/* =========================================================
   base.css — 리셋 · 타이포그래피 · 페이지 레이아웃
   ========================================================= */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100dvh;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: var(--fs-base);
  font-weight: var(--fw-normal);
  line-height: var(--lh-normal);
  letter-spacing: -0.011em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4 {
  margin: 0;
  line-height: var(--lh-tight);
  letter-spacing: -0.021em;
  font-weight: var(--fw-semibold);
  color: var(--text);
}
h1 { font-size: var(--fs-xl); }
h2 { font-size: var(--fs-lg); }
h3 { font-size: var(--fs-base); }

p { margin: 0; }

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

img, svg { max-width: 100%; vertical-align: middle; }

button, input, select, textarea {
  font: inherit;
  color: inherit;
  letter-spacing: inherit;
}

button { cursor: pointer; }
button:disabled, input:disabled, select:disabled, textarea:disabled {
  cursor: not-allowed;
}

ul, ol { margin: 0; padding: 0; list-style: none; }

:focus-visible {
  outline: none;
  box-shadow: var(--ring);
  border-radius: var(--r-xs);
}

::selection { background: var(--accent-soft); color: var(--text); }

/* 스크롤바 (webkit) */
::-webkit-scrollbar { width: 11px; height: 11px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  background: var(--border-strong);
  border-radius: var(--r-full);
  border: 3px solid var(--bg);
}
::-webkit-scrollbar-thumb:hover { background: var(--text-subtle); }

/* ---------------------------------------------------------
   App shell
   --------------------------------------------------------- */

.app {
  display: flex;
  flex-direction: column;
  min-height: 100dvh;
}

.app-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--bg); /* color-mix 미지원 브라우저 폴백 */
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--border-subtle);
}

.app-header__inner {
  max-width: var(--page-w);
  margin: 0 auto;
  min-height: var(--header-h);
  padding: 0 var(--sp-5);
  display: flex;
  align-items: center;
  gap: var(--sp-4);
}

.brand {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  min-width: 0;
}

.brand__mark {
  width: 30px;
  height: 30px;
  flex: none;
  display: grid;
  place-items: center;
  border-radius: var(--r-sm);
  background: var(--accent);
  color: var(--on-accent);
  font-size: 15px;
}

.brand__text { min-width: 0; }

.brand__title {
  font-size: var(--fs-md);
  font-weight: var(--fw-semibold);
  letter-spacing: -0.02em;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.brand__sub {
  font-size: var(--fs-xs);
  color: var(--text-subtle);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.app-header__actions {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: var(--sp-2);
}

.app-main {
  flex: 1;
  width: 100%;
  max-width: var(--page-w);
  margin: 0 auto;
  padding: var(--sp-8) var(--sp-5) var(--sp-16);
}

.app-main--narrow { max-width: var(--page-w-narrow); }

.app-footer {
  border-top: 1px solid var(--border-subtle);
  padding: var(--sp-5);
  text-align: center;
  font-size: var(--fs-xs);
  color: var(--text-subtle);
}

/* ---------------------------------------------------------
   Section / stack primitives
   --------------------------------------------------------- */

.stack   { display: flex; flex-direction: column; gap: var(--sp-4); }
.stack-2 { display: flex; flex-direction: column; gap: var(--sp-2); }
.stack-6 { display: flex; flex-direction: column; gap: var(--sp-6); }
.stack-8 { display: flex; flex-direction: column; gap: var(--sp-8); }

.row {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  flex-wrap: wrap;
}
.row--between { justify-content: space-between; }
.row--end { justify-content: flex-end; }
.row--tight { gap: var(--sp-2); }
.spacer { flex: 1 1 auto; }

.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--sp-5);
}

@media (max-width: 860px) {
  .grid-2 { grid-template-columns: 1fr; }
}

/* ---------------------------------------------------------
   Section header
   --------------------------------------------------------- */

.section-head {
  display: flex;
  align-items: flex-start;
  gap: var(--sp-3);
  margin-bottom: var(--sp-4);
}

.section-head__num {
  flex: none;
  width: 22px;
  height: 22px;
  margin-top: 1px;
  display: grid;
  place-items: center;
  border-radius: var(--r-xs);
  background: var(--surface-3);
  color: var(--text-muted);
  font-size: var(--fs-xs);
  font-weight: var(--fw-semibold);
  font-variant-numeric: tabular-nums;
}

.section-head__body { min-width: 0; }

.section-head__desc {
  margin-top: 3px;
  font-size: var(--fs-sm);
  color: var(--text-muted);
}

/* ---------------------------------------------------------
   Typography helpers
   --------------------------------------------------------- */

.muted    { color: var(--text-muted); }
.subtle   { color: var(--text-subtle); }
.small    { font-size: var(--fs-sm); }
.xsmall   { font-size: var(--fs-xs); }
.strong   { font-weight: var(--fw-semibold); }
.num      { font-variant-numeric: tabular-nums; }
.truncate { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.nowrap   { white-space: nowrap; }

.label {
  display: block;
  font-size: var(--fs-sm);
  font-weight: var(--fw-medium);
  color: var(--text-muted);
  margin-bottom: var(--sp-2);
}

.hint {
  font-size: var(--fs-xs);
  color: var(--text-subtle);
  line-height: 1.5;
}

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

@media (max-width: 640px) {
  .app-header__inner { padding: 0 var(--sp-4); }
  .app-main { padding: var(--sp-5) var(--sp-4) var(--sp-16); }
  .brand__sub { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}