/* ============================================
   DESIGN SYSTEM - Personal Blog
   Based on DESIGN.md specifications
   ============================================ */

/* ============================================
   CSS CUSTOM PROPERTIES (DESIGN TOKENS)
   ============================================ */

:root {
  /* Colors - Light Theme (Default) */
  --color-background: #FFFFFF;
  --color-surface: #FAFAFA;
  --color-foreground: #1A1A1A;
  --color-foreground-muted: #6B7280;
  --color-foreground-subtle: #9CA3AF;
  --color-accent: #2563EB;
  --color-accent-hover: #1D4ED8;
  --color-border: #E5E7EB;
  --color-border-subtle: #F3F4F6;
  --color-code-background: #F9FAFB;
  --color-code-text: #111827;
  --color-code-accent: #DC2626;
  --color-success: #059669;
  --color-warning: #D97706;
  --color-error: #DC2626;

  /* Typography */
  --font-primary: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-heading: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: "SF Mono", Monaco, "Cascadia Code", "Roboto Mono", Consolas, "Courier New", monospace;

  /* Font Sizes */
  --font-size-xs: 0.75rem;      /* 12px */
  --font-size-sm: 0.875rem;     /* 14px */
  --font-size-base: 1rem;       /* 16px */
  --font-size-lg: 1.125rem;     /* 18px */
  --font-size-xl: 1.25rem;      /* 20px */
  --font-size-2xl: 1.5rem;      /* 24px */
  --font-size-3xl: 1.875rem;    /* 30px */
  --font-size-4xl: 2.25rem;     /* 36px */
  --font-size-5xl: 3rem;        /* 48px */
  --font-size-6xl: 3.75rem;     /* 60px */

  /* Line Heights */
  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;

  /* Font Weights */
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;

  /* Spacing */
  --space-1: 0.25rem;   /* 4px */
  --space-2: 0.5rem;    /* 8px */
  --space-3: 0.75rem;   /* 12px */
  --space-4: 1rem;      /* 16px */
  --space-5: 1.25rem;   /* 20px */
  --space-6: 1.5rem;    /* 24px */
  --space-8: 2rem;      /* 32px */
  --space-10: 2.5rem;   /* 40px */
  --space-12: 3rem;     /* 48px */
  --space-16: 4rem;     /* 64px */
  --space-20: 5rem;     /* 80px */
  --space-24: 6rem;     /* 96px */

  /* Layout */
  --width-content: 760px;
  --width-wide: 1200px;
  --width-narrow: 600px;
  --breakpoint-sm: 640px;
  --breakpoint-md: 768px;
  --breakpoint-lg: 1024px;
  --breakpoint-xl: 1280px;
}

/* Dark Theme */
html[data-theme="dark"] {
  --color-background: #0F172A;
  --color-surface: #1E293B;
  --color-foreground: #F1F5F9;
  --color-foreground-muted: #94A3B8;
  --color-foreground-subtle: #64748B;
  --color-accent: #60A5FA;
  --color-accent-hover: #3B82F6;
  --color-border: #334155;
  --color-border-subtle: #1E293B;
  --color-code-background: #1E293B;
  --color-code-text: #E2E8F0;
  --color-code-accent: #F87171;
  --color-success: #34D399;
  --color-warning: #FBBF24;
  --color-error: #F87171;
  color-scheme: dark;
}

html[data-theme="light"] {
  color-scheme: light;
}

/* ============================================
   RESET & BASE STYLES
   ============================================ */

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

html {
  font-size: 16px;
}

body {
  background-color: var(--color-background);
  color: var(--color-foreground);
  font-family: var(--font-primary);
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-normal);
  line-height: var(--line-height-relaxed);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   TYPOGRAPHY
   ============================================ */

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  color: var(--color-foreground);
  margin: 0;
}

h1 {
  font-size: clamp(var(--font-size-4xl), 5vw, var(--font-size-5xl));
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  letter-spacing: -0.02em;
  margin-bottom: var(--space-4);
}

h2 {
  font-size: var(--font-size-3xl);
  font-weight: var(--font-weight-semibold);
  line-height: 1.3;
  margin-top: var(--space-12);
  margin-bottom: var(--space-4);
}

h2:first-of-type {
  margin-top: 0;
}

h3 {
  font-size: var(--font-size-2xl);
  font-weight: var(--font-weight-semibold);
  line-height: 1.4;
  margin-top: var(--space-8);
  margin-bottom: var(--space-4);
}

h4, h5, h6 {
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-semibold);
  margin-top: var(--space-8);
  margin-bottom: var(--space-4);
}

p {
  font-size: var(--font-size-lg);
  line-height: var(--line-height-relaxed);
  margin-bottom: var(--space-6);
  max-width: 65ch;
  color: var(--color-foreground);
}

strong {
  font-weight: var(--font-weight-semibold);
  color: var(--color-foreground);
}

em {
  font-style: italic;
  color: var(--color-foreground);
}

/* ============================================
   LINKS
   ============================================ */

a {
  color: var(--color-accent);
  text-decoration: none;
  font-weight: var(--font-weight-medium);
  transition: color 150ms ease;
}

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

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

/* ============================================
   HEADER & NAVIGATION
   ============================================ */

.Layout--header {
  background: var(--color-background);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
  padding: var(--space-4) 0;
}

.navigation {
  max-width: var(--width-wide);
  margin: 0 auto;
  padding: 0 var(--space-4);
  position: relative;
}

.navigation__inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.navigation__logo {
  font-family: var(--font-heading);
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-semibold);
  color: var(--color-foreground);
  text-decoration: none;
}

.navigation__logo:hover {
  text-decoration: none;
  color: var(--color-foreground);
}

.navigation nav ul {
  display: flex;
  list-style: none;
  gap: var(--space-8);
  margin: 0;
  padding: 0;
}

.navigation nav ul li {
  margin: 0;
}

.navigation nav ul li a,
.navigation nav ul li button {
  font-family: var(--font-heading);
  font-size: 0.9375rem;
  font-weight: var(--font-weight-medium);
  color: var(--color-foreground-muted);
  text-decoration: none;
  transition: color 150ms ease;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0;
}

.navigation nav ul li a:hover,
.navigation nav ul li button:hover {
  color: var(--color-foreground);
  text-decoration: none;
}

.navigation nav ul li a.active {
  color: var(--color-accent);
}

.menu-toggle {
  display: none;
  position: absolute;
  top: var(--space-4);
  right: var(--space-4);
  width: 48px;
  height: 48px;
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  cursor: pointer;
  z-index: 101;
  padding: 0;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 6px;
}

.menu-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-foreground);
  transition: all 0.3s ease;
}

.menu-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translate(6px, 6px);
}

.menu-toggle.active span:nth-child(2) {
  opacity: 0;
}

.menu-toggle.active span:nth-child(3) {
  transform: rotate(-45deg) translate(6px, -6px);
}

/* ============================================
   MAIN LAYOUT
   ============================================ */

.Layout--main {
  max-width: var(--width-content);
  margin: 0 auto;
  padding: var(--space-16) var(--space-4);
  min-height: 80vh;
}

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

/* ============================================
   HOMEPAGE HERO
   ============================================ */

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

.Intro--image {
  padding: var(--space-24) var(--space-4);
  text-align: left;
}

.Intro--image img {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  border: 3px solid var(--color-border);
  margin-bottom: var(--space-8);
  display: block;
}

.Intro--image h1 {
  font-size: clamp(var(--font-size-4xl), 8vw, var(--font-size-5xl));
  margin-bottom: var(--space-4);
}

.Intro--image h2 {
  font-size: var(--font-size-2xl);
  font-weight: var(--font-weight-normal);
  color: var(--color-foreground-muted);
  line-height: var(--line-height-normal);
  margin-top: 0;
}

/* ============================================
   BLOG POST LIST
   ============================================ */

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

.TopPosts > li {
  border-bottom: 1px solid var(--color-border-subtle);
  padding: var(--space-8) 0;
}

.TopPosts > li:last-child {
  border-bottom: none;
}

.TopPosts a {
  display: block;
  color: var(--color-foreground);
  text-decoration: none;
}

.TopPosts a:hover {
  text-decoration: none;
}

.TopPosts .post--date {
  font-family: var(--font-mono);
  font-size: var(--font-size-sm);
  color: var(--color-foreground-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-3);
  display: block;
}

.TopPosts h3 {
  font-size: var(--font-size-2xl);
  font-weight: var(--font-weight-semibold);
  line-height: 1.3;
  margin: 0 0 var(--space-2) 0;
  color: var(--color-foreground);
}

.TopPosts a:hover h3 {
  color: var(--color-accent);
}

.TopPosts p {
  font-size: var(--font-size-base);
  color: var(--color-foreground-muted);
  margin: 0;
  line-height: var(--line-height-normal);
}

/* ============================================
   INDIVIDUAL BLOG POST
   ============================================ */

.metadata {
  padding: var(--space-16) 0;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: var(--space-12);
  text-align: left;
}

.metadata h1 {
  font-size: clamp(var(--font-size-3xl), 5vw, 2.5rem);
  margin-bottom: var(--space-6);
}

.metadata .author {
  display: inline-flex;
  align-items: center;
  gap: var(--space-4);
  font-family: var(--font-mono);
  font-size: 0.9375rem;
  color: var(--color-foreground-muted);
}

.post-image {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  border: 2px solid var(--color-border);
}

.dateSection {
  font-family: var(--font-mono);
  font-size: 0.9375rem;
  text-align: left;
  margin: var(--space-8) 0 var(--space-16) 0;
  color: var(--color-foreground-muted);
}

.shadow {
  color: var(--color-foreground-muted);
  font-weight: var(--font-weight-medium);
}

.post-content {
  max-width: 65ch;
}

.post-content p {
  max-width: 65ch;
}

/* ============================================
   CONTENT ELEMENTS
   ============================================ */

blockquote {
  border-left: 3px solid var(--color-accent);
  padding-left: var(--space-6);
  margin: var(--space-8) 0;
  background: none;
  font-style: italic;
  font-size: var(--font-size-lg);
  color: var(--color-foreground-muted);
}

blockquote p {
  margin: 0;
}

ul, ol {
  margin: var(--space-6) 0;
  padding-left: var(--space-6);
}

ul {
  list-style: disc;
}

ol {
  list-style: decimal;
}

li {
  margin: var(--space-2) 0;
  padding-left: var(--space-1);
  line-height: var(--line-height-relaxed);
}

li::marker {
  color: var(--color-accent);
}

img {
  width: 100%;
  height: auto;
  border-radius: 4px;
  margin: var(--space-8) 0;
}

hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: var(--space-16) 0;
}

/* ============================================
   CODE BLOCKS
   ============================================ */

code {
  font-family: var(--font-mono);
  font-size: 0.9em;
}

:not(pre) > code {
  background: var(--color-code-background);
  color: var(--color-code-text);
  padding: 0.2em 0.4em;
  border-radius: 4px;
  border: 1px solid var(--color-border);
  font-weight: var(--font-weight-normal);
}

pre {
  background: var(--color-code-background);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: var(--space-6);
  overflow-x: auto;
  margin: var(--space-8) 0;
  font-size: var(--font-size-sm);
  line-height: var(--line-height-normal);
}

pre code {
  background: transparent;
  border: none;
  padding: 0;
  color: var(--color-code-text);
}

/* Syntax highlighting */
code[class*="language-"],
pre[class*="language-"] {
  color: var(--color-code-text);
  background: var(--color-code-background);
  font-family: var(--font-mono);
  text-align: left;
  white-space: pre;
  word-spacing: normal;
  word-break: normal;
  word-wrap: normal;
  line-height: var(--line-height-normal);
  tab-size: 4;
}

pre[class*="language-"] {
  overflow: auto;
  padding: var(--space-6);
}

.token.comment {
  color: var(--color-foreground-muted);
}

.token.string {
  color: var(--color-accent);
}

.token.keyword {
  color: var(--color-code-text);
  font-weight: var(--font-weight-semibold);
}

.token.function {
  color: var(--color-accent);
}

.token.number {
  color: var(--color-code-text);
}

.token.operator {
  color: var(--color-accent);
}

.token.punctuation {
  color: var(--color-foreground-muted);
}

/* ============================================
   NEWSLETTER SIGNUP (BUTTONDOWN)
   ============================================ */

.Buttondown--Wrapper {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: var(--space-12) var(--space-8);
  margin: var(--space-16) 0;
  text-align: left;
}

.Buttondown--Wrapper--inner h2 {
  font-size: var(--font-size-2xl);
  font-weight: var(--font-weight-semibold);
  margin: 0 0 var(--space-4) 0;
}

.Buttondown--Wrapper--inner p {
  font-size: var(--font-size-base);
  color: var(--color-foreground-muted);
  margin-bottom: var(--space-6);
}

.Buttondown--Wrapper form {
  display: flex;
  gap: var(--space-3);
}

.Buttondown--Wrapper input[type="email"] {
  flex: 1;
  background: var(--color-background);
  color: var(--color-foreground);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: 0.75rem var(--space-4);
  font-size: var(--font-size-base);
  font-family: var(--font-primary);
}

.Buttondown--Wrapper input[type="email"]::placeholder {
  color: var(--color-foreground-muted);
}

.Buttondown--Wrapper input[type="email"]:focus {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
  border-color: var(--color-accent);
}

.Buttondown--Wrapper input[type="submit"] {
  background: var(--color-accent);
  color: var(--color-background);
  border: none;
  border-radius: 4px;
  padding: 0.75rem var(--space-6);
  font-size: var(--font-size-base);
  font-family: var(--font-heading);
  font-weight: var(--font-weight-semibold);
  cursor: pointer;
  transition: background-color 150ms ease;
}

.Buttondown--Wrapper input[type="submit"]:hover {
  background: var(--color-accent-hover);
}

.Buttondown--Wrapper input[type="submit"]:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

/* ============================================
   TAGS
   ============================================ */

.tags,
.post--tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin: var(--space-6) 0;
}

.tags a,
.post--tags a {
  display: inline-block;
  font-size: 0.8125rem;
  font-family: var(--font-mono);
  font-weight: var(--font-weight-medium);
  padding: 0.375rem 0.75rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  color: var(--color-foreground-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  transition: all 150ms ease;
  text-decoration: none;
}

.tags a:hover,
.post--tags a:hover {
  background: var(--color-accent);
  color: var(--color-background);
  text-decoration: none;
}

/* ============================================
   PREV/NEXT NAVIGATION
   ============================================ */

.prevnext {
  display: flex;
  justify-content: space-between;
  list-style: none;
  margin: var(--space-16) 0;
  padding: var(--space-8) 0;
  border-top: 1px solid var(--color-border);
  gap: var(--space-8);
}

.prevnext li {
  flex: 1;
}

.prevnext li a {
  font-family: var(--font-heading);
  font-size: 0.9375rem;
  font-weight: var(--font-weight-medium);
  color: var(--color-accent);
  text-decoration: none;
}

.prevnext li a:hover {
  text-decoration: underline;
}

/* ============================================
   THEME TOGGLE
   ============================================ */

button.toggle {
  position: fixed;
  top: calc((68px - 48px) / 2);
  right: var(--space-4);
  width: 48px;
  height: 48px;
  padding: 0;
  margin: 0;
  border: 1px solid var(--color-border);
  border-radius: 50%;
  background: var(--color-surface);
  cursor: pointer;
  transition: background-color 150ms ease;
  z-index: 1000;
  text-align: initial;
  line-height: 0;
  font-size: 0;
}

button.toggle:hover {
  background: var(--color-accent);
}

button.toggle:hover svg {
  fill: var(--color-background);
}

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

button.toggle svg {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 24px;
  height: 24px;
  fill: var(--color-foreground-muted);
  transition: fill 150ms ease;
  display: block;
  margin: 0;
  padding: 0;
  vertical-align: middle;
}

button.toggle svg.size-6 {
  width: 24px;
  height: 24px;
}

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

button.toggle[aria-pressed="true"] path:nth-of-type(1) {
  display: none;
}

button.toggle[aria-pressed="false"] path:nth-of-type(2) {
  display: none;
}

/* ============================================
   UTILITIES
   ============================================ */

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

.visuallyhidden {
  position: absolute;
  left: -10000px;
  top: auto;
  width: 1px;
  height: 1px;
  overflow: hidden;
}

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

.text-subtle {
  color: var(--color-foreground-subtle);
}

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

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */

@media (max-width: 768px) {
  body {
    font-size: var(--font-size-base);
  }

  .Layout--main {
    padding: var(--space-8) var(--space-4);
  }

  .menu-toggle {
    display: flex;
  }

  .navigation nav ul {
    position: fixed;
    top: 0;
    right: -100%;
    width: 80%;
    max-width: 300px;
    height: 100vh;
    background: var(--color-background);
    flex-direction: column;
    border-left: 1px solid var(--color-border);
    transition: right 0.3s ease;
    padding-top: 5rem;
    padding-left: var(--space-4);
    overflow-y: auto;
    gap: 0;
  }

  .navigation nav ul.active {
    right: 0;
  }

  .navigation nav ul li {
    width: 100%;
    border-bottom: 1px solid var(--color-border);
  }

  .navigation nav ul li a,
  .navigation nav ul li button {
    display: block;
    padding: var(--space-4) 0;
    width: 100%;
    text-align: left;
  }

  .navigation nav ul li:last-child {
    border-bottom: none;
  }

  .Intro--image {
    padding: var(--space-12) var(--space-4);
  }

  .metadata {
    padding: var(--space-8) 0;
  }

  .Buttondown--Wrapper {
    padding: var(--space-8) var(--space-4);
  }

  .Buttondown--Wrapper form {
    flex-direction: column;
  }

  .Buttondown--Wrapper input[type="submit"] {
    width: 100%;
  }

  .prevnext {
    flex-direction: column;
  }

  pre {
    padding: var(--space-4);
  }

  h1 {
    font-size: clamp(var(--font-size-3xl), 8vw, var(--font-size-4xl));
  }

  h2 {
    font-size: var(--font-size-2xl);
  }

  h3 {
    font-size: var(--font-size-xl);
  }
}

@media (max-width: 480px) {
  .TopPosts h3 {
    font-size: var(--font-size-xl);
  }

  blockquote {
    padding-left: var(--space-4);
  }

  blockquote p {
    font-size: var(--font-size-base);
  }
}