/* KEEP THIS COMMENT INTACT: styles.css */

/* =========================================================
   DESIGN TOKENS
   ========================================================= */
:root {
  --sidebar-width: 260px;
  --sidebar-collapsed-width: 48px;

  --font-body: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  --font-mono: 'Cascadia Code', 'Fira Code', 'Consolas', monospace;

  --font-size-xs: 13px;
  --font-size-sm: 15px;
  --font-size-base: 17px;
  --font-size-md: 20px;
  --font-size-lg: 26px;

  --line-height-body: 1.55;
  --line-height-code: 1.65;

  /* Light theme (page background) */
  --color-bg-page: #f5f7fa;
  --color-bg-sidebar: #edf2f7;
  --color-bg-card: #ffffff;
  --color-border-light: #e2e8f0;
  --color-text-primary: #2d3748;
  --color-text-secondary: #5a677a;
  --color-text-muted: #8a94a6;

  --color-accent-blue: #3182ce;
  --color-accent-green: #10b981;
  --color-accent-orange: #dd6b20;

  /* ---------------------------------------------------------
     CODE THEME — HIGH CONTRAST, LOW NOISE
     --------------------------------------------------------- */

  --code-bg: #282c34;
  --code-text: #b6c6e3;
  --code-comment: #6a9955;
  --code-keyword: #c678dd;
  --code-string: #ce9178;
  --code-number: #7ea8c3;
  --code-function: #ffd166;
  --code-type: #56b6c2;
  --code-constant: #e8dcc4;
  --code-html-tag: #e06c75;
  --code-html-attr: #98c379;
  --code-selection: #3e4451;
  --code-current-line: #2c313a;

  --radius-sm: 6px;
}

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

body {
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  line-height: var(--line-height-body);
  color: var(--color-text-primary);
  background: var(--color-bg-page);
  min-height: 100vh;
}

/* =========================================================
   LAYOUT WRAPPER (lab pages with sidebar)
   ========================================================= */
body:has(.sidebar) {
  display: flex;
}

/* =========================================================
   SIDEBAR
   ========================================================= */
.sidebar {
  width: var(--sidebar-width);
  min-width: var(--sidebar-width);
  background: var(--color-bg-sidebar);
  border-right: 1px solid var(--color-border-light);
  padding: 28px 0;
  display: flex;
  flex-direction: column;
  overflow-y: auto;
}

.sidebar-header {
  padding: 0 24px 12px;
  font-size: var(--font-size-xs);
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--color-text-muted);
}

.sidebar-item {
  padding: 10px 24px;
  text-align: left;
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  cursor: pointer;
  text-decoration: none;
  border-left: 3px solid transparent;
  transition: background-color 0.15s, color 0.15s;
}

.sidebar-item:hover {
  background: #e2e8f0;
  color: var(--color-text-primary);
}

.sidebar-item.active {
  background: #e2e8f0;
  color: var(--color-accent-blue);
  border-left-color: var(--color-accent-blue);
  font-weight: 600;
}

.sidebar-back {
  display: none;
  padding: 10px 0;
  text-align: center;
  font-size: 16px;
  color: var(--color-accent-blue);
  text-decoration: none;
}

.sidebar-utilities {
  padding: 8px 24px 8px;
}

/*
   Prevent cloned per-section CTAs from appearing on desktop.
   JS injects them into every .step; CSS decides visibility.
*/
.step .sidebar-utilities {
  display: none;
}

.btn-download {
  display: inline-flex;
  align-items: center;
  gap: 0.4em;
  padding: 6px 8px;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-accent-orange);
  background: rgba(221, 107, 32, 0.08);
  border-radius: var(--radius-sm);
  border: 1px solid rgba(221, 107, 32, 0.25);
  text-decoration: none;
  transition: background-color 0.15s;
}

.btn-download:hover {
  background: rgba(221, 107, 32, 0.14);
}

.more-downloads-note {
  margin-top: 4px;
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
}

/* =========================================================
   MOBILE SIDEBAR
   ========================================================= */
@media (max-width: 768px) {
  .sidebar {
    width: var(--sidebar-collapsed-width);
    min-width: var(--sidebar-collapsed-width);
  }

  .sidebar .sidebar-header,
  .sidebar .sidebar-utilities {
    display: none;
  }

  .sidebar-item {
    padding: 10px 0;
    text-align: center;
  }

  .sidebar-item span {
    display: none;
  }

  .sidebar-item::before {
    counter-increment: step;
    content: counter(step);
    font-weight: 600;
  }

  .sidebar-back {
    display: block;
  }

  .sidebar {
    counter-reset: step;
  }

  /*
     On mobile, show the per-section CTA clones
     and ensure consistent spacing.
  */
  .step .sidebar-utilities {
    display: block;
    margin-top: 24px;
  }
}

/* =========================================================
   SVG ICON
   ========================================================= */
.icon-lock {
  display: inline-block;
  width: 1em;
  height: 1em;
  background-size: contain;
  background-repeat: no-repeat;
  background-position: center;
  vertical-align: -0.125em;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%2394a3b8' stroke-width='1.5'%3E%3Crect x='3' y='10' width='18' height='12' rx='2' ry='2'/%3E%3Cpath d='M7 10V6a5 5 0 0110 0v4'/%3E%3C/svg%3E");
}

/* =========================================================
   MAIN CONTENT
   ========================================================= */
.main {
  flex: 1;
  padding: 40px 48px;
  overflow-y: auto;
  max-width: 900px;
}

/* =========================================================
   STEPS
   ========================================================= */
.step {
  display: none;
}

.step.active {
  display: block;
}

/* =========================================================
   INFO BOXES
   ========================================================= */
.info-box {
  background: #ebf8ff;
  border-left: 3px solid var(--color-accent-blue);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 14px 18px;
  font-size: var(--font-size-sm);
  color: var(--color-text-primary);
  line-height: var(--line-height-body);
  margin-bottom: 20px;
}

.info-box.green {
  background: #f0fff4;
  border-color: var(--color-accent-green);
}

/* =========================================================
   TYPOGRAPHY
   ========================================================= */
.main h1 {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: 6px;
}

.main .subtitle {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  margin-bottom: 32px;
}

/* =========================================================
   LINKS
   ========================================================= */
a {
  color: var(--color-accent-blue);
  text-decoration: none;
  font-weight: 500;
  border-radius: var(--radius-sm);
  transition: color 0.15s, background-color 0.15s;
}

a:hover {
  color: var(--color-accent-green);
  background: rgba(16, 185, 129, 0.08);
}

/* =========================================================
   INLINE CODE
   ========================================================= */
.emph {
  font-family: var(--font-mono);
  font-size: 0.94em;
  color: var(--color-accent-blue);
  background: rgba(49, 130, 206, 0.08);
  padding: 0 5px;
  border-radius: var(--radius-sm);
}

/* =========================================================
   LISTS
   ========================================================= */
ul.styled {
  list-style: none;
  padding: 0;
  margin: 12px 0 20px;
}

ul.styled li {
  padding: 6px 0 6px 20px;
  position: relative;
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  line-height: 1.5;
}

ul.styled li::before {
  content: '•';
  position: absolute;
  left: 4px;
  color: var(--color-accent-blue);
  font-weight: bold;
}

/* =========================================================
   CODE BLOCKS
   ========================================================= */
.code-block {
  background: var(--code-bg);
  border-radius: var(--radius-sm);
  padding: 20px 24px;
  overflow-x: auto;
  margin: 16px 0 24px;
  border: 1px solid var(--code-current-line);
  font-family: var(--font-mono);
  font-size: var(--font-size-sm);
  line-height: var(--line-height-code);
  color: var(--code-text);
}

.code-block pre {
  margin: 0;
  white-space: pre;
}

.code-block .current-line {
  background: var(--code-current-line);
}

::selection {
  background: var(--code-selection);
}

/* =========================================================
   SYNTAX HIGHLIGHTING
   ========================================================= */

.cmt { color: var(--code-comment); font-style: italic; }
.kw { color: var(--code-keyword); }
.type { color: var(--code-type); }
.fn { color: var(--code-function); }
.const { color: var(--code-constant); }
.num { color: var(--code-number); }
.str { color: var(--code-string); }
.tag { color: var(--code-html-tag); }
.attr { color: var(--code-html-attr); }

.lang-html .tag { color: var(--code-html-tag); }
.lang-html .attr { color: var(--code-html-attr); }

/* =========================================================
   BYTE DISPLAY (PROTOCOL)
   ========================================================= */
.byte-display {
  margin: 16px 0 24px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.byte-row {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.byte-label {
  font-family: var(--font-mono);
  font-size: var(--font-size-xs);
  font-weight: 700;
  min-width: 32px;
  text-transform: uppercase;
}

.byte-label.tx { color: var(--color-accent-blue); }
.byte-label.rx { color: var(--color-accent-orange); }

.byte-value {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 52px;
  padding: 4px 8px;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: var(--font-size-xs);
  font-weight: 600;
}

.byte-value.tx {
  background: rgba(49, 130, 206, 0.12);
  border: 1px solid rgba(49, 130, 206, 0.4);
  color: #2b6cb0;
}

.byte-value.rx {
  background: rgba(221, 107, 32, 0.12);
  border: 1px solid rgba(221, 107, 32, 0.4);
  color: #c05621;
}

/* =========================================================
   PROGRESS BAR
   ========================================================= */
.progress {
  height: 3px;
  background: var(--color-border-light);
  border-radius: 2px;
  margin-bottom: 28px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(
    90deg,
    var(--color-accent-blue),
    var(--color-accent-green)
  );
  border-radius: 2px;
}

/* =========================================================
   PROTOCOL COMMAND BLOCK
   ========================================================= */
.protocol-cmd {
  background: var(--color-bg-card);
  border-left: 3px solid var(--color-accent-blue);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 12px 18px;
  margin-bottom: 16px;
}

.protocol-cmd strong {
  display: block;
  font-size: var(--font-size-sm);
  color: var(--color-text-primary);
  margin-bottom: 6px;
}

/* =========================================================
   NAVIGATION
   ========================================================= */
.nav-row {
  display: flex;
  justify-content: space-between;
  margin-top: 32px;
  padding-top: 20px;
  border-top: 1px solid var(--color-border-light);
}

.nav-btn {
  padding: 10px 22px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border-light);
  background: var(--color-bg-card);
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  cursor: pointer;
  transition: all 0.15s;
}

.nav-btn:hover:not(:disabled) {
  border-color: var(--color-accent-blue);
  color: var(--color-accent-blue);
}

.nav-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.nav-btn.primary {
  background: linear-gradient(135deg, var(--color-accent-blue), #2c5282);
  color: #fff;
  border-color: transparent;
}

/* =========================================================
   BADGE
   ========================================================= */
.badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  font-size: 11px;
  font-weight: 600;
  background: #ebf8ff;
  color: var(--color-accent-blue);
  margin-left: 8px;
  vertical-align: middle;
}

/* =========================================================
   HERE HIGHLIGHT
   ========================================================= */
.here {
  color: var(--color-accent-orange);
  font-weight: 600;
}