/* Precalc Study Website - Styles */
:root {
  --bg: #f8f9fa;
  --bg-card: #fff;
  --text: #1a1a2e;
  --text-muted: #6c757d;
  --accent: #4361ee;
  --accent-hover: #3a56d4;
  --correct: #2ecc71;
  --incorrect: #e74c3c;
  --border: #dee2e6;
  --radius: 8px;
  --shadow: 0 2px 8px rgba(0,0,0,0.08);
}

[data-theme="dark"] {
  --bg: #1a1a2e;
  --bg-card: #16213e;
  --text: #e8e8e8;
  --text-muted: #a0a0a0;
  --border: #2d3a4f;
  --shadow: 0 2px 8px rgba(0,0,0,0.3);
}

* {
  box-sizing: border-box;
}

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  margin: 0;
  padding: 0;
  line-height: 1.6;
  min-height: 100vh;
}

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 1.5rem;
}

header {
  margin-bottom: 1.5rem;
}

h1 {
  font-size: 1.5rem;
  font-weight: 600;
  margin: 0;
}

.logo-link {
  color: inherit;
  text-decoration: none;
}

.logo-link:hover {
  text-decoration: underline;
}

h2 {
  font-size: 1.25rem;
  font-weight: 600;
  margin: 0 0 1rem 0;
}

.card {
  background: var(--bg-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.progress-bar {
  height: 6px;
  background: var(--border);
  border-radius: 3px;
  overflow: hidden;
  margin-bottom: 1rem;
}

.progress-fill {
  height: 100%;
  background: var(--accent);
  border-radius: 3px;
  transition: width 0.3s ease;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 1.2rem;
  font-size: 0.95rem;
  font-weight: 500;
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  background: var(--accent);
  color: white;
  transition: background 0.2s;
}

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

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.btn-outline {
  background: transparent;
  border: 2px solid var(--accent);
  color: var(--accent);
}

.btn-outline:hover:not(:disabled) {
  background: var(--accent);
  color: white;
}

a.btn {
  text-decoration: none;
}

.home-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1rem;
}

/* Tab bar */
.tabs {
  display: flex;
  gap: 0;
  flex-wrap: wrap;
  margin-top: 1rem;
  border-bottom: 2px solid var(--border);
}

.tab {
  padding: 0.5rem 1rem;
  text-decoration: none;
  color: var(--text-muted);
  font-weight: 500;
  border-bottom: 3px solid transparent;
  margin-bottom: -2px;
  transition: color 0.2s, border-color 0.2s;
}

.tab:hover {
  color: var(--text);
}

.tab.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

.header-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.header-with-tabs {
  display: flex;
  flex-direction: column;
  align-items: stretch;
}

.study-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 0.75rem;
  padding: 0.5rem 0;
  font-size: 0.95rem;
}

.go-to-wrap {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.go-to-wrap label {
  font-size: 0.85rem;
  color: var(--text-muted);
  white-space: nowrap;
}

.go-to-input {
  width: 3.5rem;
  padding: 0.35rem 0.5rem;
  margin: 0;
  font-size: 0.9rem;
  border: 2px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-card);
  color: var(--text);
  text-align: center;
}

.go-to-input:focus {
  outline: none;
  border-color: var(--accent);
}

.btn-sm {
  padding: 0.35rem 0.75rem;
  font-size: 0.85rem;
}

.nav-buttons {
  display: flex;
  gap: 0.75rem;
  margin-top: 1.5rem;
}

.question-prompt {
  font-size: 1.1rem;
  margin-bottom: 1.5rem;
  padding: 1rem;
  background: var(--bg);
  border-radius: var(--radius);
  border-left: 4px solid var(--accent);
}

.step-block {
  margin: 1.25rem 0;
  padding: 1rem;
  background: var(--bg);
  border-radius: var(--radius);
}

.step-prompt {
  font-size: 1rem;
  margin: 0 0 0.75rem 0;
}

.input-answer {
  width: 100%;
  max-width: 400px;
  padding: 0.75rem 1rem;
  font-size: 1rem;
  border: 2px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-card);
  color: var(--text);
  margin: 0.5rem 0;
}

.input-answer:focus {
  outline: none;
  border-color: var(--accent);
}

.feedback {
  margin-top: 1rem;
  padding: 1rem;
  border-radius: var(--radius);
}

.feedback.correct {
  background: rgba(46, 204, 113, 0.15);
  border: 1px solid var(--correct);
  color: var(--correct);
}

.feedback.incorrect {
  background: rgba(231, 76, 60, 0.15);
  border: 1px solid var(--incorrect);
  color: var(--incorrect);
}

.explanation {
  margin-top: 0.75rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border);
  font-size: 0.95rem;
  color: var(--text-muted);
}

.concept-reminder {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-top: 0.5rem;
  font-style: italic;
}

/* Completion message when all steps done */
.step-complete-msg {
  margin-top: 1rem;
  padding: 1rem;
  background: rgba(46, 204, 113, 0.15);
  border: 1px solid var(--correct);
  border-radius: var(--radius);
  color: var(--correct);
}

.check-btn {
  margin-top: 0.5rem;
}

@media (max-width: 600px) {
  .container { padding: 1rem; }
  .card { padding: 1rem; }
  h1 { font-size: 1.15rem; }
  .nav-buttons { flex-wrap: wrap; }
  .study-toolbar { flex-wrap: wrap; gap: 0.5rem; }
  .tabs { overflow-x: auto; flex-wrap: nowrap; }
  .tab { white-space: nowrap; font-size: 0.9rem; }
}