/* ==========================================================================
   Beflower Design System (beflower.css) v1.0
   Project: yangseonghwa.github.io (Beflower의 과학 시뮬레이션 랩)
   Description: 사이트 전체 페이지(메인 허브, 과학 시뮬레이션, 수업 발표 슬라이드,
                학생 인쇄용 활동지, 미니 게임)의 일관된 디자인 시스템(컬러 팔레트,
                타이포그래피, 공통 헤더·네비게이션·푸터·슬라이드 컨트롤 바·컴포넌트).
   ========================================================================== */

:root {
  /* 1. Brand & Core Color Palette (Light Mode Default) */
  --bf-bg: #f4f9f6;
  --bf-surface: #ffffff;
  --bf-surface-soft: #eef7f3;
  --bf-surface-muted: #f8fcfa;
  --bf-ink: #1d2a30;
  --bf-sub: #5a6b72;
  --bf-muted: #7f9199;
  --bf-line: #d9e8e1;
  --bf-line-strong: #bdd5ca;

  /* Brand Primary & Accents */
  --bf-main: #1f8a70;          /* Beflower Emerald */
  --bf-main-hover: #176f59;
  --bf-main-soft: #e3f5ef;
  --bf-navy: #0f2a44;          /* Deep Science Navy */
  --bf-pink: #f08fb0;          /* Blossom Pink */
  --bf-pink-hover: #df7398;
  --bf-pink-soft: #fdebf1;
  --bf-sky: #0284c7;           /* Physics Sky */
  --bf-sky-soft: #e0f2fe;
  --bf-amber: #f59e0b;         /* Energy Amber */
  --bf-amber-soft: #fef3c7;
  --bf-danger: #e11d48;
  --bf-danger-soft: #ffe4e6;
  --bf-success: #10b981;
  --bf-success-soft: #d1fae5;

  /* 2. Subject & Category Tag Palette */
  --bf-tag-physics: #e3f0ff;
  --bf-tag-physics-ink: #1d4ed8;
  --bf-tag-chem: #fff0dc;
  --bf-tag-chem-ink: #b45309;
  --bf-tag-bio: #e2f6e6;
  --bf-tag-bio-ink: #15803d;
  --bf-tag-earth: #efe6ff;
  --bf-tag-earth-ink: #6d28d9;
  --bf-tag-coding: #ffe7f0;
  --bf-tag-coding-ink: #be185d;
  --bf-tag-game: #fef3c7;
  --bf-tag-game-ink: #92400e;

  /* 3. Typography Stack (Offline-safe System Font Stack) */
  --bf-font-sans: "Pretendard", "Noto Sans KR", "Malgun Gothic", "Apple SD Gothic Neo", -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
  --bf-font-mono: "JetBrains Mono", "D2Coding", "Consolas", "SFMono-Regular", monospace;

  /* 4. Elevation, Radius & Layout Tokens */
  --bf-radius-sm: 10px;
  --bf-radius-md: 14px;
  --bf-radius-lg: 20px;
  --bf-radius-xl: 26px;
  --bf-radius-pill: 999px;
  --bf-shadow-sm: 0 2px 8px rgba(15, 42, 68, 0.05);
  --bf-shadow-md: 0 8px 24px rgba(15, 42, 68, 0.08);
  --bf-shadow-lg: 0 18px 48px rgba(15, 42, 68, 0.14);
  --bf-topbar-height: 58px;
  --bf-max-width: 1120px;

  /* Legacy Variable Aliases (for backward compatibility across pages) */
  --bg: var(--bf-bg);
  --card: var(--bf-surface);
  --soft: var(--bf-surface-soft);
  --ink: var(--bf-ink);
  --sub: var(--bf-sub);
  --main: var(--bf-main);
  --pink: var(--bf-pink);
  --line: var(--bf-line);
}

/* Dark Theme Variant (for Space / Physics / Immersive Presentation Decks) */
html.bf-theme-dark,
body.bf-theme-dark,
[data-bf-theme="dark"] {
  --bf-bg: #080f1e;
  --bf-surface: #111c35;
  --bf-surface-soft: #1a2849;
  --bf-surface-muted: #0d162b;
  --bf-ink: #f8fafc;
  --bf-sub: #cbd5e1;
  --bf-muted: #94a3b8;
  --bf-line: #26365c;
  --bf-line-strong: #384f82;
  --bf-main: #34d399;
  --bf-main-hover: #10b981;
  --bf-main-soft: rgba(52, 211, 153, 0.15);
  --bf-sky: #38bdf8;
  --bf-sky-soft: rgba(56, 189, 248, 0.16);
  --bf-amber: #fbbf24;
  --bf-amber-soft: rgba(251, 191, 36, 0.16);
  --bf-pink: #f472b6;
  --bf-pink-soft: rgba(244, 114, 182, 0.16);
  --bf-shadow-md: 0 12px 32px rgba(0, 0, 0, 0.45);
  --bf-shadow-lg: 0 24px 60px rgba(0, 0, 0, 0.65);

  /* Re-bind Legacy Variable Aliases for Dark Theme */
  --bg: var(--bf-bg);
  --card: var(--bf-surface);
  --soft: var(--bf-surface-soft);
  --ink: var(--bf-ink);
  --sub: var(--bf-sub);
  --main: var(--bf-main);
  --pink: var(--bf-pink);
  --line: var(--bf-line);
}

/* ==========================================================================
   Base Reset & Typography
   ========================================================================== */
*, *::before, *::after {
  box-sizing: border-box;
}

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

body {
  margin: 0;
  font-family: var(--bf-font-sans);
  background-color: var(--bf-bg);
  color: var(--bf-ink);
  line-height: 1.65;
}

/* ==========================================================================
   1. Unified Global Top Navigation Bar (.bf-topbar)
   ========================================================================== */
.bf-topbar {
  position: sticky;
  top: 0;
  z-index: 100;
  width: 100%;
  min-height: var(--bf-topbar-height);
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--bf-line);
  padding: 8px 16px;
  display: flex;
  align-items: center;
  justify-content: center;
}

body.bf-theme-dark .bf-topbar,
[data-bf-theme="dark"] .bf-topbar,
.bf-topbar.bf-topbar-dark {
  background: rgba(8, 15, 30, 0.88);
  border-bottom-color: rgba(148, 163, 184, 0.2);
  color: #f1f5f9;
}

.bf-topbar.bf-topbar-fixed {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
}

.bf-topbar-inner {
  width: 100%;
  max-width: 1240px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}

.bf-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: inherit;
  min-width: 0;
}

.bf-brand-logo {
  width: 34px;
  height: 34px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--bf-navy), var(--bf-main) 65%, var(--bf-pink));
  color: #ffffff;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  font-weight: 800;
  flex-shrink: 0;
  box-shadow: 0 3px 10px rgba(31, 138, 112, 0.28);
}

.bf-brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.25;
  min-width: 0;
}

.bf-brand-title {
  font-size: 15px;
  font-weight: 800;
  letter-spacing: -0.3px;
  color: var(--bf-ink);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

body.bf-theme-dark .bf-brand-title,
[data-bf-theme="dark"] .bf-brand-title,
.bf-topbar.bf-topbar-dark .bf-brand-title {
  color: #ffffff;
}

.bf-brand-sub {
  font-size: 11.5px;
  color: var(--bf-sub);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

html.bf-theme-dark .bf-brand-sub,
body.bf-theme-dark .bf-brand-sub,
[data-bf-theme="dark"] .bf-brand-sub,
.bf-topbar.bf-topbar-dark .bf-brand-sub {
  color: #cbd5e1;
}

.bf-nav {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
}

.bf-nav a {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 6px 12px;
  border-radius: var(--bf-radius-pill);
  font-size: 13px;
  font-weight: 700;
  color: var(--bf-sub);
  text-decoration: none;
  border: 1px solid transparent;
  transition: all 0.18s ease;
  white-space: nowrap;
}

.bf-nav a:hover,
.bf-nav a:focus-visible {
  color: var(--bf-main);
  background: var(--bf-main-soft);
  border-color: rgba(31, 138, 112, 0.25);
  outline: none;
}

.bf-nav a.active,
.bf-nav a[aria-current="page"] {
  background: var(--bf-main);
  color: #ffffff;
  border-color: var(--bf-main);
}

body.bf-theme-dark .bf-nav a,
[data-bf-theme="dark"] .bf-nav a,
.bf-topbar.bf-topbar-dark .bf-nav a {
  color: #cbd5e1;
}

body.bf-theme-dark .bf-nav a:hover,
[data-bf-theme="dark"] .bf-nav a:hover,
.bf-topbar.bf-topbar-dark .bf-nav a:hover {
  color: #38bdf8;
  background: rgba(56, 189, 248, 0.15);
  border-color: rgba(56, 189, 248, 0.35);
}

body.bf-theme-dark .bf-nav a.active,
[data-bf-theme="dark"] .bf-nav a.active,
.bf-topbar.bf-topbar-dark .bf-nav a.active {
  background: #0284c7;
  color: #ffffff;
  border-color: #38bdf8;
}

.bf-topbar-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

/* ==========================================================================
   2. Standardized Page Hero / Header (.bf-page-header)
   ========================================================================== */
.bf-page-header {
  position: relative;
  overflow: hidden;
  background: linear-gradient(135deg, var(--bf-navy), var(--bf-main) 68%, var(--bf-pink));
  color: #ffffff;
  padding: 28px 20px 32px;
  border-radius: 0 0 28px 28px;
  box-shadow: var(--bf-shadow-md);
  text-align: center;
  margin-bottom: 22px;
}

.bf-page-header-inner {
  position: relative;
  z-index: 2;
  max-width: 860px;
  margin: 0 auto;
}

.bf-page-kicker {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 14px;
  border-radius: var(--bf-radius-pill);
  background: rgba(255, 255, 255, 0.18);
  border: 1px solid rgba(255, 255, 255, 0.38);
  backdrop-filter: blur(6px);
  font-size: 13px;
  font-weight: 700;
  color: #ffffff;
  margin-bottom: 10px;
}

.bf-page-header h1 {
  margin: 0 0 8px;
  font-size: clamp(24px, 4.5vw, 38px);
  font-weight: 800;
  letter-spacing: -0.5px;
  color: #ffffff;
  line-height: 1.25;
  text-shadow: 0 2px 12px rgba(0, 0, 0, 0.25);
}

.bf-page-header p {
  margin: 0 auto;
  max-width: 680px;
  font-size: clamp(14px, 2vw, 17px);
  color: rgba(255, 255, 255, 0.92);
}

/* ==========================================================================
   3. Containers, Cards, Badges, Buttons & Callouts
   ========================================================================== */
.bf-container {
  max-width: var(--bf-max-width);
  margin: 0 auto;
  padding: 0 16px;
}

.bf-card {
  background: var(--bf-surface);
  border: 1px solid var(--bf-line);
  border-radius: var(--bf-radius-lg);
  padding: 22px;
  box-shadow: var(--bf-shadow-md);
}

.bf-badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 12px;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: var(--bf-radius-pill);
  background: var(--bf-surface-soft);
  color: var(--bf-main);
}

.bf-badge.물리, .bf-badge.physics { background: var(--bf-tag-physics); color: var(--bf-tag-physics-ink); }
.bf-badge.화학, .bf-badge.chem    { background: var(--bf-tag-chem); color: var(--bf-tag-chem-ink); }
.bf-badge.생명, .bf-badge.bio     { background: var(--bf-tag-bio); color: var(--bf-tag-bio-ink); }
.bf-badge.지구과학, .bf-badge.earth { background: var(--bf-tag-earth); color: var(--bf-tag-earth-ink); }
.bf-badge.코딩, .bf-badge.coding  { background: var(--bf-tag-coding); color: var(--bf-tag-coding-ink); }
.bf-badge.게임, .bf-badge.game    { background: var(--bf-tag-game); color: var(--bf-tag-game-ink); }

.bf-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 9px 18px;
  border-radius: var(--bf-radius-pill);
  border: 1.5px solid var(--bf-main);
  background: var(--bf-surface);
  color: var(--bf-main);
  font-family: inherit;
  font-size: 14px;
  font-weight: 700;
  cursor: pointer;
  text-decoration: none;
  transition: all 0.16s ease;
}

.bf-btn:hover {
  transform: translateY(-1px);
  background: var(--bf-main-soft);
}

.bf-btn.bf-btn-primary {
  background: var(--bf-main);
  color: #ffffff;
  border-color: var(--bf-main);
  box-shadow: 0 4px 12px rgba(31, 138, 112, 0.25);
}

.bf-btn.bf-btn-primary:hover {
  background: var(--bf-main-hover);
  border-color: var(--bf-main-hover);
}

.bf-btn.bf-btn-accent {
  background: var(--bf-pink);
  color: #ffffff;
  border-color: var(--bf-pink);
  box-shadow: 0 4px 12px rgba(240, 143, 176, 0.35);
}

.bf-callout {
  border-left: 5px solid var(--bf-main);
  background: var(--bf-surface-soft);
  border-radius: var(--bf-radius-md);
  padding: 12px 16px;
  margin: 12px 0;
  font-size: 14.5px;
}

.bf-callout.warn {
  border-left-color: var(--bf-amber);
  background: var(--bf-amber-soft);
  color: #78350f;
}

/* ==========================================================================
   4. Standardized Presentation Slide Bottom Bar (.bf-slide-bar)
   ========================================================================== */
.bf-slide-bar {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  height: 56px;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 0 16px;
  background: rgba(15, 42, 68, 0.88);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-top: 1px solid rgba(255, 255, 255, 0.15);
  color: #ffffff;
  z-index: 90;
}

.bf-slide-bar a,
.bf-slide-bar button {
  border: 1px solid rgba(255, 255, 255, 0.35);
  background: rgba(255, 255, 255, 0.12);
  color: #ffffff;
  border-radius: 10px;
  padding: 7px 14px;
  font: inherit;
  font-size: 13.5px;
  font-weight: 700;
  cursor: pointer;
  text-decoration: none;
  white-space: nowrap;
  transition: all 0.15s ease;
}

.bf-slide-bar a:hover,
.bf-slide-bar button:hover {
  background: rgba(255, 255, 255, 0.25);
  border-color: var(--bf-pink);
}

.bf-slide-prog {
  flex: 1;
  height: 7px;
  background: rgba(255, 255, 255, 0.22);
  border-radius: var(--bf-radius-pill);
  overflow: hidden;
}

.bf-slide-prog > i {
  display: block;
  height: 100%;
  width: 0;
  background: linear-gradient(90deg, var(--bf-main), var(--bf-pink));
  transition: width 0.3s ease;
}

/* ==========================================================================
   5. Unified Site Footer (.bf-footer)
   ========================================================================== */
.bf-footer {
  margin-top: 40px;
  padding: 28px 16px 40px;
  border-top: 1px solid var(--bf-line);
  text-align: center;
  color: var(--bf-sub);
  font-size: 13.5px;
  background: rgba(255, 255, 255, 0.55);
}

body.bf-theme-dark .bf-footer,
[data-bf-theme="dark"] .bf-footer {
  background: rgba(8, 15, 30, 0.7);
  border-top-color: rgba(148, 163, 184, 0.2);
}

.bf-footer-inner {
  max-width: var(--bf-max-width);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
}

.bf-footer-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px 16px;
}

.bf-footer-links a {
  color: var(--bf-sub);
  text-decoration: none;
  font-weight: 600;
  transition: color 0.15s ease;
}

.bf-footer-links a:hover {
  color: var(--bf-main);
}

/* ==========================================================================
   6. Responsive & Print Rules
   ========================================================================== */
@media (max-width: 680px) {
  .bf-topbar {
    padding: 8px 12px;
  }
  .bf-brand-sub {
    display: none;
  }
  .bf-nav a {
    padding: 5px 9px;
    font-size: 12px;
  }
  .bf-slide-bar {
    gap: 6px;
    padding: 0 8px;
  }
  .bf-slide-bar a,
  .bf-slide-bar button {
    padding: 6px 9px;
    font-size: 12px;
  }
}

@media print {
  .bf-topbar,
  .bf-slide-bar,
  .bf-footer,
  .no-print {
    display: none !important;
  }
  body {
    background: #ffffff !important;
    color: #000000 !important;
    overflow: visible !important;
  }
}