/* ==========================================================================
   Gain Ground - Design System
   Defense-grade hardware aesthetic: dark, restrained, technical
   ========================================================================== */

/* --------------------------------------------------------------------------
   CSS Variables / Design Tokens
   -------------------------------------------------------------------------- */
:root {
  /* Colors */
  --color-bg: #0a0a0a;
  --color-surface: #1a1a1f;
  --color-surface-elevated: #252530;
  --color-text: #e8e8e8;
  --color-text-muted: #888888;
  --color-text-dim: #555555;
  --color-accent: #4a7c59;
  --color-accent-hover: #5a9c6a;
  --color-accent-muted: rgba(74, 124, 89, 0.2);
  --color-border: #2a2a35;
  --color-error: #c45050;
  --color-success: #4a7c59;

  /* Typography */
  --font-heading: 'Inter', system-ui, -apple-system, sans-serif;
  --font-body: 'Inter', system-ui, -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;
  --space-4xl: 6rem;

  /* Layout */
  --max-width: 1200px;
  --header-height: 72px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;

  /* Border radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
}

/* --------------------------------------------------------------------------
   CSS Reset
   -------------------------------------------------------------------------- */
*, *::before, *::after {
  box-sizing: border-box;
}

* {
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-height);
}

body {
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img, picture, video, canvas, svg {
  display: block;
  max-width: 100%;
}

input, button, textarea, select {
  font: inherit;
}

/* --------------------------------------------------------------------------
   Accessibility
   -------------------------------------------------------------------------- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  top: -100%;
  left: 50%;
  transform: translateX(-50%);
  background: var(--color-accent);
  color: var(--color-text);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-sm);
  z-index: 1000;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: var(--space-md);
}

:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* --------------------------------------------------------------------------
   Typography
   -------------------------------------------------------------------------- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 600;
  line-height: 1.2;
  color: var(--color-text);
}

h1 {
  font-size: clamp(2rem, 5vw, 3.5rem);
  letter-spacing: -0.02em;
}

h2 {
  font-size: clamp(1.5rem, 3vw, 2.25rem);
  letter-spacing: -0.01em;
}

h3 {
  font-size: clamp(1.25rem, 2vw, 1.5rem);
}

p {
  max-width: 65ch;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-accent-hover);
}

.text-muted {
  color: var(--color-text-muted);
}

.text-small {
  font-size: 0.875rem;
}

/* --------------------------------------------------------------------------
   Layout
   -------------------------------------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

section {
  padding: var(--space-4xl) 0;
}

/* --------------------------------------------------------------------------
   Header / Navigation
   -------------------------------------------------------------------------- */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: rgba(10, 10, 10, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  z-index: 100;
}

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.header__logo {
  display: flex;
  align-items: center;
  height: 40px;
}

.header__logo img {
  height: 100%;
  width: auto;
}

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

.nav__links {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  list-style: none;
}

.nav__link {
  color: var(--color-text-muted);
  font-size: 0.9375rem;
  font-weight: 500;
  transition: color var(--transition-fast);
}

.nav__link:hover {
  color: var(--color-text);
}

.nav__toggle {
  display: none;
  background: none;
  border: none;
  color: var(--color-text);
  cursor: pointer;
  padding: var(--space-sm);
}

.nav__toggle-icon {
  display: block;
  width: 24px;
  height: 2px;
  background: currentColor;
  position: relative;
  transition: background var(--transition-fast);
}

.nav__toggle-icon::before,
.nav__toggle-icon::after {
  content: '';
  position: absolute;
  left: 0;
  width: 100%;
  height: 2px;
  background: currentColor;
  transition: transform var(--transition-fast);
}

.nav__toggle-icon::before {
  top: -7px;
}

.nav__toggle-icon::after {
  bottom: -7px;
}

.nav__toggle[aria-expanded="true"] .nav__toggle-icon {
  background: transparent;
}

.nav__toggle[aria-expanded="true"] .nav__toggle-icon::before {
  transform: translateY(7px) rotate(45deg);
}

.nav__toggle[aria-expanded="true"] .nav__toggle-icon::after {
  transform: translateY(-7px) rotate(-45deg);
}

/* Mobile Navigation */
@media (max-width: 768px) {
  .nav__toggle {
    display: block;
  }

  .nav__links {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;
    flex-direction: column;
    justify-content: flex-start;
    padding: var(--space-xl);
    background: var(--color-bg);
    transform: translateX(100%);
    transition: transform var(--transition-base);
  }

  .nav__links.is-open {
    transform: translateX(0);
  }

  .nav__link {
    font-size: 1.25rem;
  }

  .nav .btn {
    width: 100%;
    margin-top: var(--space-md);
  }
}

/* --------------------------------------------------------------------------
   Buttons
   -------------------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-lg);
  font-size: 0.9375rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
}

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

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

.btn--secondary {
  background: transparent;
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
}

.btn--secondary:hover {
  background: var(--color-surface);
  color: var(--color-text);
  border-color: var(--color-text-muted);
}

.btn--large {
  padding: var(--space-md) var(--space-xl);
  font-size: 1rem;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* --------------------------------------------------------------------------
   Hero Section
   -------------------------------------------------------------------------- */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: var(--header-height);
  overflow: hidden;
}

.hero__background {
  position: absolute;
  inset: 0;
  z-index: -1;
}

.hero__background img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.4;
}

.hero__background::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    to bottom,
    rgba(10, 10, 10, 0.3) 0%,
    rgba(10, 10, 10, 0.8) 80%,
    var(--color-bg) 100%
  );
}

.hero__content {
  max-width: 800px;
}

.hero__title {
  margin-bottom: var(--space-lg);
}

.hero__description {
  font-size: clamp(1rem, 2vw, 1.25rem);
  color: var(--color-text-muted);
  margin-bottom: var(--space-xl);
  max-width: 600px;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
}

/* --------------------------------------------------------------------------
   RAMP Section
   -------------------------------------------------------------------------- */
.ramp {
  background: var(--color-bg);
}

.ramp__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-3xl);
  align-items: center;
}

.ramp__label {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--color-accent);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: var(--space-sm);
}

.ramp__title {
  margin-bottom: var(--space-sm);
}

.ramp__subtitle {
  font-size: 1.125rem;
  color: var(--color-text-muted);
  margin-bottom: var(--space-xl);
}

.ramp__list {
  list-style: none;
}

.ramp__list li {
  position: relative;
  padding-left: var(--space-lg);
  margin-bottom: var(--space-md);
  color: var(--color-text-muted);
}

.ramp__list li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.5em;
  width: 8px;
  height: 8px;
  background: var(--color-accent);
  border-radius: 2px;
}

.ramp__visual {
  display: flex;
  justify-content: center;
  align-items: center;
}

.ramp__visual img {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
}

@media (max-width: 900px) {
  .ramp__grid {
    grid-template-columns: 1fr;
    gap: var(--space-xl);
  }

  .ramp__visual {
    order: -1;
  }
}

/* --------------------------------------------------------------------------
   ISR Systems Section
   -------------------------------------------------------------------------- */
.isr {
  position: relative;
  background: var(--color-surface);
  overflow: hidden;
}

.isr__background {
  position: absolute;
  inset: 0;
  z-index: 0;
}

.isr__background img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.4;
}

.isr__background::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    to bottom,
    var(--color-surface) 0%,
    rgba(26, 26, 31, 0.4) 20%,
    rgba(26, 26, 31, 0.4) 80%,
    var(--color-surface) 100%
  );
}

.isr > .container {
  position: relative;
  z-index: 1;
}

.isr__header {
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.isr__label {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--color-accent);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: var(--space-sm);
}

.isr__title {
  margin-bottom: var(--space-md);
}

.isr__cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}

.isr__card {
  background: var(--color-surface-elevated);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-xl);
  transition: border-color var(--transition-fast);
}

.isr__card:hover {
  border-color: var(--color-accent-muted);
}

.isr__card-title {
  font-size: 1.125rem;
  margin-bottom: var(--space-md);
}

.isr__card-text {
  color: var(--color-text-muted);
  font-size: 0.9375rem;
  line-height: 1.7;
}

@media (max-width: 900px) {
  .isr__cards {
    grid-template-columns: 1fr;
  }
}

/* --------------------------------------------------------------------------
   Get Updates Section
   -------------------------------------------------------------------------- */
.signup {
  background: var(--color-bg);
}

.signup__inner {
  max-width: 500px;
  margin: 0 auto;
  text-align: center;
}

.signup__title {
  margin-bottom: var(--space-md);
}

.signup__description {
  color: var(--color-text-muted);
  margin-bottom: var(--space-xl);
  margin-left: auto;
  margin-right: auto;
}

.signup__form {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.form-group {
  text-align: left;
}

.form-label {
  display: block;
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-bottom: var(--space-xs);
}

.form-label--required::after {
  content: ' *';
  color: var(--color-error);
}

.form-input {
  width: 100%;
  padding: var(--space-sm) var(--space-md);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text);
  font-size: 1rem;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-input::placeholder {
  color: var(--color-text-dim);
}

.form-input:focus {
  outline: none;
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-accent-muted);
}

.form-input.is-error {
  border-color: var(--color-error);
}

.form-error {
  font-size: 0.8125rem;
  color: var(--color-error);
  margin-top: var(--space-xs);
}

.signup__consent {
  font-size: 0.8125rem;
  color: var(--color-text-dim);
  text-align: left;
}

.signup__submit {
  margin-top: var(--space-sm);
}

.signup__submit .btn {
  width: 100%;
}

.signup__message {
  padding: var(--space-md);
  border-radius: var(--radius-sm);
  margin-top: var(--space-md);
  display: none;
}

.signup__message.is-visible {
  display: block;
}

.signup__message--success {
  background: rgba(74, 124, 89, 0.15);
  border: 1px solid var(--color-success);
  color: var(--color-success);
}

.signup__message--error {
  background: rgba(196, 80, 80, 0.15);
  border: 1px solid var(--color-error);
  color: var(--color-error);
}

.signup__message--error a {
  color: var(--color-error);
  text-decoration: underline;
}

/* Loading state */
.btn.is-loading {
  position: relative;
  color: transparent;
}

.btn.is-loading::after {
  content: '';
  position: absolute;
  width: 16px;
  height: 16px;
  border: 2px solid var(--color-text);
  border-top-color: transparent;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */
.footer {
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding: var(--space-xl) 0;
}

.footer__inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: var(--space-md);
}

.footer__copyright {
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

.footer__links {
  display: flex;
  gap: var(--space-lg);
}

.footer__link {
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

.footer__link:hover {
  color: var(--color-text);
}

@media (max-width: 600px) {
  .footer__inner {
    flex-direction: column;
    text-align: center;
  }
}

/* --------------------------------------------------------------------------
   Privacy Modal
   -------------------------------------------------------------------------- */
.modal {
  position: fixed;
  inset: 0;
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-lg);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition-base), visibility var(--transition-base);
}

.modal.is-open {
  opacity: 1;
  visibility: visible;
}

.modal__backdrop {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.8);
}

.modal__content {
  position: relative;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-xl);
  max-width: 600px;
  max-height: 80vh;
  overflow-y: auto;
  transform: translateY(20px);
  transition: transform var(--transition-base);
}

.modal.is-open .modal__content {
  transform: translateY(0);
}

.modal__close {
  position: absolute;
  top: var(--space-md);
  right: var(--space-md);
  background: none;
  border: none;
  color: var(--color-text-muted);
  font-size: 1.5rem;
  cursor: pointer;
  padding: var(--space-xs);
  line-height: 1;
  transition: color var(--transition-fast);
}

.modal__close:hover {
  color: var(--color-text);
}

.modal__title {
  margin-bottom: var(--space-lg);
}

.modal__body {
  color: var(--color-text-muted);
  line-height: 1.8;
}

.modal__body p {
  margin-bottom: var(--space-md);
}