:root {
  /* Colors (OKLCH) */
  --color-primary: oklch(0.4427 0.1233 149.53); /* Green */
  --color-primary-light: oklch(95.726% 0.05339 152.748);
  --color-accent: oklch(85% 0.18 95); /* Yellow */
  --color-text: oklch(25% 0.02 260);
  --color-text-light: oklch(55% 0.02 260);
  --color-background: oklch(99% 0.005 260);
  --color-white: oklch(100% 0 0);

  /* Typography */
  --font-base: "Helvetica Neue", Arial, "Hiragino Kaku Gothic ProN",
    "Hiragino Sans", Meiryo, sans-serif;
  --font-heading: "Helvetica Neue", Arial, "Hiragino Kaku Gothic ProN",
    "Hiragino Sans", Meiryo, sans-serif;

  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 2rem;
  --spacing-lg: 4rem;
  --spacing-xl: 8rem;

  /* Layout */
  --container-width: 1200px;
  --header-height: 80px;
}

/* Reset */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-base);
  color: var(--color-text);
  background-color: var(--color-background);
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  text-decoration: none;
  color: inherit;
  transition: opacity 0.3s ease;
}

a:hover {
  opacity: 0.7;
}

ul {
  list-style: none;
}

/* Utilities */
.container {
  max-width: var(--container-width);
  margin-inline: auto;
  padding: 0 var(--spacing-md);
}

.section-title {
  width: fit-content;
  font-size: 2.5rem;
  font-weight: 700;
  text-align: center;
  margin-inline: auto;
  margin-bottom: var(--spacing-lg);
  color: var(--color-primary);
  position: relative;
}

.section-title::after {
  content: "";
  position: absolute;
  bottom: -10px;
  left: 0;
  width: 100%;
  height: 4px;
  background-color: var(--color-accent);
  border-radius: 2px;
}

.btn {
  display: inline-block;
  background-color: var(--color-primary);
  color: var(--color-white);
  padding: 1rem 3rem;
  border-radius: 50px;
  font-weight: bold;
  font-size: 1.1rem;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 15px rgba(0, 0, 0, 0.15);
  opacity: 1;
}

.u-desktop-only {
  display: inline;
}

@media (width < 768px) {
  .u-desktop-only {
    display: none;
  }
}