/* Solver page — matches landing page design tokens from theme.css */

/* ── Header ─────────────────────────────────────── */
.app-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1.25rem 2rem;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: var(--bg);
  z-index: 10;
}

.app-logo {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--accent);
  text-decoration: none;
  letter-spacing: -0.01em;
}

.app-tagline {
  font-size: 0.85rem;
  color: var(--fg-muted);
}

/* ── Layout ──────────────────────────────────────── */
.solver-main {
  padding: 3rem 2rem;
  max-width: 1200px;
  margin: 0 auto;
}

.solver-container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2.5rem;
  align-items: start;
}

/* ── Input panel ─────────────────────────────────── */
.solver-title {
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 3vw, 2.4rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 0.5rem;
}

.solver-subtitle {
  color: var(--fg-muted);
  font-size: 0.95rem;
  margin-bottom: 1.75rem;
}

.input-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
}

.input-label {
  display: block;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--fg-muted);
  font-weight: 500;
  margin-bottom: 0.75rem;
}

.problem-textarea {
  width: 100%;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--fg);
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.6;
  padding: 1rem;
  resize: vertical;
  transition: border-color 0.2s;
  min-height: 130px;
}

.problem-textarea:focus {
  outline: none;
  border-color: rgba(74, 222, 128, 0.4);
}

.problem-textarea::placeholder {
  color: var(--fg-muted);
  opacity: 0.6;
}

.problem-textarea:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.input-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 1rem;
}

.char-count {
  font-size: 0.8rem;
  color: var(--fg-muted);
}

.char-over {
  color: #f87171;
}

/* ── Solve button ────────────────────────────────── */
.solve-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.65rem 1.5rem;
  background: var(--accent);
  color: var(--bg);
  border: none;
  border-radius: 8px;
  font-family: var(--font-display);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: opacity 0.2s, transform 0.1s;
}

.solve-btn:hover:not(:disabled) {
  opacity: 0.9;
  transform: translateY(-1px);
}

.solve-btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
}

/* Spinner — hidden by default, shown via .loading class */
.btn-spinner {
  display: none;
  width: 14px;
  height: 14px;
  border: 2px solid rgba(10,10,15,0.3);
  border-top-color: var(--bg);
  border-radius: 50%;
}

.solve-btn.loading .btn-spinner {
  display: block;
  animation: spin 0.7s linear infinite;
}

.solve-btn.loading .btn-text {
  opacity: 0.7;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ── Example chips ───────────────────────────────── */
.example-problems {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  margin-top: 1.25rem;
}

.example-label {
  font-size: 0.8rem;
  color: var(--fg-muted);
}

.example-chip {
  padding: 0.3rem 0.75rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 100px;
  color: var(--fg-muted);
  font-family: var(--font-body);
  font-size: 0.8rem;
  cursor: pointer;
  transition: border-color 0.15s, color 0.15s;
}

.example-chip:hover {
  border-color: rgba(74, 222, 128, 0.3);
  color: var(--accent);
}

/* ── Solution panel ──────────────────────────────── */
.solution-panel {
  position: sticky;
  top: 5rem;
}

/* Empty state */
.solution-empty,
.solution-error {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 320px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  gap: 1rem;
}

.empty-icon {
  font-size: 3rem;
  color: var(--fg-muted);
  opacity: 0.3;
  font-family: var(--font-display);
}

.empty-text {
  color: var(--fg-muted);
  font-size: 0.95rem;
}

/* Error state */
.error-icon {
  font-size: 2rem;
  color: #f87171;
}

.error-message {
  color: #f87171;
  font-size: 0.95rem;
  text-align: center;
  max-width: 300px;
}

/* Solution content */
.solution-content {
  background: var(--bg-elevated);
  border: 1px solid rgba(74, 222, 128, 0.15);
  border-radius: var(--radius);
  padding: 1.75rem;
  animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

.solution-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.5rem;
}

.problem-type-badge {
  display: inline-block;
  padding: 0.3rem 0.8rem;
  background: var(--accent-dim);
  border: 1px solid rgba(74, 222, 128, 0.2);
  border-radius: 100px;
  font-size: 0.8rem;
  color: var(--accent);
  font-weight: 500;
}

.solution-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--fg-muted);
  font-weight: 500;
}

/* Steps */
.steps-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.step-item {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
}

.step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  background: var(--accent);
  color: var(--bg);
  border-radius: 50%;
  font-size: 0.75rem;
  font-weight: 700;
  font-family: var(--font-display);
  flex-shrink: 0;
  margin-top: 1px;
}

.step-body {
  flex: 1;
}

.step-action {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--fg);
  margin-bottom: 0.35rem;
  font-family: var(--font-display);
}

.step-explanation {
  font-size: 0.85rem;
  color: var(--fg-muted);
  line-height: 1.5;
}

/* Final answer */
.final-answer-card {
  background: linear-gradient(135deg, var(--bg-card) 0%, rgba(74, 222, 128, 0.05) 100%);
  border: 1px solid rgba(74, 222, 128, 0.25);
  border-radius: 8px;
  padding: 1.25rem;
  margin-bottom: 1rem;
}

.final-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent);
  font-weight: 500;
  margin-bottom: 0.5rem;
}

.final-value {
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--fg);
}

/* Tip */
.tip-card {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
}

.tip-icon {
  font-size: 1rem;
  flex-shrink: 0;
  margin-top: 1px;
}

.tip-text {
  font-size: 0.875rem;
  color: var(--fg-muted);
  line-height: 1.5;
}

/* ── Responsive ──────────────────────────────────── */
@media (max-width: 900px) {
  .solver-container {
    grid-template-columns: 1fr;
  }

  .solution-panel {
    position: static;
  }

  .solver-main {
    padding: 2rem 1.25rem;
  }
}

@media (max-width: 480px) {
  .app-tagline {
    display: none;
  }

  .input-footer {
    flex-direction: column;
    align-items: flex-end;
    gap: 0.75rem;
  }
}