/* ============================================================
   Khurk Secret — Shamir's Secret Sharing Web App
   Dark theme with emerald/teal accents, responsive layout
   ============================================================ */

/* --- CSS Custom Properties --- */
:root {
  --bg-deep: #07070e;
  --bg-card: #111122;
  --bg-card-hover: #151530;
  --bg-input: #0a0a1a;
  --border-subtle: #1e1e3a;
  --border-active: #00d4aa;
  --text-primary: #e0e0f0;
  --text-secondary: #8888aa;
  --text-muted: #555577;
  --accent: #00d4aa;
  --accent-glow: rgba(0, 212, 170, 0.3);
  --accent-dim: #00a080;
  --danger: #ff4466;
  --danger-glow: rgba(255, 68, 102, 0.3);
  --warning: #ffaa22;
  --warning-bg: rgba(255, 170, 34, 0.1);
  --font-mono: 'SF Mono', 'Fira Code', 'Cascadia Code', 'JetBrains Mono', 'Consolas', monospace;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --radius: 8px;
  --radius-lg: 12px;
  --transition: 0.2s ease;
}

/* --- Reset --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-deep);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.6;
  position: relative;
  overflow-x: hidden;
}

/* --- Grid Background --- */
.bg-grid {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  opacity: 0.03;
  background-image:
    linear-gradient(rgba(0, 212, 170, 0.5) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 212, 170, 0.5) 1px, transparent 1px);
  background-size: 40px 40px;
}

/* --- Container --- */
.container {
  position: relative;
  z-index: 1;
  max-width: 1100px;
  margin: 0 auto;
  padding: 2rem 1.5rem 3rem;
}

/* --- Header --- */
.app-header {
  text-align: center;
  margin-bottom: 1.5rem;
}

.app-title {
  font-size: 2.4rem;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: -0.5px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
}

.title-icon {
  font-size: 1.8rem;
  color: var(--accent);
  text-shadow: 0 0 12px var(--accent-glow);
}

.app-subtitle {
  color: var(--text-secondary);
  font-size: 1rem;
  margin-top: 0.3rem;
}

/* --- Info Banner --- */
.info-banner {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius);
  padding: 0.75rem 1rem;
  margin-bottom: 1rem;
  cursor: pointer;
  max-width: 700px;
  margin-left: auto;
  margin-right: auto;
}

.info-banner summary {
  font-weight: 600;
  color: var(--accent);
  user-select: none;
}

.info-banner p {
  margin-top: 0.5rem;
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.5;
}

/* --- Security Notice --- */
.security-notice {
  background: var(--warning-bg);
  border: 1px solid rgba(255, 170, 34, 0.3);
  border-radius: var(--radius);
  padding: 0.6rem 1rem;
  margin-bottom: 1.5rem;
  font-size: 0.85rem;
  color: var(--warning);
  max-width: 700px;
  margin-left: auto;
  margin-right: auto;
  text-align: center;
}

/* --- Main Panels --- */
.main-panels {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  align-items: start;
}

@media (max-width: 768px) {
  .main-panels {
    grid-template-columns: 1fr;
  }
}

/* --- Panels / Cards --- */
.panel {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.panel:focus-within {
  border-color: var(--border-active);
  box-shadow: 0 0 20px var(--accent-glow);
}

.panel-title {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.2rem;
}

.panel-desc {
  color: var(--text-secondary);
  font-size: 0.85rem;
  margin-bottom: 1.25rem;
}

/* --- Form Elements --- */
.form-group {
  margin-bottom: 1rem;
}

.form-group label {
  display: block;
  font-weight: 600;
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 0.3rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.form-group small {
  display: block;
  color: var(--text-muted);
  font-size: 0.75rem;
  margin-top: 0.2rem;
}

.form-group textarea,
.form-group input[type="number"],
.form-group input[type="text"],
.result-textarea {
  width: 100%;
  background: var(--bg-input);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius);
  padding: 0.6rem 0.75rem;
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 0.9rem;
  transition: border-color var(--transition);
  resize: vertical;
}

.form-group textarea:focus,
.form-group input:focus,
.result-textarea:focus {
  outline: none;
  border-color: var(--border-active);
  box-shadow: 0 0 8px var(--accent-glow);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

@media (max-width: 480px) {
  .form-row {
    grid-template-columns: 1fr;
  }
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.65rem 1.25rem;
  font-size: 0.9rem;
  font-weight: 600;
  font-family: var(--font-sans);
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  transition: all var(--transition);
  user-select: none;
}

.btn:active {
  transform: scale(0.97);
}

.btn-primary {
  background: var(--accent);
  color: #000;
  width: 100%;
}

.btn-primary:hover {
  background: #00ffcc;
  box-shadow: 0 0 16px var(--accent-glow);
}

.btn-primary:disabled {
  background: var(--border-subtle);
  color: var(--text-muted);
  cursor: not-allowed;
  box-shadow: none;
}

.btn-secondary {
  background: transparent;
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  width: 100%;
  margin-top: 0.75rem;
}

.btn-secondary:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.btn-copy {
  background: transparent;
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  padding: 0.4rem 0.8rem;
  font-size: 0.8rem;
  margin-top: 0.5rem;
}

.btn-copy:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.btn-small {
  padding: 0.3rem 0.6rem;
  font-size: 0.75rem;
}

/* --- Share Inputs --- */
.share-inputs {
  margin-bottom: 0.5rem;
}

.share-input-group {
  margin-bottom: 0.75rem;
  animation: fadeIn 0.3s ease;
}

.share-input-group label {
  display: block;
  font-weight: 600;
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin-bottom: 0.2rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.share-input-group textarea {
  width: 100%;
  background: var(--bg-input);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius);
  padding: 0.5rem 0.65rem;
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  resize: vertical;
  min-height: 3em;
  transition: border-color var(--transition);
}

.share-input-group textarea:focus {
  outline: none;
  border-color: var(--border-active);
  box-shadow: 0 0 8px var(--accent-glow);
}

/* --- Results Area --- */
.results-area {
  margin-top: 1.25rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border-subtle);
  animation: fadeIn 0.4s ease;
}

.results-area h3 {
  font-size: 0.95rem;
  color: var(--accent);
  margin-bottom: 0.75rem;
}

.shares-list {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.share-card {
  background: var(--bg-input);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius);
  padding: 0.6rem 0.75rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transition: border-color var(--transition);
}

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

.share-number {
  font-weight: 700;
  color: var(--accent);
  font-size: 1rem;
  min-width: 2.5rem;
  flex-shrink: 0;
  text-align: center;
}

.share-value {
  flex: 1;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-primary);
  word-break: break-all;
  overflow-wrap: anywhere;
}

.share-card .btn-copy {
  flex-shrink: 0;
  margin-top: 0;
}

/* --- Error Messages --- */
.error-msg {
  background: rgba(255, 68, 102, 0.1);
  border: 1px solid rgba(255, 68, 102, 0.3);
  border-radius: var(--radius);
  padding: 0.6rem 1rem;
  color: var(--danger);
  font-size: 0.85rem;
  margin-top: 0.75rem;
  animation: fadeIn 0.3s ease;
}

/* --- Toast Notifications --- */
.toast-container {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  z-index: 999;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.toast {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius);
  padding: 0.6rem 1rem;
  color: var(--text-primary);
  font-size: 0.85rem;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.5);
  animation: slideIn 0.3s ease, fadeOut 0.3s ease 2.5s forwards;
  max-width: 320px;
}

.toast.success {
  border-color: var(--accent);
  color: var(--accent);
}

.toast.error {
  border-color: var(--danger);
  color: var(--danger);
}

/* --- Footer --- */
.app-footer {
  text-align: center;
  margin-top: 2rem;
  color: var(--text-muted);
  font-size: 0.75rem;
}

/* --- Animations --- */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(-6px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes slideIn {
  from { opacity: 0; transform: translateX(40px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes fadeOut {
  from { opacity: 1; }
  to { opacity: 0; }
}

/* --- Accessibility --- */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

/* --- Scrollbar --- */
::-webkit-scrollbar {
  width: 6px;
}
::-webkit-scrollbar-track {
  background: var(--bg-deep);
}
::-webkit-scrollbar-thumb {
  background: var(--border-subtle);
  border-radius: 3px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}