:root {
  --bg: #f5f4f0;
  --surface: #ffffff;
  --surface2: #f9f8f5;
  --border: #e2e0d8;
  --border2: #d0cdc3;
  --text: #2c2b27;
  --text2: #6b6860;
  --text3: #9b9890;
  --accent: #3b6ea8;
  --accent-bg: #eef3f9;
  --accent-border: #c5d8ef;
  --green: #2e7d52;
  --green-bg: #ebf5ef;
  --green-border: #b8ddc8;
  --red: #b94040;
  --red-bg: #fdf0f0;
  --red-border: #e8bcbc;
  --yellow: #8a6914;
  --yellow-bg: #fdf6e3;
  --yellow-border: #e8d49a;
  --orange: #c47c2b;
  --orange-bg: #fef4e8;
  --orange-border: #f0d0a0;
  --purple: #7b5ea7;
  --purple-bg: #f3effe;
  --purple-border: #d5c4f0;
  --code-bg: #f0eeea;
  --shadow: 0 1px 4px rgba(0,0,0,0.08), 0 0 1px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.10), 0 0 1px rgba(0,0,0,0.06);
}

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

body {
  font-family: 'Noto Sans KR', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  font-size: 14px;
  line-height: 1.6;
}

.app { display: flex; flex-direction: column; min-height: 100vh; }

/* TOPBAR */
.topbar {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 0 20px;
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 200;
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}
.topbar.hidden {
  transform: translateY(-100%);
}
.logo { font-size: 15px; font-weight: 700; color: var(--text); letter-spacing: -0.3px; }
.logo span { color: var(--accent); }
.topbar-nav { display: flex; align-items: center; gap: 6px; }
.btn-nav-top {
  padding: 5px 12px;
  border: 1px solid var(--border2);
  border-radius: 6px;
  background: var(--surface);
  color: var(--text2);
  cursor: pointer;
  font-size: 12px;
  font-family: inherit;
  transition: all 0.15s;
  white-space: nowrap;
}
.btn-nav-top:hover { background: var(--surface2); color: var(--text); border-color: var(--text3); }
.btn-nav-top.accent { background: var(--accent); color: white; border-color: var(--accent); }
.btn-nav-top.accent:hover { background: #2d5a8a; }
.btn-clear-cache {
  padding: 5px 10px;
  border: 1px solid var(--border2);
  border-radius: 6px;
  background: var(--surface);
  color: var(--text3);
  cursor: pointer;
  font-size: 11px;
  font-family: inherit;
  transition: all 0.15s;
  white-space: nowrap;
}
.btn-clear-cache:hover { background: var(--red-bg); color: var(--red); border-color: var(--red-border); }

/* SCREEN */
.screen { display: none; }
.screen.active { display: block; }

/* HOME */
.home-wrap { max-width: 960px; margin: 0 auto; padding: 36px 20px 28px; }
.home-header { margin-bottom: 32px; }
.home-header h1 { font-size: 22px; font-weight: 700; margin-bottom: 8px; }
.home-header p { color: var(--text2); font-size: 13px; line-height: 1.8; }
.how-to { background: var(--surface); border: 1px solid var(--border); border-radius: 10px; padding: 18px 22px; margin-bottom: 28px; }
.how-to h3 { font-size: 11px; font-weight: 700; color: var(--text3); margin-bottom: 14px; text-transform: uppercase; letter-spacing: 0.6px; }
.how-to-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; }
.level-info { padding: 12px 14px; background: var(--surface2); border: 1px solid var(--border); border-radius: 8px; }
.level-info .lv-tag { display: inline-block; font-size: 10px; font-weight: 700; padding: 2px 8px; border-radius: 4px; margin-bottom: 6px; }
.lv-tag.lv1 { background: var(--accent-bg); color: var(--accent); }
.lv-tag.lv2 { background: var(--green-bg); color: var(--green); }
.lv-tag.lv3 { background: var(--yellow-bg); color: var(--yellow); }
.lv-tag.lv4 { background: var(--red-bg); color: var(--red); }
.level-info .lv-name { font-size: 12px; font-weight: 700; margin-bottom: 4px; }
.level-info .lv-desc { font-size: 11px; color: var(--text2); line-height: 1.5; }
.section-label { font-size: 11px; font-weight: 700; color: var(--text3); text-transform: uppercase; letter-spacing: 0.6px; margin-bottom: 14px; }

/* Category grid */
.category-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.cat-card {
  background: var(--surface); border: 1px solid var(--border); border-radius: 10px;
  padding: 18px 20px; cursor: pointer; transition: all 0.15s; position: relative; overflow: hidden;
}
.cat-card:hover { border-color: var(--accent); box-shadow: var(--shadow-md); transform: translateY(-1px); }
.cat-card::before { content: ''; position: absolute; top: 0; left: 0; right: 0; height: 3px; }
.cat-card.c0::before { background: #3b6ea8; }
.cat-card.c1::before { background: #2e7d52; }
.cat-card.c2::before { background: #7b5ea7; }
.cat-card.c3::before { background: #c47c2b; }
.cat-card.c4::before { background: #b94040; }
.cat-card.c5::before { background: #2e7d7d; }
.cat-card-top { display: flex; align-items: flex-start; justify-content: space-between; margin-bottom: 10px; }
.cat-icon { font-size: 20px; }
.cat-badges { display: flex; flex-direction: column; gap: 4px; align-items: flex-end; }
.badge-freq { font-size: 10px; font-weight: 700; padding: 2px 7px; border-radius: 4px; white-space: nowrap; }
.badge-freq.must { background: #fde8e8; color: #b94040; }
.badge-freq.high { background: #fff3e0; color: #c47c2b; }
.badge-freq.mid { background: #e8f5e9; color: #2e7d52; }
.badge-freq.adv { background: #f3e5f5; color: #7b5ea7; }
.badge-diff { font-size: 9px; color: var(--text3); padding: 1px 6px; border: 1px solid var(--border); border-radius: 3px; background: var(--surface2); white-space: nowrap; }
.cat-title { font-size: 14px; font-weight: 700; margin-bottom: 4px; }
.cat-sub { font-size: 12px; color: var(--text2); margin-bottom: 10px; line-height: 1.5; }
.cat-footer { display: flex; align-items: center; justify-content: space-between; }
.cat-count { font-size: 11px; color: var(--text3); }
.cat-importance { font-size: 11px; display: flex; gap: 2px; }
/* 홈 카드 진행률 표시 */
.cat-progress-bar {
  height: 3px;
  background: var(--border);
  border-radius: 2px;
  margin-top: 10px;
  overflow: hidden;
}
.cat-progress-bar-fill {
  height: 100%;
  background: var(--green);
  border-radius: 2px;
  transition: width 0.3s;
}
.cat-progress-label {
  font-size: 10px;
  color: var(--green);
  font-weight: 700;
  margin-top: 3px;
}

/* CATEGORY SCREEN */
.cat-screen-wrap { max-width: 960px; margin: 0 auto; padding: 28px 20px 60px; }
.cat-switcher { display: flex; gap: 6px; margin-bottom: 20px; flex-wrap: wrap; }
.cat-switch-btn {
  padding: 6px 12px; border: 1px solid var(--border); border-radius: 20px;
  background: var(--surface); cursor: pointer; font-family: inherit; font-size: 12px;
  color: var(--text2); transition: all 0.15s; white-space: nowrap; position: relative;
}
.cat-switch-btn:hover { border-color: var(--border2); color: var(--text); }
.cat-switch-btn.active { background: var(--accent); border-color: var(--accent); color: white; font-weight: 700; }
.cat-switch-btn .prog-dot { display: inline-block; width: 5px; height: 5px; background: var(--green); border-radius: 50%; margin-left: 4px; vertical-align: middle; }

.cat-screen-header { margin-bottom: 20px; }
.cat-screen-header h2 { font-size: 18px; font-weight: 700; margin-bottom: 6px; }
.cat-desc-row { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.cat-screen-header p { font-size: 13px; color: var(--text2); }
.level-tabs { display: flex; gap: 6px; margin-bottom: 20px; background: var(--surface); border: 1px solid var(--border); border-radius: 8px; padding: 5px; }
.level-tab { flex: 1; padding: 8px 10px; border-radius: 6px; border: none; background: transparent; cursor: pointer; font-family: inherit; font-size: 12px; font-weight: 500; color: var(--text2); transition: all 0.15s; text-align: center; }
.level-tab:hover { background: var(--surface2); color: var(--text); }
.level-tab.active { background: var(--accent); color: white; font-weight: 700; }

.question-list { display: flex; flex-direction: column; gap: 6px; }
.q-item {
  background: var(--surface); border: 1px solid var(--border); border-radius: 8px;
  padding: 12px 16px; cursor: pointer; display: flex; align-items: flex-start; gap: 12px; transition: all 0.15s;
}
.q-item:hover { border-color: var(--accent); background: var(--accent-bg); }
.q-item.completed { border-left: 3px solid var(--green); background: var(--green-bg); }
.q-num { font-size: 11px; font-weight: 700; color: var(--text3); min-width: 28px; font-family: 'JetBrains Mono', monospace; padding-top: 1px; }
.q-item.completed .q-num { color: var(--green); }
.q-item-body { flex: 1; }
.q-title-text { font-size: 13px; font-weight: 500; margin-bottom: 3px; }
.q-item-prompt { font-size: 11px; color: var(--text2); line-height: 1.5; }
.q-arrow { color: var(--text3); font-size: 12px; padding-top: 2px; }
.q-done-tag { font-size: 9px; font-weight: 700; background: var(--green-bg); color: var(--green); border: 1px solid var(--green-border); border-radius: 4px; padding: 1px 6px; white-space: nowrap; }

/* PRACTICE LAYOUT — 개념 패널 왼쪽 */
.practice-layout {
  display: grid;
  grid-template-columns: 300px 1fr;
  grid-template-areas: "concept main";
  gap: 0;
  min-height: calc(100vh - 52px);
}
.practice-concept-panel {
  grid-area: concept;
  padding: 20px 18px;
  overflow-y: auto;
  background: var(--surface2);
  border-right: 1px solid var(--border);
  position: sticky;
  top: 52px;
  max-height: calc(100vh - 52px);
}
.practice-main {
  grid-area: main;
  padding: 24px 28px;
  border-left: 1px solid var(--border);
  overflow-y: auto;
}

/* Breadcrumb */
.practice-nav { display: flex; align-items: center; gap: 6px; font-size: 12px; color: var(--text3); margin-bottom: 18px; flex-wrap: wrap; }
.practice-nav .nav-link { color: var(--accent); cursor: pointer; }
.practice-nav .nav-link:hover { text-decoration: underline; }
.practice-nav .sep { color: var(--border2); }
.practice-nav .nav-cur { color: var(--text2); }

.level-selector { display: flex; gap: 5px; margin-bottom: 20px; flex-wrap: wrap; }
.lv-btn { padding: 6px 12px; border-radius: 6px; border: 1px solid var(--border); background: var(--surface); cursor: pointer; font-family: inherit; font-size: 12px; font-weight: 500; color: var(--text2); transition: all 0.15s; }
.lv-btn:hover { border-color: var(--border2); color: var(--text); }
.lv-btn.active.lv1 { background: var(--accent); border-color: var(--accent); color: white; }
.lv-btn.active.lv2 { background: var(--green); border-color: var(--green); color: white; }
.lv-btn.active.lv3 { background: var(--yellow); border-color: var(--yellow); color: white; }
.lv-btn.active.lv4 { background: var(--red); border-color: var(--red); color: white; }

.problem-statement {
  background: var(--yellow-bg); border: 1px solid var(--yellow-border);
  border-radius: 8px; padding: 14px 18px; margin-bottom: 16px; font-size: 13px; line-height: 1.75;
}
.problem-statement code { font-family: 'JetBrains Mono', monospace; font-size: 12px; background: rgba(138,105,20,0.10); padding: 1px 5px; border-radius: 3px; color: var(--yellow); }
.ps-label { font-size: 10px; font-weight: 800; color: var(--accent); text-transform: uppercase; letter-spacing: 0.6px; margin-bottom: 6px; }
.ps-body { color: var(--text); font-size: 13px; line-height: 1.75; }

.code-block { background: var(--code-bg); border: 1px solid var(--border); border-radius: 6px; padding: 12px 16px; font-family: 'JetBrains Mono', monospace; font-size: 12px; white-space: pre; overflow-x: auto; margin-bottom: 12px; color: #3a3836; line-height: 1.8; position: relative; }
.code-label { position: absolute; top: 6px; right: 8px; font-size: 9px; font-weight: 700; color: var(--text3); background: var(--border); padding: 1px 6px; border-radius: 3px; font-family: inherit; }
.blank-spot { display: inline-block; background: var(--accent-bg); border-bottom: 2px solid var(--accent); min-width: 40px; border-radius: 2px; }

.options-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 6px; margin-bottom: 8px; }
.opt { padding: 9px 14px; border: 1px solid var(--border2); border-radius: 7px; background: var(--surface); cursor: pointer; font-family: 'JetBrains Mono', monospace; font-size: 12px; color: var(--text); text-align: left; transition: all 0.12s; }
.opt:hover:not(:disabled) { border-color: var(--accent); background: var(--accent-bg); }
.opt:disabled { cursor: default; }
.opt.correct { background: var(--green-bg); border-color: var(--green); color: var(--green); font-weight: 700; }
.opt.wrong { background: var(--red-bg); border-color: var(--red); color: var(--red); }

.fill-row { display: flex; gap: 8px; margin-bottom: 8px; }
.fill-input { flex: 1; padding: 9px 12px; border: 1px solid var(--border2); border-radius: 7px; font-family: 'JetBrains Mono', monospace; font-size: 13px; background: var(--surface); color: var(--text); outline: none; transition: border-color 0.15s; }
.fill-input:focus { border-color: var(--accent); }
.fill-input.correct { border-color: var(--green); background: var(--green-bg); }
.fill-input.wrong { border-color: var(--red); background: var(--red-bg); }
.btn-check { padding: 9px 18px; background: var(--accent); color: white; border: none; border-radius: 7px; cursor: pointer; font-family: inherit; font-size: 12px; font-weight: 700; transition: background 0.15s; white-space: nowrap; }
.btn-check:hover { background: #2d5a8a; }

.type-wrap { margin-bottom: 10px; }
.type-area { width: 100%; min-height: 120px; padding: 12px 14px; border: 1px solid var(--border2); border-radius: 8px; font-family: 'JetBrains Mono', monospace; font-size: 12px; background: var(--surface); color: var(--text); resize: vertical; outline: none; line-height: 1.8; tab-size: 4; transition: border-color 0.15s; }
.type-area:focus { border-color: var(--accent); }

.btn-submit-full { padding: 9px 18px; background: var(--accent); color: white; border: none; border-radius: 7px; cursor: pointer; font-family: inherit; font-size: 12px; font-weight: 700; transition: background 0.15s; }
.btn-submit-full:hover { background: #2d5a8a; }

.feedback { padding: 12px 16px; border-radius: 8px; font-size: 13px; margin-bottom: 16px; display: none; line-height: 1.6; }
.feedback.ok { background: var(--green-bg); border: 1px solid var(--green-border); color: var(--green); }
.feedback.err { background: var(--red-bg); border: 1px solid var(--red-border); color: var(--red); }
.feedback code { font-family: 'JetBrains Mono', monospace; font-size: 12px; }

.q-nav { display: flex; align-items: center; gap: 10px; margin-top: 24px; padding-top: 16px; border-top: 1px solid var(--border); }
.btn-qnav { padding: 9px 18px; border: 1px solid var(--border2); border-radius: 7px; background: var(--surface); color: var(--text2); cursor: pointer; font-family: inherit; font-size: 13px; font-weight: 500; transition: all 0.15s; }
.btn-qnav:hover { background: var(--surface2); color: var(--text); }
.btn-qnav.primary { background: var(--accent); color: white; border-color: var(--accent); }
.btn-qnav.primary:hover { background: #2d5a8a; }

/* 사이드바 (개념 패널 안) */
.sidebar-section { margin-bottom: 22px; }
.sidebar-label { font-size: 10px; font-weight: 800; color: var(--text3); text-transform: uppercase; letter-spacing: 0.6px; margin-bottom: 10px; padding-bottom: 6px; border-bottom: 1px solid var(--border); }

/* 개념 네비게이션 */
.concept-nav { display: flex; flex-direction: column; gap: 6px; margin-bottom: 12px; }
.concept-nav-btn {
  width: 100%; padding: 7px 10px; border: 1px solid var(--border); border-radius: 7px;
  background: var(--surface); cursor: pointer; font-family: inherit; font-size: 11px;
  color: var(--text2); transition: all 0.15s; text-align: left; line-height: 1.4;
}
.concept-nav-btn:hover:not(:disabled) { border-color: var(--accent); background: var(--accent-bg); color: var(--accent); }
.concept-nav-btn:disabled { opacity: 0.35; cursor: default; }
.concept-nav-btn .nav-dir { display: block; font-size: 9px; font-weight: 800; color: var(--text3); text-transform: uppercase; letter-spacing: 0.4px; margin-bottom: 2px; }
.concept-nav-btn .nav-cat-title { display: block; font-size: 11px; font-weight: 600; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }

/* 모바일(<900px): 패널이 가로 전체로 펼쳐지므로 버튼 다시 좌우 나란히 */
@media (max-width: 900px) {
  .concept-nav { flex-direction: row; }
  .concept-nav-btn { width: auto; flex: 1; text-align: center; }
}

/* 개념 박스 */
.concept-box { background: var(--surface); border: 1px solid var(--border); border-radius: 10px; overflow: hidden; }
.c-head { padding: 10px 14px; background: var(--accent-bg); border-bottom: 1px solid var(--accent-border); font-size: 12px; font-weight: 700; color: var(--accent); }
.c-body { padding: 12px 14px; display: flex; flex-direction: column; gap: 10px; }
.c-desc { font-size: 12px; color: var(--text2); line-height: 1.8; }
.c-syntax { background: var(--code-bg); border: 1px solid var(--border); border-radius: 6px; padding: 10px 12px; font-family: 'JetBrains Mono', monospace; font-size: 11px; white-space: pre; overflow-x: auto; color: #3a3836; line-height: 1.9; }
.c-note { font-size: 11px; background: var(--yellow-bg); border: 1px solid var(--yellow-border); border-radius: 6px; padding: 8px 10px; color: var(--yellow); line-height: 1.7; }

/* 언어 비교표 */
.c-lang-table-wrap { overflow-x: auto; }
.lang-table { width: 100%; border-collapse: collapse; font-size: 10px; }
.lang-table th { background: var(--surface2); padding: 5px 7px; text-align: left; font-weight: 700; border: 1px solid var(--border); color: var(--text2); }
.lang-table td { padding: 5px 7px; border: 1px solid var(--border); font-family: 'JetBrains Mono', monospace; font-size: 10px; color: var(--text); vertical-align: top; line-height: 1.6; }
.lang-table tr:nth-child(even) td { background: var(--surface2); }
.lang-table .py { color: #3b6ea8; font-weight: 700; }
.lang-table .dart-col { color: #7b5ea7; }
.lang-table .java { color: #b94040; }
.lang-table .js { color: #8a6914; }
.lang-table .note-cell { color: var(--red); font-weight: 700; font-family: inherit; font-size: 10px; }

/* Dart 비교 섹션 */
.c-dart { font-size: 11px; background: var(--purple-bg); border: 1px solid var(--purple-border); border-radius: 6px; padding: 8px 10px; color: var(--purple); line-height: 1.8; font-family: 'JetBrains Mono', monospace; white-space: pre-wrap; }

/* 힌트 */
.hint-box { background: var(--surface); border: 1px solid var(--border); border-radius: 8px; overflow: hidden; }
.hint-toggle-btn { width: 100%; padding: 10px 13px; background: none; border: none; cursor: pointer; font-family: inherit; font-size: 12px; color: var(--text2); text-align: left; display: flex; align-items: center; justify-content: space-between; transition: background 0.12s; }
.hint-toggle-btn:hover { background: var(--surface2); }
.hint-content { padding: 10px 13px; font-size: 12px; color: var(--text2); line-height: 1.7; border-top: 1px solid var(--border); display: none; }
.hint-content.show { display: block; }

.progress-wrap { margin-top: 4px; }
.progress-track { height: 5px; background: var(--border); border-radius: 3px; overflow: hidden; margin-bottom: 4px; }
.progress-fill { height: 100%; background: var(--accent); border-radius: 3px; transition: width 0.3s ease; }
.progress-text { font-size: 11px; color: var(--text3); }

.sidebar-cat-list { display: flex; flex-direction: column; gap: 4px; }
.sidebar-cat-btn { padding: 7px 10px; border: 1px solid var(--border); border-radius: 6px; background: var(--surface); cursor: pointer; font-family: inherit; font-size: 11px; color: var(--text2); text-align: left; transition: all 0.15s; display: flex; align-items: center; gap: 7px; }
.sidebar-cat-btn:hover { border-color: var(--border2); color: var(--text); background: var(--surface2); }
.sidebar-cat-btn.active { border-color: var(--accent); background: var(--accent-bg); color: var(--accent); font-weight: 700; }

/* DRILL CARDS */
.drills-container { display: flex; flex-direction: column; gap: 20px; margin-top: 4px; }
.drill-card { background: var(--surface); border: 1px solid var(--border); border-radius: 12px; overflow: hidden; }
.drill-card.drill-done { border-color: var(--green-border); }
.drill-card.drill-done .drill-card-header { background: var(--green-bg); border-color: var(--green-border); }
.drill-card-header { display: flex; align-items: center; gap: 10px; padding: 12px 20px; background: var(--surface2); border-bottom: 1px solid var(--border); }
.drill-num { font-size: 10px; font-weight: 800; color: var(--accent); background: var(--accent-bg); border: 1px solid var(--accent-border); padding: 2px 9px; border-radius: 20px; letter-spacing: 0.3px; white-space: nowrap; }
.drill-title-text { font-size: 13px; font-weight: 700; color: var(--text); }
.drill-done-tag { font-size: 9px; font-weight: 700; background: var(--green); color: white; padding: 2px 7px; border-radius: 10px; margin-left: auto; }

/* 각 레벨 위에 반복되는 문제 지문 */
.drill-problem-repeat {
  background: var(--yellow-bg);
  border-bottom: 1px solid var(--yellow-border);
  padding: 8px 20px;
  font-size: 12px;
  color: var(--text2);
  line-height: 1.7;
}
.drill-problem-repeat code { font-family: 'JetBrains Mono', monospace; font-size: 11px; background: rgba(138,105,20,0.10); padding: 1px 4px; border-radius: 3px; color: var(--yellow); }
.drill-problem-label { font-size: 9px; font-weight: 800; color: var(--yellow); text-transform: uppercase; letter-spacing: 0.5px; margin-bottom: 2px; }

.drill-section { padding: 16px 20px; border-bottom: 1px solid var(--border); }
.drill-section:last-of-type { border-bottom: none; }
.drill-section-label { font-size: 10px; font-weight: 800; color: var(--text3); text-transform: uppercase; letter-spacing: 0.7px; margin-bottom: 12px; padding-bottom: 8px; border-bottom: 1px dashed var(--border); }

.drill-feedback { padding: 10px 14px; border-radius: 7px; font-size: 12px; margin-top: 10px; line-height: 1.6; display: none; }
.drill-feedback.ok { background: var(--green-bg); border: 1px solid var(--green-border); color: var(--green); }
.drill-feedback.err { background: var(--red-bg); border: 1px solid var(--red-border); color: var(--red); }
.drill-feedback code { font-family: 'JetBrains Mono', monospace; font-size: 11px; background: rgba(0,0,0,0.06); padding: 1px 5px; border-radius: 3px; }

.drill-hint-details { padding: 12px 20px; border-top: 1px solid var(--border); background: var(--yellow-bg); margin-top: 16px; }
.drill-hint-details summary { font-size: 12px; color: var(--yellow); cursor: pointer; font-weight: 700; list-style: none; }
.drill-hint-details summary::-webkit-details-marker { display: none; }
.drill-hint-body { margin-top: 8px; font-size: 12px; color: var(--text2); line-height: 1.7; }

.drop-area { min-height: 36px; background: var(--accent-bg); border: 2px dashed var(--accent-border); border-radius: 7px; padding: 8px; display: flex; flex-wrap: wrap; gap: 5px; margin-bottom: 10px; }
.block-pool { display: flex; flex-wrap: wrap; gap: 5px; margin-bottom: 8px; }
.code-chip { padding: 5px 10px; background: var(--surface); border: 1px solid var(--border2); border-radius: 5px; font-family: 'JetBrains Mono', monospace; font-size: 11px; cursor: pointer; transition: all 0.12s; user-select: none; }
.code-chip:hover { border-color: var(--accent); background: var(--accent-bg); }
.code-chip.placed { background: var(--accent); border-color: var(--accent); color: white; }

.footer-reset-btn {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 5px 12px;
  border: 1px solid var(--border2);
  border-radius: 6px;
  background: var(--surface);
  color: var(--text2);
  cursor: pointer;
  font-size: 12px;
  font-family: inherit;
  transition: all 0.15s;
  white-space: nowrap;
  width: fit-content;
}
.footer-reset-btn:hover {
  background: var(--red-bg);
  color: var(--red);
  border-color: var(--red-border);
}
.c-dart-compare {
  background: var(--purple-bg);
  border: 1px solid var(--purple-border);
  border-radius: 8px;
  overflow: hidden;
}
.dart-compare-row {
  display: grid;
  grid-template-columns: auto 1fr auto auto 1fr;
  align-items: center;
  gap: 6px;
  padding: 7px 10px;
  border-bottom: 1px solid var(--purple-border);
  font-size: 11px;
}
.dart-compare-row:last-child { border-bottom: none; }
.dc-lang {
  font-size: 9px;
  font-weight: 800;
  padding: 2px 5px;
  border-radius: 4px;
  white-space: nowrap;
  letter-spacing: 0.3px;
}
.dart-lang { background: var(--purple); color: white; }
.py-lang { background: var(--accent); color: white; }
.dc-code {
  font-family: 'JetBrains Mono', monospace;
  font-size: 10.5px;
  color: var(--text);
  word-break: break-all;
}
.dc-arrow { color: var(--text3); font-size: 12px; }
.dart-compare-comment {
  padding: 4px 10px;
  font-size: 10px;
  color: var(--text3);
  font-style: italic;
  border-bottom: 1px solid var(--purple-border);
}
.dart-compare-comment:last-child { border-bottom: none; }

/* 언어 비교표 스크롤 힌트 */
.lang-table-scroll-hint {
  font-size: 9px;
  color: var(--text3);
  text-align: center;
  padding: 3px 0 5px;
  letter-spacing: 0.3px;
  display: none;
}
@media (max-width: 900px) {
  .lang-table-scroll-hint { display: block; }
}

/* 드릴 카드 아코디언 토글 아이콘 */
.drill-toggle-icon {
  margin-left: auto;
  font-size: 12px;
  color: var(--text3);
  transition: transform 0.2s;
}

/* ─── ENCOURAGE / STREAK SYSTEM ──────────────────────── */

/* 스트릭 카운터 (우상단 고정) */
@keyframes streak-pop {
  0%   { transform: scale(0.5); opacity: 0; }
  60%  { transform: scale(1.25); }
  100% { transform: scale(1); opacity: 1; }
}

.streak-indicator {
  position: fixed;
  top: 60px;
  right: 16px;
  z-index: 10001;
  background: linear-gradient(135deg, #ff6b35, #f7c948);
  color: white;
  font-size: 18px;
  font-weight: 900;
  padding: 8px 14px;
  border-radius: 20px;
  box-shadow: 0 4px 16px rgba(255, 107, 53, 0.4);
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.2s;
  letter-spacing: -0.5px;
}
.streak-indicator.visible {
  opacity: 1;
  animation: streak-pop 0.35s cubic-bezier(0.34, 1.56, 0.64, 1) forwards;
}
.streak-indicator.hot {
  background: linear-gradient(135deg, #ff2d2d, #ff6b35);
  box-shadow: 0 4px 20px rgba(255, 45, 45, 0.5);
  font-size: 20px;
}

/* 스트릭 토스트 (상단 중앙) */
@keyframes streak-toast-in-out {
  0%   { transform: translateX(-50%) translateY(-30px); opacity: 0; }
  15%  { transform: translateX(-50%) translateY(0); opacity: 1; }
  75%  { transform: translateX(-50%) translateY(0); opacity: 1; }
  100% { transform: translateX(-50%) translateY(-20px); opacity: 0; }
}

.streak-toast {
  position: fixed;
  left: 50%;
  top: 70px;
  z-index: 10001;
  background: linear-gradient(135deg, #ff6b35, #f7c948);
  color: white;
  font-size: 14px;
  font-weight: 800;
  padding: 10px 22px;
  border-radius: 20px;
  box-shadow: 0 6px 20px rgba(255, 107, 53, 0.45);
  white-space: nowrap;
  pointer-events: none;
  animation: streak-toast-in-out 2.5s ease forwards;
}

/* 오답 셰이크 애니메이션 */
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  15%  { transform: translateX(-8px); }
  30%  { transform: translateX(8px); }
  45%  { transform: translateX(-6px); }
  60%  { transform: translateX(6px); }
  75%  { transform: translateX(-3px); }
  90%  { transform: translateX(3px); }
}
.shake-anim {
  animation: shake 0.5s ease forwards;
}

/* q-drill-count: 드릴 개수 태그 — 오른쪽에 여백 확보 */
.q-drill-count {
  font-size: 11px;
  color: var(--accent);
  font-weight: 700;
  margin-right: 8px;
}

/* 진행중 / 완료 태그 왼쪽 여백 */
.q-partial-tag, .q-done-tag {
  margin-left: 6px;
}

/* ─── CONFETTI 파티클 애니메이션 강화 ────────────────── */

/* 개별 파티클: 중앙에서 바깥으로 터져나가는 burst */
@keyframes burst-out {
  0%   { transform: translate(0, 0) scale(1.2) rotate(0deg); opacity: 1; }
  40%  { opacity: 1; }
  70%  { transform: translate(calc(var(--tx) * 0.85), calc(var(--ty) * 0.85)) scale(0.8) rotate(calc(var(--rot) * 0.7)); opacity: 0.9; }
  100% { transform: translate(var(--tx), var(--ty)) scale(0) rotate(var(--rot)); opacity: 0; }
}

/* 폭죽 터질 때 중심 플래시 */
@keyframes flash-pop {
  0%   { transform: scale(0); opacity: 0.9; }
  40%  { transform: scale(1.4); opacity: 0.7; }
  100% { transform: scale(2.5); opacity: 0; }
}

/* 별 모양 파티클 (milestone용) */
@keyframes star-burst {
  0%   { transform: translate(0,0) scale(1.2) rotate(0deg); opacity: 1; }
  70%  { opacity: 0.9; }
  100% { transform: translate(var(--tx), var(--ty)) scale(0) rotate(var(--rot)); opacity: 0; }
}

/* 리본 스트리머 */
@keyframes streamer-fall {
  0%   { transform: translate(var(--sx), var(--sy)) scaleY(0) rotate(var(--sr)); opacity: 1; }
  20%  { transform: translate(var(--sx), var(--sy)) scaleY(1) rotate(var(--sr)); opacity: 1; }
  100% { transform: translate(var(--ex), var(--ey)) scaleY(1) rotate(var(--er)); opacity: 0; }
}

.confetti-burst-container {
  position: fixed;
  z-index: 9999;
  pointer-events: none;
  /* 중앙 좌표는 JS에서 left/top으로 설정 */
}

.burst-flash {
  position: fixed;
  border-radius: 50%;
  pointer-events: none;
  z-index: 12000;
  animation: flash-pop 0.4s ease-out forwards;
}

.burst-particle {
  position: fixed;
  border-radius: 50%;
  pointer-events: none;
  z-index: 12001;
  animation: burst-out ease-out forwards;
}

.burst-star {
  position: fixed;
  pointer-events: none;
  z-index: 12001;
  animation: star-burst ease-out forwards;
  clip-path: polygon(50% 0%, 61% 35%, 98% 35%, 68% 57%, 79% 91%, 50% 70%, 21% 91%, 32% 57%, 2% 35%, 39% 35%);
}

.burst-streamer {
  position: fixed;
  pointer-events: none;
  z-index: 12001;
  border-radius: 2px;
  animation: streamer-fall ease-out forwards;
}

/* 완료 메시지 토스트 */
@keyframes toast-in-out {
  0%   { transform: translateX(-50%) translateY(20px); opacity: 0; }
  15%  { transform: translateX(-50%) translateY(0); opacity: 1; }
  75%  { transform: translateX(-50%) translateY(0); opacity: 1; }
  100% { transform: translateX(-50%) translateY(-10px); opacity: 0; }
}

.confetti-toast {
  position: fixed;
  left: 50%;
  bottom: 90px;
  z-index: 10000;
  background: var(--surface);
  border: 2px solid var(--green-border);
  border-radius: 16px;
  padding: 12px 24px;
  font-size: 15px;
  font-weight: 700;
  color: var(--green);
  box-shadow: 0 8px 24px rgba(0,0,0,0.15);
  white-space: normal;
  text-align: center;
  pointer-events: none;
  animation: toast-in-out 2.8s ease forwards;
}

.confetti-toast .ct-main { font-size: 15px; font-weight: 900; color: var(--green); line-height: 1.25; }
.confetti-toast .ct-sub { font-size: 12px; font-weight: 700; color: var(--text2); margin-top: 4px; line-height: 1.35; }

/* ─── 하단 고정 드릴 진행바 ───────────────────────── */
.drill-progress-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 300;
  background: var(--surface);
  border-top: 1px solid var(--border);
  padding: 8px 20px;
  box-shadow: 0 -2px 8px rgba(0,0,0,0.06);
}
.dpb-inner {
  max-width: 960px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 10px;
}
.dpb-label {
  font-size: 11px;
  font-weight: 700;
  color: var(--text3);
  white-space: nowrap;
  letter-spacing: 0.3px;
}
.dpb-track {
  flex: 1;
  height: 6px;
  background: var(--border);
  border-radius: 3px;
  overflow: hidden;
}
.dpb-fill {
  height: 100%;
  background: var(--green);
  border-radius: 3px;
  transition: width 0.4s ease;
}
.dpb-count {
  font-size: 12px;
  font-weight: 700;
  color: var(--green);
  white-space: nowrap;
  font-family: 'JetBrains Mono', monospace;
  min-width: 42px;
  text-align: right;
}

/* practice 화면에서 하단 여백 확보 (진행바 높이만큼) */
#screen-practice .practice-main {
  padding-bottom: 60px;
}

/* ─── 🎉 큰 격려 메시지 오버레이 (화면 채우기!) ─────── */
.big-encourage-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.7);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  animation: encourage-fade-in 0.3s ease;
}

.big-encourage-overlay.fade-out {
  animation: encourage-fade-out 0.5s ease forwards;
}

.big-encourage-content {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  padding: 60px 80px;
  border-radius: 30px;
  box-shadow: 0 30px 80px rgba(0, 0, 0, 0.5);
  text-align: center;
  animation: encourage-bounce 0.6s cubic-bezier(0.68, -0.55, 0.265, 1.55);
  max-width: 90vw;
}

.big-encourage-main {
  font-size: clamp(42px, 8vw, 72px);
  font-weight: 900;
  color: white;
  margin-bottom: 16px;
  text-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
  letter-spacing: -0.5px;
}

.big-encourage-sub {
  font-size: clamp(20px, 3vw, 32px);
  color: rgba(255, 255, 255, 0.95);
  font-weight: 600;
  text-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
}

@keyframes encourage-fade-in {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

@keyframes encourage-fade-out {
  to {
    opacity: 0;
  }
}

@keyframes encourage-bounce {
  0% {
    transform: scale(0.3) rotate(-5deg);
    opacity: 0;
  }
  50% {
    transform: scale(1.05) rotate(2deg);
  }
  70% {
    transform: scale(0.95) rotate(-1deg);
  }
  100% {
    transform: scale(1) rotate(0deg);
    opacity: 1;
  }
}

/* ─── 🔥 강화된 스트릭 인디케이터 ─────── */
.streak-indicator {
  position: fixed;
  top: 70px;
  right: 20px;
  background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
  color: white;
  padding: 12px 20px;
  border-radius: 50px;
  font-size: 20px;
  font-weight: 900;
  box-shadow: 0 8px 24px rgba(245, 87, 108, 0.4);
  z-index: 500;
  opacity: 0;
  transform: translateY(-20px) scale(0.8);
  transition: all 0.3s cubic-bezier(0.68, -0.55, 0.265, 1.55);
  pointer-events: none;
  font-family: 'JetBrains Mono', monospace;
  letter-spacing: 1px;
}

.streak-indicator.visible {
  opacity: 1;
  transform: translateY(0) scale(1);
}

.streak-indicator.hot {
  background: linear-gradient(135deg, #f6d365 0%, #fda085 100%);
  box-shadow: 0 8px 32px rgba(253, 160, 133, 0.6);
  animation: streak-pulse 1s ease-in-out infinite;
}

.streak-indicator.mega-hot {
  background: linear-gradient(135deg, #fa709a 0%, #fee140 100%);
  box-shadow: 0 8px 40px rgba(254, 225, 64, 0.8);
  animation: streak-mega-pulse 0.8s ease-in-out infinite;
}

@keyframes streak-pulse {
  0%, 100% {
    transform: translateY(0) scale(1);
  }
  50% {
    transform: translateY(-5px) scale(1.05);
  }
}

@keyframes streak-mega-pulse {
  0%, 100% {
    transform: translateY(0) scale(1) rotate(0deg);
    box-shadow: 0 8px 40px rgba(254, 225, 64, 0.8);
  }
  25% {
    transform: translateY(-8px) scale(1.1) rotate(2deg);
    box-shadow: 0 12px 50px rgba(254, 225, 64, 1);
  }
  75% {
    transform: translateY(-8px) scale(1.1) rotate(-2deg);
    box-shadow: 0 12px 50px rgba(254, 225, 64, 1);
  }
}

/* RESPONSIVE */
@media (max-width: 900px) {
  .practice-layout {
    grid-template-columns: 1fr;
    grid-template-areas: "concept" "main";
  }
  .practice-concept-panel {
    position: static;
    max-height: none;
    border-right: none;
    border-bottom: 1px solid var(--border);
  }
  .practice-main { border-left: none; }
}
@media (max-width: 768px) {
  .category-grid { grid-template-columns: repeat(2, 1fr); }
  .how-to-grid { grid-template-columns: repeat(2, 1fr); }
  .practice-main { padding: 16px; }
}
@media (max-width: 480px) {
  .category-grid { grid-template-columns: 1fr; }
  .options-grid { grid-template-columns: 1fr; }
}
/* PRACTICE MODE — 모바일에서 로고 숨기고 버튼 2개만 */
@media (max-width: 600px) {
  .topbar.practice-mode .logo {
    display: none;
  }
  .topbar.practice-mode .topbar-nav {
    width: 100%;
    justify-content: space-between;
  }
  .topbar.practice-mode .btn-nav-top {
    flex: 1;
    text-align: center;
  }
}