/* ════════════════════════════════════════════════════════════════════
   StudyPulse — Design Tokens & Shared Components
   ════════════════════════════════════════════════════════════════════ */

:root {
  /* ── Brand Identity ── */
  --color-primary: #0071E3;
  --color-primary-hover: #0077ED;
  --color-primary-light: rgba(0, 113, 227, 0.12);
  --color-primary-subtle: rgba(0, 113, 227, 0.06);

  /* ── Neutrals ── */
  --color-text-primary: #1D1D1F;
  --color-text-secondary: #6E6E73;
  --color-text-tertiary: #86868B;
  --color-text-link: #0071E3;
  --color-text-inverse: #FFFFFF;
  --color-surface-primary: #FFFFFF;
  --color-surface-secondary: #F5F5F7;
  --color-surface-tertiary: #FBFBFD;
  --color-border: rgba(0, 0, 0, 0.08);
  --color-border-strong: rgba(0, 0, 0, 0.15);
  --color-divider: rgba(0, 0, 0, 0.06);

  /* ── State ── */
  --state-success: #34C759;
  --state-warning: #FF9F0A;
  --state-error: #FF3B30;
  --state-info: #0071E3;

  /* ── Accent Tints ── */
  --color-hrv-green: #30D158;
  --color-hrv-yellow: #FFD60A;
  --color-hrv-orange: #FF9F0A;
  --color-hrv-red: #FF453A;
  --color-chart-blue: #0A84FF;
  --color-chart-purple: #BF5AF2;
  --color-chart-teal: #64D2FF;

  /* ── Radius ── */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 9999px;

  /* ── Typography ── */
  --font-primary: 'SF Pro Display', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-body: 'SF Pro Text', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'SF Mono', SFMono-Regular, ui-monospace, Menlo, monospace;

  --font-size-xs: 0.75rem;
  --font-size-sm: 0.8125rem;
  --font-size-base: 0.9375rem;
  --font-size-md: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  --font-size-5xl: 3rem;
  --font-size-6xl: 3.75rem;
  --font-size-display: 4.5rem;

  --font-weight-regular: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  --font-weight-heavy: 800;

  --line-height-tight: 1.15;
  --line-height-snug: 1.25;
  --line-height-normal: 1.47;
  --line-height-relaxed: 1.6;

  --letter-spacing-tight: -0.02em;
  --letter-spacing-normal: -0.01em;
  --letter-spacing-wide: 0.02em;

  /* ── Spacing ── */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
  --spacing-2xl: 48px;
  --spacing-3xl: 64px;
  --spacing-4xl: 96px;
  --spacing-5xl: 128px;

  /* ── Shadows ── */
  --shadow-subtle: 0 1px 3px rgba(0, 0, 0, 0.04);
  --shadow-card: 0 2px 8px rgba(0, 0, 0, 0.04);
  --shadow-elevated: 0 8px 32px rgba(0, 0, 0, 0.08);
  --shadow-modal: 0 24px 80px rgba(0, 0, 0, 0.15);

  /* ── Transitions ── */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow: 400ms ease;
  --transition-spring: 500ms cubic-bezier(0.34, 1.56, 0.64, 1);

  /* ── Layout ── */
  --container-max: 980px;
  --container-narrow: 720px;
  --container-tight: 480px;
  --nav-height: 48px;
}

/* Dark theme */
html.dark {
  --color-text-primary: #F5F5F7;
  --color-text-secondary: #98989D;
  --color-text-tertiary: #6E6E73;
  --color-text-link: #2997FF;
  --color-surface-primary: #1D1D1F;
  --color-surface-secondary: #2C2C2E;
  --color-surface-tertiary: #3A3A3C;
  --color-border: rgba(255, 255, 255, 0.08);
  --color-border-strong: rgba(255, 255, 255, 0.15);
  --color-divider: rgba(255, 255, 255, 0.06);
  --color-primary: #2997FF;
  --color-primary-hover: #409CFF;
  --color-primary-light: rgba(41, 151, 255, 0.15);
  --color-primary-subtle: rgba(41, 151, 255, 0.08);
  --shadow-subtle: 0 1px 3px rgba(0, 0, 0, 0.2);
  --shadow-card: 0 2px 8px rgba(0, 0, 0, 0.2);
  --shadow-elevated: 0 8px 32px rgba(0, 0, 0, 0.3);
  --shadow-modal: 0 24px 80px rgba(0, 0, 0, 0.5);
}

/* ════════════════════════════════════════════════════════════════════
   Base
   ════════════════════════════════════════════════════════════════════ */

* {
  box-sizing: border-box;
  -webkit-tap-highlight-color: transparent;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  font-feature-settings: "kern" 1, "liga" 1, "calt" 1;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  margin: 0;
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-regular);
  line-height: var(--line-height-normal);
  letter-spacing: var(--letter-spacing-normal);
  color: var(--color-text-primary);
  background: var(--color-surface-primary);
  transition: background var(--transition-normal), color var(--transition-normal);
  text-wrap: pretty; /* 避免段落末尾出现单字/单词独行（孤寡行控制） */
}

h1, h2, h3, h4, h5, h6 {
  text-wrap: balance; /* 标题行长度均衡 */
}

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

button {
  font-family: inherit;
  border: none;
  background: none;
  cursor: pointer;
  color: inherit;
}

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

::selection {
  background: var(--color-primary);
  color: #fff;
}

/* ════════════════════════════════════════════════════════════════════
   Layout Containers
   ════════════════════════════════════════════════════════════════════ */

.container {
  width: 100%;
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

.container-narrow {
  max-width: var(--container-narrow);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

.container-tight {
  max-width: var(--container-tight);
  margin-left: auto;
  margin-right: auto;
}

main {
  padding-top: var(--nav-height);
}

section {
  position: relative;
}

/* ════════════════════════════════════════════════════════════════════
   Typography Classes
   ════════════════════════════════════════════════════════════════════ */

.display-xl {
  font-family: var(--font-primary);
  font-size: var(--font-size-display);
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  letter-spacing: var(--letter-spacing-tight);
}

.display-lg {
  font-family: var(--font-primary);
  font-size: var(--font-size-6xl);
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  letter-spacing: var(--letter-spacing-tight);
}

.heading-1 {
  font-family: var(--font-primary);
  font-size: var(--font-size-5xl);
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  letter-spacing: var(--letter-spacing-tight);
}

.heading-2 {
  font-family: var(--font-primary);
  font-size: var(--font-size-4xl);
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  letter-spacing: var(--letter-spacing-tight);
}

.heading-3 {
  font-family: var(--font-primary);
  font-size: var(--font-size-3xl);
  font-weight: var(--font-weight-semibold);
  line-height: var(--line-height-snug);
  letter-spacing: var(--letter-spacing-normal);
}

.heading-4 {
  font-family: var(--font-primary);
  font-size: var(--font-size-2xl);
  font-weight: var(--font-weight-semibold);
  line-height: var(--line-height-snug);
  letter-spacing: var(--letter-spacing-normal);
}

.body-large {
  font-family: var(--font-body);
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-regular);
  line-height: var(--line-height-normal);
  letter-spacing: var(--letter-spacing-normal);
}

.body-base {
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-regular);
  line-height: var(--line-height-normal);
  letter-spacing: var(--letter-spacing-normal);
}

.body-small {
  font-family: var(--font-body);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-regular);
  line-height: var(--line-height-normal);
  letter-spacing: var(--letter-spacing-normal);
}

.caption {
  font-family: var(--font-body);
  font-size: var(--font-size-xs);
  font-weight: var(--font-weight-medium);
  line-height: var(--line-height-normal);
  letter-spacing: var(--letter-spacing-wide);
  text-transform: uppercase;
}

.label {
  font-family: var(--font-body);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
  line-height: var(--line-height-snug);
  letter-spacing: var(--letter-spacing-normal);
}

/* ════════════════════════════════════════════════════════════════════
   Navigation
   ════════════════════════════════════════════════════════════════════ */

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 50;
  height: var(--nav-height);
  background: rgba(29, 29, 31, 0.8);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  transition: background var(--transition-normal);
}

.nav-inner {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.nav-logo {
  font-family: var(--font-primary);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-semibold);
  letter-spacing: var(--letter-spacing-normal);
  color: var(--color-text-inverse);
  transition: opacity var(--transition-fast);
}

.nav-logo:hover {
  opacity: 0.7;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 24px;
}

.nav-link {
  font-family: var(--font-body);
  font-size: var(--font-size-xs);
  color: rgba(255, 255, 255, 0.8);
  transition: color var(--transition-fast);
  position: relative;
}

.nav-link:hover {
  color: #fff;
}

.nav-link.is-active {
  color: #fff;
}

.nav-link.is-active::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -16px;
  height: 2px;
  background: #fff;
  border-radius: 2px;
}

.nav-cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  background: var(--color-primary);
  font-family: var(--font-body);
  font-size: var(--font-size-xs);
  font-weight: var(--font-weight-medium);
  padding: 6px 16px;
  border-radius: var(--radius-full);
  transition: filter var(--transition-fast), transform var(--transition-fast);
}

.nav-cta:hover {
  filter: brightness(0.92);
  transform: translateY(-1px);
}

.nav-cta svg {
  display: inline-block;
  margin-right: 4px;
}

.nav-hamburger {
  display: none;
  width: 32px;
  height: 32px;
  align-items: center;
  justify-content: center;
  color: #fff;
  border-radius: 8px;
}

.nav-hamburger span {
  position: relative;
  display: block;
  width: 18px;
  height: 1.5px;
  background: currentColor;
  border-radius: 2px;
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.nav-hamburger span::before,
.nav-hamburger span::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: 1.5px;
  background: currentColor;
  border-radius: 2px;
  transition: transform var(--transition-fast), top var(--transition-fast);
}

.nav-hamburger span::before { top: -6px; }
.nav-hamburger span::after { top: 6px; }

.nav.is-open .nav-hamburger span {
  background: transparent;
}

.nav.is-open .nav-hamburger span::before {
  top: 0;
  transform: rotate(45deg);
}

.nav.is-open .nav-hamburger span::after {
  top: 0;
  transform: rotate(-45deg);
}

.nav-drawer {
  position: fixed;
  top: var(--nav-height);
  left: 0;
  right: 0;
  background: rgba(29, 29, 31, 0.95);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  padding: 16px 24px 24px;
  display: none;
  flex-direction: column;
  gap: 4px;
  transform: translateY(-10px);
  opacity: 0;
  transition: transform var(--transition-normal), opacity var(--transition-normal);
}

.nav.is-open + .nav-drawer {
  display: flex;
  transform: translateY(0);
  opacity: 1;
}

.nav-drawer a {
  display: block;
  padding: 12px 8px;
  color: rgba(255, 255, 255, 0.9);
  font-family: var(--font-body);
  font-size: 15px;
  border-radius: 8px;
  transition: background var(--transition-fast);
}

.nav-drawer a:hover {
  background: rgba(255, 255, 255, 0.08);
}

.nav-drawer .nav-cta {
  display: inline-flex;
  margin-top: 8px;
  padding: 12px 20px;
  font-size: 15px;
  width: fit-content;
}

@media (max-width: 767px) {
  .nav-links { display: none; }
  .nav-hamburger { display: inline-flex; }
}

/* Theme toggle */
.theme-toggle {
  width: 28px;
  height: 28px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  border-radius: 8px;
  margin-left: 4px;
  transition: background var(--transition-fast);
}

.theme-toggle:hover {
  background: rgba(255, 255, 255, 0.1);
}

.theme-toggle svg {
  width: 16px;
  height: 16px;
}

.theme-toggle .icon-sun { display: none; }
html.dark .theme-toggle .icon-moon { display: none; }
html.dark .theme-toggle .icon-sun { display: block; }

/* ════════════════════════════════════════════════════════════════════
   Buttons
   ════════════════════════════════════════════════════════════════════ */

.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--color-primary);
  color: #fff;
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: var(--font-weight-medium);
  padding: 12px 24px;
  border-radius: var(--radius-full);
  transition: filter var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
}

.btn-primary:hover {
  filter: brightness(0.92);
  transform: translateY(-1px);
  box-shadow: 0 8px 20px rgba(0, 113, 227, 0.35);
}

.btn-ghost {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  color: var(--color-primary);
  font-family: var(--font-body);
  font-size: 17px;
  font-weight: var(--font-weight-medium);
  transition: opacity var(--transition-fast);
}

.btn-ghost:hover {
  opacity: 0.7;
}

.btn-outline-light {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: transparent;
  color: #fff;
  border: 1px solid rgba(255, 255, 255, 0.2);
  font-family: var(--font-body);
  font-size: 15px;
  font-weight: var(--font-weight-medium);
  padding: 12px 24px;
  border-radius: var(--radius-full);
  transition: border-color var(--transition-fast), background var(--transition-fast);
}

.btn-outline-light:hover {
  border-color: rgba(255, 255, 255, 0.4);
  background: rgba(255, 255, 255, 0.05);
}

/* ════════════════════════════════════════════════════════════════════
   Hero
   ════════════════════════════════════════════════════════════════════ */

.hero-dark {
  background: #000;
  color: #fff;
}

.hero-light {
  background: var(--color-surface-primary);
  color: var(--color-text-primary);
}

.hero-soft {
  background: var(--color-surface-secondary);
  color: var(--color-text-primary);
}

.hero {
  min-height: calc(100vh - var(--nav-height));
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 100px 24px 80px;
  position: relative;
  overflow: hidden;
}

.hero-2col {
  min-height: auto;
  padding: 96px 0;
  text-align: left;
  align-items: stretch;
  justify-content: center;
}

.hero-2col .container {
  display: flex;
  align-items: center;
  gap: 64px;
}

.hero-2col .hero-text {
  flex: 1;
}

.hero-2col .hero-media {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
}

@media (max-width: 900px) {
  .hero-2col .container {
    flex-direction: column;
    gap: 48px;
    text-align: center;
  }
  .hero-2col .hero-text {
    text-align: center;
  }
}

.hero h1 {
  margin: 0 0 16px;
  font-size: clamp(2.5rem, 8vw, 4.5rem);
}

.hero-2col h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  text-align: left;
  margin: 0 0 20px;
}

@media (max-width: 900px) {
  .hero-2col h1 { text-align: center; }
}

.hero-sub {
  font-family: var(--font-primary);
  font-size: clamp(1.25rem, 2.5vw, 1.5rem);
  font-weight: 400;
  line-height: var(--line-height-snug);
  color: rgba(255, 255, 255, 0.8);
  max-width: 720px;
  margin: 0 auto 24px;
}

.hero-tagline {
  font-family: var(--font-primary);
  font-size: clamp(1.25rem, 2.4vw, 1.625rem);
  font-weight: var(--font-weight-medium);
  color: rgba(255, 255, 255, 0.92);
  letter-spacing: 0.01em;
  max-width: 720px;
  margin: 8px auto 20px;
  line-height: var(--line-height-snug);
}

.hero-tagline em {
  font-style: normal;
  color: var(--color-hrv-green);
  font-weight: var(--font-weight-semibold);
}

.footer-tagline {
  font-family: var(--font-primary);
  font-size: 14px;
  font-weight: var(--font-weight-semibold);
  color: rgba(255, 255, 255, 0.85);
  letter-spacing: 0.01em;
  margin: 0 0 6px;
}

.hero-desc {
  font-family: var(--font-body);
  font-size: 17px;
  line-height: var(--line-height-relaxed);
  color: rgba(255, 255, 255, 0.6);
  max-width: 680px;
  margin: 0 auto 40px;
}

.hero-2col .hero-desc {
  text-align: left;
  margin: 0 0 32px;
  max-width: 480px;
  color: var(--color-text-secondary);
}

@media (max-width: 900px) {
  .hero-2col .hero-desc { text-align: center; margin-left: auto; margin-right: auto; }
}

.hero-caption {
  color: var(--color-primary);
  margin: 0 0 12px;
  display: inline-block;
}

.hero-cta-row {
  margin-top: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}

.hero-2col .hero-cta-row {
  justify-content: flex-start;
}

@media (max-width: 900px) {
  .hero-2col .hero-cta-row { justify-content: center; }
}

/* Device glow behind phone */
.device-glow {
  position: relative;
}

.device-glow::before {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 120%;
  height: 120%;
  background: radial-gradient(ellipse at center, rgba(0, 113, 227, 0.18) 0%, rgba(0, 113, 227, 0.05) 40%, transparent 70%);
  filter: blur(40px);
  z-index: -1;
  pointer-events: none;
  animation: pulse 6s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 0.8; transform: translate(-50%, -50%) scale(1); }
  50% { opacity: 1; transform: translate(-50%, -50%) scale(1.05); }
}

.device-img {
  width: 100%;
  max-width: 320px;
  height: auto;
  border-radius: 8px;
  display: block;
  margin: 0 auto;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.5);
  transition: transform var(--transition-slow);
}

.device-img:hover {
  transform: translateY(-4px) scale(1.02);
}

@media (min-width: 768px) {
  .device-img { max-width: 360px; }
}

/* Hero stats */
.hero-stats {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0;
  margin-top: 64px;
  flex-wrap: wrap;
}

.hero-stats > div {
  text-align: center;
  padding: 0 24px;
}

@media (min-width: 768px) {
  .hero-stats > div { padding: 0 40px; }
}

.hero-stats .stat-value {
  color: #fff;
  font-family: var(--font-primary);
  font-weight: var(--font-weight-semibold);
  font-size: var(--font-size-md);
  margin: 0;
}

.hero-stats .stat-label {
  color: rgba(255, 255, 255, 0.5);
  font-family: var(--font-body);
  font-size: var(--font-size-xs);
  font-weight: var(--font-weight-medium);
  letter-spacing: var(--letter-spacing-wide);
  text-transform: uppercase;
  margin: 4px 0 0;
}

.hero-stats .divider {
  width: 1px;
  height: 32px;
  background: rgba(255, 255, 255, 0.1);
}

@media (max-width: 600px) {
  .hero-stats .divider { display: none; }
  .hero-stats > div { padding: 12px 16px; }
}

/* ════════════════════════════════════════════════════════════════════
   Feature Grid
   ════════════════════════════════════════════════════════════════════ */

.features-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

@media (min-width: 768px) {
  .features-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (min-width: 1024px) {
  .features-grid { grid-template-columns: repeat(3, 1fr); }
}

.feature-card {
  background: var(--color-surface-primary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-subtle);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
  position: relative;
  overflow: hidden;
}

.feature-card::after {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at top right, var(--color-primary-light) 0%, transparent 50%);
  opacity: 0;
  transition: opacity var(--transition-normal);
  pointer-events: none;
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-elevated);
  border-color: var(--color-border-strong);
}

.feature-card:hover::after {
  opacity: 1;
}

.feature-card h3 {
  font-family: var(--font-primary);
  font-size: 20px;
  font-weight: var(--font-weight-bold);
  color: var(--color-text-primary);
  line-height: var(--line-height-snug);
  margin: 16px 0 8px;
}

.feature-card p {
  font-family: var(--font-body);
  font-size: 15px;
  color: var(--color-text-secondary);
  line-height: var(--line-height-normal);
  margin: 0;
}

.feature-icon {
  width: 40px;
  height: 40px;
  display: block;
  flex-shrink: 0;
}

/* ════════════════════════════════════════════════════════════════════
   Stats / Highlight row
   ════════════════════════════════════════════════════════════════════ */

.highlight-row {
  display: grid;
  grid-template-columns: 1fr;
  gap: 48px;
  text-align: center;
}

@media (min-width: 768px) {
  .highlight-row { grid-template-columns: repeat(3, 1fr); gap: 64px; }
}

.highlight-item {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.highlight-icon {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--color-primary-light);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
  transition: transform var(--transition-normal);
}

.highlight-item:hover .highlight-icon {
  transform: scale(1.1) rotate(6deg);
}

.highlight-item h3 {
  font-family: var(--font-primary);
  font-size: 16px;
  font-weight: var(--font-weight-bold);
  color: var(--color-text-primary);
  margin: 0 0 8px;
}

.highlight-item p {
  font-family: var(--font-body);
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: var(--line-height-normal);
  margin: 0;
}

/* ════════════════════════════════════════════════════════════════════
   HRV Ring
   ════════════════════════════════════════════════════════════════════ */
.hrv-card {
  background: var(--color-surface-secondary);
  border-radius: var(--radius-xl);
  padding: 32px;
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 100%;
  max-width: 360px;
}

/* Physical condition phone screenshot in hero */
.hero-physical {
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100%;
}

.hero-physical-img {
  display: block;
  width: 100%;
  max-width: 360px;
  height: auto;
  border-radius: var(--radius-xl);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.18);
}

.hrv-ring {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  background: conic-gradient(
    var(--color-hrv-green) 0deg 331deg,
    var(--color-hrv-yellow) 331deg 345deg,
    var(--color-hrv-orange) 345deg 355deg,
    var(--color-hrv-red) 355deg 360deg
  );
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  animation: ringAppear 1s var(--transition-spring);
}

.hrv-ring::after {
  content: "";
  position: absolute;
  width: 168px;
  height: 168px;
  border-radius: 50%;
  background: var(--color-surface-secondary);
}

.hrv-ring-center {
  position: relative;
  z-index: 1;
  text-align: center;
}

.hrv-score {
  font-family: var(--font-primary);
  font-size: 48px;
  font-weight: var(--font-weight-bold);
  color: var(--color-hrv-green);
  line-height: 1.1;
  letter-spacing: var(--letter-spacing-tight);
}

.hrv-label {
  font-family: var(--font-body);
  font-size: 14px;
  color: var(--color-text-secondary);
  margin-top: 2px;
}

@keyframes ringAppear {
  from { transform: scale(0.7); opacity: 0; }
  to { transform: scale(1); opacity: 1; }
}

.metric-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 24px;
  width: 100%;
}

.metric-card {
  background: var(--color-surface-primary);
  border-radius: var(--radius-lg);
  padding: 12px 16px;
  display: flex;
  align-items: center;
  gap: 10px;
  border: 1px solid var(--color-border);
  transition: transform var(--transition-fast);
}

.metric-card:hover {
  transform: translateY(-2px);
}

.metric-icon {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.metric-icon svg {
  width: 16px;
  height: 16px;
}

.metric-label {
  font-family: var(--font-body);
  font-size: 11px;
  color: var(--color-text-tertiary);
  margin: 0;
}

.metric-value {
  font-family: var(--font-primary);
  font-size: 17px;
  font-weight: var(--font-weight-semibold);
  color: var(--color-text-primary);
  line-height: 1.1;
  margin: 0;
}

.metric-unit {
  font-size: 12px;
  font-weight: var(--font-weight-regular);
  color: var(--color-text-secondary);
}

/* ════════════════════════════════════════════════════════════════════
   Signal Rows (Algorithm)
   ════════════════════════════════════════════════════════════════════ */

.signal-list {
  max-width: 640px;
  margin: 48px auto 0;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.signal-row {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 20px;
  border-radius: var(--radius-lg);
  border: 1px solid rgba(255, 255, 255, 0.06);
  background: rgba(255, 255, 255, 0.03);
  transition: background var(--transition-normal), border-color var(--transition-normal), transform var(--transition-fast);
}

.signal-row:hover {
  background: rgba(255, 255, 255, 0.06);
  border-color: rgba(255, 255, 255, 0.12);
  transform: translateX(4px);
}

.signal-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
  box-shadow: 0 0 12px currentColor;
}

.signal-title {
  font-family: var(--font-body);
  font-size: 15px;
  color: rgba(255, 255, 255, 0.8);
  font-weight: var(--font-weight-medium);
  margin: 0;
}

.signal-desc {
  font-family: var(--font-body);
  font-size: 13px;
  color: rgba(255, 255, 255, 0.4);
  margin: 2px 0 0;
}

/* ════════════════════════════════════════════════════════════════════
   Widget cards (Exams page)
   ════════════════════════════════════════════════════════════════════ */

.widget-row {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 20px;
  margin-top: 48px;
}

@media (min-width: 640px) {
  .widget-row { flex-direction: row; }
}

.widget-card {
  flex: 1;
  max-width: 240px;
  width: 100%;
  background: #1C1C1E;
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--radius-xl);
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  min-height: 180px;
  transition: transform var(--transition-normal), border-color var(--transition-normal);
}

.widget-card:hover {
  transform: translateY(-4px);
  border-color: rgba(255, 255, 255, 0.25);
}

.widget-header {
  display: flex;
  align-items: center;
  gap: 8px;
}

.widget-header span {
  font-family: var(--font-primary);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-semibold);
  color: rgba(255, 255, 255, 0.85);
}

.widget-row-mini {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 0 4px;
}

.widget-icon-mini {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.widget-icon-mini svg { width: 16px; height: 16px; }

.widget-row-mini .name {
  font-family: var(--font-primary);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-semibold);
  color: #fff;
  margin: 0;
}

.widget-row-mini .date {
  font-family: var(--font-body);
  font-size: var(--font-size-xs);
  color: rgba(255, 255, 255, 0.5);
  margin: 0;
}

.widget-trend {
  flex: 1;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  padding: 0 4px;
}

.widget-trend-caption {
  font-family: var(--font-body);
  font-size: var(--font-size-xs);
  color: rgba(255, 255, 255, 0.4);
  margin: 0;
}

.widget-hrv {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 6px;
}

.widget-hrv-ring {
  position: relative;
}

.widget-hrv-ring span {
  font-family: var(--font-primary);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-bold);
  color: var(--color-hrv-green);
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.widget-hrv-label {
  font-family: var(--font-body);
  font-size: var(--font-size-xs);
  color: rgba(255, 255, 255, 0.5);
  margin: 0;
}

/* ════════════════════════════════════════════════════════════════════
   Chip / Tag
   ════════════════════════════════════════════════════════════════════ */

.chip {
  display: inline-block;
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  padding: 6px 12px;
  font-family: var(--font-body);
  font-size: 13px;
  color: var(--color-text-secondary);
  transition: transform var(--transition-fast), border-color var(--transition-fast), color var(--transition-fast);
  cursor: default;
}

.chip:hover {
  transform: translateY(-1px);
  border-color: var(--color-primary);
  color: var(--color-primary);
}

html.dark .chip {
  background: var(--color-surface-secondary);
  color: var(--color-text-secondary);
}

.chip-list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px;
  margin-top: 40px;
}

.lang-list {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 24px;
  margin-top: 32px;
  flex-wrap: wrap;
}

.lang-list span {
  font-family: var(--font-body);
  font-size: 17px;
  color: var(--color-text-secondary);
}

.lang-dot { color: var(--color-border-strong); }

/* ════════════════════════════════════════════════════════════════════
   Footer
   ════════════════════════════════════════════════════════════════════ */

footer {
  background: #1D1D1F;
  color: rgba(255, 255, 255, 0.6);
  padding: 48px 0;
}

.footer-row {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 32px;
  padding-top: 24px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

@media (min-width: 768px) {
  .footer-row { flex-direction: row; justify-content: space-between; align-items: flex-start; }
}

.footer-meta p {
  margin: 0;
  font-family: var(--font-body);
  font-size: var(--font-size-xs);
  color: rgba(255, 255, 255, 0.4);
}

.footer-meta p + p { margin-top: 8px; }

.footer-links {
  display: flex;
  gap: 32px;
}

.footer-links a {
  font-family: var(--font-body);
  font-size: var(--font-size-xs);
  color: rgba(255, 255, 255, 0.5);
  transition: color var(--transition-fast);
}

.footer-links a:hover { color: #fff; }

/* ════════════════════════════════════════════════════════════════════
   Section padding
   ════════════════════════════════════════════════════════════════════ */

.section {
  padding: 80px 0;
}

@media (min-width: 768px) {
  .section { padding: 96px 0; }
}

.section-tight { padding: 64px 0; }

.section-head {
  text-align: center;
  max-width: 720px;
  margin: 0 auto 48px;
}

.section-head h2 {
  margin: 16px 0 16px;
  font-size: clamp(1.75rem, 4vw, 2.25rem);
  line-height: var(--line-height-tight);
  letter-spacing: var(--letter-spacing-tight);
  color: var(--color-text-primary);
}

.section-head.dark h2 { color: #fff; }

.section-head p {
  font-family: var(--font-body);
  font-size: 17px;
  line-height: var(--line-height-normal);
  color: var(--color-text-secondary);
  margin: 0 auto;
  max-width: 720px;
}

.section-head.dark p { color: rgba(255, 255, 255, 0.6); }

/* ════════════════════════════════════════════════════════════════════
   Reveal on scroll
   ════════════════════════════════════════════════════════════════════ */

.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 600ms ease, transform 600ms cubic-bezier(0.22, 1, 0.36, 1);
  will-change: opacity, transform;
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.reveal-delay-1 { transition-delay: 80ms; }
.reveal-delay-2 { transition-delay: 160ms; }
.reveal-delay-3 { transition-delay: 240ms; }
.reveal-delay-4 { transition-delay: 320ms; }
.reveal-delay-5 { transition-delay: 400ms; }
.reveal-delay-6 { transition-delay: 480ms; }

/* ════════════════════════════════════════════════════════════════════
   Misc
   ════════════════════════════════════════════════════════════════════ */

.check-list {
  list-style: none;
  margin: 0 0 32px;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.check-list li {
  display: flex;
  align-items: center;
  gap: 8px;
  color: rgba(255, 255, 255, 0.7);
  font-family: var(--font-body);
  font-size: 15px;
}

.check-list.light li { color: var(--color-text-primary); }

.text-center { text-align: center; }

.bg-soft { background: var(--color-surface-secondary); }

.bg-dark { background: #000; color: #fff; }

.mb-2 { margin-bottom: 8px; }
.mb-3 { margin-bottom: 12px; }
.mb-4 { margin-bottom: 16px; }
.mb-6 { margin-bottom: 24px; }
.mb-8 { margin-bottom: 32px; }
.mb-10 { margin-bottom: 40px; }
.mb-12 { margin-bottom: 48px; }

.mt-2 { margin-top: 8px; }
.mt-4 { margin-top: 16px; }
.mt-6 { margin-top: 24px; }
.mt-8 { margin-top: 32px; }
.mt-10 { margin-top: 40px; }
.mt-12 { margin-top: 48px; }

/* Stacked images (offset overlap) */
.stack-images {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  width: 100%;
}

.stack-images img:first-child {
  margin-bottom: -32px;
  max-width: 300px;
  position: relative;
  z-index: 2;
}

.stack-images img:last-child {
  max-width: 300px;
  margin-left: auto;
  position: relative;
  z-index: 1;
}

@media (min-width: 768px) {
  .stack-images { flex-direction: row; justify-content: center; }
  .stack-images img:first-child {
    max-width: 320px;
    transform: translateX(20px) translateY(-10px);
  }
  .stack-images img:last-child {
    max-width: 300px;
    margin-top: 32px;
    transform: translateX(-20px);
  }
}

/* Apple Health Badge */
.apple-health-badge {
  display: inline-block;
  height: 44px;
  width: auto;
  vertical-align: middle;
  transition: opacity var(--transition-fast), transform var(--transition-fast);
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.18);
  border-radius: 6px;
}

.apple-health-badge:hover {
  opacity: 0.9;
  transform: translateY(-1px);
}

.apple-health-badge--sm {
  height: 32px;
}

.apple-health-badge--lg {
  height: 56px;
}

.apple-health-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 16px;
}

/* No-scrollbar utility */
.no-scrollbar::-webkit-scrollbar { display: none; }
.no-scrollbar { -ms-overflow-style: none; scrollbar-width: none; }

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
  .reveal { opacity: 1; transform: none; }
  html { scroll-behavior: auto; }
}