/* Design tokens */
:root {
  --font-sans: 'IBM Plex Sans KR', 'Noto Sans KR', system-ui, sans-serif;
  --font-mono: 'IBM Plex Mono', 'Fira Code', monospace;

  --color-bg: #ffffff;
  --color-surface: #f5f5f5;
  --color-border: #e0e0e0;
  --color-text: #161616;
  --color-text-secondary: #525252;
  --color-accent: #0f62fe;
  --color-accent-hover: #0353e9;
  --color-success: #24a148;
  --color-error: #da1e28;
  --color-warning: #f1c21b;

  --radius: 4px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,.12);
  --shadow-md: 0 4px 8px rgba(0,0,0,.12);
  --max-width: 900px;
  --header-height: 52px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #161616;
    --color-surface: #262626;
    --color-border: #393939;
    --color-text: #f4f4f4;
    --color-text-secondary: #a8a8a8;
    --color-accent: #78a9ff;
    --color-accent-hover: #a6c8ff;
  }
}

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

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

body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
}

a { color: var(--color-accent); text-decoration: none; }
a:hover { text-decoration: underline; }

h1 { font-size: 1.75rem; font-weight: 600; line-height: 1.25; }
h2 { font-size: 1.25rem; font-weight: 600; margin-top: 2rem; margin-bottom: .75rem; }
h3 { font-size: 1rem; font-weight: 600; margin-top: 1.5rem; margin-bottom: .5rem; }

p { margin-bottom: 1rem; }

/* Layout */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  height: var(--header-height);
  display: flex;
  align-items: center;
  padding: 0 1.5rem;
}

.site-header .logo {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-text);
  text-decoration: none;
  letter-spacing: -.5px;
}

.site-header nav {
  margin-left: auto;
  display: flex;
  gap: 1.5rem;
  font-size: .875rem;
}

.site-footer {
  border-top: 1px solid var(--color-border);
  padding: 2rem 1.5rem;
  text-align: center;
  font-size: .8125rem;
  color: var(--color-text-secondary);
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2rem 1.5rem;
}

/* Tool Layout */
.tool-header {
  margin-bottom: 2rem;
}

.tool-header h1 {
  margin-bottom: .5rem;
}

.tool-header .subtitle {
  color: var(--color-text-secondary);
  font-size: .9375rem;
}

.privacy-badge {
  display: inline-flex;
  align-items: center;
  gap: .375rem;
  background: #d4edda;
  color: #155724;
  border: 1px solid #c3e6cb;
  border-radius: 100px;
  padding: .2rem .75rem;
  font-size: .75rem;
  font-weight: 500;
  margin-top: .75rem;
}

@media (prefers-color-scheme: dark) {
  .privacy-badge {
    background: #1a3a1e;
    color: #6fcf97;
    border-color: #2d6a35;
  }
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: .375rem;
  padding: .5rem 1rem;
  border-radius: var(--radius);
  border: none;
  font-size: .875rem;
  font-family: inherit;
  cursor: pointer;
  transition: background .15s, color .15s;
  white-space: nowrap;
}

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

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

.btn-sm { padding: .3rem .75rem; font-size: .8125rem; }

/* Forms */
textarea, input[type="text"], input[type="number"], select {
  width: 100%;
  font-family: var(--font-sans);
  font-size: .9375rem;
  background: var(--color-surface);
  color: var(--color-text);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: .625rem .75rem;
  outline: none;
  transition: border-color .15s;
}
textarea:focus, input:focus, select:focus {
  border-color: var(--color-accent);
}

textarea { resize: vertical; min-height: 180px; }

.mono { font-family: var(--font-mono); }

label {
  display: block;
  font-size: .875rem;
  font-weight: 500;
  margin-bottom: .375rem;
  color: var(--color-text-secondary);
}

/* Cards */
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.25rem;
}

/* Tool grid on home */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1rem;
  margin-top: 1.5rem;
}

.tool-card {
  display: block;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.25rem;
  text-decoration: none;
  color: var(--color-text);
  transition: box-shadow .15s, border-color .15s;
}
.tool-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--color-accent);
  text-decoration: none;
}

.tool-card .icon { font-size: 1.75rem; margin-bottom: .625rem; }
.tool-card .name { font-weight: 600; font-size: 1rem; margin-bottom: .25rem; }
.tool-card .desc { font-size: .8125rem; color: var(--color-text-secondary); }
.tool-card .badge {
  display: inline-block;
  font-size: .7rem;
  background: var(--color-accent);
  color: #fff;
  padding: .1rem .45rem;
  border-radius: 100px;
  margin-top: .5rem;
}

/* FAQ */
.faq { margin-top: 3rem; }
.faq details {
  border-top: 1px solid var(--color-border);
  padding: .875rem 0;
}
.faq details:last-child { border-bottom: 1px solid var(--color-border); }
.faq summary {
  cursor: pointer;
  font-weight: 500;
  list-style: none;
  user-select: none;
  padding-right: 1.5rem;
  position: relative;
}
.faq summary::after {
  content: '+';
  position: absolute;
  right: 0;
  font-size: 1.2rem;
  color: var(--color-text-secondary);
}
.faq details[open] summary::after { content: '−'; }
.faq details p {
  margin-top: .625rem;
  color: var(--color-text-secondary);
  font-size: .9rem;
}

/* Ad slots */
.ad-slot {
  background: var(--color-surface);
  border: 1px dashed var(--color-border);
  border-radius: var(--radius);
  min-height: 90px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-secondary);
  font-size: .75rem;
  margin: 1.5rem 0;
}

/* Notification */
.notify {
  display: none;
  padding: .5rem 1rem;
  border-radius: var(--radius);
  font-size: .875rem;
  margin-top: .75rem;
}
.notify.success { display: block; background: #d4edda; color: #155724; }
.notify.error   { display: block; background: #f8d7da; color: #721c24; }

/* Responsive */
@media (max-width: 640px) {
  h1 { font-size: 1.375rem; }
  .container { padding: 1.25rem 1rem; }
}