frontend/src/App.css

/* ── Layout ──────────────────────────────────────────────────────── */

.app {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 24px;
  background: var(--card-bg);
  border-bottom: 1px solid var(--border-primary);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(12px);
}

.header-left {
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
}

.icon-btn.sidebar-toggle {
  display: none;
}

.header-brand-link {
  display: flex;
  align-items: center;
  gap: 6px;
  text-decoration: none;
  transition: opacity 0.15s;
  flex-shrink: 0;
}

.header-brand-link:hover {
  opacity: 0.8;
}

.app-logo {
  height: 32px;
  width: auto;
}

.app-title {
  font-size: 20px;
  font-weight: 700;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  min-width: 0;
}

.app-title-link {
  all: unset;
  cursor: pointer;
}

.app-title-link:hover {
  opacity: 0.8;
}

.header-right {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}

.icon-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border: 1px solid var(--border-primary);
  border-radius: 8px;
  background: var(--bg-primary);
  color: var(--text-secondary);
  transition: all 0.15s;
}

.icon-btn:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border-color: var(--accent-primary);
}

.spin {
  animation: spin 1s linear infinite;
}

@keyframes spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

/* ── Settings dropdown ─────────────────────────────────────────── */

.settings-wrapper {
  position: relative;
}

.settings-dropdown {
  position: absolute;
  top: calc(100% + 6px);
  right: 0;
  min-width: 230px;
  background: var(--card-bg);
  border: 1px solid var(--border-primary);
  border-radius: 10px;
  box-shadow: var(--shadow-lg);
  padding: 8px;
  z-index: 200;
}

.settings-section {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.settings-section + .settings-section {
  margin-top: 4px;
  padding-top: 4px;
  border-top: 1px solid var(--border-muted);
}

.settings-label {
  font-size: 11px;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  padding: 4px 10px 6px;
}

.settings-option {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 10px;
  border: none;
  border-radius: 6px;
  background: none;
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 500;
  text-align: left;
  transition: background 0.12s, color 0.12s;
}

.settings-option:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}

.settings-option.active {
  background: var(--accent-light);
  color: var(--accent-primary);
  font-weight: 600;
}

/* ── Main layout ────────────────────────────────────────────────── */

.app-main {
  display: flex;
  flex: 1;
  overflow: hidden;
  position: relative;
}

.sidebar-overlay {
  display: none;
}

.sidebar {
  width: 320px;
  min-width: 320px;
  padding: 16px;
  overflow-y: auto;
  border-right: 1px solid var(--border-primary);
  background: var(--bg-secondary);
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-height: calc(100vh - 57px);
}

.sidebar-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--text-primary);
  text-align: center;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--accent-primary);
  margin: 0;
}

.content {
  flex: 1;
  padding: 20px 24px;
  overflow-y: auto;
  max-height: calc(100vh - 57px);
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.content-hint {
  font-size: 15px;
  font-weight: 700;
  color: var(--text-primary);
  margin: 0;
}

.content-hint-mobile {
  display: none;
}

/* ── Error banner ───────────────────────────────────────────────── */

.error-banner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 16px;
  background: #FEE2E2;
  color: #991B1B;
  border: 1px solid #FECACA;
  border-radius: 8px;
  font-size: 14px;
}

:root[data-theme="dark"] .error-banner {
  background: #450A0A;
  color: #FCA5A5;
  border-color: #7F1D1D;
}

.error-banner button {
  background: none;
  border: none;
  color: inherit;
  font-size: 18px;
  padding: 0 4px;
  line-height: 1;
}

/* ── Footer ─────────────────────────────────────────────────────── */

.app-footer {
  padding: 8px 24px;
  text-align: center;
  font-size: 10px;
  color: var(--text-muted);
  border-top: 1px solid var(--border-primary);
  background: var(--bg-secondary);
}

.app-footer a {
  color: var(--text-muted);
  text-decoration: underline;
  transition: color 0.15s;
}

.app-footer a:hover {
  color: var(--text-secondary);
}

/* ── Responsive: Tablet (<= 900px) ───────────────────────────── */

@media (max-width: 900px) {
  .app-header {
    padding: 10px 16px;
  }

  .icon-btn.sidebar-toggle {
    display: flex;
  }

  .content-hint-desktop {
    display: none;
  }

  .content-hint-mobile {
    display: block;
  }

  .app-title {
    font-size: 16px;
  }

  .app-main {
    flex-direction: column;
  }

  .sidebar-overlay {
    display: block;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.4);
    z-index: 49;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.25s;
  }

  .sidebar-overlay.visible {
    opacity: 1;
    pointer-events: auto;
  }

  .sidebar {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: 320px;
    min-width: 320px;
    max-height: 100vh;
    z-index: 50;
    transform: translateX(-100%);
    transition: transform 0.25s ease;
    border-right: 1px solid var(--border-primary);
    border-bottom: none;
    padding-top: 60px;
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .content {
    max-height: none;
    padding: 16px;
    flex: 1;
    overflow-y: auto;
  }
}

/* ── Responsive: Phone (<= 480px) ────────────────────────────── */

@media (max-width: 480px) {
  .app-header {
    padding: 8px 12px;
    gap: 4px;
  }

  .header-left {
    gap: 6px;
  }

  .app-logo {
    height: 24px;
  }

  .app-brand-name {
    display: none;
  }

  .app-title {
    font-size: 14px;
  }

  .header-right {
    gap: 4px;
  }

  .icon-btn {
    width: 40px;
    height: 40px;
  }

  .sidebar {
    width: 85vw;
    min-width: 85vw;
  }

  .content {
    padding: 12px 10px;
    gap: 14px;
  }

  .app-footer {
    padding: 6px 12px;
  }
}