:root {
  --bg-1: #fff7d6;
  --bg-2: #d9f3ff;
  --panel: #ffffffcc;
  --line: #2f3e46;
  --ink: #1f2933;
  --accent-a: #ff7b89;
  --accent-b: #5ec2f7;
  --accent-soft: #ffe27a;
  --good: #0c9a55;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Pretendard", "Noto Sans KR", sans-serif;
  color: var(--ink);
  background: radial-gradient(circle at 15% 10%, #fffef6 0%, var(--bg-1) 35%, var(--bg-2) 100%);
  min-height: 100vh;
}

.app {
  max-width: 1200px;
  margin: 0 auto;
  padding: 12px;
}

.app-header {
  text-align: center;
  margin-bottom: 16px;
}

.app-header h1 {
  margin: 0;
  font-size: clamp(1.6rem, 3vw, 2.4rem);
}

.achievement-text {
  font-size: 0.9rem;
  line-height: 1.35;
  margin-top: 6px;
}

.layout {
  display: grid;
  grid-template-columns: minmax(280px, 360px) 1fr;
  gap: 12px;
  align-items: start;
}

.control-panel {
  position: sticky;
  top: 10px;
  max-height: calc(100vh - 20px);
  overflow: auto;
}

.panel {
  background: var(--panel);
  border: 2px solid #ffffff;
  border-radius: 18px;
  padding: 10px;
  box-shadow: 0 10px 25px #00000014;
  backdrop-filter: blur(4px);
}

.panel h2 {
  margin: 2px 0 8px;
}

.control-block {
  padding: 8px;
  margin-bottom: 8px;
  border: 2px dashed #c9def6;
  border-radius: 12px;
  background: #ffffffbd;
}

.control-block h3 {
  margin: 0 0 6px;
  font-size: 1.15rem;
}

.control-block p {
  margin: 4px 0 8px;
}

label {
  display: block;
  margin-top: 4px;
  font-weight: 600;
  line-height: 1.25;
}

.difficulty-label {
  margin-top: 14px;
}

input[type="range"] {
  width: 100%;
  accent-color: #ff9f1a;
  margin: 2px 0 4px;
}

select {
  width: 100%;
  border-radius: 10px;
  border: 2px solid #d7e3f4;
  padding: 8px;
  font-size: 1rem;
  background: #fff;
}

.shape-toggle {
  display: flex;
  flex-direction: column;
  gap: 2px;
  margin-top: 4px;
}

#unitMode {
  margin-right: 6px;
}

.quiz-buttons {
  display: grid;
  grid-template-columns: 1fr;
  gap: 8px;
  margin-bottom: 10px;
}

#startQuizBtn {
  margin-top: 6px;
  width: 100%;
}

#nextBtn {
  width: 100%;
  margin-top: 6px;
}

#stopQuizBtn {
  width: 100%;
  margin-top: 6px;
  background: #ffdfe2;
}

.progress-text {
  min-height: 18px;
  margin: 6px 0;
  font-weight: 700;
}

button {
  border: 0;
  border-radius: 12px;
  padding: 8px 12px;
  font-weight: 700;
  cursor: pointer;
  background: #eaf4ff;
  transition: transform 0.18s ease, box-shadow 0.18s ease;
}

button:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px #00000018;
}

button:focus-visible,
input:focus-visible,
select:focus-visible {
  outline: 3px solid #1f7a8c;
  outline-offset: 2px;
}

.primary {
  background: #ffcd4f;
}

.quiz-buttons button[aria-pressed="true"] {
  background: #ffcd4f;
  box-shadow: inset 0 0 0 2px var(--line);
}

.result-text {
  min-height: 24px;
  font-weight: 700;
}

.models {
  display: grid;
  grid-template-columns: repeat(2, minmax(220px, 1fr));
  gap: 12px;
}

.model-card {
  background: #ffffff;
  border-radius: 16px;
  border: 2px solid #e7eff8;
  padding: 10px;
  text-align: center;
}

canvas {
  width: 100%;
  max-width: 260px;
  height: auto;
}

.formula {
  margin: 4px 0 0;
  font-size: 1.5rem;
  font-weight: 800;
}

.merge-card {
  margin-top: 12px;
  background: linear-gradient(135deg, #fff7c8, #ffed9a);
  border: 2px solid #ffd971;
  border-radius: 16px;
  padding: 12px;
  font-size: 1.05rem;
}

.ok {
  color: var(--good);
}

.bad {
  color: #cc2c2c;
}

.locked {
  opacity: 0.65;
}

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

  .control-panel {
    position: static;
    max-height: none;
    overflow: visible;
  }

  .models {
    grid-template-columns: 1fr;
  }
}