:root {
  --font-main: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'Noto Sans SC', sans-serif;
  --color-bg: #f5f3ee;
  --color-surface: #ffffff;
  --color-text: #1a1a1a;
  --color-text-secondary: #555555;
  --color-text-light: #8a8a8a;
  --color-accent: #ff4d4d;
  --color-border: #e8e6e3;
  --color-border-light: #f0efeb;
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.04);
  --shadow-md: 0 8px 24px rgba(0,0,0,0.08);
  --shadow-lg: 0 16px 48px rgba(0,0,0,0.12);
  --radius-sm: 8px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --radius-full: 100px;
}

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

body {
  font-family: var(--font-main);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  background-image:
    radial-gradient(circle at 20% 30%, rgba(255, 77, 77, 0.03) 0%, transparent 50%),
    radial-gradient(circle at 80% 70%, rgba(255, 140, 66, 0.03) 0%, transparent 50%);
}

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ===== Header ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(245, 243, 238, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--color-border);
  padding: 16px 0;
}

.site-header .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.site-title {
  font-size: 18px;
  font-weight: 800;
  letter-spacing: -0.5px;
}

.site-title a {
  color: var(--color-text);
  text-decoration: none;
}

.site-nav {
  display: flex;
  gap: 2px;
}

.site-nav a {
  color: var(--color-text-light);
  text-decoration: none;
  font-size: 13px;
  font-weight: 600;
  padding: 6px 12px;
  border-radius: var(--radius-full);
  transition: all 0.2s;
}

.site-nav a:hover {
  color: var(--color-text);
  background: var(--color-surface);
}

/* ===== Main ===== */
.site-main {
  padding: 48px 0 80px;
}

/* ===== Footer ===== */
.site-footer {
  border-top: 1px solid var(--color-border-light);
  padding: 32px 0;
  text-align: center;
}

.site-footer p {
  font-size: 13px;
  color: var(--color-text-light);
}

/* ===== Hero Section ===== */
.hero {
  text-align: center;
  padding: 24px 0 48px;
}

.hero h1 {
  font-size: clamp(28px, 6vw, 42px);
  font-weight: 800;
  letter-spacing: -1.5px;
  line-height: 1.15;
  margin-bottom: 12px;
}

.hero h1 span {
  color: var(--color-accent);
}

.hero p {
  font-size: 15px;
  color: var(--color-text-light);
  font-weight: 500;
}

/* ===== Homepage Masonry Grid ===== */
.post-masonry {
  column-count: 2;
  column-gap: 24px;
  padding-bottom: 8px;
}

.masonry-item {
  break-inside: avoid;
  margin-bottom: 28px;
  background: var(--color-surface);
  border-radius: var(--radius-md);
  overflow: hidden;
  position: relative;
  transition: all 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
  transform: rotate(var(--rot));
  border: 1px solid var(--color-border-light);
}

.masonry-item:hover {
  transform: rotate(0deg) scale(1.02);
  box-shadow: var(--shadow-lg);
  z-index: 10;
}

.card-bg-number {
  position: absolute;
  top: -6px;
  right: -2px;
  font-size: 72px;
  font-weight: 900;
  letter-spacing: -4px;
  color: var(--color-border-light);
  line-height: 1;
  pointer-events: none;
  user-select: none;
  transition: all 0.3s;
}

.masonry-item:hover .card-bg-number {
  color: var(--color-accent);
  opacity: 0.12;
}

.card-body {
  padding: 24px 28px 28px;
  position: relative;
  z-index: 1;
}

.card-tag {
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  color: var(--card-color, var(--color-accent));
  background: var(--card-bg, rgba(255, 77, 77, 0.08));
  padding: 3px 12px;
  border-radius: 3px;
  letter-spacing: 0.3px;
  margin-bottom: 14px;
  text-transform: uppercase;
}

.card-title {
  font-size: 22px;
  font-weight: 800;
  line-height: 1.25;
  margin-bottom: 10px;
  letter-spacing: -0.5px;
}

.card-title a {
  color: var(--color-text);
  text-decoration: none;
  transition: color 0.2s;
}

.card-title a:hover {
  color: var(--card-color, var(--color-accent));
}

.card-excerpt {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.75;
  margin-bottom: 18px;
}

.card-meta {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  color: var(--color-text-light);
}

.meta-dot {
  opacity: 0.4;
}

.card-link {
  margin-left: auto;
  font-size: 12px;
  font-weight: 700;
  color: var(--color-text);
  text-decoration: none;
  padding: 4px 12px;
  border-radius: var(--radius-full);
  border: 1px solid var(--color-border);
  transition: all 0.2s;
}

.card-link:hover {
  background: var(--card-color, var(--color-accent));
  color: #fff;
  border-color: var(--card-color, var(--color-accent));
}

/* Color themes */
.card-red {
  --card-color: #e74c3c;
  --card-bg: rgba(231, 76, 60, 0.08);
  border-left: 3px solid #e74c3c;
}

.card-blue {
  --card-color: #3498db;
  --card-bg: rgba(52, 152, 219, 0.08);
  border-left: 3px solid #3498db;
}

.card-green {
  --card-color: #2ecc71;
  --card-bg: rgba(46, 204, 113, 0.08);
  border-left: 3px solid #2ecc71;
}

.card-orange {
  --card-color: #e67e22;
  --card-bg: rgba(230, 126, 34, 0.08);
  border-left: 3px solid #e67e22;
}

.card-purple {
  --card-color: #9b59b6;
  --card-bg: rgba(155, 89, 182, 0.08);
  border-left: 3px solid #9b59b6;
}

/* nth-child chaos: make even items tilt opposite */
.masonry-item:nth-child(even) {
  margin-top: 16px;
}

.masonry-item:nth-child(3n) .card-bg-number {
  font-size: 88px;
  top: -10px;
  right: 4px;
}

.masonry-item:nth-child(4n) {
  border-radius: var(--radius-lg);
}

.masonry-item:nth-child(5n) .card-body {
  padding-top: 32px;
}

/* ===== Post Detail ===== */
.post-detail {
  max-width: 680px;
  margin: 0 auto;
}

.post-detail-title {
  font-size: clamp(26px, 5vw, 36px);
  font-weight: 800;
  letter-spacing: -1px;
  line-height: 1.2;
  margin-bottom: 16px;
}

.post-detail .post-meta {
  display: flex;
  gap: 12px;
  font-size: 13px;
  color: var(--color-text-light);
  margin-bottom: 32px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--color-border-light);
}

.post-content {
  font-size: 16px;
  line-height: 1.9;
  color: var(--color-text-secondary);
}

.post-content p {
  margin-bottom: 1.2em;
}

.post-actions {
  display: flex;
  gap: 8px;
  margin-top: 40px;
  padding-top: 24px;
  border-top: 1px solid var(--color-border-light);
}

/* ===== Login Form ===== */
.login-form,
.write-form {
  max-width: 460px;
  margin: 0 auto;
}

.login-form h1,
.write-form h1 {
  font-size: 24px;
  font-weight: 800;
  letter-spacing: -0.5px;
  margin-bottom: 24px;
}

/* ===== Form Elements ===== */
.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 6px;
}

.form-group input[type="text"],
.form-group input[type="password"],
.form-group textarea {
  width: 100%;
  padding: 12px 16px;
  background: var(--color-surface);
  border: 2px solid var(--color-border-light);
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-family: inherit;
  transition: all 0.2s;
  outline: none;
  color: var(--color-text);
}

.form-group input:focus,
.form-group textarea:focus {
  border-color: var(--color-accent);
}

.form-group textarea {
  min-height: 280px;
  resize: vertical;
  line-height: 1.7;
}

.form-actions {
  display: flex;
  gap: 8px;
  margin-top: 24px;
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 22px;
  border-radius: var(--radius-full);
  text-decoration: none;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: all 0.2s;
  font-family: inherit;
  white-space: nowrap;
  line-height: 1.4;
}

.btn-primary {
  background: var(--color-text);
  color: #fff;
}

.btn-primary:hover {
  background: #000;
  transform: scale(1.03);
}

.btn-secondary {
  background: var(--color-surface);
  color: var(--color-text);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover {
  background: var(--color-border);
}

.btn-edit {
  background: var(--color-surface);
  color: var(--color-text);
  border: 1px solid var(--color-border);
  font-size: 13px;
  padding: 6px 16px;
}

.btn-edit:hover {
  background: var(--color-border);
}

.btn-delete {
  background: none;
  color: var(--color-accent);
  border: 1px solid rgba(255, 77, 77, 0.2);
  font-size: 13px;
  padding: 6px 16px;
  cursor: pointer;
  font-family: inherit;
  font-weight: 600;
  border-radius: var(--radius-full);
  transition: all 0.2s;
}

.btn-delete:hover {
  background: rgba(255, 77, 77, 0.06);
  border-color: var(--color-accent);
}

/* ===== Changelog ===== */
.changelog h1 {
  font-size: 28px;
  font-weight: 800;
  letter-spacing: -1px;
  margin-bottom: 32px;
}

.changelog-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.changelog-item {
  position: relative;
  padding: 24px 0 24px 28px;
  border-left: 2px solid var(--color-border);
}

.changelog-item::before {
  content: '';
  position: absolute;
  left: -6px;
  top: 28px;
  width: 10px;
  height: 10px;
  background: var(--color-surface);
  border: 2px solid var(--color-border);
  border-radius: 50%;
  transition: all 0.2s;
}

.changelog-item:hover::before {
  background: var(--color-accent);
  border-color: var(--color-accent);
}

.changelog-item:last-child {
  border-left-color: transparent;
}

.changelog-version {
  font-size: 18px;
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.3px;
  margin-bottom: 6px;
}

.changelog-desc {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 6px;
}

.changelog-date time {
  font-size: 12px;
  color: var(--color-text-light);
}

/* ===== Empty State ===== */
.empty-state {
  text-align: center;
  padding: 60px 20px;
}

.empty-state p {
  font-size: 15px;
  color: var(--color-text-light);
}

/* ===== Alert ===== */
.alert {
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  margin-bottom: 20px;
}

.alert-error {
  background: rgba(255, 77, 77, 0.08);
  color: var(--color-accent);
  border: 1px solid rgba(255, 77, 77, 0.15);
}

/* ===== Responsive ===== */
@media (max-width: 640px) {
  .container {
    padding: 0 16px;
  }

  .site-header {
    padding: 12px 0;
  }

  .site-title {
    font-size: 16px;
  }

  .site-nav a {
    font-size: 12px;
    padding: 5px 10px;
  }

  .site-main {
    padding: 24px 0 60px;
  }

  .hero {
    padding: 16px 0 32px;
  }

  .post-masonry {
    column-count: 1;
    column-gap: 0;
  }

  .masonry-item {
    margin-bottom: 20px;
  }

  .masonry-item:nth-child(even) {
    margin-top: 0;
  }

  .masonry-item:hover {
    transform: rotate(var(--rot)) scale(1.01);
  }

  .card-body {
    padding: 20px 22px 24px;
  }

  .card-bg-number {
    font-size: 56px;
  }

  .masonry-item:nth-child(3n) .card-bg-number {
    font-size: 64px;
  }

  .card-title {
    font-size: 18px;
  }

  .post-detail-title {
    font-size: 22px;
  }

  .form-group textarea {
    min-height: 200px;
  }

  .login-form,
  .write-form {
    max-width: 100%;
  }

  .changelog-item {
    padding-left: 20px;
  }

  .changelog-version {
    font-size: 16px;
  }
}

@media (max-width: 400px) {
  .site-nav {
    gap: 0;
  }

  .site-nav a {
    font-size: 11px;
    padding: 4px 8px;
  }

  .card-meta {
    flex-wrap: wrap;
  }

  .card-link {
    margin-left: 0;
  }
}