/* ============================================================
   Security+ Study Guide — styles.css
   ============================================================ */

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

:root {
  --c-bg:            #0d1117;
  --c-surface:       #161b22;
  --c-surface-2:     #21262d;
  --c-border:        #30363d;
  --c-text:          #e6edf3;
  --c-text-muted:    #8b949e;
  --c-accent:        #2f81f7;
  --c-accent-bright: #58a6ff;
  --c-accent-glow:   #1f6feb;
  --c-success:       #3fb950;
  --c-warning:       #d29922;
  --c-danger:        #f85149;

  --spinner-outer-size: 72px;
  --spinner-inner-size: 44px;
  --ring-thickness:      5px;

  --spinner-grad: conic-gradient(
    from 0deg,
    transparent 0deg 200deg,
    #1f6feb      200deg 240deg,
    #2f81f7      240deg 280deg,
    #58a6ff      280deg 320deg,
    #a5d6ff      320deg 340deg,
    transparent  340deg 360deg
  );

  --t-fast:   150ms ease;
  --t-medium: 200ms ease;
  --t-slow:   250ms ease;

  --sidebar-w: 260px;
  --mobile-menu-size: 52px;
  --mobile-menu-offset: 16px;
  --z-menu-backdrop: 180;
  --z-menu-toggle: 220;
}

html, body { height: 100%; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen,
               Ubuntu, Cantarell, sans-serif;
  background: var(--c-bg);
  color: var(--c-text);
  line-height: 1.6;
  min-height: 100vh;
}

::-webkit-scrollbar              { width: 6px; }
::-webkit-scrollbar-track        { background: var(--c-bg); }
::-webkit-scrollbar-thumb        { background: var(--c-border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover  { background: var(--c-accent); }

/* ── App Shell ── */
.app-shell {
  display: grid;
  grid-template-columns: var(--sidebar-w) 1fr;
  min-height: 100vh;
}

/* ── Sidebar ── */
.sidebar {
  background: var(--c-surface);
  border-right: 1px solid var(--c-border);
  display: flex;
  flex-direction: column;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  overflow-x: hidden;
  z-index: 10;
}

.sidebar-header {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 20px 18px 16px;
  border-bottom: 1px solid var(--c-border);
}

.sidebar-logo { font-size: 1.5rem; }

.sidebar-title {
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--c-text);
}

.sidebar-plus { color: var(--c-accent-bright); font-weight: 900; }

.nav-tree { flex: 1; padding: 12px 0; }

.nav-domain { padding: 6px 18px 2px; }

.nav-domain-label {
  display: block;
  font-size: 0.68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--c-text-muted);
  padding: 4px 0 2px;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 14px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.875rem;
  color: var(--c-text-muted);
  transition: background var(--t-fast), color var(--t-fast);
  border: 1px solid transparent;
  user-select: none;
  position: relative;
}

.nav-item:hover { background: var(--c-surface-2); color: var(--c-text); }

.nav-item.is-active {
  background: color-mix(in srgb, var(--c-accent) 15%, transparent);
  color: var(--c-accent-bright);
  border-color: color-mix(in srgb, var(--c-accent) 30%, transparent);
  font-weight: 600;
}

.nav-item.is-loading::after {
  content: "";
  position: absolute;
  right: 10px;
  width: 10px;
  height: 10px;
  border: 2px solid var(--c-accent);
  border-top-color: transparent;
  border-radius: 50%;
  animation: spin-simple 0.6s linear infinite;
}

.nav-item-number {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--c-accent);
  min-width: 28px;
}

.nav-item-label { flex: 1; }

.sidebar-footer {
  padding: 12px 18px;
  border-top: 1px solid var(--c-border);
  font-size: 0.72rem;
  color: var(--c-text-muted);
}

.menu-toggle {
  display: none;
  position: fixed;
  top: var(--mobile-menu-offset);
  right: var(--mobile-menu-offset);
  flex-direction: column;
  width: var(--mobile-menu-size);
  height: var(--mobile-menu-size);
  border-radius: 999px;
  border: 1px solid color-mix(in srgb, var(--c-accent) 45%, var(--c-border));
  background: color-mix(in srgb, var(--c-surface) 86%, black);
  box-shadow: 0 12px 30px rgba(0, 0, 0, 0.38);
  cursor: pointer;
  z-index: var(--z-menu-toggle);
  align-items: center;
  justify-content: center;
  gap: 5px;
  padding: 10px;
  transition: transform var(--t-fast), border-color var(--t-fast), background var(--t-fast);
}

.menu-toggle:hover {
  transform: translateY(-1px);
  border-color: var(--c-accent-bright);
}

.menu-toggle:focus-visible {
  outline: 2px solid var(--c-accent-bright);
  outline-offset: 2px;
}

.menu-toggle[aria-expanded="true"] {
  background: color-mix(in srgb, var(--c-accent) 32%, var(--c-surface));
}

.menu-toggle-bar {
  display: block;
  width: 22px;
  height: 2px;
  border-radius: 999px;
  background: var(--c-text);
}

.menu-backdrop {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.45);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--t-medium);
  z-index: var(--z-menu-backdrop);
}

.menu-backdrop.is-visible {
  opacity: 1;
  pointer-events: auto;
}

/* ── Main ── */
.main {
  display: flex;
  flex-direction: column;
  position: relative;
  min-height: 100vh;
}

.content-host {
  flex: 1;
  padding: 36px 48px;
  max-width: 900px;
  width: 100%;
  margin: 0 auto;
}

.welcome-screen {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 60vh;
  text-align: center;
  gap: 16px;
}

.welcome-icon { font-size: 4rem; }

.welcome-title {
  font-size: 1.75rem;
  font-weight: 700;
  background: linear-gradient(135deg, var(--c-accent-bright), #a5d6ff);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.welcome-sub { color: var(--c-text-muted); font-size: 1rem; }

.is-hidden { display: none !important; }

.content-pane { opacity: 1; transition: opacity var(--t-medium); }
.content-pane.is-fading-out { opacity: 0; }
.content-pane.is-fading-in  { opacity: 0; }

/* ── Content typography ── */
.obj-header { margin-bottom: 32px; border-bottom: 1px solid var(--c-border); padding-bottom: 20px; }

.obj-domain-badge {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  background: color-mix(in srgb, var(--c-accent) 18%, transparent);
  color: var(--c-accent-bright);
  border: 1px solid color-mix(in srgb, var(--c-accent) 35%, transparent);
  border-radius: 4px;
  padding: 3px 8px;
  margin-bottom: 10px;
}

.obj-number { font-size: 0.85rem; color: var(--c-text-muted); font-weight: 600; margin-bottom: 6px; }
.obj-title { font-size: 1.6rem; font-weight: 700; line-height: 1.3; margin-bottom: 10px; }
.obj-description { color: var(--c-text-muted); font-size: 0.95rem; max-width: 72ch; }

.obj-meta { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 14px; }

.meta-chip {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-size: 0.75rem;
  background: var(--c-surface-2);
  border: 1px solid var(--c-border);
  border-radius: 20px;
  padding: 3px 10px;
  color: var(--c-text-muted);
}

.meta-chip .chip-icon { font-size: 0.8rem; }
.meta-chip.weight  .chip-icon { color: var(--c-accent); }
.meta-chip.status-chip .chip-icon { color: var(--c-success); }

.progress-bar-wrap { margin: 24px 0; }

.progress-label {
  display: flex;
  justify-content: space-between;
  font-size: 0.78rem;
  color: var(--c-text-muted);
  margin-bottom: 6px;
}

.progress-track {
  height: 6px;
  background: var(--c-surface-2);
  border-radius: 3px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  border-radius: 3px;
  background: linear-gradient(90deg, var(--c-accent-glow), var(--c-accent-bright));
  transition: width 0.6s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

.section-block { 
  margin-bottom: 32px; 
  gap: 20px;
  display: flex;
  flex-direction: column;
}

.section-heading {
  font-size: 1rem;
  font-weight: 700;
  color: var(--c-accent-bright);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.section-subheading {
  color: lightblue;
}

.section-heading::after { content: ""; flex: 1; height: 1px; background: var(--c-border); }

.topic-list { list-style: none; display: flex; flex-direction: column; gap: 8px; }

.topic-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 10px 14px;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: 8px;
  font-size: 0.9rem;
  transition: border-color var(--t-fast), background var(--t-fast);
}

.topic-item:hover {
  border-color: var(--c-accent);
  background: color-mix(in srgb, var(--c-accent) 6%, var(--c-surface));
}

.topic-icon { font-size: 0.85rem; margin-top: 2px; flex-shrink: 0; }

.terms-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 12px;
}

.term-card {
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: 8px;
  padding: 14px 16px;
  transition: border-color var(--t-fast), transform var(--t-fast);
}

.term-card:hover { border-color: var(--c-accent); transform: translateY(-1px); }
.term-name { font-size: 0.82rem; font-weight: 700; color: var(--c-accent-bright); margin-bottom: 4px; }
.term-def  { font-size: 0.83rem; color: var(--c-text-muted); line-height: 1.5; }

.tips-list { list-style: none; display: flex; flex-direction: column; gap: 10px; }

.tip-item {
  display: flex;
  gap: 12px;
  padding: 12px 16px;
  background: color-mix(in srgb, var(--c-warning) 8%, var(--c-surface));
  border: 1px solid color-mix(in srgb, var(--c-warning) 30%, transparent);
  border-radius: 8px;
  font-size: 0.88rem;
  line-height: 1.5;
}

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

.questions-list { display: flex; flex-direction: column; gap: 20px; }

.question-block {
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: 10px;
  overflow: hidden;
  display: block;
  width: 100%;
  min-height: fit-content;
  word-break: break-word;
}

.question-number {
  font-size: 0.74rem;
  font-weight: 700;
  color: var(--c-accent-bright);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  margin-bottom: 6px;
}

.question-stem {
  padding: 14px 16px;
  font-size: 0.9rem;
  font-weight: 600;
  border-bottom: 1px solid var(--c-border);
  background: var(--c-surface-2);
  white-space: normal;
  word-break: break-word;
}

.question-options { list-style: none; padding: 10px 16px; display: flex; flex-direction: column; gap: 10px; }

.q-option {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: 6px;
  font-size: 0.92rem;
  cursor: pointer;
  transition: background var(--t-fast), color var(--t-fast);
  border: 1px solid transparent;
  min-height: 40px;
  white-space: normal;
  line-height: 1.4;
  word-break: break-word;
}

.q-option:hover { background: var(--c-surface-2); }

.q-option.is-correct {
  /* Fallback solid rgba for browsers without color-mix support */
  background-color: rgba(63,185,80,0.12);
  border-color: rgba(63,185,80,0.35);
  color: var(--c-success);
  /* Prefer modern color-mix when available */
  background: color-mix(in srgb, var(--c-success) 15%, transparent);
  border-color: color-mix(in srgb, var(--c-success) 35%, transparent);
}

.q-option.is-wrong {
  /* Fallback solid rgba for browsers without color-mix support */
  background-color: rgba(248,81,73,0.12);
  border-color: rgba(248,81,73,0.30);
  color: var(--c-danger);
  /* Prefer modern color-mix when available */
  background: color-mix(in srgb, var(--c-danger) 12%, transparent);
  border-color: color-mix(in srgb, var(--c-danger) 30%, transparent);
}

.q-option-key { font-weight: 700; font-size: 0.78rem; width: 20px; text-align: center; flex-shrink: 0; }

.question-rationale {
  padding: 10px 16px 14px;
  font-size: 0.82rem;
  color: var(--c-text-muted);
  border-top: 1px solid var(--c-border);
  display: none;
}

.question-rationale.is-visible { display: block; }

ul, li {
  margin-left: 10px;
  padding: 0;

}

.expanded-bullets {
  margin-left: 1.5rem;
  list-style-type: disc;
  list-style-position: outside;
}

.expanded-item {
  margin-top: 20px;
  margin-bottom: 1.5rem;
}

.expanded-name {
  margin-bottom: 0.25rem;
}



/* ── Error pane ── */
.error-pane {
  display: flex !important;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 60vh;
  text-align: center;
  gap: 12px;
}
.error-pane.is-hidden { display: none !important; }
.error-icon  { font-size: 3rem; }
.error-title { font-size: 1.4rem; font-weight: 700; color: var(--c-danger); }
.error-message { color: var(--c-text-muted); font-size: 0.9rem; max-width: 44ch; }

.btn-retry {
  margin-top: 8px;
  padding: 9px 22px;
  background: var(--c-accent);
  color: #fff;
  border: none;
  border-radius: 6px;
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  transition: background var(--t-fast), transform var(--t-fast);
}
.btn-retry:hover  { background: var(--c-accent-bright); }
.btn-retry:active { transform: scale(0.97); }

/* ── Loading Overlay ── */
.loading-overlay {
  position: absolute;
  inset: 0;
  z-index: 100;
  background: rgba(13, 17, 23, 0.08);
  backdrop-filter: blur(1.5px);
  -webkit-backdrop-filter: blur(1.5px);
  pointer-events: all;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  opacity: 1;
  transition: opacity var(--t-slow);
}

.loading-overlay.is-hidden {
  opacity: 0;
  pointer-events: none;
  visibility: hidden;
}

.loading-overlay.is-entering { opacity: 0; }

.exam-pane {
  position: fixed;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  background: rgba(13, 17, 23, 0.82);
  z-index: 150;
  overflow-y: auto;
}

.exam-pane.is-hidden {
  display: none !important;
}

.exam-modal-card {
  width: min(100%, 980px);
  max-width: 960px;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: 20px;
  box-shadow: 0 28px 80px rgba(0, 0, 0, 0.4);
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.exam-modal-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
}

.exam-modal-header h2 {
  margin: 0;
  font-size: 1.5rem;
}

.exam-modal-subtitle {
  margin: 8px 0 0;
  color: var(--c-text-muted);
  font-size: 0.95rem;
  line-height: 1.5;
}

.btn-icon {
  background: transparent;
  border: 1px solid transparent;
  color: var(--c-text);
  font-size: 1.05rem;
  padding: 10px;
  border-radius: 999px;
  cursor: pointer;
  transition: background var(--t-fast);
}

.btn-icon:hover {
  background: rgba(255, 255, 255, 0.06);
}

.exam-summary {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
}

.exam-summary div {
  background: var(--c-surface-2);
  border: 1px solid var(--c-border);
  border-radius: 16px;
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.exam-summary strong {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--c-text-muted);
}

.exam-summary span {
  font-size: 1rem;
  font-weight: 700;
  color: var(--c-text);
}

.exam-cooldown-note {
  color: var(--c-text-muted);
  font-size: 0.93rem;
  line-height: 1.6;
}

.exam-modal-footer,
.exam-footer {
  display: flex;
  justify-content: flex-end;
  gap: 12px;
  flex-wrap: wrap;
}

.btn-primary {
  background: var(--c-accent);
  color: #fff;
  border: none;
  border-radius: 10px;
  padding: 12px 22px;
  font-weight: 700;
  cursor: pointer;
  transition: background var(--t-fast), transform var(--t-fast);
}

.btn-primary:hover:not([disabled]) {
  background: var(--c-accent-bright);
}

.btn-primary:disabled {
  background: var(--c-border);
  color: var(--c-text-muted);
  cursor: not-allowed;
}

.btn-secondary {
  background: transparent;
  color: var(--c-text);
  border: 1px solid var(--c-border);
  border-radius: 10px;
  padding: 12px 22px;
  cursor: pointer;
  transition: background var(--t-fast), border-color var(--t-fast);
}

.btn-secondary:hover {
  border-color: var(--c-accent);
  background: rgba(47, 129, 247, 0.08);
}

.exam-meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  color: var(--c-text-muted);
  font-size: 0.95rem;
}

.exam-meta-row span {
  background: var(--c-surface-2);
  border: 1px solid var(--c-border);
  border-radius: 12px;
  padding: 10px 14px;
}

.exam-body {
  display: flex;
  flex-direction: column;
  gap: 18px;
  max-height: min(62vh, 720px);
  overflow: auto;
  padding-right: 2px;
}

.exam-results {
  margin-top: 4px;
  padding: 18px;
  background: color-mix(in srgb, var(--c-accent) 10%, var(--c-surface));
  border: 1px solid rgba(47, 129, 247, 0.24);
  border-radius: 16px;
}

.exam-results p {
  margin: 10px 0 0;
  color: var(--c-text);
}

.loading-label {
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--c-accent-bright);
  opacity: 0.85;
}

/* ── Spinner ── */
.spinner {
  position: relative;
  width: var(--spinner-outer-size);
  height: var(--spinner-outer-size);
}

.ring { position: absolute; inset: 0; border-radius: 50%; }

.ring-outer {
  width: var(--spinner-outer-size);
  height: var(--spinner-outer-size);
  background: var(--spinner-grad);
  border-radius: 50%;
  animation: ring-spin 1.1s linear infinite;
  -webkit-mask: radial-gradient(
    farthest-side,
    transparent calc(100% - var(--ring-thickness) - 1px),
    #000        calc(100% - var(--ring-thickness))
  );
  mask: radial-gradient(
    farthest-side,
    transparent calc(100% - var(--ring-thickness) - 1px),
    #000        calc(100% - var(--ring-thickness))
  );
}

.ring-inner {
  top: 50%;
  left: 50%;
  width: var(--spinner-inner-size);
  height: var(--spinner-inner-size);
  border: var(--ring-thickness) solid transparent;
  border-top-color: var(--c-accent);
  border-right-color: color-mix(in srgb, var(--c-accent) 40%, transparent);
  animation:
    ring-inner-spin  0.75s linear      infinite,
    ring-pulse       1.4s  ease-in-out infinite;
}

@keyframes ring-spin       { to { transform: rotate(360deg); } }
@keyframes ring-inner-spin {
  from { transform: translate(-50%, -50%) rotate(0deg);   }
  to   { transform: translate(-50%, -50%) rotate(360deg); }
}
@keyframes ring-pulse {
  0%, 100% { opacity: 1;    }
  50%       { opacity: 0.45; }
}
@keyframes spin-simple { to { transform: rotate(360deg); } }

/* ── Responsive ── */
@media (max-width: 720px) {
  .app-shell { grid-template-columns: 1fr; }
  .sidebar {
    position: fixed; left: -100%; top: 0; height: 100vh;
    width: 80vw; max-width: 300px;
    transition: left 0.25s ease; z-index: 200;
  }
  .sidebar.is-open { left: 0; }
  .menu-toggle { display: inline-flex; }
  .menu-backdrop { display: block; }
  .content-host { padding: 82px 20px 24px; }
}