:root {
  --bg-gradient: linear-gradient(135deg, #0f172a, #1e1b4b, #0f172a);
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --card-bg: rgba(30, 41, 59, 0.6);
  --card-border: rgba(255, 255, 255, 0.1);
  --container-bg: rgba(15, 23, 42, 0.75);
  --container-border: rgba(255, 255, 255, 0.12);
  --container-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
  --btn-bg: linear-gradient(135deg, #6366f1, #4f46e5);
  --btn-text: #ffffff;
  --btn-hover: linear-gradient(135deg, #4f46e5, #4338ca);
  --btn-shadow: 0 10px 20px -5px rgba(99, 102, 241, 0.4);
  --toggle-bg: rgba(255, 255, 255, 0.1);
  --toggle-hover: rgba(255, 255, 255, 0.2);
  --toggle-color: #f1f5f9;
}

[data-theme="light"] {
  --bg-gradient: linear-gradient(135deg, #e0f2fe, #f0f9ff, #e0e7ff);
  --text-main: #0f172a;
  --text-muted: #475569;
  --card-bg: rgba(255, 255, 255, 0.85);
  --card-border: rgba(226, 232, 240, 0.8);
  --container-bg: rgba(255, 255, 255, 0.7);
  --container-border: rgba(255, 255, 255, 0.8);
  --container-shadow: 0 20px 40px -15px rgba(148, 163, 184, 0.3);
  --btn-bg: linear-gradient(135deg, #2563eb, #1d4ed8);
  --btn-text: #ffffff;
  --btn-hover: linear-gradient(135deg, #1d4ed8, #1e40af);
  --btn-shadow: 0 10px 20px -5px rgba(37, 99, 235, 0.3);
  --toggle-bg: rgba(0, 0, 0, 0.05);
  --toggle-hover: rgba(0, 0, 0, 0.1);
  --toggle-color: #1e293b;
}

* {
  box-sizing: border-box;
  transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}

body {
  margin: 0;
  font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg-gradient);
  background-attachment: fixed;
  color: var(--text-main);
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  padding: 1rem;
}

.container {
  width: min(100%, 500px);
  text-align: center;
  background: var(--container-bg);
  border: 1px solid var(--container-border);
  padding: 2.2rem 2rem;
  border-radius: 28px;
  box-shadow: var(--container-shadow);
  backdrop-filter: blur(16px);
}

.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.8rem;
}

h1 {
  margin: 0;
  font-size: clamp(1.8rem, 4vw, 2.2rem);
  font-weight: 800;
  letter-spacing: -0.5px;
}

.theme-toggle {
  background: var(--toggle-bg);
  color: var(--toggle-color);
  border: 1px solid var(--card-border);
  width: 42px;
  height: 42px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  padding: 0;
}

.theme-toggle:hover {
  background: var(--toggle-hover);
  transform: scale(1.08);
}

.sun-icon {
  display: none;
}

.moon-icon {
  display: block;
}

[data-theme="light"] .sun-icon {
  display: block;
}

[data-theme="light"] .moon-icon {
  display: none;
}

.description {
  margin: 0 0 1.8rem;
  line-height: 1.6;
  color: var(--text-muted);
  font-size: 0.95rem;
}

.controls {
  margin-bottom: 1.8rem;
}

.draw-btn {
  padding: 0.9rem 2rem;
  border: none;
  border-radius: 14px;
  background: var(--btn-bg);
  color: var(--btn-text);
  font-size: 1.05rem;
  font-weight: 700;
  cursor: pointer;
  box-shadow: var(--btn-shadow);
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.3s ease;
}

.draw-btn:hover {
  transform: translateY(-2px);
  background: var(--btn-hover);
}

.draw-btn:active {
  transform: translateY(0);
}

.result-card,
.info-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 20px;
  padding: 1.4rem 1.2rem;
  margin-top: 1.2rem;
}

.result-card h2 {
  margin: 0 0 1.2rem;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-main);
}

.ball-list {
  display: flex;
  justify-content: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.ball {
  width: 3.2rem;
  height: 3.2rem;
  display: grid;
  place-items: center;
  border-radius: 50%;
  color: #ffffff;
  font-weight: 800;
  font-size: 1.1rem;
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.25);
  animation: popIn 0.3s ease forwards;
}

@keyframes popIn {
  0% {
    opacity: 0;
    transform: scale(0.5);
  }
  100% {
    opacity: 1;
    transform: scale(1);
  }
}

.info-card p {
  margin: 0;
  font-size: 0.85rem;
  color: var(--text-muted);
}

@media (max-width: 480px) {
  .container {
    padding: 1.6rem 1.2rem;
  }

  .ball {
    width: 2.6rem;
    height: 2.6rem;
    font-size: 0.95rem;
  }
}