/* variables & reset */
:root {
  --bg-color: #ffffff;
  --text-color: #111111;
  --link-color: #111111;
  --link-hover-color: #666666;
  --border-color: #eaeaea;
  --accent-color: #000000;
  --input-bg: #f9f9f9;
  
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  --font-mono: ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-color: #111111;
    --text-color: #eeeeee;
    --link-color: #eeeeee;
    --link-hover-color: #aaaaaa;
    --border-color: #333333;
    --accent-color: #ffffff;
    --input-bg: #222222;
  }
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

a {
  color: var(--link-color);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 4px;
  transition: color 0.2s ease, text-decoration-color 0.2s ease;
}

a:hover {
  color: var(--link-hover-color);
  text-decoration-color: var(--link-hover-color);
}

/* structure */
.container {
  max-width: 640px;
  margin: 0 auto;
  padding: 60px 20px;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.header {
  margin-bottom: 60px;
}

.title {
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.content {
  flex: 1;
}

/* article list */
.article-list {
  list-style: none;
  margin-bottom: 60px;
}

.article-list li {
  margin-bottom: 16px;
}

.article-link {
  font-size: 1.125rem;
  font-weight: 400;
  text-decoration: none;
  border-bottom: 1px solid transparent;
}

.article-link:hover {
  border-bottom-color: var(--link-hover-color);
  text-decoration: none;
}

/* newsletter */
.newsletter {
  margin-bottom: 60px;
  padding-top: 40px;
  border-top: 1px solid var(--border-color);
}

.newsletter p {
  margin-bottom: 20px;
  font-size: 0.95rem;
  color: var(--text-color);
  opacity: 0.8;
}

.newsletter-form {
  display: flex;
  gap: 10px;
  max-width: 400px;
}

.email-input {
  flex: 1;
  padding: 10px 14px;
  border: 1px solid var(--border-color);
  background-color: var(--input-bg);
  color: var(--text-color);
  border-radius: 6px;
  font-family: var(--font-sans);
  font-size: 0.95rem;
  transition: border-color 0.2s;
  outline: none;
}

.email-input:focus {
  border-color: var(--accent-color);
}

.submit-button {
  background-color: var(--accent-color);
  color: var(--bg-color);
  border: none;
  padding: 10px 20px;
  border-radius: 6px;
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 500;
  cursor: pointer;
  transition: opacity 0.2s;
}

.submit-button:hover {
  opacity: 0.8;
}

/* article specific styles */
.article-container {
  max-width: 680px;
}

.article-header {
  margin-bottom: 40px;
}

.back-link {
  font-size: 0.95rem;
  color: var(--text-color);
  opacity: 0.7;
  text-decoration: none;
}
.back-link:hover {
  opacity: 1;
}

.article-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 10px;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

.article-meta {
  font-size: 0.9rem;
  color: var(--text-color);
  opacity: 0.6;
  margin-bottom: 40px;
}

.article-body h2 {
  font-size: 1.25rem;
  font-weight: 600;
  margin: 40px 0 15px;
}

.article-body p {
  margin-bottom: 20px;
}

.article-body h3 {
  font-size: 1.1rem;
  font-weight: 500;
  margin: 30px 0 10px;
}

.article-body ul {
  list-style-type: none;
  padding-left: 0;
  margin-bottom: 20px;
}

.article-body ul li {
  margin-bottom: 8px;
  position: relative;
  padding-left: 20px;
}

.article-body ul:not(.clean-list) li::before {
  content: "—";
  position: absolute;
  left: 0;
  opacity: 0.5;
}

.article-body ul.clean-list {
  padding-left: 0;
}

.article-body ul.clean-list li {
  padding-left: 0;
  margin-bottom: 6px;
}

.article-newsletter {
  margin-top: 60px;
  padding-top: 60px;
}

/* footer */
.footer {
  margin-top: auto;
  padding-top: 40px;
}

.social-links {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 15px;
  font-size: 0.85rem;
}

.social-links a {
  text-decoration: none;
  opacity: 0.7;
}

.social-links a:hover {
  opacity: 1;
}