/* ── Collatz Loops — Home ──────────────────────────────────────────────────── */

:root {
  --cl-bg:          #0b0e14;
  --cl-panel:       #0f1319;
  --cl-panel-2:     #141820;
  --cl-border:      rgba(255,255,255,0.07);
  --cl-border-mid:  rgba(255,255,255,0.12);
  --cl-grid-line:   rgba(255,255,255,0.025);
  --cl-grid-glow:   rgba(232,160,32,0.04);
  --cl-text:        #e8e4da;
  --cl-text-2:      #8a8680;
  --cl-text-dim:    #4a4845;
  --cl-amber:       #e8a020;
  --cl-amber-dim:   #b07a18;
  --cl-amber-glow:  rgba(232,160,32,0.12);
  --cl-amber-tint:  rgba(232,160,32,0.06);
  --cl-teal:        #2ec4a0;
  --cl-teal-dim:    #1a8a70;
  --cl-teal-glow:   rgba(46,196,160,0.12);
  --cl-teal-tint:   rgba(46,196,160,0.05);
  --cl-toggle-bg:     rgba(255,255,255,0.05);
  --cl-toggle-border: rgba(255,255,255,0.1);
}

[data-theme="light"] {
  --cl-bg:          #f4f1eb;
  --cl-panel:       #faf8f4;
  --cl-panel-2:     #eeebe3;
  --cl-border:      rgba(0,0,0,0.07);
  --cl-border-mid:  rgba(0,0,0,0.14);
  --cl-grid-line:   rgba(0,0,0,0.035);
  --cl-grid-glow:   rgba(232,160,32,0.06);
  --cl-text:        #1a1814;
  --cl-text-2:      #6b6660;
  --cl-text-dim:    #aaa59e;
  --cl-amber-glow:  rgba(232,160,32,0.18);
  --cl-amber-tint:  rgba(232,160,32,0.08);
  --cl-teal-glow:   rgba(46,196,160,0.15);
  --cl-teal-tint:   rgba(46,196,160,0.07);
  --cl-toggle-bg:     rgba(0,0,0,0.04);
  --cl-toggle-border: rgba(0,0,0,0.12);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; }

body {
  background: var(--cl-bg);
  color: var(--cl-text);
  font-family: 'DM Sans', sans-serif;
  font-weight: 300;
  min-height: 100vh;
  overflow-x: hidden;
  transition: background 0.2s, color 0.2s;
}
a { text-decoration: none; color: inherit; }

/* ── Background grid ───────────────────────────────────────────────────────── */

.bg-grid {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background-image:
    linear-gradient(var(--cl-grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--cl-grid-line) 1px, transparent 1px);
  background-size: 40px 40px;
}
.bg-grid::after {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse 80% 60% at 50% -10%, var(--cl-grid-glow) 0%, transparent 70%);
}

/* ── Header ────────────────────────────────────────────────────────────────── */

.site-header {
  position: relative;
  z-index: 10;
  border-bottom: 1px solid var(--cl-border);
  padding: 1.1rem 2rem;
}
.header-inner {
  max-width: 620px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 1rem;
}
.wordmark {
  font-family: 'Instrument Serif', Georgia, serif;
  font-size: 1.45rem;
  letter-spacing: -0.01em;
  line-height: 1;
  flex: 1;
}
.wordmark-main   { color: var(--cl-text); }
.wordmark-accent { color: var(--cl-amber); font-style: italic; margin-left: 0.3em; }

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}
.how-btn {
  background: transparent;
  border: 1px solid var(--cl-border-mid);
  border-radius: 4px;
  color: var(--cl-text-dim);
  cursor: pointer;
  font-family: 'DM Mono', monospace;
  font-size: 0.6rem;
  letter-spacing: 0.08em;
  padding: 5px 10px;
  text-transform: uppercase;
  transition: color 0.15s, border-color 0.15s;
}
.how-btn:hover { color: var(--cl-amber); border-color: var(--cl-amber-dim); }

.theme-toggle {
  display: flex;
  background: var(--cl-toggle-bg);
  border: 1px solid var(--cl-toggle-border);
  border-radius: 4px;
  overflow: hidden;
}
.theme-btn {
  background: none;
  border: none;
  cursor: pointer;
  font-family: 'DM Mono', monospace;
  font-size: 0.6rem;
  letter-spacing: 0.08em;
  padding: 5px 10px;
  color: var(--cl-text-dim);
  transition: color 0.15s, background 0.15s;
}
.theme-btn:hover { color: var(--cl-text); }
.theme-btn.active { background: var(--cl-amber-glow); color: var(--cl-amber); }
.theme-btn + .theme-btn { border-left: 1px solid var(--cl-toggle-border); }

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

.main {
  position: relative;
  z-index: 10;
  max-width: 620px;
  margin: 0 auto;
  padding: 2.5rem 2rem 3rem;
  display: flex;
  flex-direction: column;
  gap: 2.5rem;
}

/* ── Hero ──────────────────────────────────────────────────────────────────── */

.hero {
  position: relative;
  border-radius: 12px;
  overflow: hidden;
  border: 1px solid var(--cl-border);
  background: var(--cl-panel);
}

.hero-bg {
  position: absolute;
  inset: 0;
  pointer-events: none;
}
.hero-svg {
  width: 100%;
  height: 100%;
  color: var(--cl-text);
}

.hero-content {
  position: relative;
  padding: 3rem 2.25rem 2.5rem;
}

.hero-heading {
  font-family: 'Instrument Serif', Georgia, serif;
  font-size: clamp(2.4rem, 7vw, 3.6rem);
  font-weight: 400;
  line-height: 1.1;
  letter-spacing: -0.03em;
  color: var(--cl-text);
  margin-bottom: 0.75rem;
}
.hero-heading em {
  font-style: italic;
  color: var(--cl-amber);
}

.hero-sub {
  font-size: 0.9rem;
  color: var(--cl-text-dim);
  letter-spacing: 0.01em;
}

/* ── Generator groups ──────────────────────────────────────────────────────── */

.generators {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.gen-group { display: flex; flex-direction: column; }

.gen-group__label {
  font-family: 'Instrument Serif', Georgia, serif;
  font-size: 1.2rem;
  font-style: normal;
  letter-spacing: -0.01em;
  margin-bottom: 6px;
  padding-left: 3px;
}

.gen-group--collatz .gen-group__label { color: var(--cl-amber); }
.gen-group--freestyle .gen-group__label { color: var(--cl-teal); }

/* ── Items ─────────────────────────────────────────────────────────────────── */

.gen-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.8rem 1rem;
  border: 1px solid var(--cl-border);
  border-bottom: none;
  transition: background 0.15s, border-color 0.15s;
  position: relative;
  cursor: pointer;
}

.gen-group .gen-item:first-of-type { border-radius: 8px 8px 0 0; }
.gen-group .gen-item:last-of-type  { border-radius: 0 0 8px 8px; border-bottom: 1px solid var(--cl-border); }
.gen-group .gen-item:only-of-type  { border-radius: 8px; border-bottom: 1px solid var(--cl-border); }
.gen-item + .gen-item { border-top: none; }

.gen-item::before {
  content: '';
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 3px;
  border-radius: 2px 0 0 2px;
  transition: opacity 0.15s;
}

/* Collatz items — amber tint */
.gen-group--collatz .gen-item {
  background: var(--cl-amber-tint);
}
.gen-group--collatz .gen-item::before { background: var(--cl-amber); opacity: 0.4; }
.gen-group--collatz .gen-item:hover   { background: var(--cl-amber-glow); border-color: rgba(232,160,32,0.2); }
.gen-group--collatz .gen-item:hover::before { opacity: 1; }

/* Freestyle items — teal tint */
.gen-group--freestyle .gen-item {
  background: var(--cl-teal-tint);
}
.gen-group--freestyle .gen-item::before { background: var(--cl-teal); opacity: 0.4; }
.gen-group--freestyle .gen-item:hover   { background: var(--cl-teal-glow); border-color: rgba(46,196,160,0.2); }
.gen-group--freestyle .gen-item:hover::before { opacity: 1; }

.gen-item__name {
  font-size: 0.88rem;
  color: var(--cl-text);
  flex-shrink: 0;
}

.gen-item__hint {
  font-family: 'DM Mono', monospace;
  font-size: 0.63rem;
  color: var(--cl-text-dim);
  flex: 1;
}

/* ── Promo ─────────────────────────────────────────────────────────────────── */

.promo {
  display: block;
  text-align: center;
  padding: 0.75rem 1rem;
  background: var(--cl-panel);
  border: 1px solid var(--cl-border);
  border-radius: 8px;
  font-size: 0.82rem;
  color: var(--cl-text-2);
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}
.promo:hover { background: var(--cl-panel-2); border-color: var(--cl-border-mid); color: var(--cl-amber); }

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

.site-footer {
  position: relative;
  z-index: 10;
  border-top: 1px solid var(--cl-border);
  padding: 1rem 2rem;
  text-align: center;
  font-family: 'DM Mono', monospace;
  font-size: 0.6rem;
  color: var(--cl-text-dim);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

/* ── Modal ─────────────────────────────────────────────────────────────────── */

.modal-backdrop {
  position: fixed;
  inset: 0;
  z-index: 100;
  background: rgba(0,0,0,0.55);
  backdrop-filter: blur(6px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.18s;
}
.modal-backdrop.is-open { opacity: 1; pointer-events: all; }

.modal {
  background: var(--cl-panel);
  border: 1px solid var(--cl-border-mid);
  border-radius: 14px;
  width: 100%;
  max-width: 520px;
  max-height: 80vh;
  display: flex;
  flex-direction: column;
  box-shadow: 0 32px 80px rgba(0,0,0,0.5);
  transform: translateY(8px);
  transition: transform 0.18s;
}
.modal-backdrop.is-open .modal { transform: translateY(0); }

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--cl-border);
  flex-shrink: 0;
}
.modal-title {
  font-family: 'Instrument Serif', Georgia, serif;
  font-size: 1.15rem;
  font-weight: 400;
  color: var(--cl-text);
}
.modal-close {
  background: none;
  border: none;
  color: var(--cl-text-dim);
  cursor: pointer;
  font-size: 0.85rem;
  padding: 4px 8px;
  border-radius: 4px;
  transition: color 0.12s;
  line-height: 1;
}
.modal-close:hover { color: var(--cl-text); }

.modal-body {
  padding: 1.5rem;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 0.9rem;
  scrollbar-width: thin;
  scrollbar-color: var(--cl-border-mid) transparent;
}
.modal-body p { font-size: 0.85rem; color: var(--cl-text-2); line-height: 1.7; }
.modal-body h3 {
  font-family: 'DM Mono', monospace;
  font-size: 0.6rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--cl-amber);
  padding-top: 0.25rem;
}
.modal-body strong { color: var(--cl-text); font-weight: 500; }
.how-purple { color: #9b7fe8; font-weight: 500; }
.how-orange { color: #e8a020; font-weight: 500; }

/* ── Responsive ────────────────────────────────────────────────────────────── */
@media (max-width: 480px) {
  .site-header { padding: 1rem; }
  .main { padding: 1.5rem 1rem 2rem; }
  .how-btn { display: none; }
}