@import url('https://fonts.googleapis.com/css2?family=Playfair+Display:wght@400;700;900&family=IBM+Plex+Mono:wght@400;600&family=Lato:wght@300;400;700&display=swap');

/* ===== 设计语言：复古化学教科书 × 现代排版 ===== */
/* 米黄纸张底色 + 深墨绿主色 + 铁锈红强调 + 印刷质感 */

:root {
  --paper:       #f5f0e8;
  --paper-dark:  #ede7d9;
  --paper-deep:  #e0d8c8;
  --ink:         #1a1a18;
  --ink-light:   #4a4a44;
  --ink-faint:   #8a8a80;
  --green:       #1e4d3a;
  --green-mid:   #2d6b52;
  --green-light: #4a9070;
  --rust:        #b84c2a;
  --rust-light:  #d4693f;
  --gold:        #c8922a;
  --blue-ink:    #1a3a5c;

  --font-display: 'Playfair Display', Georgia, serif;
  --font-mono:    'IBM Plex Mono', 'Courier New', monospace;
  --font-body:    'Lato', 'Helvetica Neue', sans-serif;

  --shadow-sm:  2px 3px 0 rgba(0,0,0,0.12);
  --shadow-md:  4px 6px 0 rgba(0,0,0,0.14);
  --shadow-lg:  6px 10px 0 rgba(0,0,0,0.16);
  --border:     1.5px solid rgba(26,26,24,0.2);
  --radius:     4px;
  --transition: 0.18s ease;
}

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

body {
  font-family: var(--font-body);
  background-color: var(--paper);
  background-image:
    url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='400' height='400'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.75' numOctaves='4' stitchTiles='stitch'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='400' height='400' filter='url(%23n)' opacity='0.04'/%3E%3C/svg%3E");
  color: var(--ink);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ===== 顶部导航 ===== */
.header {
  background: var(--green);
  border-bottom: 4px solid var(--rust);
  padding: 0;
  position: sticky; top: 0; z-index: 100;
}

.header-top {
  display: flex; align-items: center;
  padding: 0.7rem 2rem; gap: 1.5rem;
  border-bottom: 1px solid rgba(255,255,255,0.1);
}

.logo {
  display: flex; align-items: baseline; gap: 0.5rem;
  text-decoration: none;
}
.logo-text {
  font-family: var(--font-display);
  font-size: 1.5rem; font-weight: 900;
  color: var(--paper); letter-spacing: -0.5px;
}
.logo-sub {
  font-family: var(--font-mono);
  font-size: 0.65rem; color: rgba(245,240,232,0.55);
  letter-spacing: 3px; text-transform: uppercase;
}

.header-stats {
  margin-left: auto;
  display: flex; gap: 1.5rem; align-items: center;
}
.hstat {
  display: flex; flex-direction: column; align-items: center;
  gap: 1px;
}
.hstat-val {
  font-family: var(--font-mono); font-size: 1rem; font-weight: 600;
  color: var(--paper); line-height: 1;
  transition: var(--transition);
}
.hstat-val.bump { animation: bump 0.25s ease; }
@keyframes bump { 0%,100%{transform:scale(1)} 50%{transform:scale(1.25)} }
.hstat-label {
  font-size: 0.6rem; color: rgba(245,240,232,0.5);
  letter-spacing: 1.5px; text-transform: uppercase;
}

.reset-btn {
  padding: 0.35rem 0.9rem;
  border: 1px solid rgba(245,240,232,0.3);
  border-radius: var(--radius);
  background: transparent; color: rgba(245,240,232,0.6);
  font-family: var(--font-body); font-size: 0.78rem;
  cursor: pointer; transition: var(--transition);
}
.reset-btn:hover {
  background: rgba(184,76,42,0.4);
  border-color: var(--rust-light); color: var(--paper);
}

/* 模式导航标签 */
.mode-nav {
  display: flex; gap: 0; overflow-x: auto;
  padding: 0 2rem;
  scrollbar-width: none;
}
.mode-nav::-webkit-scrollbar { display: none; }

.mode-btn {
  display: flex; align-items: center; gap: 0.45rem;
  padding: 0.6rem 1.2rem;
  border: none; border-right: 1px solid rgba(255,255,255,0.08);
  background: transparent;
  color: rgba(245,240,232,0.55);
  font-family: var(--font-body); font-size: 0.82rem; font-weight: 700;
  letter-spacing: 0.3px;
  cursor: pointer; transition: var(--transition);
  white-space: nowrap; position: relative;
}
.mode-btn:hover { color: var(--paper); background: rgba(255,255,255,0.06); }
.mode-btn.active {
  color: var(--paper);
  background: rgba(255,255,255,0.1);
}
.mode-btn.active::after {
  content: '';
  position: absolute; bottom: 0; left: 0; right: 0;
  height: 3px; background: var(--rust);
}
.btn-icon { font-size: 0.95rem; }

/* ===== 主内容 ===== */
.main-content {
  flex: 1; padding: 2rem;
  max-width: 1400px; margin: 0 auto; width: 100%;
}

.game-section { display: none; }
.game-section.active {
  display: block;
  animation: pageIn 0.3s ease;
}
@keyframes pageIn { from { opacity:0; transform:translateY(8px); } to { opacity:1; transform:translateY(0); } }

/* 区块标题 */
.section-title {
  margin-bottom: 1.8rem;
  padding-bottom: 1rem;
  border-bottom: 2px solid var(--ink);
  display: flex; align-items: baseline; gap: 1rem;
}
.section-title h2 {
  font-family: var(--font-display);
  font-size: 1.8rem; font-weight: 900;
  color: var(--green); line-height: 1;
}
.section-title p {
  font-size: 0.85rem; color: var(--ink-faint);
  font-style: italic;
}

/* ===== 元素卡片 ===== */
.element-card {
  width: 62px; height: 70px;
  background: var(--paper-dark);
  border: var(--border);
  border-radius: var(--radius);
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  cursor: grab;
  transition: transform var(--transition), box-shadow var(--transition);
  position: relative;
  box-shadow: var(--shadow-sm);
  user-select: none;
}
.element-card:hover {
  transform: translateY(-3px) rotate(-1deg);
  box-shadow: var(--shadow-md);
  z-index: 2;
}
.element-card:active { cursor: grabbing; transform: scale(0.96); }
.element-card.dragging { opacity: 0.4; transform: scale(0.92) rotate(3deg); }

.el-num {
  font-family: var(--font-mono); font-size: 0.55rem;
  color: var(--ink-faint); align-self: flex-start;
  padding: 3px 5px; line-height: 1;
}
.el-sym {
  font-family: var(--font-mono); font-size: 1.35rem; font-weight: 600;
  color: var(--ink); line-height: 1;
}
.el-name {
  font-size: 0.5rem; color: var(--ink-light);
  margin-top: 2px; letter-spacing: 0.3px;
}

/* 元素类型色块（左侧竖条） */
.element-card::before {
  content: ''; position: absolute;
  left: 0; top: 0; bottom: 0; width: 3px;
  border-radius: var(--radius) 0 0 var(--radius);
}
.el-nonmetal::before  { background: var(--green); }
.el-metal::before     { background: var(--gold); }
.el-noble::before     { background: var(--blue-ink); }
.el-halogen::before   { background: var(--rust); }
.el-metalloid::before { background: var(--green-mid); }

.el-nonmetal .el-sym  { color: var(--green); }
.el-metal .el-sym     { color: var(--gold); }
.el-noble .el-sym     { color: var(--blue-ink); }
.el-halogen .el-sym   { color: var(--rust); }
.el-metalloid .el-sym { color: var(--green-mid); }

/* ===== 模式1: 元素合成 ===== */
.synthesis-layout {
  display: grid;
  grid-template-columns: 260px 1fr 200px;
  gap: 1.5rem;
  align-items: start;
}

.panel-box {
  background: var(--paper-dark);
  border: var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
}
.panel-head {
  padding: 0.6rem 1rem;
  border-bottom: var(--border);
  background: var(--paper-deep);
  border-radius: var(--radius) var(--radius) 0 0;
}
.panel-head h3 {
  font-family: var(--font-mono); font-size: 0.7rem;
  letter-spacing: 2px; text-transform: uppercase;
  color: var(--ink-light);
}
.panel-body {
  padding: 0.8rem;
  max-height: calc(100vh - 260px); overflow-y: auto;
}
.panel-body::-webkit-scrollbar { width: 3px; }
.panel-body::-webkit-scrollbar-thumb { background: var(--paper-deep); }

.elements-grid { display: flex; flex-wrap: wrap; gap: 5px; }

/* 烧杯区域 */
.beaker-area {
  display: flex; flex-direction: column;
  align-items: center; gap: 1.2rem;
}

.beaker-wrap {
  position: relative;
  display: flex; flex-direction: column; align-items: center;
}

/* 纯CSS烧杯 */
.beaker {
  width: 160px; height: 200px;
  position: relative;
  background: rgba(245,240,232,0.6);
  border: 2px solid var(--ink);
  border-top: none;
  clip-path: polygon(8% 0%, 92% 0%, 100% 100%, 0% 100%);
  overflow: hidden;
  transition: border-color 0.2s;
}
.beaker.drag-over { border-color: var(--green); }

.beaker-liquid {
  position: absolute; bottom: 0; left: 0; right: 0;
  height: 0;
  background: rgba(30,77,58,0.18);
  transition: height 0.6s cubic-bezier(0.34,1.2,0.64,1), background 0.5s;
}
.beaker-bubbles { position: absolute; inset: 0; pointer-events: none; }
.bubble {
  position: absolute; border-radius: 50%;
  background: rgba(30,77,58,0.35);
  animation: bubbleUp 1.4s ease-in infinite;
}
@keyframes bubbleUp {
  0%   { transform: translateY(0) scale(1); opacity: 0.7; }
  100% { transform: translateY(-180px) scale(0.2); opacity: 0; }
}
.beaker-elements {
  position: absolute; inset: 0;
  display: flex; flex-wrap: wrap;
  align-content: flex-end; padding: 6px; gap: 3px;
}
.beaker-hint {
  position: absolute; inset: 0;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.75rem; color: var(--ink-faint);
  font-style: italic; pointer-events: none;
}

/* 烧杯颈部 */
.beaker-neck {
  width: 180px; height: 10px;
  background: var(--ink);
  clip-path: polygon(0% 0%, 100% 0%, 92% 100%, 8% 100%);
}
.beaker-base {
  width: 180px; height: 8px;
  background: var(--ink);
  border-radius: 0 0 3px 3px;
}

.beaker-el-tag {
  background: var(--paper);
  border: 1px solid rgba(26,26,24,0.25);
  border-radius: 2px; padding: 1px 5px;
  font-family: var(--font-mono); font-size: 0.68rem;
  color: var(--ink); cursor: pointer;
  transition: var(--transition);
}
.beaker-el-tag:hover {
  background: var(--rust); color: var(--paper);
  border-color: var(--rust);
}

.beaker-controls { display: flex; gap: 0.6rem; }

.react-btn {
  padding: 0.65rem 1.6rem;
  background: var(--green); color: var(--paper);
  border: 2px solid var(--green);
  border-radius: var(--radius);
  font-family: var(--font-body); font-size: 0.9rem; font-weight: 700;
  cursor: pointer; transition: var(--transition);
  box-shadow: var(--shadow-sm);
  letter-spacing: 0.3px;
}
.react-btn:hover {
  background: var(--green-mid);
  transform: translateY(-2px); box-shadow: var(--shadow-md);
}
.react-btn:active { transform: translateY(0); box-shadow: var(--shadow-sm); }

.clear-btn {
  padding: 0.65rem 0.9rem;
  background: transparent; color: var(--ink-light);
  border: var(--border); border-radius: var(--radius);
  font-family: var(--font-body); font-size: 0.85rem;
  cursor: pointer; transition: var(--transition);
}
.clear-btn:hover { border-color: var(--rust); color: var(--rust); }

/* 结果卡片 */
.result-card {
  width: 100%; max-width: 340px;
  background: var(--paper);
  border: 2px solid var(--green);
  border-radius: var(--radius);
  padding: 1.2rem;
  box-shadow: var(--shadow-md);
  animation: popIn 0.35s cubic-bezier(0.34,1.4,0.64,1);
}
@keyframes popIn { from { transform:scale(0.85); opacity:0; } to { transform:scale(1); opacity:1; } }

.result-header {
  display: flex; align-items: flex-start; gap: 0.8rem;
  margin-bottom: 0.8rem;
  padding-bottom: 0.8rem;
  border-bottom: 1px solid var(--paper-deep);
}
.result-icon { font-size: 1.8rem; line-height: 1; }
.result-name {
  font-family: var(--font-display); font-size: 1.1rem; font-weight: 700;
  color: var(--green);
}
.result-formula {
  font-family: var(--font-mono); font-size: 0.85rem;
  color: var(--ink-light); margin-top: 2px;
}
.result-score {
  margin-left: auto; font-family: var(--font-mono);
  font-size: 1rem; color: var(--rust); font-weight: 600;
}
.result-desc {
  font-size: 0.83rem; color: var(--ink-light);
  line-height: 1.65; margin-bottom: 0.9rem;
}
.close-result {
  width: 100%; padding: 0.45rem;
  border: 1.5px solid var(--green); border-radius: var(--radius);
  background: transparent; color: var(--green);
  font-family: var(--font-body); font-size: 0.82rem; font-weight: 700;
  cursor: pointer; transition: var(--transition);
}
.close-result:hover { background: var(--green); color: var(--paper); }

/* 已发现面板 */
.discovered-list { display: flex; flex-direction: column; gap: 4px; }
.discovered-item {
  display: flex; align-items: center; gap: 0.5rem;
  padding: 0.35rem 0.6rem;
  background: var(--paper); border: var(--border);
  border-radius: var(--radius);
  animation: slideIn 0.25s ease;
}
@keyframes slideIn { from { transform:translateX(12px); opacity:0; } to { transform:translateX(0); opacity:1; } }
.disc-formula {
  font-family: var(--font-mono); font-size: 0.72rem;
  color: var(--green); min-width: 44px; font-weight: 600;
}
.disc-name { font-size: 0.78rem; color: var(--ink-light); }

/* ===== 模式2: 化学配对 ===== */
.matching-layout { max-width: 860px; margin: 0 auto; }

.level-selector {
  display: flex; gap: 0; margin-bottom: 1.5rem;
  border: var(--border); border-radius: var(--radius);
  overflow: hidden; width: fit-content;
}
.level-btn {
  padding: 0.5rem 1rem;
  border: none; border-right: var(--border);
  background: var(--paper-dark); color: var(--ink-light);
  font-family: var(--font-body); font-size: 0.8rem; font-weight: 700;
  cursor: pointer; transition: var(--transition);
}
.level-btn:last-child { border-right: none; }
.level-btn:hover { background: var(--paper-deep); color: var(--ink); }
.level-btn.active { background: var(--green); color: var(--paper); }

.matching-board {
  display: grid; grid-template-columns: 1fr 1fr;
  gap: 1.5rem; min-height: 380px;
}
.match-col { display: flex; flex-direction: column; gap: 0.5rem; }
.match-col-label {
  font-family: var(--font-mono); font-size: 0.65rem;
  letter-spacing: 2px; text-transform: uppercase;
  color: var(--ink-faint); margin-bottom: 0.3rem;
}

.match-item {
  padding: 0.65rem 1rem;
  background: var(--paper-dark); border: var(--border);
  border-radius: var(--radius);
  cursor: pointer; transition: var(--transition);
  font-size: 0.88rem; font-weight: 600;
  box-shadow: var(--shadow-sm);
  position: relative;
}
.match-item:hover {
  border-color: var(--green-mid);
  background: var(--paper);
  transform: translateX(3px);
}
.match-item.selected {
  border-color: var(--green); border-width: 2px;
  background: var(--paper);
  box-shadow: var(--shadow-md);
}
.match-item.correct {
  border-color: var(--green); background: rgba(30,77,58,0.08);
  color: var(--green); pointer-events: none;
}
.match-item.correct::after {
  content: '✓'; position: absolute; right: 0.8rem; top: 50%;
  transform: translateY(-50%); color: var(--green); font-weight: 900;
}
.match-item.wrong {
  border-color: var(--rust); background: rgba(184,76,42,0.06);
  animation: shake 0.35s ease;
}
@keyframes shake { 0%,100%{transform:translateX(0)} 25%{transform:translateX(-5px)} 75%{transform:translateX(5px)} }

.matching-result {
  text-align: center; margin-top: 1rem;
  font-family: var(--font-display); font-size: 1rem;
  min-height: 1.5rem;
}

/* ===== 模式3: 元素识别 ===== */
.identify-layout {
  max-width: 580px; margin: 0 auto;
  display: flex; flex-direction: column; align-items: center; gap: 1.2rem;
}

.identify-card {
  width: 100%;
  background: var(--paper-dark); border: var(--border);
  border-radius: var(--radius); padding: 1.8rem;
  display: flex; gap: 2rem; align-items: center;
  box-shadow: var(--shadow-md);
}

.mystery-element {
  width: 90px; height: 100px; flex-shrink: 0;
  background: var(--paper);
  border: 2px solid var(--ink);
  border-radius: var(--radius);
  display: flex; flex-direction: column;
  align-items: center; justify-content: center; gap: 3px;
  box-shadow: var(--shadow-md);
  position: relative;
}
.mystery-element .element-number {
  font-family: var(--font-mono); font-size: 0.65rem;
  color: var(--ink-faint); position: absolute; top: 4px; left: 6px;
}
.mystery-element .element-symbol {
  font-family: var(--font-mono); font-size: 2.4rem; font-weight: 600;
  color: var(--ink); line-height: 1;
}
.mystery-element .hidden-symbol { color: var(--paper-deep); }
.mystery-element .element-name {
  font-size: 0.6rem; color: var(--ink-faint);
}

.clues-box { flex: 1; display: flex; flex-direction: column; gap: 0.5rem; }
.clue {
  display: flex; justify-content: space-between; align-items: center;
  padding: 0.35rem 0.7rem;
  background: var(--paper); border: var(--border);
  border-radius: var(--radius);
}
.clue-label { font-size: 0.75rem; color: var(--ink-faint); }
.clue-val { font-family: var(--font-mono); font-size: 0.82rem; color: var(--green); font-weight: 600; }

.identify-input-area { display: flex; gap: 0.6rem; width: 100%; }
.identify-input {
  flex: 1; padding: 0.65rem 1rem;
  background: var(--paper); border: 2px solid var(--ink);
  border-radius: var(--radius); color: var(--ink);
  font-family: var(--font-mono); font-size: 1.1rem; text-align: center;
  outline: none; transition: var(--transition);
}
.identify-input:focus { border-color: var(--green); }

.submit-btn, .next-btn {
  padding: 0.65rem 1.1rem; border-radius: var(--radius);
  font-family: var(--font-body); font-size: 0.85rem; font-weight: 700;
  cursor: pointer; transition: var(--transition);
}
.submit-btn {
  background: var(--green); color: var(--paper);
  border: 2px solid var(--green); box-shadow: var(--shadow-sm);
}
.submit-btn:hover { background: var(--green-mid); transform: translateY(-1px); box-shadow: var(--shadow-md); }
.next-btn {
  background: transparent; color: var(--ink-light);
  border: var(--border);
}
.next-btn:hover { border-color: var(--ink); color: var(--ink); }

.identify-feedback {
  font-size: 0.9rem; font-weight: 700; min-height: 1.4rem;
  text-align: center; font-family: var(--font-mono);
}
.identify-feedback.correct { color: var(--green); }
.identify-feedback.wrong   { color: var(--rust); }

.identify-progress { width: 100%; }
.identify-progress span {
  font-size: 0.78rem; color: var(--ink-faint);
  display: block; margin-bottom: 0.4rem;
  font-family: var(--font-mono);
}
.progress-bar {
  height: 5px; background: var(--paper-deep);
  border-radius: 2px; overflow: hidden;
  border: 1px solid rgba(26,26,24,0.1);
}
.progress-fill {
  height: 100%; background: var(--green);
  border-radius: 2px; transition: width 0.4s ease; width: 0%;
}

/* ===== 模式4: 方程配平 ===== */
.balance-layout { max-width: 780px; margin: 0 auto; }

.difficulty-bar {
  display: flex; align-items: center; gap: 0.8rem;
  margin-bottom: 1.2rem; padding: 0.7rem 1rem;
  background: var(--paper-dark); border: var(--border);
  border-radius: var(--radius);
}
.diff-label { font-size: 0.78rem; color: var(--ink-faint); font-family: var(--font-mono); }
.diff-stars { display: flex; gap: 2px; }
.diff-star { font-size: 0.9rem; }
.diff-num {
  font-family: var(--font-mono); font-size: 0.78rem;
  color: var(--ink-light); margin-right: auto;
}
.hint-btn {
  padding: 0.3rem 0.8rem;
  border: 1.5px solid var(--gold); border-radius: var(--radius);
  background: transparent; color: var(--gold);
  font-family: var(--font-body); font-size: 0.78rem; font-weight: 700;
  cursor: pointer; transition: var(--transition);
}
.hint-btn:hover { background: rgba(200,146,42,0.1); }

.equation-display {
  background: var(--paper-dark); border: var(--border);
  border-radius: var(--radius); padding: 2rem 1.5rem;
  text-align: center; margin-bottom: 1.2rem;
  min-height: 90px; display: flex;
  align-items: center; justify-content: center;
  flex-wrap: wrap; gap: 0.4rem;
  box-shadow: var(--shadow-sm);
  font-size: 1.15rem;
}

.eq-coeff {
  width: 46px; height: 38px; text-align: center;
  background: var(--paper); border: 2px solid var(--ink);
  border-radius: var(--radius); color: var(--ink);
  font-family: var(--font-mono); font-size: 1rem;
  outline: none; transition: var(--transition);
}
.eq-coeff:focus { border-color: var(--green); box-shadow: 0 0 0 3px rgba(30,77,58,0.12); }
.eq-coeff.correct { border-color: var(--green); background: rgba(30,77,58,0.08); color: var(--green); }
.eq-coeff.wrong   { border-color: var(--rust);  background: rgba(184,76,42,0.06); }

.eq-molecule {
  font-family: var(--font-mono); font-size: 1.05rem;
  color: var(--ink); font-weight: 600;
}
.eq-molecule sub { font-size: 0.65rem; }
.eq-arrow { color: var(--ink-light); font-size: 1.3rem; margin: 0 0.3rem; }
.eq-plus  { color: var(--ink-faint); margin: 0 0.2rem; }

.balance-controls { display: flex; gap: 0.7rem; justify-content: center; margin-bottom: 0.8rem; }
.check-btn, .next-eq-btn {
  padding: 0.65rem 1.6rem; border-radius: var(--radius);
  font-family: var(--font-body); font-size: 0.9rem; font-weight: 700;
  cursor: pointer; transition: var(--transition);
}
.check-btn {
  background: var(--green); color: var(--paper);
  border: 2px solid var(--green); box-shadow: var(--shadow-sm);
}
.check-btn:hover { background: var(--green-mid); transform: translateY(-1px); box-shadow: var(--shadow-md); }
.next-eq-btn {
  background: transparent; color: var(--ink-light); border: var(--border);
}
.next-eq-btn:hover { border-color: var(--ink); color: var(--ink); }

.balance-feedback {
  text-align: center; font-size: 0.9rem; font-weight: 700;
  min-height: 1.4rem; font-family: var(--font-mono);
}
.balance-feedback.correct { color: var(--green); }
.balance-feedback.wrong   { color: var(--rust); }

.balance-hint-box {
  background: rgba(200,146,42,0.08);
  border: 1.5px solid var(--gold); border-radius: var(--radius);
  padding: 0.9rem 1rem; margin-top: 0.8rem;
  color: var(--ink-light); font-size: 0.85rem; line-height: 1.65;
  font-style: italic;
}

/* ===== 模式5: 周期表挑战 ===== */
.periodic-layout { max-width: 900px; margin: 0 auto; }

.task-selector {
  display: flex; gap: 0; margin-bottom: 1rem;
  border: var(--border); border-radius: var(--radius);
  overflow: hidden; flex-wrap: wrap;
  width: fit-content;
}
.task-btn {
  padding: 0.45rem 0.9rem;
  border: none; border-right: var(--border);
  background: var(--paper-dark); color: var(--ink-light);
  font-family: var(--font-body); font-size: 0.78rem; font-weight: 700;
  cursor: pointer; transition: var(--transition);
}
.task-btn:last-child { border-right: none; }
.task-btn:hover { background: var(--paper-deep); color: var(--ink); }
.task-btn.active { background: var(--rust); color: var(--paper); }

.periodic-task-desc {
  font-size: 0.85rem; color: var(--ink-light);
  margin-bottom: 1.2rem; font-style: italic;
  min-height: 1.3rem;
}

.periodic-game-area { display: flex; flex-direction: column; gap: 1.2rem; }

.drag-pool {
  background: var(--paper-dark); border: var(--border);
  border-radius: var(--radius); padding: 0.8rem;
  display: flex; flex-wrap: wrap; gap: 6px; min-height: 70px;
}
.drag-pool-label {
  font-family: var(--font-mono); font-size: 0.62rem;
  letter-spacing: 2px; text-transform: uppercase;
  color: var(--ink-faint); width: 100%; margin-bottom: 0.3rem;
}

.drop-slots {
  display: flex; flex-wrap: wrap; gap: 8px; justify-content: center;
}
.drop-slot {
  width: 68px; height: 76px;
  background: var(--paper-dark);
  border: 2px dashed rgba(26,26,24,0.2);
  border-radius: var(--radius);
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  transition: var(--transition); position: relative;
}
.drop-slot.drag-over { border-color: var(--green); border-style: solid; background: rgba(30,77,58,0.06); }
.drop-slot.filled    { border-style: solid; border-color: rgba(26,26,24,0.25); }
.drop-slot.correct   { border-color: var(--green); background: rgba(30,77,58,0.08); }
.drop-slot.wrong     { border-color: var(--rust);  background: rgba(184,76,42,0.06); }
.slot-label {
  font-size: 0.55rem; color: var(--ink-faint);
  position: absolute; bottom: 3px;
  font-family: var(--font-mono); letter-spacing: 0.5px;
  text-align: center; padding: 0 2px;
}

.periodic-feedback {
  text-align: center; font-size: 0.9rem; font-weight: 700;
  min-height: 1.4rem; margin-top: 0.5rem;
  font-family: var(--font-mono);
}
.periodic-feedback.correct { color: var(--green); }
.periodic-feedback.wrong   { color: var(--rust); }

.check-periodic-btn {
  display: block; margin: 1rem auto 0;
  padding: 0.65rem 2rem;
  background: var(--rust); color: var(--paper);
  border: 2px solid var(--rust); border-radius: var(--radius);
  font-family: var(--font-body); font-size: 0.9rem; font-weight: 700;
  cursor: pointer; transition: var(--transition);
  box-shadow: var(--shadow-sm);
}
.check-periodic-btn:hover { background: var(--rust-light); transform: translateY(-1px); box-shadow: var(--shadow-md); }

/* ===== 底部仪表盘（已移入顶部，保留兼容） ===== */
.dashboard { display: none; }

/* ===== 成就弹窗 ===== */
.achievement-popup {
  position: fixed; top: 80px; right: 1.5rem; z-index: 999;
  animation: slideInRight 0.4s cubic-bezier(0.34,1.4,0.64,1);
}
@keyframes slideInRight { from { transform:translateX(110%); opacity:0; } to { transform:translateX(0); opacity:1; } }

.achievement-inner {
  display: flex; align-items: center; gap: 0.9rem;
  background: var(--paper);
  border: 2px solid var(--gold);
  border-radius: var(--radius);
  padding: 0.9rem 1.2rem;
  box-shadow: var(--shadow-lg);
}
.achievement-medal { font-size: 2rem; }
.achievement-title {
  font-family: var(--font-mono); font-size: 0.62rem;
  letter-spacing: 2px; text-transform: uppercase; color: var(--gold);
}
.achievement-desc {
  font-family: var(--font-display); font-size: 0.95rem; font-weight: 700;
  color: var(--ink); margin-top: 2px;
}

/* ===== 响应式 ===== */
@media (max-width: 960px) {
  .synthesis-layout { grid-template-columns: 1fr; }
  .panel-body { max-height: 180px; }
  .elements-grid { justify-content: center; }
  .matching-board { grid-template-columns: 1fr; gap: 0.8rem; }
}
@media (max-width: 640px) {
  .main-content { padding: 1rem; }
  .header-top { padding: 0.6rem 1rem; }
  .mode-nav { padding: 0 1rem; }
  .mode-btn .btn-label { display: none; }
  .header-stats { gap: 0.8rem; }
  .identify-card { flex-direction: column; align-items: center; }
  .section-title { flex-direction: column; gap: 0.3rem; }
}