@import url('https://fonts.googleapis.com/css2?family=Bricolage+Grotesque:opsz,wdth,wght@12..96,75..100,200..800&family=Noto+Sans+JP:wght@300;400;500;700;900&family=Outfit:wght@300;400;500;600;700;800&display=swap');

:root {
  /* Transitions */
  --transition-speed: 0.4s;
  --transition-bounce: cubic-bezier(0.34, 1.56, 0.64, 1);
  --transition-smooth: cubic-bezier(0.4, 0, 0.2, 1);

  /* Light Theme - Sakura & Cream Minimalist */
  --bg-primary: hsl(30, 24%, 96%);
  --bg-secondary: hsl(0, 0%, 100%);
  --bg-tertiary: hsl(30, 15%, 88%);
  --text-primary: hsl(340, 20%, 15%);
  --text-secondary: hsl(340, 10%, 45%);
  --accent: hsl(350, 75%, 62%); /* Sakura Pink */
  --accent-light: hsl(350, 75%, 95%);
  --accent-hover: hsl(350, 75%, 52%);
  --border-color: hsl(30, 15%, 88%);
  --card-shadow: 0 10px 30px -10px rgba(139, 92, 26, 0.08), 0 4px 12px -5px rgba(139, 92, 26, 0.03);
  --glass-bg: rgba(255, 255, 255, 0.75);
  --glass-border: rgba(255, 255, 255, 0.5);
  
  /* Gradient colors */
  --gradient-start: hsl(350, 75%, 62%);
  --gradient-end: hsl(15, 85%, 60%);
}

[data-theme="dark"] {
  /* Dark Theme - Sumi Ink & Crimson */
  --bg-primary: hsl(240, 12%, 6%);
  --bg-secondary: hsl(240, 12%, 10%);
  --bg-tertiary: hsl(240, 8%, 18%);
  --text-primary: hsl(40, 20%, 95%);
  --text-secondary: hsl(240, 5%, 70%);
  --accent: hsl(352, 85%, 60%); /* Crimson Red */
  --accent-light: hsl(352, 30%, 15%);
  --accent-hover: hsl(352, 85%, 68%);
  --border-color: hsl(240, 8%, 16%);
  --card-shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.5), 0 4px 12px -5px rgba(0, 0, 0, 0.3);
  --glass-bg: rgba(18, 18, 24, 0.75);
  --glass-border: rgba(255, 255, 255, 0.03);

  --gradient-start: hsl(352, 85%, 60%);
  --gradient-end: hsl(352, 100%, 72%);
}

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

body {
  font-family: 'Outfit', 'Noto Sans JP', sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  transition: background-color var(--transition-speed) var(--transition-smooth), 
              color var(--transition-speed) var(--transition-smooth);
  min-height: 100vh;
  overflow-x: hidden;
}

/* Glassmorphism Header */
header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  padding: 1.2rem 2rem;
  background: var(--glass-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--glass-border);
  z-index: 1000;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: background-color var(--transition-speed) var(--transition-smooth),
              border-color var(--transition-speed) var(--transition-smooth);
}

.logo {
  font-family: 'Bricolage Grotesque', sans-serif;
  font-size: 1.5rem;
  font-weight: 800;
  letter-spacing: -0.5px;
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
}

.logo-icon {
  font-size: 1.8rem;
  animation: pulse 3s infinite ease-in-out;
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.1) rotate(10deg); }
}

/* Theme Toggle */
.theme-switch-wrapper {
  display: flex;
  align-items: center;
  gap: 8px;
}

.theme-switch {
  display: inline-block;
  height: 34px;
  position: relative;
  width: 64px;
}

.theme-switch input {
  display: none;
}

.slider {
  background-color: var(--bg-tertiary);
  bottom: 0;
  cursor: pointer;
  left: 0;
  position: absolute;
  right: 0;
  top: 0;
  transition: background-color var(--transition-speed) var(--transition-smooth);
  border-radius: 34px;
  border: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 6px;
}

.slider:before {
  background-color: var(--bg-secondary);
  bottom: 3px;
  content: "";
  height: 26px;
  left: 3px;
  position: absolute;
  transition: transform var(--transition-speed) var(--transition-bounce),
              background-color var(--transition-speed) var(--transition-smooth);
  width: 26px;
  border-radius: 50%;
  z-index: 2;
  box-shadow: 0 2px 5px rgba(0,0,0,0.2);
}

input:checked + .slider {
  background-color: var(--accent);
}

input:checked + .slider:before {
  transform: translateX(30px);
}

.slider-icons {
  display: flex;
  justify-content: space-between;
  width: 100%;
  font-size: 1.1rem;
  z-index: 1;
  pointer-events: none;
}

.slider-icons span {
  width: 26px;
  height: 26px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform var(--transition-speed) var(--transition-bounce);
}

input:checked + .slider .icon-sun {
  transform: scale(0.6) rotate(90deg);
  opacity: 0.3;
}
input:not(:checked) + .slider .icon-moon {
  transform: scale(0.6) rotate(-90deg);
  opacity: 0.3;
}

/* Hero Section */
.hero {
  margin-top: 80px;
  padding: 5rem 2rem 3rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero-gradient-overlay {
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, var(--accent-light) 0%, transparent 60%);
  z-index: -1;
  opacity: 0.6;
  pointer-events: none;
  transition: background var(--transition-speed) var(--transition-smooth);
}

.hero h1 {
  font-family: 'Bricolage Grotesque', sans-serif;
  font-size: 3.5rem;
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: 1rem;
  letter-spacing: -1.5px;
}

.hero h1 span {
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero p {
  font-size: 1.2rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
  line-height: 1.6;
}

/* Daily Expression Widget (오늘의 표현) */
.daily-widget-container {
  max-width: 600px;
  margin: 2rem auto 0;
}

.daily-card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 24px;
  padding: 1.8rem;
  box-shadow: var(--card-shadow);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  transition: all 0.3s var(--transition-smooth);
  position: relative;
  overflow: hidden;
}

.daily-card::before {
  content: "今日";
  position: absolute;
  right: -10px;
  bottom: -20px;
  font-size: 5rem;
  font-weight: 900;
  color: var(--border-color);
  opacity: 0.25;
  font-family: 'Noto Sans JP', sans-serif;
  pointer-events: none;
}

.daily-content {
  text-align: left;
}

.daily-tag {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--accent);
  background-color: var(--accent-light);
  padding: 0.3rem 0.8rem;
  border-radius: 50px;
  display: inline-block;
  margin-bottom: 0.8rem;
}

.daily-jp {
  font-size: 2.2rem;
  font-weight: 900;
  font-family: 'Noto Sans JP', sans-serif;
  line-height: 1.2;
  margin-bottom: 0.3rem;
}

.daily-reading {
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
  font-weight: 500;
}

.daily-kr {
  font-size: 1.15rem;
  font-weight: 600;
}

.daily-audio-btn {
  background: var(--accent-light);
  border: none;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: var(--accent);
  transition: all 0.2s var(--transition-smooth);
  z-index: 1;
}

.daily-audio-btn:hover {
  background-color: var(--accent);
  color: white;
  transform: scale(1.08);
}

/* Dashboard Grid */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem 5rem;
}

.dashboard-grid {
  display: grid;
  grid-template-columns: 1.8fr 1.2fr;
  gap: 2.5rem;
}

@media (max-width: 900px) {
  .dashboard-grid {
    grid-template-columns: 1fr;
  }
}

.card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 24px;
  padding: 2.2rem;
  box-shadow: var(--card-shadow);
  transition: background-color var(--transition-speed) var(--transition-smooth),
              border-color var(--transition-speed) var(--transition-smooth),
              box-shadow var(--transition-speed) var(--transition-smooth);
}

.card-title {
  font-family: 'Bricolage Grotesque', sans-serif;
  font-size: 1.5rem;
  font-weight: 800;
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  letter-spacing: -0.5px;
}

/* 3D Flashcard System */
.flashcards-container {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.mode-selector {
  display: flex;
  gap: 0.5rem;
  background-color: var(--bg-primary);
  padding: 0.4rem;
  border-radius: 14px;
  border: 1px solid var(--border-color);
}

.mode-btn {
  flex: 1;
  background: none;
  border: none;
  padding: 0.6rem;
  border-radius: 10px;
  font-family: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.3s var(--transition-smooth);
}

.mode-btn.active {
  background-color: var(--bg-secondary);
  color: var(--accent);
  box-shadow: var(--card-shadow);
}

/* Flashcard Grid */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
  gap: 1rem;
}

/* 3D Flip Card Styles */
.flip-card {
  background-color: transparent;
  height: 140px;
  perspective: 1000px; /* Enable 3D depth */
  cursor: pointer;
}

.flip-card-inner {
  position: relative;
  width: 100%;
  height: 100%;
  text-align: center;
  transition: transform 0.6s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  transform-style: preserve-3d;
  box-shadow: var(--card-shadow);
  border-radius: 16px;
}

.flip-card.flipped .flip-card-inner {
  transform: rotateY(180deg);
}

.flip-card-front, .flip-card-back {
  position: absolute;
  width: 100%;
  height: 100%;
  -webkit-backface-visibility: hidden; /* Safari */
  backface-visibility: hidden;
  border-radius: 16px;
  border: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.flip-card-front {
  background-color: var(--bg-secondary);
  color: var(--text-primary);
}

.flip-card-back {
  background-color: var(--accent-light);
  color: var(--accent);
  transform: rotateY(180deg);
}

.card-jp {
  font-size: 2.8rem;
  font-weight: 800;
  font-family: 'Noto Sans JP', sans-serif;
  line-height: 1;
}

.card-reading {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-top: 0.3rem;
}

.card-kr {
  font-size: 1.3rem;
  font-weight: 700;
}

.card-hint {
  font-size: 0.75rem;
  margin-top: 0.4rem;
  opacity: 0.8;
}

/* Word Notebook (단어장) */
.notebook-wrapper {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
}

.input-row {
  display: grid;
  grid-template-columns: 1fr 1.2fr auto;
  gap: 0.5rem;
}

.input-row input {
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 0.8rem;
  font-family: inherit;
  font-size: 0.95rem;
  color: var(--text-primary);
  transition: all 0.3s var(--transition-smooth);
}

.input-row input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-light);
}

.btn-add-word {
  background-color: var(--accent);
  color: #fff;
  border: none;
  border-radius: 12px;
  padding: 0.8rem 1.2rem;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s var(--transition-smooth);
}

.btn-add-word:hover {
  background-color: var(--accent-hover);
}

/* List styling */
.word-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  max-height: 380px;
  overflow-y: auto;
}

.word-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background-color: var(--bg-primary);
  padding: 0.8rem 1.2rem;
  border-radius: 12px;
  border: 1px solid var(--border-color);
  transition: all 0.3s var(--transition-smooth);
  animation: slideIn 0.3s var(--transition-bounce) forwards;
}

.word-content {
  display: flex;
  align-items: baseline;
  gap: 0.8rem;
  flex: 1;
}

.word-jp-text {
  font-size: 1.25rem;
  font-weight: 700;
  font-family: 'Noto Sans JP', sans-serif;
}

.word-kr-text {
  font-size: 0.95rem;
  color: var(--text-secondary);
}

.btn-word-delete {
  background: none;
  border: none;
  color: var(--text-secondary);
  font-size: 1.1rem;
  cursor: pointer;
  padding: 0.2rem;
  border-radius: 6px;
  transition: all 0.2s var(--transition-smooth);
  display: flex;
  align-items: center;
  justify-content: center;
}

.btn-word-delete:hover {
  color: hsl(0, 80%, 60%);
  background-color: rgba(239, 68, 68, 0.1);
}

.word-list::-webkit-scrollbar {
  width: 6px;
}

.word-list::-webkit-scrollbar-track {
  background: transparent;
}

.word-list::-webkit-scrollbar-thumb {
  background-color: var(--border-color);
  border-radius: 10px;
}