/* ============================================
   ICU Sepsis Decision Support System
   Website styles – scroll-based layout
   ============================================ */

/* Light theme (default) */
:root,
[data-theme="light"] {
  --color-bg: #f8fafc;
  --color-bg-alt: #eff6ff;
  --color-text: #0f172a;
  --color-text-muted: #475569;
  --color-accent: #0369a1;
  --color-accent-hover: #0284c7;
  --color-accent-light: #e0f2fe;
  --color-accent-subtle: #bae6fd;
  --color-border: #e2e8f0;
  --color-surface: #ffffff;
  --color-card-bg: #ffffff;
  --color-card-border: #e2e8f0;
  --color-nav-hover: rgba(3, 105, 161, 0.08);
  --hero-gradient-start: #eff6ff;
  --hero-gradient-mid: #dbeafe;
  --hero-gradient-end: #f0f9ff;
  --section-alt-gradient: linear-gradient(180deg, #f0f9ff 0%, #e8f4fe 50%, #f8fafc 100%);
  --section-gradient: linear-gradient(180deg, #f8fafc 0%, #f4f8fb 50%, #f0f9ff 100%);
}

/* Dark theme */
[data-theme="dark"] {
  --color-bg: #0f172a;
  --color-bg-alt: #1e293b;
  --color-text: #f1f5f9;
  --color-text-muted: #94a3b8;
  --color-accent: #38bdf8;
  --color-accent-hover: #7dd3fc;
  --color-accent-light: #0c4a6e;
  --color-accent-subtle: #0e7490;
  --color-border: #334155;
  --color-surface: #1e293b;
  --color-card-bg: #1e293b;
  --color-card-border: #334155;
  --color-nav-hover: rgba(56, 189, 248, 0.15);
  --hero-gradient-start: #0f172a;
  --hero-gradient-mid: #1e293b;
  --hero-gradient-end: #0c4a6e;
  --section-alt-gradient: linear-gradient(180deg, #162032 0%, #1a2740 50%, #0f172a 100%);
  --section-gradient: linear-gradient(180deg, #0f172a 0%, #131d2e 50%, #162032 100%);
}

:root {
  --font-sans: 'Outfit', system-ui, -apple-system, sans-serif;
  --font-display: 'Syne', system-ui, sans-serif;
  --max-width: 68rem;
  --section-padding: 4rem;
  --nav-height: 4rem;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 1.0625rem;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
  transition: background 0.3s ease, color 0.3s ease;
}

/* Scroll-reveal scrollytelling */
.scroll-reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.5s ease-out, transform 0.5s ease-out;
}

.scroll-reveal.revealed {
  opacity: 1;
  transform: translateY(0);
}


/* Hero: stagger reveal on load */
.hero .scroll-reveal:nth-child(1) { transition-delay: 0.1s; }
.hero .scroll-reveal:nth-child(2) { transition-delay: 0.2s; }
.hero .scroll-reveal:nth-child(3) { transition-delay: 0.3s; }
.hero .scroll-reveal:nth-child(4) { transition-delay: 0.4s; }
.hero .scroll-reveal:nth-child(5) { transition-delay: 0.5s; }
.hero .scroll-reveal:nth-child(6) { transition-delay: 0.6s; }

/* Theme toggle button */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  padding: 0;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  cursor: pointer;
  color: var(--color-text);
  transition: background 0.2s, border-color 0.2s, color 0.2s;
}

.theme-toggle:hover {
  background: var(--color-accent-light);
  border-color: var(--color-accent);
}

.theme-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  position: absolute;
}

.theme-icon svg {
  width: 18px;
  height: 18px;
}

[data-theme="light"] .theme-moon,
[data-theme="dark"] .theme-sun {
  opacity: 0;
  pointer-events: none;
}

[data-theme="light"] .theme-sun,
[data-theme="dark"] .theme-moon {
  opacity: 1;
}

.theme-toggle {
  position: relative;
}

.theme-icon {
  transition: opacity 0.2s ease;
}

/* Navigation */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--nav-height);
  background: var(--color-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  transition: background 0.3s, border-color 0.3s;
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}

.nav-logo {
  font-weight: 700;
  font-size: 1.125rem;
  color: var(--color-text);
  text-decoration: none;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 2rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-links a {
  color: var(--color-text-muted);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.2s, background 0.2s;
}

.nav-links a:not(.nav-cta) {
  padding: 0.4rem 0.85rem;
  border-radius: 10px;
}

.nav-links a:hover:not(.nav-cta) {
  color: var(--color-accent);
  background: var(--color-nav-hover);
}

.nav-links a.active:hover {
  background: color-mix(in srgb, var(--color-accent-light) 80%, var(--color-bg));
}

.nav-links a.active {
  background: var(--color-accent-light);
  color: var(--color-accent);
}

.nav-cta {
  color: var(--color-accent) !important;
  font-weight: 600;
}

.nav-cta:hover {
  color: var(--color-accent-hover) !important;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.nav-toggle span {
  width: 24px;
  height: 2px;
  background: var(--color-text);
}

/* Hero */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: calc(var(--nav-height) + 4rem) 1.5rem 4rem;
  background:
    radial-gradient(ellipse 80% 50% at 50% -20%, var(--hero-gradient-mid), transparent),
    radial-gradient(ellipse 60% 40% at 100% 50%, var(--color-accent-subtle), transparent 50%),
    radial-gradient(ellipse 60% 40% at 0% 50%, var(--color-accent-subtle), transparent 50%),
    linear-gradient(180deg, var(--hero-gradient-start) 0%, var(--hero-gradient-mid) 50%, var(--hero-gradient-end) 100%);
  transition: background 0.3s ease;
}

.hero-content {
  max-width: var(--max-width);
  text-align: center;
}

.hero-title {
  font-family: var(--font-display);
  font-size: clamp(2.25rem, 5vw, 3.5rem);
  font-weight: 700;
  line-height: 1.15;
  margin: 0 0 1rem;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

.hero-tagline {
  font-family: var(--font-sans);
  font-size: 1.0625rem;
  color: var(--color-text-muted);
  margin: 0 0 2rem;
  max-width: 36rem;
  margin-left: auto;
  margin-right: auto;
}

.btn {
  display: inline-block;
  padding: 0.75rem 1.75rem;
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 600;
  text-decoration: none;
  border-radius: 8px;
  transition: background 0.2s, transform 0.15s;
}

.btn-primary {
  background: var(--color-accent);
  color: white;
  border: none;
}

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

.hero-visual {
  margin-top: 3rem;
}

.hero-placeholder {
  background: linear-gradient(135deg, var(--color-bg-alt) 0%, var(--color-accent-light) 100%);
  border: 2px dashed var(--color-accent);
  border-radius: 12px;
  padding: 4rem 2rem;
  color: var(--color-text-muted);
  font-size: 0.9rem;
  opacity: 0.9;
  transition: background 0.3s, border-color 0.3s, color 0.3s;
}

/* Sections */
.section {
  padding: calc(var(--nav-height) + 4rem) 1.5rem 5rem;
  min-height: 100vh;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  transition: background 0.3s ease;
}

.section__title {
  font-family: var(--font-sans);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-text);
  text-align: center;
  margin: 0 0 0.5rem;
}

.section__subtitle {
  font-size: 1rem;
  color: var(--color-text-muted);
  text-align: center;
  margin: 0 0 2rem;
  max-width: 40rem;
  margin-left: auto;
  margin-right: auto;
}

.section:not(.section-alt) {
  background: var(--section-gradient);
}

.section-alt {
  background: var(--section-alt-gradient);
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
}

.container--wide {
  max-width: min(90vw, 68rem);
}

/* Content rows and boxes – aligned grid for consistent column widths */
.content-row {
  margin-bottom: 4rem;
}

.content-row:last-child {
  margin-bottom: 0;
}

/* Image + text rows: fixed grid so columns align across all rows */
.content-row--image-left,
.content-row--image-right {
  display: grid;
  grid-template-columns: 1fr 2.5rem 1fr;
  align-items: center;
}

.content-row--image-left .content-box--text,
.content-row--image-right .content-box--text {
  grid-column: 1;
}

.content-row--image-left .content-box--image,
.content-row--image-right .content-box--image {
  grid-column: 3;
}

/* Text-only rows */
.content-row:not(.content-row--image-left):not(.content-row--image-right) {
  display: block;
}

/* Text container – standalone box */
.content-box--text {
  min-width: 0;
  padding: 1rem 1rem;
  background: var(--color-card-bg);
  border-radius: 16px;
  border: 1px solid var(--color-card-border);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
}

[data-theme="dark"] .content-box--text {
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
}

.content-box__title {
  font-family: var(--font-sans);
  font-size: 1.0625rem;
  font-weight: 600;
  margin: 0 0 1rem;
  color: var(--color-accent);
}

.content-box--text p {
  margin: 0 0 1rem;
  color: var(--color-text);
  font-size: 1.0625rem;
}

.content-box--text p:last-child {
  margin-bottom: 0;
}

.content-box--text .btn {
  margin-top: 1rem;
}

/* Image container – standalone box */
.content-box--image {
  min-width: 0;
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  align-items: stretch;
  justify-content: flex-start;
  background: var(--color-card-bg);
  border-radius: 16px;
  border: 1px solid var(--color-card-border);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
}

[data-theme="dark"] .content-box--image {
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
}

.content-row:not(.content-row--image-left):not(.content-row--image-right) .content-box--image {
  display: none;
}

.content-box--image .image-placeholder {
  margin: 0;
  width: 100%;
  min-height: 12rem;
  flex: 1;
}

.content-box__img {
  width: 100%;
  height: auto;
  max-height: 20rem;
  object-fit: cover;
  border-radius: 8px;
  display: block;
}

.image-caption {
  margin: 0.75rem 0 0;
  color: var(--color-text-muted);
  font-size: 0.9rem;
  line-height: 1.45;
  text-align: left;
}

.img-expandable {
  cursor: zoom-in;
}

/* Lightbox overlay */
.lightbox {
  position: fixed;
  inset: 0;
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.2s, visibility 0.2s;
}

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

.lightbox[hidden] {
  display: flex !important;
}

.lightbox.is-open[hidden] {
  opacity: 1;
  visibility: visible;
}

.lightbox__backdrop {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.85);
  cursor: pointer;
}

.lightbox__close {
  position: absolute;
  top: 1rem;
  right: 1rem;
  z-index: 1;
  width: 2.5rem;
  height: 2.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.75rem;
  font-weight: 300;
  line-height: 1;
  color: #fff;
  background: rgba(255, 255, 255, 0.1);
  border: none;
  border-radius: 50%;
  cursor: pointer;
  transition: background 0.2s;
}

.lightbox__close:hover {
  background: rgba(255, 255, 255, 0.2);
}

.lightbox__content {
  position: relative;
  z-index: 1;
  max-width: 95vw;
  max-height: 95vh;
}

.lightbox__img {
  max-width: 100%;
  max-height: 85vh;
  width: auto;
  height: auto;
  object-fit: contain;
  border-radius: 8px;
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
}

.image-placeholder {
  background: linear-gradient(135deg, var(--color-bg) 0%, var(--color-accent-light) 100%);
  border: 2px dashed var(--color-accent);
  border-radius: 8px;
  padding: 2.5rem;
  margin: 1.5rem 0;
  color: var(--color-text-muted);
  font-size: 0.875rem;
  text-align: center;
  transition: background 0.3s, border-color 0.3s, color 0.3s;
}

/* Approach section header */
.approach-header {
  text-align: center;
  margin-bottom: 1rem;
}

.approach-header__title {
  font-family: var(--font-display);
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--color-text);
  margin: 0 0 1rem;
}

.approach-header p {
  color: var(--color-text);
  font-size: 1.0625rem;
  max-width: 40rem;
  margin: 0 auto;
}

/* Approach cards – three-column grid */
.approach-cards {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 2rem;
  margin: 2rem 0;
  align-items: stretch;
}

.approach-card--wide {
  grid-column: 1 / -1;
}

.approach-card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-card-border);
  border-radius: 16px;
  padding: 2.5rem 2rem;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
  transition: box-shadow 0.2s, transform 0.2s;
  display: flex;
  flex-direction: column;
}

.approach-card:hover {
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  transform: translateY(-2px);
}

.approach-card__title {
  font-family: var(--font-sans);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-accent);
  margin: 0 0 1rem;
}

.approach-card p {
  color: var(--color-text);
  font-size: 1.0625rem;
  line-height: 1.7;
  margin: 0 0 1.5rem;
}

.approach-card__list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.approach-card__list li {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--color-text);
  font-size: 1rem;
  padding: 0.5rem 0;
}

.approach-card__list li svg {
  flex-shrink: 0;
  color: var(--color-accent);
}

.approach-card__features {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.approach-card--wide .approach-card__features {
  flex-direction: row;
  gap: 1.25rem;
}

.approach-card__screen {
  flex: 1;
  border-radius: 10px;
  overflow: hidden;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
}

.screen__titlebar {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 0.5rem 0.75rem;
  background: var(--color-bg-alt);
  border-bottom: 1px solid var(--color-border);
}

.screen__dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--color-border);
}

.screen__dot:nth-child(1) { background: #ef4444; }
.screen__dot:nth-child(2) { background: #f59e0b; }
.screen__dot:nth-child(3) { background: #22c55e; }

.screen__title {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-text-muted);
  margin-left: 0.5rem;
}

.screen__body {
  padding: 1rem;
}

.screen__desc {
  font-size: 0.9rem;
  color: var(--color-text);
  margin: 0;
  line-height: 1.5;
}

@media (max-width: 768px) {
  .approach-cards {
    grid-template-columns: 1fr;
  }

  .approach-card--wide .approach-card__features {
    flex-direction: column;
  }

  .approach-card__screen {
    flex: none;
  }
}

/* Product rows – 2/3 image, 1/3 text */
.product-row {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 2rem;
  align-items: center;
  margin-bottom: 3rem;
}

.product-row:last-child {
  margin-bottom: 0;
}

.product-row__image {
  min-width: 0;
}

.product-row__img {
  width: 100%;
  height: auto;
  border-radius: 12px;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.1);
  cursor: zoom-in;
  transition: box-shadow 0.2s;
}

.product-row__img:hover {
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
}

.product-row__title {
  font-family: var(--font-sans);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-accent);
  margin: 0 0 0.75rem;
}

.product-row__text p {
  color: var(--color-text);
  font-size: 1rem;
  line-height: 1.6;
  margin: 0 0 1rem;
}

.product-row__features {
  list-style: none;
  padding: 0;
  margin: 0;
}

.product-row__features li {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  padding: 0.3rem 0;
  padding-left: 1.25rem;
  position: relative;
}

.product-row__features li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.65rem;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-accent);
}

@media (max-width: 768px) {
  .product-row {
    grid-template-columns: 1fr;
  }
}

/* Pipeline / Dataflow */
.pipeline {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0;
}

.pipeline__node {
  background: var(--color-card-bg);
  border: 1px solid var(--color-card-border);
  border-radius: 12px;
  padding: 1.75rem 1.25rem;
  text-align: center;
  width: 14rem;
  flex-shrink: 0;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
}

.pipeline__node--storage {
  width: 16rem;
}

.pipeline__icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  background: var(--color-accent-light);
  border-radius: 10px;
  margin: 0 auto 0.75rem;
  color: var(--color-accent);
}

.pipeline__label {
  font-family: var(--font-sans);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-text);
  margin: 0 0 0.5rem;
}

.pipeline__desc {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.4;
}

/* Horizontal arrows between nodes */
.pipeline__arrow {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 4.5rem;
  flex-shrink: 0;
  position: relative;
}

.pipeline__line {
  width: 100%;
  height: 2px;
  background: var(--color-border);
  position: relative;
}

.pipeline__line::after {
  content: '';
  position: absolute;
  right: -1px;
  top: -4px;
  width: 0;
  height: 0;
  border-top: 5px solid transparent;
  border-bottom: 5px solid transparent;
  border-left: 8px solid var(--color-accent);
}

/* Animated dots */
.pipeline__dot {
  position: absolute;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--color-accent);
  opacity: 0;
}

.pipeline__dot--h {
  top: 50%;
  transform: translateY(-50%);
  left: 0;
}

.revealed .pipeline__dot--h {
  animation: flowRight 2.4s ease-in-out infinite;
}

.revealed .pipeline__dot--v {
  animation: flowDown 2.4s ease-in-out infinite;
}

@keyframes flowRight {
  0% { left: 0; opacity: 0; }
  10% { opacity: 1; }
  80% { opacity: 1; }
  100% { left: calc(100% - 8px); opacity: 0; }
}

@keyframes flowDown {
  0% { top: 0; opacity: 0; }
  10% { opacity: 1; }
  80% { opacity: 1; }
  100% { top: calc(100% - 8px); opacity: 0; }
}

@keyframes flowUp {
  0% { top: calc(100% - 8px); opacity: 0; }
  10% { opacity: 1; }
  80% { opacity: 1; }
  100% { top: 0; opacity: 0; }
}

/* Database branch */
.pipeline__storage {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin-top: 0;
  position: relative;
}

.pipeline__vlines {
  display: flex;
  justify-content: center;
  gap: 13rem;
  height: 3rem;
}

.pipeline__vline {
  width: 2px;
  height: 100%;
  background: var(--color-border);
  position: relative;
}

.pipeline__vline .pipeline__dot--v {
  left: -3px;
}

.pipeline__vline .pipeline__dot--up {
  left: -3px;
}

.revealed .pipeline__dot--up {
  animation: flowUp 2.4s ease-in-out infinite;
}

@media (max-width: 768px) {
  .pipeline {
    flex-direction: column;
    align-items: center;
    gap: 0;
  }

  .pipeline__node {
    width: 80%;
  }

  .pipeline__arrow {
    width: 2px;
    height: 2.5rem;
    padding-top: 0;
    flex-direction: column;
  }

  .pipeline__line {
    width: 2px;
    height: 100%;
  }

  .pipeline__line::after {
    right: auto;
    top: auto;
    bottom: -1px;
    left: -4px;
    border-top: 8px solid var(--color-accent);
    border-left: 5px solid transparent;
    border-right: 5px solid transparent;
    border-bottom: none;
  }

  .pipeline__dot--h {
    top: 0;
    left: -3px;
  }

  .revealed .pipeline__dot--h {
    animation: flowDown 2.4s ease-in-out infinite;
  }

  .pipeline__vlines {
    gap: 0;
  }

  .pipeline__vline--right {
    display: none;
  }

  .pipeline__node--storage {
    width: 80%;
  }
}

/* Architecture diagram */
.arch {
  max-width: 64rem;
  margin: 2rem auto 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0;
}

/* AWS environment wrappers */
.arch__ec2,
.arch__rds {
  position: relative;
  border: 2px dashed var(--color-border);
  border-radius: 16px;
  padding: 3rem 2.5rem 2.5rem;
}

.arch__ec2 {
  width: 100%;
  border-color: #f97316;
}

.arch__rds {
  border-color: #3b82f6;
}

.arch__env-label {
  position: absolute;
  top: -0.85rem;
  left: 1.25rem;
  background: var(--color-bg);
  padding: 0 0.6rem;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-muted);
}

.arch__ec2 > .arch__env-label {
  color: #f97316;
}

.arch__rds > .arch__env-label {
  color: #3b82f6;
}

/* EC2 inner layout — horizontal row */
.arch__ec2-inner {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0;
}

/* User icon */
.arch__user {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  flex-shrink: 0;
  color: var(--color-text);
}

.arch__user-label {
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 1rem;
}

/* Horizontal double arrows */
.arch__darrow {
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 7rem;
  flex-shrink: 0;
  padding: 0 0.75rem;
}

.arch__darrow-cap {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  white-space: nowrap;
  line-height: 1;
}

.arch__darrow-cap:first-child {
  margin-bottom: 0.35rem;
}

.arch__darrow-cap:last-child {
  margin-top: 0.35rem;
}

.arch__darrow-line {
  width: 100%;
  height: 3px;
  background: #94a3b8;
  position: relative;
}

/* Left arrowhead */
.arch__darrow-line::before {
  content: '';
  position: absolute;
  left: -10px;
  top: 50%;
  transform: translateY(-50%);
  border-top: 7px solid transparent;
  border-bottom: 7px solid transparent;
  border-right: 10px solid #94a3b8;
}

/* Right arrowhead */
.arch__darrow-line::after {
  content: '';
  position: absolute;
  right: -10px;
  top: 50%;
  transform: translateY(-50%);
  border-top: 7px solid transparent;
  border-bottom: 7px solid transparent;
  border-left: 10px solid #94a3b8;
}

/* Vertical double arrow */
.arch__varrow {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem 0;
}

.arch__varrow-line {
  width: 3px;
  height: 3rem;
  background: #94a3b8;
  position: relative;
}

/* Top arrowhead */
.arch__varrow-line::before {
  content: '';
  position: absolute;
  top: -10px;
  left: 50%;
  transform: translateX(-50%);
  border-left: 7px solid transparent;
  border-right: 7px solid transparent;
  border-bottom: 10px solid #94a3b8;
}

/* Bottom arrowhead */
.arch__varrow-line::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 50%;
  transform: translateX(-50%);
  border-left: 7px solid transparent;
  border-right: 7px solid transparent;
  border-top: 10px solid #94a3b8;
}

.arch__varrow-cap {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  white-space: nowrap;
}

/* Layer cards */
.arch__layer {
  background: var(--color-card-bg);
  border: 2px solid var(--color-card-border);
  border-radius: 12px;
  padding: 1.75rem 1.5rem;
  text-align: center;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
  flex: 1 1 auto;
}

.arch__layer--view {
  border-color: #4ade80;
}

.arch__layer--model {
  border-color: #facc15;
}

.arch__layer--db {
  border-color: #3b82f6;
}

.arch__layer--template {
  border-color: #60a5fa;
}

.arch__layer-title {
  font-family: var(--font-sans);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text);
  margin: 0 0 0.2rem;
}

.arch__layer-subtitle {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-accent);
  margin: 0 0 0.5rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.arch__layer-desc {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.5;
}

/* Model row inside EC2 */
.arch__model-row {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin-top: 1rem;
}

.arch__darrow--vertical {
  width: auto;
  flex-direction: row;
  gap: 0.5rem;
  padding: 1rem 0;
}

.arch__darrow-line--v {
  width: 3px;
  height: 3.5rem;
  background: #94a3b8;
  position: relative;
}

/* Reset horizontal arrowheads and apply vertical ones */
.arch__darrow-line--v::before {
  content: '';
  position: absolute;
  top: -10px;
  left: 50%;
  right: auto;
  transform: translateX(-50%);
  border: none;
  border-left: 7px solid transparent;
  border-right: 7px solid transparent;
  border-bottom: 10px solid #94a3b8;
}

.arch__darrow-line--v::after {
  content: '';
  position: absolute;
  bottom: -10px;
  top: auto;
  left: 50%;
  right: auto;
  transform: translateX(-50%);
  border: none;
  border-left: 7px solid transparent;
  border-right: 7px solid transparent;
  border-top: 10px solid #94a3b8;
}

@media (max-width: 768px) {
  .arch__ec2,
  .arch__rds {
    padding: 2rem 1rem 1.5rem;
    width: 100%;
  }

  .arch__ec2-inner {
    flex-direction: column;
    gap: 0;
  }

  .arch__darrow {
    width: auto;
    flex-direction: row;
    gap: 0.5rem;
    padding: 0.5rem 0;
  }

  .arch__darrow-line {
    width: 2px;
    height: 2rem;
  }

  .arch__darrow-cap:first-child {
    margin-bottom: 0;
  }

  .arch__darrow-cap:last-child {
    margin-top: 0;
  }

  .arch__darrow-line::before {
    left: -4px;
    top: 0;
    border: none;
    border-left: 5px solid transparent;
    border-right: 5px solid transparent;
    border-bottom: 7px solid var(--color-accent);
  }

  .arch__darrow-line::after {
    right: auto;
    left: -4px;
    top: auto;
    bottom: 0;
    border: none;
    border-left: 5px solid transparent;
    border-right: 5px solid transparent;
    border-top: 7px solid var(--color-accent);
  }

  .arch__layer {
    width: 100%;
    min-width: auto !important;
  }
}

/* Summary CTA */
#summary .btn {
  margin-top: 1rem;
}

/* Reduce gap before acknowledgements */
#summary {
  padding-bottom: 2rem;
}

/* Acknowledgements & References */
.acknowledgements {
  background: var(--section-alt-gradient);
  padding: var(--section-padding) 1.5rem;
  color: var(--color-text);
  transition: background 0.3s ease, color 0.3s ease;
}

.acknowledgements__heading {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-text);
  margin: 0 0 1.25rem;
}

.acknowledgements__heading + .references,
.acknowledgements__heading + .team-list {
  margin-top: 0;
}

.team-list {
  list-style: none;
  padding: 0;
  margin: 0 0 2.5rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 2rem;
}

.team-list li {
  color: var(--color-text);
  font-size: 1.0625rem;
}

.team-list a {
  color: var(--color-accent);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.2s;
}

.team-list a:hover {
  color: var(--color-accent-hover);
  text-decoration: underline;
}

.references {
  padding-left: 1.25rem;
  margin: 0;
  color: var(--color-text);
}

.references li {
  color: var(--color-text);
  font-size: 0.95rem;
  line-height: 1.6;
  margin-bottom: 0.75rem;
}

.references li:last-child {
  margin-bottom: 0;
}

/* Footer */
.footer {
  padding: 2rem 1.5rem;
  background: var(--color-bg-alt);
  border-top: 1px solid var(--color-border);
  color: var(--color-text-muted);
  transition: background 0.3s, border-color 0.3s, color 0.3s;
}

.footer .container {
  max-width: var(--max-width);
  margin: 0 auto;
}

.footer-links {
  display: flex;
  gap: 1.5rem;
  margin-bottom: 1rem;
}

.footer-links a {
  color: var(--color-text);
  text-decoration: none;
  font-weight: 500;
}

.footer-links a:hover {
  color: var(--color-accent);
  text-decoration: underline;
}

.footer-credits {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin: 0;
}

/* Desktop: wider containers to fill more screen */
@media (min-width: 769px) {
  .container--wide {
    max-width: min(95vw, 72rem);
  }

  .content-box--text {
    padding: 1.5rem 1.5rem;
  }

  .content-box--image {
    padding: 0rem;
  }

  .content-box__img--large {
    max-height: 50rem;
  }
}


/* Mobile */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .nav-toggle {
    display: flex;
  }

  .nav.open .nav-links {
    display: flex;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    padding: 1rem;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
  }

  .section {
    padding: 3rem 1.5rem;
  }

  .content-row--image-left,
  .content-row--image-right {
    grid-template-columns: 1fr;
    grid-template-rows: auto auto;
    gap: 1rem;
  }

  .content-row--image-left .content-box--text,
  .content-row--image-left .content-box--image,
  .content-row--image-right .content-box--text,
  .content-row--image-right .content-box--image {
    grid-column: 1;
  }

  .content-row--image-left .content-box--text,
  .content-row--image-right .content-box--text {
    grid-row: 1;
  }

  .content-row--image-left .content-box--image,
  .content-row--image-right .content-box--image {
    grid-row: 2;
  }

  .content-box--text {
    padding: 1.5rem 1.25rem;
  }

  .content-box--image {
    flex: none;
    padding: 1rem 1.25rem;
  }
}