:root {
  color-scheme: light;
  --bg: #ffffff;
  --panel: #ffffff;
  --border: #000000;
  --text: #000000;
  --muted: #555555;
  --accent: #000000;
  --danger: #000000;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Pretendard", -apple-system, "Segoe UI", sans-serif;
  line-height: 1.5;
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 2rem;
  border-bottom: 1px solid var(--border);
  background: var(--panel);
}

.brand {
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--accent);
  text-decoration: none;
}

.nav-links a {
  color: var(--text);
  text-decoration: none;
  margin-left: 1.25rem;
}

.nav-links a:hover { color: var(--accent); }

.nav-user { margin-left: 1.25rem; color: var(--muted); }

.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 2rem;
}

.flash-list { margin-bottom: 1.5rem; }

.flash {
  padding: 0.75rem 1rem;
  border-radius: 6px;
  margin-bottom: 0.5rem;
  border: 1px solid var(--border);
}

.flash-success { border-color: var(--accent); color: var(--accent); }
.flash-error { border-color: var(--danger); color: var(--danger); }

h1, h2, h3 { color: #000000; }

.landing-hero {
  display: flex;
  gap: 2rem;
  align-items: flex-start;
}

.landing-image {
  max-width: 300px;
  width: 100%;
  flex-shrink: 0;
}

.challenge-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.challenge-card {
  display: block;
  padding: 1rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--panel);
  text-decoration: none;
  color: var(--text);
}

.challenge-card:hover { border-color: var(--accent); }

.challenge-card.solved { border-color: var(--accent); background: #f0f0f0; }

.challenge-card .points { color: var(--muted); font-size: 0.9rem; }

form { display: flex; flex-direction: column; gap: 0.75rem; max-width: 480px; }

label { font-size: 0.9rem; color: var(--muted); }

input[type=text], input[type=password], input[type=email], input[type=number], textarea {
  background: var(--panel);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 0.6rem;
  border-radius: 6px;
  font-family: inherit;
  font-size: 1rem;
}

textarea { min-height: 120px; }

button, input[type=submit] {
  background: var(--accent);
  color: #ffffff;
  border: none;
  padding: 0.6rem 1.2rem;
  border-radius: 6px;
  font-weight: 600;
  cursor: pointer;
  width: fit-content;
}

.errors { color: var(--danger); font-size: 0.85rem; margin: 0; padding-left: 1rem; }

.conn-info {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.75rem 1rem;
  font-family: "SFMono-Regular", Consolas, monospace;
  margin-bottom: 1rem;
}

table { width: 100%; border-collapse: collapse; }
th, td { text-align: left; padding: 0.6rem; border-bottom: 1px solid var(--border); }
.badge { display: inline-block; padding: 0.15rem 0.5rem; border-radius: 4px; font-size: 0.75rem; background: #f0f0f0; border: 1px solid var(--border); }
.badge.solved { background: var(--accent); color: #ffffff; }
.actions a, .actions form { display: inline-block; margin-right: 0.5rem; }

@media (max-width: 600px) {
  .landing-hero { flex-direction: column; }
  .landing-image { max-width: 160px; }
}