:root {
  --color-bg: #f6f5f2;
  --color-surface: #ffffff;
  --color-border: #e2e0da;
  --color-text: #2b2b28;
  --color-text-muted: #6b6a63;
  --color-accent: #3f6b52;
  --color-accent-hover: #325640;
  --color-danger: #b3432b;
  --radius: 10px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
  font-family: -apple-system, "Segoe UI", Roboto, Arial, sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 24px;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
}

.topbar .brand {
  font-weight: 700;
  font-size: 1.1rem;
}

.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 32px 20px;
}

.center-page {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 28px;
}

.auth-card { width: 100%; max-width: 380px; }

h1, h2, h3 { line-height: 1.25; }

label {
  display: block;
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin: 14px 0 4px;
}

input[type="email"],
input[type="password"],
input[type="text"] {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  font-size: 0.95rem;
  background: #fff;
}

button, .btn {
  cursor: pointer;
  border: none;
  border-radius: 8px;
  padding: 10px 18px;
  font-size: 0.95rem;
  font-weight: 600;
  background: var(--color-accent);
  color: #fff;
  transition: background 0.15s ease;
}

button:hover, .btn:hover { background: var(--color-accent-hover); }

.btn-secondary {
  background: transparent;
  color: var(--color-accent);
  border: 1px solid var(--color-accent);
}
.btn-secondary:hover { background: #eef2ef; }

.btn-link {
  background: none;
  color: var(--color-accent);
  padding: 0;
  font-weight: 500;
  text-decoration: underline;
}
.btn-link:hover { background: none; color: var(--color-accent-hover); }

.error-msg {
  color: var(--color-danger);
  font-size: 0.85rem;
  margin-top: 10px;
  min-height: 1.1em;
}

.tabs { display: flex; gap: 8px; margin-bottom: 8px; }
.tabs button {
  flex: 1;
  background: var(--color-bg);
  color: var(--color-text-muted);
}
.tabs button.active { background: var(--color-accent); color: #fff; }

.course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 20px;
  margin-top: 20px;
}

.course-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  text-decoration: none;
  color: var(--color-text);
  display: block;
}

.course-card img {
  width: 100%;
  height: 120px;
  object-fit: cover;
  background: #ddd;
  display: block;
}

.course-card .body { padding: 14px; }
.course-card h3 { margin: 0 0 6px; font-size: 1rem; }
.course-card p { margin: 0; font-size: 0.85rem; color: var(--color-text-muted); }

.empty-state {
  text-align: center;
  color: var(--color-text-muted);
  padding: 60px 20px;
}

.course-layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 24px;
  align-items: start;
}

@media (max-width: 720px) {
  .course-layout { grid-template-columns: 1fr; }
}

.lesson-nav {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
}

.lesson-nav .module-title {
  padding: 10px 14px;
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  color: var(--color-text-muted);
  background: var(--color-bg);
  border-top: 1px solid var(--color-border);
}
.lesson-nav .module-title:first-child { border-top: none; }

.lesson-item {
  display: flex;
  align-items: center;
  gap: 8px;
  width: 100%;
  text-align: left;
  padding: 10px 14px;
  background: transparent;
  color: var(--color-text);
  font-weight: 400;
  border-radius: 0;
}
.lesson-item:hover { background: var(--color-bg); }
.lesson-item.active { background: #eef2ef; color: var(--color-accent-hover); font-weight: 600; }
.lesson-item .check {
  width: 16px; height: 16px; border-radius: 50%;
  border: 2px solid var(--color-border);
  flex-shrink: 0;
}
.lesson-item.completed .check { background: var(--color-accent); border-color: var(--color-accent); }

.video-wrapper {
  position: relative;
  background: #000;
  border-radius: var(--radius);
  overflow: hidden;
}
.video-wrapper video {
  width: 100%;
  display: block;
  max-height: 480px;
}
.video-watermark {
  position: absolute;
  bottom: 10px;
  right: 14px;
  color: rgba(255, 255, 255, 0.55);
  font-size: 0.75rem;
  pointer-events: none;
  text-shadow: 0 1px 2px rgba(0,0,0,0.6);
}

.resource-list { list-style: none; padding: 0; margin: 16px 0; }
.resource-list li {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 14px;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  margin-bottom: 8px;
  background: var(--color-surface);
}

.actions-row { display: flex; gap: 10px; margin-top: 18px; }