@font-face{
  font-family:'Friends';
  src:url('fonts/FRIENDS.TTF') format('truetype');
  font-weight:400 700;
  font-display:swap;
}
:root{
  --bg1:#fff3e6; --bg2:#ffe0c7;
  --purple:#6d4aa6; --orange:#ef7d3b; --teal:#2bb6a8;
  --ink:#3a2a1f; --muted:#8a7a6d;
  --card-front:#ffffff; --card-back:#fdeede;
}
*{box-sizing:border-box;-webkit-tap-highlight-color:transparent;}
html,body{margin:0;padding:0;height:100%;}
body{
  font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Helvetica Neue",Arial,sans-serif;
  background:linear-gradient(160deg,var(--bg1),var(--bg2));
  color:var(--ink);
  min-height:100vh;
  display:flex;justify-content:center;
}
.app{width:100%;max-width:430px;min-height:100vh;display:flex;flex-direction:column;padding:0 18px 28px;}
.topbar{text-align:center;padding:26px 0 10px;}
.logo{
  font-family:'Friends','Caveat',cursive,Bradley Hand,-apple-system,BlinkMacSystemFont,sans-serif;
  font-weight:700;
  font-size:36px;
  color:var(--ink);
  display:flex;
  align-items:center;
  justify-content:center;
  gap:2px;
  line-height:1;
}
.logo .ltr{display:inline-block;line-height:1;}
.logo .dot{
  width:7px;
  height:7px;
  border-radius:50%;
  align-self:center;
  margin:0 2px;
  box-shadow:0 1px 2px rgba(0,0,0,.12);
}
.logo .dot.red{background:#e84a5f;}
.logo .dot.yellow{background:#f9c80e;}
.logo .dot.blue{background:#3a86ff;}
.subtitle{color:var(--muted);font-size:14px;margin-top:4px;}

/* flip card */
.stage{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:18px;}
.flip-card{width:100%;height:330px;perspective:1200px;cursor:pointer;}
.flip-inner{position:relative;width:100%;height:100%;transition:transform .6s;transform-style:preserve-3d;}
.flip-card.flipped .flip-inner{transform:rotateY(180deg);}
.flip-face{position:absolute;inset:0;backface-visibility:hidden;-webkit-backface-visibility:hidden;
  border-radius:22px;padding:24px;display:flex;flex-direction:column;
  box-shadow:0 14px 30px rgba(120,70,30,.18);overflow:hidden;}
.flip-front{background:linear-gradient(155deg,#fff,#fff6ee);border:2px solid #ffe2c4;}
.flip-back{background:linear-gradient(155deg,#fdeede,#fcd9b8);transform:rotateY(180deg);border:2px solid var(--orange);}
.face-tag{font-size:12px;letter-spacing:3px;color:var(--orange);font-weight:700;}
.flip-back .face-tag{color:var(--purple);}
.face-text{flex:1;display:flex;align-items:center;justify-content:center;text-align:center;
  font-size:20px;line-height:1.5;font-weight:600;padding:6px 4px;overflow:auto;white-space:pre-wrap;word-break:break-word;}
.face-hint{text-align:center;color:var(--muted);font-size:13px;flex:none;}

.front-stars{text-align:center;color:var(--orange);font-size:18px;letter-spacing:3px;flex:none;}
.meta-box{display:flex;flex-direction:column;gap:7px;font-size:13px;color:var(--muted);
  overflow:auto;flex:none;max-height:140px;}
.meta-box img{max-width:100%;max-height:120px;border-radius:10px;align-self:center;}
.meta-box .meta-row{line-height:1.4;}
.meta-box .meta-row strong{color:var(--ink);}

/* 翻页方向动画：
   下一张 → 当前卡向左下倒下、移出页面；新卡从右侧滑入。
   上一张 → 当前卡平滑向右划去；新卡从左下反方向进入。
   退场终点与进场起点完全一致，且换内容在卡片屏外（不可见）时完成，故不会露出答案背面。 */
.flip-card.exit-next{transform-origin:bottom left;animation:exitNext .42s cubic-bezier(.55,.06,.68,.19) forwards;}
.flip-card.exit-prev{transform-origin:center right;animation:exitPrev .42s cubic-bezier(.55,.06,.68,.19) forwards;}
.flip-card.enter-next{animation:enterNext .46s cubic-bezier(.22,1,.36,1) forwards;}
.flip-card.enter-prev{animation:enterPrev .46s cubic-bezier(.22,1,.36,1) forwards;}
@keyframes exitNext{
  0%{transform:translate(0,0) rotate(0);opacity:1;}
  100%{transform:translate(-60%,65%) rotate(-16deg);opacity:0;}
}
@keyframes exitPrev{
  0%{transform:translate(0,0) rotate(0);opacity:1;}
  100%{transform:translate(60%,0) rotate(6deg);opacity:0;}
}
@keyframes enterNext{
  0%{transform:translate(60%,0) rotate(6deg);opacity:0;}
  100%{transform:translate(0,0) rotate(0);opacity:1;}
}
@keyframes enterPrev{
  0%{transform:translate(-60%,65%) rotate(-16deg);opacity:0;}
  100%{transform:translate(0,0) rotate(0);opacity:1;}
}

.counter{color:var(--muted);font-size:14px;}

/* 答题页操作区：位于卡片下方、页码之下两行 */
.quiz-actions{display:flex;flex-direction:column;gap:10px;width:100%;margin-top:14px;}
.main-actions{display:flex;gap:12px;}
.btn{flex:1;border:none;border-radius:14px;padding:14px;font-size:16px;font-weight:700;cursor:pointer;}
.btn-primary{background:var(--purple);color:#fff;}
.btn-ghost{background:rgba(255,255,255,.7);color:var(--purple);border:1px solid #e6d3f2;}

.admin-link{display:block;text-align:center;margin-top:16px;color:var(--purple);text-decoration:none;font-size:14px;font-weight:600;}

/* 底部样式切换：纯文字按钮 浅色 | 深色 */
.theme-toggle{display:flex;align-items:center;justify-content:center;gap:8px;margin-top:2px;}
.link-btn{background:none;border:none;cursor:pointer;color:var(--ink);font-size:14px;font-weight:400;font-family:inherit;padding:0;line-height:inherit;}
.link-btn.active{color:var(--purple);font-weight:700;text-decoration:none;}
.toggle-sep{color:var(--muted);user-select:none;}

/* difficulty modal */
.modal{position:fixed;inset:0;background:rgba(58,42,31,.55);backdrop-filter:blur(2px);
  display:flex;align-items:center;justify-content:center;padding:24px;z-index:50;}
.modal.hidden{display:none;}
.modal-card{background:#fff;border-radius:22px;width:100%;max-width:360px;padding:26px 22px;
  box-shadow:0 20px 50px rgba(80,40,10,.3);text-align:center;}
.modal-title{font-size:20px;font-weight:800;color:var(--ink);}
.modal-sub{font-size:13px;color:var(--muted);margin:6px 0 18px;}
.diff-options{display:flex;flex-wrap:wrap;gap:10px;justify-content:center;margin-bottom:20px;}
.diff-chip{border:1px solid #ecdcc9;background:#fffaf4;color:var(--muted);border-radius:999px;
  padding:9px 14px;font-size:14px;font-weight:600;cursor:pointer;transition:all .15s;letter-spacing:1px;}
.diff-chip.on{background:var(--purple);color:#fff;border-color:var(--purple);}
.diff-chip.all{background:#fffaf4;}
.diff-chip.all.on{background:var(--orange);border-color:var(--orange);}
.modal-start{width:100%;}
.modal-start:disabled{background:var(--muted);cursor:not-allowed;opacity:.7;}
.modal-count{font-size:13px;color:var(--purple);font-weight:700;margin:0 0 14px;}

/* admin */
.admin{flex:1;overflow:auto;}
.card-form{background:#fff;border-radius:18px;padding:18px;box-shadow:0 10px 24px rgba(120,70,30,.12);display:flex;flex-direction:column;gap:4px;}
.card-form label{font-size:13px;color:var(--muted);font-weight:600;margin-top:10px;display:flex;justify-content:space-between;align-items:center;}
.card-form .req{color:#e0573e;font-size:11px;font-weight:700;}
.card-form textarea,.card-form input[type=text]{
  border:1px solid #ecdcc9;border-radius:12px;padding:12px;font-size:15px;font-family:inherit;resize:none;background:#fffaf4;
  line-height:1.5;white-space:pre-wrap;word-break:break-word;min-height:56px;max-height:340px;overflow-y:auto;}
.card-form input[type=file]{font-size:13px;margin-top:2px;}

/* 出处：二级联动 + 多条目 */
.source-list{display:flex;flex-wrap:wrap;gap:6px;margin:4px 0 2px;}
.source-chip{display:inline-flex;align-items:center;gap:6px;background:#e7e0f7;color:#6d4aa6;border-radius:999px;padding:4px 10px;font-size:13px;}
.source-chip button{border:none;background:none;color:#6d4aa6;cursor:pointer;font-size:15px;line-height:1;padding:0;}
.source-add{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin-top:2px;}
.src-select,.src-other{border:1px solid #ecdcc9;border-radius:10px;padding:8px 10px;font-size:14px;font-family:inherit;background:#fffaf4;}
.src-select:disabled{background:#f1ece4;color:#b3a797;cursor:not-allowed;opacity:.85;}
.src-other{flex:1;min-width:150px;}

.img-preview{margin-top:6px;}
.img-preview img{max-width:120px;border-radius:10px;border:1px solid #ecdcc9;}

/* star selector */
.star-widget{display:flex;gap:6px;margin-top:4px;}
.star-widget button{background:none;border:none;cursor:pointer;font-size:26px;line-height:1;padding:0;color:#d9c2a8;transition:color .15s;}
.star-widget button.on{color:var(--orange);}

/* 列表「难度」列的可点击星星 */
.diff-stars{display:inline-flex;gap:1px;align-items:center;}
.diff-stars button{background:none;border:none;cursor:pointer;font-size:15px;line-height:1;padding:0 1px;color:#d9c2a8;transition:color .15s;}
.diff-stars button.on{color:var(--orange);}
.diff-stars button:hover{color:#f3a35d;}

.form-actions{margin-top:14px;}
.btn-sm{padding:8px 14px;font-size:13px;flex:none;}

.list-tools{display:flex;justify-content:space-between;align-items:center;margin:18px 4px 8px;}
.list-title{font-weight:700;font-size:15px;}

.table-scroll{overflow-x:auto;-webkit-overflow-scrolling:touch;}
.data-table{min-width:620px;width:100%;border-collapse:collapse;background:#fff;border-radius:14px;overflow:hidden;font-size:13px;box-shadow:0 8px 20px rgba(120,70,30,.1);border:1px solid #ede3f7;}
.data-table th{background:#e7e0f7;color:var(--purple);text-align:left;padding:11px 10px;font-size:12px;font-weight:800;white-space:nowrap;letter-spacing:.5px;}
.data-table td{padding:11px 10px;border-top:1px solid #f3e7da;vertical-align:top;max-width:160px;white-space:pre-wrap;word-break:break-word;}
.data-table tbody tr{height:48px;}
.data-table tbody tr.pad-row td{color:transparent;border-top:1px solid #f3e7da;}
.data-table tbody tr.pad-row:hover td{background:transparent;}
.data-table tr:hover td{background:#f9f6ff;}
.data-table td:first-child{font-weight:600;}
.data-table .thumb{max-width:60px;max-height:60px;border-radius:8px;display:block;}
.del-btn{border:none;background:#ffdede;color:#d64545;border-radius:8px;padding:6px 10px;font-size:12px;cursor:pointer;white-space:nowrap;}
.edit-btn{border:none;background:#e7e0f7;color:#6d4aa6;border-radius:8px;padding:6px 10px;font-size:12px;cursor:pointer;white-space:nowrap;}
.edit-btn:active{background:#d8cdf0;}

/* admin 宽屏自适应（不再限制为移动端窄列） */
.app--wide{max-width:900px;}
@media (min-width:768px){
  .app--wide .card-form{padding:24px;}
  .app--wide .data-table{min-width:auto;}
  .app--wide .table-scroll{overflow:visible;}
}

/* admin 宽屏：列表在左、新建表单在右（MacBook Air 等约 ≥1100px 视口触发） */
@media (min-width:1100px){
  .app--wide{max-width:1440px;}
  .admin{display:flex;flex-direction:row;align-items:flex-start;gap:28px;}
  .card-form{order:2;flex:0 0 clamp(380px,34%,480px);position:sticky;top:0;margin-top:18px;align-self:flex-start;}
  .list-panel{order:1;flex:1 1 auto;min-width:0;}
}

/* 小屏：列表可左右滑动，冻结左（题目/答案）与右（操作）列 */
@media (max-width:767px){
  /* 卡片外观移到可滚动容器上，并解除 .data-table 的 overflow:hidden，
     否则 position:sticky 会被 .data-table 捕获而失效 */
  .table-scroll{
    border:1px solid #ede3f7;border-radius:14px;
    box-shadow:0 8px 20px rgba(120,70,30,.1);
    overflow-x:auto;-webkit-overflow-scrolling:touch;
  }
  .data-table{
    border:none;border-radius:0;box-shadow:none;overflow:visible;
    table-layout:fixed;border-collapse:separate;border-spacing:0;min-width:600px;
  }
  .data-table th,.data-table td{width:auto;}
  .data-table th:nth-child(1),.data-table td:nth-child(1){width:120px;}
  .data-table th:nth-child(2),.data-table td:nth-child(2){width:100px;}
  .data-table th:nth-child(6),.data-table td:nth-child(6){width:84px;}
  /* 冻结左列：题目(left:0) + 答案(left:120) */
  .data-table th:nth-child(1),.data-table td:nth-child(1){position:sticky;left:0;z-index:2;}
  .data-table th:nth-child(2),.data-table td:nth-child(2){position:sticky;left:120px;z-index:2;}
  /* 冻结右列：操作(right:0) */
  .data-table th:nth-child(6),.data-table td:nth-child(6){position:sticky;right:0;z-index:2;}
  /* 不透明背景，遮挡滑动经过的中间列 */
  .data-table th:nth-child(1),.data-table th:nth-child(2),.data-table th:nth-child(6){z-index:3;background:#e7e0f7;}
  .data-table td:nth-child(1),.data-table td:nth-child(2),.data-table td:nth-child(6){background:#fff;}
  /* 冻结列分隔线 */
  .data-table td:nth-child(2),.data-table th:nth-child(2){border-right:1px solid #ece9f3;}
  .data-table td:nth-child(6),.data-table th:nth-child(6){border-left:1px solid #ece9f3;}
}

.filter-bar{display:flex;flex-wrap:wrap;align-items:center;gap:8px;margin:16px 0 10px;}
.filter-label{font-size:13px;color:var(--muted);}
.filter-chip{border:1px solid #ecdcc9;background:#fffaf4;color:var(--muted);border-radius:999px;
  padding:6px 12px;font-size:13px;font-weight:600;cursor:pointer;letter-spacing:1px;}
.filter-chip.on{background:var(--purple);color:#fff;border-color:var(--purple);}

.pager{display:flex;align-items:center;justify-content:center;gap:14px;margin-top:14px;}
.page-info{font-size:13px;color:var(--muted);}
.pager .btn:disabled{opacity:.45;cursor:not-allowed;}

.empty-tip{text-align:center;color:var(--muted);font-size:14px;margin-top:14px;}

/* 题目编号与左右提示（卡片下方一行） */
.counter-row{display:flex;align-items:center;justify-content:space-between;width:100%;margin-top:2px;padding:0 2px;}
.hint-side{font-size:12px;color:var(--muted);white-space:nowrap;cursor:default;user-select:none;}
.counter{flex:none;text-align:center;min-width:54px;}

/* 主题切换按钮：当前选中项高亮为橙色 */
.btn.active{background:var(--orange);color:#fff;border-color:var(--orange);box-shadow:0 4px 12px rgba(239,125,59,.35);}

/* ===== 深色主题（仅答题页 Friends 风格；admin 页不加 .theme-dark，故不受影响） ===== */
body.theme-dark{
  --bg1:#241d18; --bg2:#140f0b;
  --ink:#f4ede2; --muted:#b6a692;
  --purple:#9b78e0; --orange:#ff9a52; --teal:#3fd0c0;
}
body.theme-dark .flip-front{background:linear-gradient(155deg,#3b3127,#2b231c);border-color:#5b4631;}
body.theme-dark .flip-back{background:linear-gradient(155deg,#3a2f24,#4a3829);border-color:var(--orange);}
body.theme-dark .btn-ghost{background:rgba(255,255,255,.08);color:var(--ink);border:1px solid rgba(255,255,255,.16);}
body.theme-dark .link-btn{color:var(--ink);}
body.theme-dark .link-btn.active{color:var(--purple);}
body.theme-dark .toggle-sep{color:var(--muted);}
body.theme-dark .modal{background:rgba(0,0,0,.6);}
body.theme-dark .modal-card{background:#2a221b;box-shadow:0 20px 50px rgba(0,0,0,.5);}
body.theme-dark .diff-chip{background:rgba(255,255,255,.06);color:var(--muted);border-color:rgba(255,255,255,.16);}