/* ============================================================
   SolarSails Design System V2
   Unified Design Tokens & Component Styles
   All pages must reference this file for consistent styling.
   ============================================================ */

/* ── Design Tokens (CSS Custom Properties) ────────────────── */
:root {
  /* Color System */
  --color-primary: #4CAF50;
  --color-primary-hover: #66BB6A;
  --color-primary-active: #388E3C;
  --color-primary-disabled: #2E7D32;
  --color-error: #f44336;

  /* Primary with opacity */
  --color-primary-4: rgba(76,175,80,0.04);
  --color-primary-6: rgba(76,175,80,0.06);
  --color-primary-8: rgba(76,175,80,0.08);
  --color-primary-10: rgba(76,175,80,0.10);
  --color-primary-15: rgba(76,175,80,0.15);
  --color-primary-20: rgba(76,175,80,0.20);
  --color-primary-25: rgba(76,175,80,0.25);
  --color-primary-30: rgba(76,175,80,0.30);
  --color-primary-40: rgba(76,175,80,0.40);
  --color-primary-50: rgba(76,175,80,0.50);

  /* Background */
  --bg-primary: #000000;
  --bg-secondary: #0d0d0d;
  --bg-card: #151515;
  --bg-nav: rgba(0,0,0,0.88);

  /* Surface / Border */
  --border-subtle: rgba(255,255,255,0.04);
  --border-light: rgba(255,255,255,0.06);
  --border-medium: rgba(255,255,255,0.08);
  --border-white-15: rgba(255,255,255,0.15);
  --border-white-20: rgba(255,255,255,0.20);
  --border-white-40: rgba(255,255,255,0.40);

  /* Text */
  --text-primary: #ffffff;
  --text-secondary: #e5e7eb;
  --text-body: #9ca3af;
  --text-muted: #8b929e;
  --text-dim: #7a8290;
  --text-on-primary: #000000;

  /* Spacing Scale (8px base) */
  --space-1: 4px;
  --space-2: 8px;
  --space-2_5: 10px;
  --space-3: 12px;
  --space-3_5: 14px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-7: 28px;
  --space-8: 32px;
  --space-9: 36px;
  --space-10: 40px;
  --space-12: 48px;
  --space-15: 60px;
  --space-16: 64px;
  --space-20: 80px;
  --space-24: 96px;
  --space-30: 120px;
  --space-32: 128px;
  --space-35: 140px;
  --space-40: 160px;

  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

  --text-xs: 0.75rem;     /* 12px */
  --text-sm: 0.875rem;    /* 14px */
  --text-base: 1rem;      /* 16px */
  --text-lg: 1.125rem;    /* 18px */
  --text-xl: 1.25rem;     /* 20px */
  --text-2xl: 1.5rem;     /* 24px */
  --text-3xl: 1.875rem;   /* 30px */
  --text-4xl: 2.25rem;    /* 36px */
  --text-5xl: 3rem;       /* 48px */
  --text-6xl: 3.75rem;    /* 60px */

  --leading-none: 1;
  --leading-tight: 1.1;
  --leading-snug: 1.25;
  --leading-normal: 1.5;
  --leading-relaxed: 1.7;
  --leading-loose: 1.85;

  --tracking-tight: -0.03em;
  --tracking-normal: 0;
  --tracking-wide: 0.15em;

  /* Border Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --radius-2xl: 24px;
  --radius-full: 9999px;

  /* Shadow */
  --shadow-card-hover: 0 8px 24px rgba(0,0,0,0.3);
  --shadow-button-hover: 0 4px 12px rgba(76,175,80,0.2);

  /* Transition */
  --transition-fast: 0.15s ease;
  --transition-base: 0.25s ease;
  --transition-slow: 0.4s ease;

  /* Layout */
  --content-xs: 560px;
  --content-sm: 640px;
  --content-narrow: 680px;
  --content-default: 800px;
  --content-lg: 900px;
  --content-visual: 960px;
  --content-wide: 1200px;
  --section-padding: 96px 24px;
  --hero-min-height: 80vh;
  --nav-height: 64px;
}

/* ── Base Reset & Global ──────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; }

body {
  margin: 0;
  padding: 0;
  font-family: var(--font-family);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  overflow-x: hidden;
  line-height: var(--leading-relaxed);
  font-size: var(--text-base);
}

/* Scrollbar */
::-webkit-scrollbar { width: 5px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--color-primary-30); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--color-primary-50); }

/* ── Typography System ────────────────────────────────────── */
h1, h2, h3, h4, h5, h6 { margin: 0; color: var(--text-primary); }

h1 {
  font-size: clamp(2.5rem, 5vw, 4.5rem);
  font-weight: 700;
  line-height: var(--leading-tight);
  letter-spacing: -0.04em;
}

h2 {
  font-size: clamp(1.75rem, 3vw, 3rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.03em;
}

h3 {
  font-size: var(--text-xl);
  font-weight: 600;
  line-height: var(--leading-snug);
  letter-spacing: -0.01em;
}

p { margin: 0; color: var(--text-body); line-height: var(--leading-relaxed); }

a { color: inherit; text-decoration: none; }

/* Section Label */
.section-label {
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  color: var(--color-primary);
  margin-bottom: var(--space-4);
}

/* ── Navigation System ────────────────────────────────────── */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: var(--bg-nav);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-light);
  padding: 0 var(--space-6);
}

.nav-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--nav-height);
}

.nav-logo {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  text-decoration: none;
}

.nav-logo span { color: var(--color-primary); }

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-8);
}

.nav-links a {
  font-size: var(--text-sm);
  color: var(--text-body);
  transition: color var(--transition-base);
  text-decoration: none;
  position: relative;
}

.nav-links a:hover,
.nav-links a.active { color: var(--text-primary); }

.nav-links a.active::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--color-primary);
  border-radius: 1px;
}

.nav-cta {
  display: inline-flex;
  align-items: center;
  font-size: var(--text-sm);
  font-weight: 600;
  background: var(--color-primary);
  color: var(--text-on-primary);
  padding: var(--space-2) var(--space-5);
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  text-decoration: none;
  transition: background var(--transition-base), transform var(--transition-base);
}

.nav-cta:hover {
  background: var(--color-primary-hover);
  transform: translateY(-1px);
}

.nav-cta:active { transform: translateY(0); }

/* Hamburger */
.hamburger {
  display: none;
  background: none;
  border: none;
  color: var(--text-primary);
  font-size: 1.5rem;
  cursor: pointer;
  padding: var(--space-2);
  line-height: 1;
  aria-label: "Menu";
}

/* Mobile Nav */
@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: rgba(0,0,0,0.95);
    flex-direction: column;
    padding: var(--space-6);
    gap: var(--space-4);
    border-bottom: 1px solid var(--border-light);
  }
  .nav-links.open { display: flex; }
  .nav-links a { font-size: var(--text-base); padding: var(--space-3) 0; }
  .nav-cta { margin-top: var(--space-2); }
  .hamburger { display: block; }
}

/* ── Button System ────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  font-family: var(--font-family);
  font-size: var(--text-base);
  font-weight: 600;
  padding: 14px 32px;
  border-radius: 12px;
  border: none;
  cursor: pointer;
  text-decoration: none;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  line-height: 1;
}

.btn-primary {
  background: var(--color-primary);
  color: var(--text-on-primary);
}

.btn-primary:hover {
  background: var(--color-primary-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow-button-hover);
}

.btn-primary:active {
  transform: scale(0.98);
  background: var(--color-primary-active);
}

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

.btn-secondary {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border-white-15);
  font-weight: 500;
}

.btn-secondary:hover {
  border-color: var(--border-white-40);
  transform: translateY(-2px);
}

.btn-secondary:active { transform: scale(0.98); }

.btn-outline {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border-white-20);
  font-weight: 600;
}

.btn-outline:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  transform: translateY(-2px);
}

.btn-outline:active { transform: scale(0.98); }

.btn-ghost {
  background: transparent;
  color: var(--color-primary);
  border: 1px solid var(--color-primary-30);
  padding: 12px 28px;
}

.btn-ghost:hover {
  background: var(--color-primary-8);
  border-color: var(--color-primary-50);
}

.btn-pill {
  border-radius: var(--radius-full);
  padding: 10px 20px;
  font-size: var(--text-sm);
  font-weight: 500;
  background: rgba(255,255,255,0.05);
  border: 1px solid rgba(255,255,255,0.10);
  color: var(--text-body);
  transition: all var(--transition-base);
}

.btn-pill:hover {
  background: var(--color-primary-10);
  border-color: var(--color-primary-30);
  color: var(--text-primary);
}

.btn-pill.active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--text-on-primary);
  font-weight: 600;
}

/* Button Row */
.btn-row,
.hero-buttons,
.cta-buttons {
  display: flex;
  gap: var(--space-4);
  justify-content: center;
  flex-wrap: wrap;
}

/* ── Card System ──────────────────────────────────────────── */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-lg);
  padding: var(--space-10);
  box-shadow: 0 2px 8px rgba(0,0,0,0.2);
  transition: border-color var(--transition-base), transform var(--transition-base), box-shadow var(--transition-base);
}

.card:hover {
  border-color: var(--color-primary-40);
  transform: translateY(-2px);
  box-shadow: var(--shadow-card-hover);
}

.card-icon {
  width: 48px;
  height: 48px;
  margin-bottom: var(--space-4);
  color: var(--color-primary);
}

.card-icon svg {
  width: 100%;
  height: 100%;
  stroke: currentColor;
  stroke-width: 1.5;
  fill: none;
}

/* Lucide Icon Base */
[data-lucide] {
  display: inline-block;
  width: 1em;
  height: 1em;
  vertical-align: -0.125em;
}

.icon-sm { width: 16px; height: 16px; }
.icon-md { width: 20px; height: 20px; }
.icon-lg { width: 24px; height: 24px; }
.icon-xl { width: 32px; height: 32px; }

.card h3 {
  color: var(--text-primary);
  margin-bottom: var(--space-2);
}

.card p {
  color: var(--text-body);
  font-size: 0.9375rem;
  line-height: var(--leading-relaxed);
}

/* Spec Item (Technology) */
.spec-item {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: var(--space-5);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.spec-label {
  font-size: var(--text-sm);
  color: var(--text-muted);
}

.spec-value {
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--text-primary);
}

/* ── Hero System ──────────────────────────────────────────── */
.hero {
  min-height: var(--hero-min-height);
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: calc(var(--nav-height) + var(--space-20)) var(--space-6) var(--space-20);
  position: relative;
  background: var(--bg-primary);
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 80%;
  height: 60%;
  background: radial-gradient(ellipse at center, var(--color-primary-15) 0%, transparent 70%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: var(--content-default);
  margin: 0 auto;
}

.hero h1 { margin-bottom: var(--space-6); }

.hero h1 .accent { color: var(--color-primary); }

.hero p {
  font-size: var(--text-lg);
  color: var(--text-muted);
  line-height: var(--leading-normal);
  max-width: var(--content-xs);
  margin: 0 auto var(--space-8);
}

/* ── Section System ───────────────────────────────────────── */
.section {
  padding: var(--space-32) var(--space-6);
  position: relative;
}

.section-dark { background: var(--bg-primary); }
.section-alt { background: var(--bg-secondary); }

.section-content {
  max-width: var(--content-default);
  margin: 0 auto;
}

.section-content--narrow {
  max-width: var(--content-narrow);
}

.section-content--wide {
  max-width: var(--content-wide);
}

/* ── CTA Section ──────────────────────────────────────────── */
.cta-section {
  padding: var(--space-40) var(--space-6);
  text-align: center;
  background: var(--bg-primary);
  position: relative;
}

.cta-section::before {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 60%;
  height: 50%;
  background: radial-gradient(ellipse at center, var(--color-primary-6) 0%, transparent 70%);
  pointer-events: none;
}

.cta-content {
  position: relative;
  z-index: 1;
  max-width: var(--content-narrow);
  margin: 0 auto;
}

.cta-section h2 { margin-bottom: var(--space-6); }

.cta-section p {
  font-size: var(--text-lg);
  color: var(--text-body);
  margin-bottom: var(--space-8);
}

/* ── Footer System ────────────────────────────────────────── */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-light);
  padding: var(--space-12) var(--space-6) var(--space-8);
}

.footer-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

.footer-slogan {
  font-size: 0.9375rem;
  color: var(--color-primary);
  font-weight: 500;
  letter-spacing: 0.02em;
  margin-bottom: var(--space-6);
}

.footer-links {
  display: flex;
  gap: var(--space-6);
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: var(--space-6);
}

.footer-links a {
  font-size: var(--text-sm);
  color: var(--text-muted);
  transition: color var(--transition-base);
}

.footer-links a:hover { color: var(--color-primary); }

.footer-divider {
  width: 100%;
  border-top: 1px solid var(--border-light);
  padding-top: var(--space-6);
}

.footer-copy {
  font-size: 0.8125rem;
  color: var(--text-muted);
}

.footer-copy a {
  color: var(--text-muted);
  text-decoration: none;
}

.footer-copy a:hover { color: var(--color-primary); }

/* ── Image Container ──────────────────────────────────────── */
.visual-container {
  max-width: var(--content-visual);
  margin: var(--space-16) auto 0;
  aspect-ratio: 16 / 9;
  border-radius: var(--radius-xl);
  background: var(--bg-secondary);
  border: 1px solid var(--border-subtle);
  overflow: hidden;
  position: relative;
}

.visual-container img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.visual-container .placeholder {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100%;
  color: var(--text-dim);
  font-size: var(--text-sm);
}

/* ── FAQ System ───────────────────────────────────────────── */
.faq-item {
  border-bottom: 1px solid var(--border-medium);
}

.faq-item summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-5) 0;
  font-size: var(--text-base);
  font-weight: 500;
  color: var(--text-primary);
  cursor: pointer;
  list-style: none;
  transition: color var(--transition-base);
}

.faq-item summary:hover { color: var(--color-primary); }

.faq-item summary::-webkit-details-marker { display: none; }

.faq-answer {
  padding: 0 0 var(--space-5);
  color: var(--text-body);
  font-size: var(--text-base);
  line-height: var(--leading-relaxed);
}

.faq-answer .highlight { color: var(--color-primary); }

/* FAQ Arrow */
.q-arrow {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  flex-shrink: 0;
  transition: transform var(--transition-base);
}

.q-arrow svg {
  width: 20px;
  height: 20px;
  stroke: var(--text-body);
  stroke-width: 2;
  fill: none;
  transition: stroke var(--transition-base);
}

.faq-item[open] .q-arrow { transform: rotate(180deg); }
.faq-item[open] .q-arrow svg { stroke: var(--color-primary); }
.faq-item summary:hover .q-arrow svg { stroke: var(--color-primary); }

/* ── Form System ──────────────────────────────────────────── */
.form-group { margin-bottom: var(--space-5); }

.form-group label {
  display: block;
  font-size: var(--text-sm);
  color: var(--text-secondary);
  margin-bottom: var(--space-2);
}

.form-group label .required { color: var(--color-primary); }

.form-input,
.form-select,
.form-textarea {
  width: 100%;
  padding: 12px var(--space-4);
  background: var(--bg-secondary);
  border: 1px solid var(--color-primary-20);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: var(--text-base);
  font-family: var(--font-family);
  transition: border-color var(--transition-base), box-shadow var(--transition-base);
  outline: none;
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-15);
}

.form-input::placeholder,
.form-textarea::placeholder {
  color: var(--text-muted);
}

.form-submit {
  width: 100%;
  padding: 14px var(--space-6);
  border-radius: var(--radius-md);
  background: var(--color-primary);
  color: var(--text-on-primary);
  font-size: var(--text-base);
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: background var(--transition-base), transform var(--transition-base);
}

.form-submit:hover {
  background: var(--color-primary-hover);
  transform: translateY(-1px);
}

.form-submit:active { transform: translateY(0); }

.form-submit:disabled {
  background: var(--color-primary-disabled);
  cursor: not-allowed;
  transform: none;
}

.form-message {
  padding: var(--space-4);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
}

.form-message.success {
  background: var(--color-primary-15);
  border: 1px solid var(--color-primary-30);
  color: var(--color-primary);
}

.form-message.error {
  background: rgba(244,67,54,0.15);
  border: 1px solid rgba(244,67,54,0.3);
  color: var(--color-error);
}

/* ── Timeline System ──────────────────────────────────────── */
.timeline {
  position: relative;
  padding-left: var(--space-8);
}

.timeline::before {
  content: '';
  position: absolute;
  left: 5px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--color-primary-30);
}

.timeline-item {
  position: relative;
  padding-bottom: var(--space-12);
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: calc(-1 * var(--space-8) + 1px);
  top: 4px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--color-primary);
  border: 3px solid var(--bg-primary);
}

.timeline-item.future::before {
  background: var(--color-primary-30);
  border-color: var(--bg-secondary);
}

.timeline-item.future .timeline-year,
.timeline-item.future .timeline-title {
  color: var(--text-muted);
}

/* ── Utility Classes ──────────────────────────────────────── */
.text-accent { color: var(--color-primary); }
.text-body { color: var(--text-body); }
.text-muted { color: var(--text-muted); }
.text-secondary { color: var(--text-secondary); }
.bg-dark { background: var(--bg-primary); }
.bg-alt { background: var(--bg-secondary); }

/* ── Continue Reading ─────────────────────────────────────── */
.continue-section {
  text-align: center;
  padding: var(--space-32) var(--space-6);
  background: var(--bg-primary);
}

.continue-link {
  display: inline-block;
  font-size: var(--text-3xl);
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  letter-spacing: -0.02em;
  transition: color var(--transition-base);
}

.continue-link:hover { color: var(--color-primary); }

.continue-desc {
  font-size: var(--text-lg);
  color: var(--text-body);
  max-width: var(--content-xs);
  margin: var(--space-4) auto 0;
}

/* ── Responsive ───────────────────────────────────────────── */
@media (max-width: 768px) {
  :root {
    --section-padding: 64px 20px;
    --hero-min-height: 70vh;
  }

  .section { padding: var(--space-20) var(--space-5); }
  .cta-section { padding: var(--space-24) var(--space-5); }
  .card { padding: var(--space-6); }
  .visual-container { border-radius: var(--radius-lg); margin-top: var(--space-10); }
}

/* ── Image System ─────────────────────────────────────────── */
.img-hero {
  width: 100%;
  max-width: var(--content-wide);
  margin: var(--space-12) auto 0;
  border-radius: var(--radius-xl);
  overflow: hidden;
  position: relative;
  aspect-ratio: 21 / 9;
  background: var(--bg-secondary);
}

.img-hero img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.img-section {
  width: 100%;
  max-width: var(--content-default);
  margin: var(--space-12) auto;
  border-radius: var(--radius-lg);
  overflow: hidden;
  position: relative;
  aspect-ratio: 16 / 9;
  background: var(--bg-secondary);
}

.img-section img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.img-full {
  width: 100vw;
  margin-left: calc(-1 * (100vw - 100%) / 2);
  position: relative;
  overflow: hidden;
  aspect-ratio: 21 / 9;
  background: var(--bg-secondary);
}

.img-full img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.img-caption {
  font-size: var(--text-xs);
  color: var(--text-muted);
  text-align: center;
  margin-top: var(--space-3);
}

@media (max-width: 768px) {
  .img-hero { aspect-ratio: 16 / 9; border-radius: var(--radius-lg); }
  .img-section { aspect-ratio: 4 / 3; }
  .img-full { aspect-ratio: 16 / 9; }
}