:root {
  --bg-dark: #0f172a;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --accent: #FFD700;
  --panel-bg: rgba(15, 23, 42, 0.6);
}

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

body {
  font-family: 'Inter', 'Noto Sans JP', sans-serif;
  background-color: var(--bg-dark);
  color: var(--text-main);
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  overflow: hidden;
  position: relative;
}

/* 背景エフェクト */
.background-blur {
  position: absolute;
  top: -10%;
  left: -10%;
  width: 120%;
  height: 120%;
  background-size: cover;
  background-position: center;
  filter: blur(40px) brightness(0.4);
  z-index: 1;
  transition: background-image 0.5s ease;
}

.background-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, rgba(15, 23, 42, 0.7) 0%, rgba(15, 23, 42, 0.9) 100%);
  z-index: 2;
}

/* プレイヤーコンテナ */
.player-container {
  position: relative;
  z-index: 10;
  width: 100%;
  max-width: 480px;
  padding: 2rem;
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.header {
  text-align: center;
  margin-bottom: 1rem;
}

.logo {
  font-size: 1rem;
  font-weight: 700;
  color: var(--accent);
  text-decoration: none;
  letter-spacing: 2px;
}

.player-content {
  background: var(--panel-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 24px;
  padding: 2rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.4);
}

.artwork-container {
  width: 100%;
  max-width: 280px;
  aspect-ratio: 1/1;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
  margin-bottom: 2rem;
}

.artwork-container img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s ease;
}

.playing .artwork-container img {
  transform: scale(1.05);
}

.track-info {
  text-align: center;
  width: 100%;
  margin-bottom: 1.5rem;
}

#trackTitle {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  color: #fff;
}

#albumArtist {
  font-size: 0.9rem;
  font-weight: 400;
  color: var(--text-muted);
}

.progress-container {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 1rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 2rem;
}

input[type="range"] {
  -webkit-appearance: none;
  width: 100%;
  height: 4px;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 2px;
  outline: none;
  cursor: pointer;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 12px;
  height: 12px;
  background: var(--accent);
  border-radius: 50%;
  cursor: pointer;
  transition: transform 0.1s;
}

input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.2);
}

.controls {
  display: flex;
  justify-content: center;
  align-items: center;
  margin-bottom: 1.5rem;
}

.play-btn {
  background: var(--accent);
  color: var(--bg-dark);
  border: none;
  width: 64px;
  height: 64px;
  border-radius: 50%;
  font-size: 1.5rem;
  cursor: pointer;
  display: flex;
  justify-content: center;
  align-items: center;
  transition: all 0.2s;
  box-shadow: 0 4px 15px rgba(255, 215, 0, 0.3);
}

.play-btn:hover {
  transform: scale(1.05);
  box-shadow: 0 6px 20px rgba(255, 215, 0, 0.4);
}

.play-btn:active {
  transform: scale(0.95);
}

.play-btn.loading {
  opacity: 0.7;
  cursor: wait;
}

.volume-container {
  width: 100%;
  max-width: 200px;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.vol-icon {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.error-message {
  text-align: center;
  background: rgba(220, 38, 38, 0.1);
  border: 1px solid rgba(220, 38, 38, 0.3);
  border-radius: 12px;
  padding: 2rem;
}

.error-message h2 {
  color: #ef4444;
  margin-bottom: 1rem;
}

.back-link {
  display: inline-block;
  margin-top: 1.5rem;
  color: var(--text-main);
  text-decoration: underline;
}