/* ============================================================
   그래픽스 프로그래밍 비주얼 가이드 - 스타일
   ============================================================ */

:root {
  --bg: #0f1117;
  --bg-panel: #171a23;
  --bg-card: #1e222e;
  --border: #2a2f3d;
  --text: #e6e8ee;
  --text-dim: #9aa1b2;
  --accent: #6ea8fe;
  --accent2: #7ee787;
  --accent3: #ff7b72;
  --accent4: #ffd166;
  --shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
  --radius: 14px;
  --sidebar-w: 280px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Pretendard", -apple-system, BlinkMacSystemFont, "Segoe UI",
    "Malgun Gothic", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
  font-size: 16px;
}

/* ---------- 레이아웃 ---------- */
.layout { display: flex; min-height: 100vh; }

.sidebar {
  width: var(--sidebar-w);
  flex-shrink: 0;
  background: var(--bg-panel);
  border-right: 1px solid var(--border);
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  padding: 24px 0;
}

.sidebar h1 {
  font-size: 18px;
  margin: 0 20px 4px;
  color: var(--text);
}
.sidebar .subtitle {
  font-size: 12px;
  color: var(--text-dim);
  margin: 0 20px 20px;
}

.nav-group { margin-bottom: 8px; }
.nav-group > .nav-title {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent);
  padding: 10px 20px 6px;
  font-weight: 700;
}
.sidebar a {
  display: block;
  padding: 7px 20px 7px 32px;
  color: var(--text-dim);
  text-decoration: none;
  font-size: 14px;
  border-left: 3px solid transparent;
  transition: all 0.15s;
}
.sidebar a:hover { color: var(--text); background: rgba(255, 255, 255, 0.03); }
.sidebar a.active {
  color: var(--accent);
  border-left-color: var(--accent);
  background: rgba(110, 168, 254, 0.08);
}

.content {
  flex: 1;
  max-width: 860px;
  margin: 0 auto;
  padding: 48px 40px 120px;
}

/* ---------- 타이포 ---------- */
.hero {
  padding: 40px;
  border-radius: var(--radius);
  background: linear-gradient(135deg, #1b2233, #171a23);
  border: 1px solid var(--border);
  margin-bottom: 48px;
}
.hero h1 { font-size: 32px; margin: 0 0 12px; }
.hero p { color: var(--text-dim); margin: 0; font-size: 16px; }

section { margin-bottom: 72px; scroll-margin-top: 24px; }

/* ---------- 단일 섹션 뷰 (SPA 토글) ---------- */
/* .layout 안에서만 적용되므로 impl/ 페이지에는 영향 없음 */
.layout main.content > section { display: none; }
.layout main.content > section.section-active { display: block; }
section > h2 {
  font-size: 26px;
  border-bottom: 2px solid var(--border);
  padding-bottom: 12px;
  margin: 0 0 8px;
}
h3 { font-size: 20px; margin: 40px 0 12px; color: var(--accent2); }
h4 { font-size: 16px; margin: 24px 0 8px; color: var(--accent4); }

p { margin: 12px 0; }
.lead { color: var(--text-dim); font-size: 15px; margin-top: 0; }

code {
  background: #0b0d13;
  padding: 2px 7px;
  border-radius: 6px;
  font-family: "JetBrains Mono", Consolas, monospace;
  font-size: 0.9em;
  color: var(--accent4);
}
pre {
  background: #0b0d13;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 18px;
  overflow-x: auto;
}
pre code { background: none; padding: 0; color: var(--text); }

strong { color: #fff; }

/* ---------- 카드/데모 ---------- */
.demo {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin: 24px 0;
  box-shadow: var(--shadow);
}
.demo-title {
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent);
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.demo-title::before { content: "▶"; font-size: 10px; }

.demo canvas {
  display: block;
  background: #0b0d13;
  border-radius: 10px;
  width: 100%;
  max-width: 100%;
  touch-action: none;
  cursor: crosshair;
}

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  margin-top: 16px;
  align-items: center;
}
.control {
  display: flex;
  flex-direction: column;
  gap: 4px;
  font-size: 13px;
  color: var(--text-dim);
  min-width: 140px;
}
.control label { display: flex; justify-content: space-between; }
.control .val { color: var(--accent4); font-family: monospace; }
input[type="range"] { width: 100%; accent-color: var(--accent); }

button {
  background: var(--accent);
  color: #0b0d13;
  border: none;
  padding: 8px 16px;
  border-radius: 8px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: filter 0.15s;
}
button:hover { filter: brightness(1.1); }
button.ghost { background: transparent; color: var(--text-dim); border: 1px solid var(--border); }

.readout {
  font-family: "JetBrains Mono", monospace;
  font-size: 13px;
  background: #0b0d13;
  border-radius: 8px;
  padding: 10px 14px;
  margin-top: 12px;
  color: var(--accent2);
  white-space: pre-wrap;
}

.tip {
  border-left: 3px solid var(--accent4);
  background: rgba(255, 209, 102, 0.06);
  padding: 12px 16px;
  border-radius: 0 8px 8px 0;
  margin: 16px 0;
  font-size: 14px;
}
.tip strong { color: var(--accent4); }

.hint { font-size: 13px; color: var(--text-dim); font-style: italic; }

.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
@media (max-width: 720px) { .grid2 { grid-template-columns: 1fr; } }

/* ---------- 반응형 ---------- */
.menu-toggle {
  display: none;
  position: fixed;
  top: 16px;
  left: 16px;
  z-index: 100;
}
@media (max-width: 900px) {
  .sidebar {
    position: fixed;
    left: 0; top: 0;
    z-index: 90;
    transform: translateX(-100%);
    transition: transform 0.2s;
    box-shadow: var(--shadow);
  }
  .sidebar.open { transform: translateX(0); }
  .menu-toggle { display: block; }
  .content { padding: 64px 20px 80px; }
}

.footer {
  text-align: center;
  color: var(--text-dim);
  font-size: 13px;
  padding: 40px 0;
  border-top: 1px solid var(--border);
  margin-top: 60px;
}