media (min-width: 1024px) { .bk-grid { grid-template-columns: repeat(3, 1fr); } }
@media (min-width: 1280px) { .bk-grid { grid-template-columns: repeat(4, 1fr); } }

/* ========================================
   题目卡片 v5.0 - 玻璃质感 + 3D悬浮 + 流光边框
   ======================================== */
.bk-card {
  background: rgba(255,255,255,.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid rgba(226,232,240,.7);
  border-radius: 18px;
  transition: all .45s cubic-bezier(.16,1,.3,1.1);
  position: relative; overflow: hidden; cursor: pointer;
  display: flex; flex-direction: column;
  box-shadow: var(--bk-shadow-sm);
  perspective: 800px;
}

/* 3D悬浮 */
.bk-card:not(.bk-card-locked):hover {
  transform: translateY(-8px) scale(1.015);
  box-shadow: var(--bk-shadow-xl);
  border-color: rgba(165,180,252,.6);
}
/* 流光边框效果 */
.bk-card:not(.bk-card-locked)::before {
  content: '';
  position: absolute; inset: -1px; z-index: 0;
  border-radius: 19px;
  background: linear-gradient(
    135deg,
    rgba(99,102,241,.3),
    rgba(139,92,246,.15),
    rgba(236,72,153,.1),
    rgba(16,185,129,.15)
  );
  background-size: 300% 300%;
  animation: bkBorderGlow 6s ease-in-out infinite;
  opacity: 0;
  transition: opacity .45s;
  pointer-events: none;
}
.bk-card:not(.bk-card-locked):hover::before { opacity: 1; }
@keyframes bkBorderGlow {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

/* 鼠标追踪光效 */
.bk-card::after {
  content: '';
  position: absolute; inset: 0; z-index: 0;
  border-radius: 18px;
  opacity: 0; transition: opacity .45s; pointer-events: none;
  background: radial-gradient(
    700px circle at var(--mx, 50%) var(--my, 50%),
    rgba(99,102,241,.07),
    transparent 45%
  );
}
.bk-card:hover::after { opacity: 1; }

/* 顶部色条 */
.bk-card-bar {
  position: absolute; top: 0; left: 0; right: 0; height: 4px; z-index: 2;
  background: var(--bar, #e2e8f0);
  transition: all .45s;
  border-radius: 18px 18px 0 0;
}
.bk-card:not(.bk-card-locked):hover .bk-card-bar {
  height: 6px;
  box-shadow: 0 4px 16px color-mix(in srgb, var(--bar, #6366f1) 40%, transparent);
}

/* 已完成标记 v5.0 */
.bk-card-check {
  position: absolute; top: 0; right: 0; z-index: 10;
  background: linear-gradient(135deg, #10b981, #059669);
  color: #fff; font-size: .58rem; font-weight: 800;
  padding: 5px 12px; border-radius: 0 16px 0 14px;
  display: flex; align-items: center; gap: 4px;
  box-shadow: 0 3px 12px rgba(16,185,129,.35);
  letter-spacing: .02em;
}

/* 序号徽章 */
.bk-card-num {
  position: absolute; top: 14px; right: 14px; z-index: 1;
  width: 30px; height: 30px; border-radius: 10px;
  background: rgba(248,250,252,.95);
  border: 1px solid rgba(226,232,240,.8);
  display: flex; align-items: center; justify-content: center;
  font-size: .7rem; font-weight: 800; color: #94a3b8;
  backdrop-filter: blur(8px);
  transition: all .35s;
}
.bk-card-done .bk-card-num { background: #ecfdf5; border-color: #6ee7b7; color: #059669; }
.bk-card:not(.bk-card-locked):hover .bk-card-num {
  background: rgba(238,242,255,.95);
  border-color: #a5b4fc;
  color: #4f46e5;
  transform: scale(1.08);
}

/* 锁定覆盖层 */
.bk-card-overlay {
  position: absolute; inset: 0; z-index: 3;
  background: rgba(248,250,252,.8);
  backdrop-filter: blur(3px);
  -webkit-backdrop-filter: blur(3px);
  display: flex; align-items: center; justify-content: center;
  border-radius: 18px;
}
.bk-card-overlay-tag {
  background: rgba(255,255,255,.94);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  padding: 10px 22px; border-radius: 9999px;
  font-size: .78rem; font-weight: 700; color: #64748b;
  border: 1px solid rgba(226,232,240,.8);
  box-shadow: 0 4px 16px rgba(0,0,0,.06);
}

/* 卡片内容区 */
.bk-card-body { padding: 16px 20px 18px; flex: 1; display: flex; flex-direction: column; position: relative; z-index: 1; }
.bk-card-header {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: 12px;
}
.bk-card-diff {
  display: inline-flex; align-items: center; gap: 4px;
  padding: 4px 12px; border-radius: 9999px;
  font-size: .64rem; font-weight: 700;
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  transition: all .3s;
}
.bk-card:not(.bk-card-locked):hover .bk-card-diff {
  transform: scale(1.04);
}
.bk-card-badges { display: flex; align-items: center; gap: 6px; }
.bk-card-title {
  font-size: .9rem; font-weight: 800; color: #1e293b;
  line-height: 1.45; margin-bottom: 8px;
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical;
  overflow: hidden;
}
.bk-card-locked .bk-card-title { color: #94a3b8; }
.bk-card-kw {
  font-size: .7rem; color: #94a3b8; margin-bottom: 10px;
  display: flex; align-items: center; gap: 5px;
}

/* 考试标签 */
.bk-exam-badge {
  display: inline-flex; align-items: center;
  padding: 3px 10px; border-radius: 9999px;
  font-size: .62rem; font-weight: 700;
}
.bk-exam-badge.cspj {
  background: linear-gradient(135deg, #ecfdf5, #d1fae5);
  color: #059669;
  border: 1px solid #6ee7b7;
}
.bk-exam-badge.csps {
  background: linear-gradient(135deg, #f5f3ff, #ede9fe);
  color: #7c3aed;
  border: 1px solid #c4b5fd;
}

/* 迷你代码预览 v5.0 */
.bk-card-preview {
  background: #f8fafc;
  border-radius: 12px;
  padding: 12px 14px;
  font-family: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', 'Consolas', monospace;
  font-size: .63rem;
  line-height: 1.7;
  color: #64748b;
  border: 1px solid #f1f5f9;
  overflow: hidden;
  white-space: pre;
  max-height: 52px;
  flex: 1;
  margin-bottom: 12px;
  transition: all .4s;
}
.bk-card:not(.bk-card-locked):hover .bk-card-preview {
  background: #0f172a;
  color: #94a3b8;
  border-color: #1e293b;
  box-shadow: inset 0 2px 12px rgba(0,0,0,.2);
}

/* 用户进度星 */
.bk-card-progress {
  display: flex; align-items: center; gap: 3px;
  padding: 7px 12px; border-radius: 10px;
  background: linear-gradient(135deg, #fffbeb, #fef3c7);
  border: 1px solid #fde68a;
  margin-bottom: 10px;
}
.bk-star-on {
  color: #f59e0b;
  font-size: 1.05rem;
  filter: drop-shadow(0 1px 3px rgba(245,158,11,.4));
  text-shadow: 0 1px 4px rgba(245,158,11,.3);
}
.bk-star-off { color: #d1d5db; font-size: 1.05rem; }
.bk-card-acc {
  font-size: .64rem; font-weight: 700; color: #64748b;
  margin-left: auto;
  background: rgba(255,255,255,.7);
  padding: 2px 8px; border-radius: 6px;
}

/* 元信息行 */
.bk-card-meta {
  display: flex; align-items: center; justify-content: space-between;
  font-size: .64rem; color: #94a3b8;
  padding-top: 12px;
  border-top: 1px solid #f1f5f9;
  margin-top: auto;
  gap: 6px;
}
.bk-card-meta span {
  display: flex; align-items: center; gap: 4px; white-space: nowrap;
}
.bk-card-tags-text { max-width: 70px; overflow: hidden; text-overflow: ellipsis; }

/* ========================================
   列表视图 v5.0
   ======================================== */
.bk-card.list-view {
  flex-direction: row; align-items: center;
  padding: 14px 20px; gap: 16px; border-radius: 16px;
}
.bk-card.list-view .bk-card-bar { height: 100% !important; width: 4px; left: 0; top: 0; right: auto; border-radius: 16px 0 0 16px; }
.bk-card.list-view:not(.bk-card-locked):hover .bk-card-bar { width: 6px; height: 100% !important; }
.bk-card.list-view .bk-card-preview { display: none; }
.bk-card.list-view .bk-card-num { position: static; flex-shrink: 0; }
.bk-card.list-view .bk-card-body { padding: 0; flex: 1; }

/* ========================================
   滚动淡入 v5.0
   ======================================== */
.bk-card-reveal {
  opacity: 0;
  transform: translateY(36px);
  transition: all .7s cubic-bezier(.16,1,.3,1);
}
.bk-card-reveal.visible { opacity: 1; transform: translateY(0); }

/* ========================================
   回到顶部 v5.0
   ======================================== */
.bk-btt {
  position: fixed; bottom: 32px; right: 32px; z-index: 900;
  width: 48px; height: 48px; border-radius: 16px;
  background: rgba(255,255,255,.94);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid rgba(226,232,240,.8);
  display: flex; align-items: center; justify-content: center;
  cursor: pointer;
  box-shadow: 0 4px 24px rgba(0,0,0,.1);
  opacity: 0; visibility: hidden;
  transform: translateY(16px);
  transition: all .4s cubic-bezier(.16,1,.3,1);
  color: #64748b;
}
.bk-btt.show { opacity: 1; visibility: visible; transform: translateY(0); }
.bk-btt:hover {
  background: linear-gradient(135deg, #4f46e5, #6366f1);
  border-color: transparent;
  color: #fff;
  transform: translateY(-3px);
  box-shadow: 0 8px 28px rgba(79,70,229,.35);
}

/* ========================================
   分页 v5.0
   ======================================== */
.bk-pagination {
  display: flex; justify-content: center; align-items: center; gap: 8px;
  margin-top: 32px; padding-bottom: 32px;
}
.bk-page-btn {
  width: 40px; height: 40px; border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
  font-size: .84rem; font-weight: 700; text-decoration: none;
  transition: all .25s cubic-bezier(.25,.8,.25,1.2);
  background: #fff; border: 1.5px solid #e2e8f0; color: #64748b;
}
.bk-page-btn:hover {
  border-color: #a5b4fc; color: #4f46e5;
  background: #f8fafc;
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(99,102,241,.1);
}
.bk-page-btn.active {
  background: linear-gradient(135deg, #4f46e5, #7c3aed);
  color: #fff; border-color: transparent;
  box-shadow: 0 6px 20px rgba(79,70,229,.35);
}
.bk-page-dots {
  color: #cbd5e1; font-weight: 700; padding: 0 4px;
}

/* ========================================
   空状态 v5.0
   ======================================== */
.bk-empty {
  text-align: center; padding: 80px 20px;
}
.bk-empty-illus {
  width: 108px; height: 108px; margin: 0 auto 24px;
  background: linear-gradient(135deg, #f1f5f9, #e2e8f0);
  border-radius: 50%; display: flex; align-items: center; justify-content: center;
}
.bk-empty h3 {
  font-size: 1.15rem; font-weight: 800; color: #475569; margin-bottom: 8px;
}
.bk-empty p { font-size: .85rem; color: #94a3b8; }

/* ========================================
   弹窗系统 v5.0 - 影院级遮罩
   ======================================== */
.bk-modal-overlay {
  position: fixed; inset: 0; z-index: 1000;
  background: rgba(15,23,42,.6);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  display: flex; align-items: center; justify-content: center;
  padding: 20px;
  animation: bkFadeIn .3s ease;
}
.bk-modal-overlay.closing { animation: bkFadeOut .25s ease forwards; }
@keyframes bkFadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes bkFadeOut { from { opacity: 1; } to { opacity: 0; } }

.bk-modal {
  background: rgba(255,255,255,.98);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-radius: 24px;
  width: 100%; max-width: 920px;
  max-height: 88vh; overflow-y: auto;
  box-shadow: 0 32px 80px rgba(0,0,0,.2), 0 8px 24px rgba(0,0,0,.08);
  animation: bkSlideUp .4s cubic-bezier(.16,1,.3,1);
  position: relative;
  border: 1px solid rgba(226,232,240,.6);
}
.bk-modal.closing { animation: bkSlideDown .25s ease forwards; }
@keyframes bkSlideUp {
  from { opacity: 0; transform: translateY(56px) scale(.95); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}
@keyframes bkSlideDown {
  from { opacity: 1; transform: translateY(0) scale(1); }
  to { opacity: 0; transform: translateY(56px) scale(.95); }
}

.bk-modal-loading { padding: 64px; text-align: center; }
.bk-modal-spinner {
  width: 44px; height: 44px; border: 4px solid #e2e8f0;
  border-top-color: #6366f1; border-radius: 50%;
  animation: bkSpin .7s linear infinite; margin: 0 auto 16px;
}
@keyframes bkSpin { to { transform: rotate(360deg); } }

.bk-modal-error { padding: 56px; text-align: center; }
.bk-modal-error div:first-child { font-size: 52px; margin-bottom: 12px; }
.bk-modal-error h3 { color: #1e293b; font-weight: 700; margin-bottom: 8px; }
.bk-modal-error p { color: #94a3b8; margin-bottom: 20px; }

.bk-modal-close {
  position: sticky; top: 0; float: right;
  margin: 14px 14px -40px 0; z-index: 10;
  width: 38px; height: 38px; border-radius: 50%;
  background: rgba(255,255,255,.95);
  border: 1px solid rgba(226,232,240,.8);
  font-size: 18px; color: #94a3b8; cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: all .25s;
}
.bk-modal-close:hover { background: #fee2e2; color: #ef4444; border-color: #fecaca; }

.bk-modal-inner { padding: 28px 32px 32px; }

.bk-modal-head {
  display: flex; align-items: flex-start; justify-content: space-between;
  flex-wrap: wrap; gap: 12px; margin-bottom: 22px;
}
.bk-modal-head-left { flex: 1; min-width: 0; }
.bk-modal-head-left h2 {
  font-size: 1.25rem; font-weight: 800; color: #0f172a;
  margin: 0 0 12px; line-height: 1.4;
  padding-right: 44px;
}
.bk-modal-badges {
  display: flex; align-items: center; flex-wrap: wrap; gap: 8px;
}
.bk-modal-diff {
  display: inline-flex; align-items: center; gap: 5px;
  padding: 5px 14px; border-radius: 9999px;
  font-size: .72rem; font-weight: 700;
  backdrop-filter: blur(4px);
}
.bk-modal-exam {
  padding: 5px 14px; border-radius: 9999px;
  font-size: .72rem; font-weight: 700;
}
.bk-modal-exam.cspj {
  background: linear-gradient(135deg, #ecfdf5, #d1fae5);
  color: #059669; border: 1px solid #6ee7b7;
}
.bk-modal-exam.csps {
  background: linear-gradient(135deg, #f5f3ff, #ede9fe);
  color: #7c3aed; border: 1px solid #c4b5fd;
}
.bk-modal-kw {
  display: inline-flex; align-items: center; gap: 5px;
  padding: 5px 14px; border-radius: 9999px; font-size: .72rem;
  color: #475569; background: #f8fafc; border: 1px solid #e2e8f0;
}

.bk-modal-info {
  display: flex; align-items: center; flex-wrap: wrap; gap: 18px;
  padding: 14px 18px;
  background: linear-gradient(135deg, #f8fafc, #f1f5f9);
  border-radius: 16px;
  border: 1px solid #e2e8f0;
  margin-bottom: 20px;
}
.bk-modal-info-item {
  display: flex; align-items: center; gap: 7px;
  font-size: .78rem; color: #64748b;
}
.bk-modal-info-item svg { flex-shrink: 0; }
.bk-modal-info-item b { color: #334155; }

.bk-modal-tags { margin-bottom: 20px; }
.bk-tag {
  display: inline-flex; align-items: center; gap: 4px;
  padding: 6px 14px; border-radius: 10px; font-size: .72rem;
  font-weight: 600;
  background: linear-gradient(135deg, #f8fafc, #f1f5f9);
  color: #64748b;
  border: 1px solid #e2e8f0;
  margin-right: 8px; margin-bottom: 6px;
  transition: all .25s;
}
.bk-tag:hover { border-color: #a5b4fc; color: #4f46e5; }

.bk-modal-section-head {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: 12px;
}
.bk-modal-section-head h3 {
  font-size: .92rem; font-weight: 700; color: #1e293b;
  display: flex; align-items: center; gap: 10px;
}
.bk-modal-section-head h3 span {
  display: inline-flex; align-items: center; justify-content: center;
  width: 28px; height: 28px; border-radius: 9px;
  background: linear-gradient(135deg, #4f46e5, #7c3aed);
  color: #fff; font-size: .7rem; font-weight: 700;
}

/* 代码块 v5.1：带行号 + 后端高亮兼容 */
.bk-code-block {
  background: #0f172a;
  border-radius: 18px;
  padding: 18px 20px 18px 8px;
  font-family: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', 'Consolas', monospace;
  font-size: .82rem;
  line-height: 1.75;
  color: #e2e8f0;
  overflow-x: auto; overflow-y: auto;
  border: 1px solid #1e293b;
  max-height: 460px;
  margin-bottom: 16px;
  box-shadow: inset 0 2px 12px rgba(0,0,0,.15);
}
.bk-code-lines {
  display: flex;
  flex-direction: column;
  min-width: fit-content;
}
.bk-code-line {
  display: flex;
  align-items: flex-start;
  border-radius: 6px;
  transition: background .15s ease;
}
.bk-code-line:hover {
  background: rgba(255,255,255,.04);
}
.bk-lineno {
  width: 44px;
  flex-shrink: 0;
  text-align: right;
  padding-right: 14px;
  color: #475569;
  font-size: .75rem;
  line-height: 1.75;
  user-select: none;
}
.bk-line-code {
  flex: 1;
  white-space: pre;
  tab-size: 4;
  color: #e2e8f0;
}
.bk-code-empty {
  padding: 24px;
  text-align: center;
  color: #94a3b8;
}
.bk-code-block .hl-kw   { color: #c084fc; font-weight: 600; }
.bk-code-block .hl-str  { color: #86efac; }
.bk-code-block .hl-num  { color: #fde68a; }
.bk-code-block .hl-cmt  { color: #64748b; font-style: italic; }
.bk-code-block .hl-fn   { color: #60a5fa; }
.bk-code-block .hl-type { color: #f9a8d4; }

.bk-modal-section {
  background: #f8fafc; border-radius: 16px; padding: 20px 22px;
  border: 1px solid #e2e8f0; margin-top: 14px;
}
.bk-modal-section h4 {
  font-size: .88rem; font-weight: 700; color: #1e293b;
  display: flex; align-items: center; gap: 8px; margin-bottom: 12px;
}
.bk-modal-section div {
  font-size: .82rem; line-height: 1.9; color: #475569;
  white-space: pre-wrap;
}
.bk-modal-section-hilite {
  background: linear-gradient(135deg, #fefce8, #faf5ff) !important;
  border-color: rgba(245,158,11,.3) !important;
  border-width: 1.5px !important;
}

.bk-modal-foot {
  display: flex; align-items: center; justify-content: space-between;
  flex-wrap: wrap; gap: 14px;
  margin-top: 24px; padding-top: 20px;
  border-top: 1px solid #f1f5f9;
}

/* ========================================
   锁定弹窗 v5.0
   ======================================== */
.bk-modal-lock {
  background: rgba(255,255,255,.98);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-radius: 28px; padding: 36px 32px;
  max-width: 420px; width: 100%; text-align: center;
  box-shadow: 0 32px 64px rgba(0,0,0,.25);
  border: 1px solid rgba(226,232,240,.6);
  animation: bkSlideUp .4s cubic-bezier(.16,1,.3,1);
}
.bk-modal-lock-icon {
  font-size: 56px; margin-bottom: 16px;
  animation: bkFloat 3s ease-in-out infinite;
}
@keyframes bkFloat {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}
.bk-modal-lock h3 {
  font-size: 1.2rem; font-weight: 800; color: #1e293b;
  margin-bottom: 10px;
}
.bk-modal-lock p {
  color: #64748b; font-size: .88rem;
  line-height: 1.8; margin-bottom: 24px;
}
.bk-modal-lock-btns {
  display: flex; gap: 12px; justify-content: center;
}
.bk-text-muted { color: #94a3b8; font-size: .76rem; }

/* ========================================
   Shimmer 动画
   ======================================== */
@keyframes shimmer {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}
.animate-shimmer { animation: shimmer 3.5s ease-in-out infinite; }

/* ========================================
   移动端响应式 v5.0
   ======================================== */
@media (max-width: 768px) {
  .bk-hero::after { background-size: 40px 40px; }
  .bk-filter { border-radius: 16px; padding: 14px; }
  .bk-pill { padding: 5px 12px; font-size: .68rem; }
  .bk-card { border-radius: 16px; }
  .bk-card:not(.bk-card-locked):hover { transform: translateY(-4px) scale(1.01); }
  .bk-card::after, .bk-card::before { display: none; }
  .bk-btt { bottom: 20px; right: 20px; width: 42px; height: 42px; border-radius: 14px; }
  .bk-modal { max-width: 100%; border-radius: 20px; }
  .bk-modal-inner { padding: 20px 18px 24px; }
  .bk-stats { grid-template-columns: repeat(2, 1fr); gap: 10px; }
  .bk-hero-wave { height: 40px; }
}

@media (max-width: 480px) {
  .bk-filter-row { flex-direction: column; }
  .bk-filter-actions { flex-wrap: wrap; width: 100%; }
  .bk-sort-select[class*="min-w"] { min-width: auto !important; }
  .bk-btn-search { flex: 1; }
  .bk-stats { grid-template-columns: repeat(2, 1fr); gap: 8px; }
  .bk-stat-card { padding: 12px; border-radius: 14px; }
  .bk-stat-val { font-size: 1.3rem; }
  .bk-modal-lock { border-radius: 22px; padding: 28px 20px; }
  .bk-modal-lock-btns { flex-direction: column; }
  .bk-modal-foot { flex-direction: column; }
  .bk-modal-foot .bk-btn-ghost,
  .bk-modal-foot .bk-btn-primary,
  .bk-modal-foot .bk-btn-vip {
    width: 100%; justify-content: center; min-height: 48px;
  }
  .bk-pagination { gap: 5px; }
  .bk-page-btn { width: 36px; height: 36px; border-radius: 10px; font-size: .78rem; }
  .bk-grid { gap: 14px; }
  .bk-hero-title { font-size: 1.5rem; }
}

/* 触摸设备优化 */
@media (hover: none) {
  .bk-card:not(.bk-card-locked) { cursor: pointer; }
  .bk-card::after, .bk-card::before { display: none; }
  .bk-btn-ghost, .bk-btn-primary, .bk-btn-vip,
  .bk-btn-clear, .bk-btn-search, .bk-btn-copy-sm { min-height: 46px; }
  .bk-page-btn { min-height: 40px; }
}