/* SkillSwap — Global Styles
   Color palette: strictly black (#000) and white (#fff)
   Grays only for hierarchy: borders, disabled, subtle backgrounds */

/* ── Reset & Base ─────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --black:       #000000;
  --white:       #ffffff;
  --gray-100:    #f5f5f5;
  --gray-200:    #e8e8e8;
  --gray-400:    #aaaaaa;
  --gray-600:    #666666;
  --gray-800:    #222222;
  --font-sans:   'Inter', system-ui, -apple-system, sans-serif;
  --radius:      4px;
  --radius-lg:   8px;
  --transition:  0.15s ease;
  --max-w:       1100px;
  --nav-h:       60px;
}

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

body {
  font-family: var(--font-sans);
  background: var(--white);
  color: var(--black);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a { color: inherit; text-decoration: none; }
a:hover { text-decoration: underline; }
img { display: block; max-width: 100%; }
ul { list-style: none; }
button { cursor: pointer; font-family: inherit; }
input, textarea, select { font-family: inherit; }

/* ── Typography ───────────────────────────────────────────────── */
h1 { font-size: clamp(2rem, 5vw, 3.5rem); font-weight: 800; line-height: 1.1; letter-spacing: -0.03em; }
h2 { font-size: clamp(1.4rem, 3vw, 2rem);  font-weight: 700; line-height: 1.2; letter-spacing: -0.02em; }
h3 { font-size: 1.2rem; font-weight: 600; }
h4 { font-size: 1rem;   font-weight: 600; }
p  { color: var(--gray-800); }
small { font-size: 0.8rem; color: var(--gray-600); }

/* ── Layout helpers ───────────────────────────────────────────── */
.container { width: 100%; max-width: var(--max-w); margin: 0 auto; padding: 0 1.5rem; }
.page-content { flex: 1; padding-top: calc(var(--nav-h) + 2rem); padding-bottom: 4rem; }
.center { text-align: center; }
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-1 { gap: 0.5rem; }
.gap-2 { gap: 1rem; }
.gap-3 { gap: 1.5rem; }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.hidden { display: none !important; }

/* ── Navigation ───────────────────────────────────────────────── */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  height: var(--nav-h);
  background: var(--white);
  border-bottom: 1px solid var(--gray-200);
  display: flex; align-items: center;
}
.nav .container { display: flex; align-items: center; justify-content: space-between; }
.nav-logo {
  font-size: 1.25rem; font-weight: 800; letter-spacing: -0.04em;
  color: var(--black);
}
.nav-logo span { opacity: 0.35; }
.nav-links { display: flex; align-items: center; gap: 0.25rem; }
.nav-link {
  padding: 0.4rem 0.75rem; border-radius: var(--radius);
  font-size: 0.9rem; font-weight: 500; color: var(--gray-600);
  transition: color var(--transition), background var(--transition);
}
.nav-link:hover { color: var(--black); background: var(--gray-100); text-decoration: none; }
.nav-link.active { color: var(--black); font-weight: 600; }
.nav-avatar {
  width: 34px; height: 34px; border-radius: 50%;
  background: var(--black); color: var(--white);
  display: flex; align-items: center; justify-content: center;
  font-size: 0.8rem; font-weight: 700; cursor: pointer;
  border: none; transition: opacity var(--transition);
  overflow: hidden; flex-shrink: 0; padding: 0;
}
.nav-avatar img {
  width: 100%; height: 100%; object-fit: cover; border-radius: 50%; display: block;
}
.nav-avatar:hover { opacity: 0.75; }

/* ── Hamburger button ─────────────────────────────────────────── */
.hamburger-btn {
  display: none;
  flex-direction: column; justify-content: center; align-items: center;
  gap: 5px; width: 36px; height: 36px;
  background: none; border: none; cursor: pointer; padding: 4px;
  border-radius: var(--radius);
  transition: background var(--transition);
}
.hamburger-btn:hover { background: var(--gray-100); }
.hamburger-btn span {
  display: block; width: 20px; height: 2px;
  background: var(--black); border-radius: 2px;
  transition: transform 0.25s ease, opacity 0.25s ease;
}
.hamburger-btn[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger-btn[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.hamburger-btn[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ── Mobile drawer ────────────────────────────────────────────── */
.drawer-overlay {
  position: fixed; inset: 0;
  background: rgba(0,0,0,0.4); z-index: 150;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s ease;
}
.drawer-overlay.open { opacity: 1; pointer-events: auto; }

.drawer {
  position: fixed; top: 0; right: 0; bottom: 0;
  width: min(300px, 85vw);
  background: var(--white); z-index: 200;
  display: flex; flex-direction: column;
  transform: translateX(100%);
  transition: transform 0.28s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: -4px 0 24px rgba(0,0,0,0.12);
}
.drawer.open { transform: translateX(0); }

.drawer-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--gray-200);
  height: var(--nav-h);
}
.drawer-close {
  background: none; border: none; cursor: pointer;
  color: var(--gray-600); padding: 0.25rem;
  border-radius: var(--radius); display: flex;
  transition: color var(--transition), background var(--transition);
}
.drawer-close:hover { color: var(--black); background: var(--gray-100); }

.drawer-nav {
  flex: 1; display: flex; flex-direction: column;
  padding: 1rem 0.75rem; gap: 0.25rem; overflow-y: auto;
}
.drawer-link {
  display: flex; align-items: center; gap: 0.75rem;
  padding: 0.75rem 0.75rem; border-radius: var(--radius);
  font-size: 1rem; font-weight: 500; color: var(--gray-600);
  text-decoration: none;
  transition: color var(--transition), background var(--transition);
}
.drawer-link:hover { color: var(--black); background: var(--gray-100); text-decoration: none; }
.drawer-link.active { color: var(--black); font-weight: 700; background: var(--gray-100); }

.drawer-footer {
  padding: 0.75rem;
  border-top: 1px solid var(--gray-200);
}
.drawer-footer .drawer-link {
  gap: 0.75rem; font-size: 0.9rem;
}

/* ── Buttons ──────────────────────────────────────────────────── */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 0.4rem;
  padding: 0.6rem 1.25rem; border-radius: var(--radius);
  font-size: 0.9rem; font-weight: 600; border: 2px solid transparent;
  transition: background var(--transition), color var(--transition), border-color var(--transition), opacity var(--transition);
  white-space: nowrap;
}
.btn:hover { text-decoration: none; }
.btn:disabled { opacity: 0.4; cursor: not-allowed; }

.btn-primary { background: var(--black); color: var(--white); border-color: var(--black); }
.btn-primary:hover:not(:disabled) { background: var(--gray-800); border-color: var(--gray-800); }

.btn-outline { background: transparent; color: var(--black); border-color: var(--black); }
.btn-outline:hover:not(:disabled) { background: var(--black); color: var(--white); }

.btn-ghost { background: transparent; color: var(--gray-600); border-color: transparent; }
.btn-ghost:hover:not(:disabled) { background: var(--gray-100); color: var(--black); }

.btn-sm { padding: 0.35rem 0.75rem; font-size: 0.8rem; }
.btn-lg { padding: 0.85rem 2rem; font-size: 1rem; }
.btn-full { width: 100%; }
.btn-icon { padding: 0.5rem; border-radius: 50%; }

/* ── Forms ────────────────────────────────────────────────────── */
.form-group { display: flex; flex-direction: column; gap: 0.4rem; }
.form-label { font-size: 0.85rem; font-weight: 600; color: var(--black); }
.form-hint  { font-size: 0.78rem; color: var(--gray-600); }

.form-input, .form-textarea, .form-select {
  width: 100%; padding: 0.65rem 0.9rem;
  border: 1.5px solid var(--gray-200); border-radius: var(--radius);
  background: var(--white); color: var(--black);
  font-size: 0.95rem; outline: none;
  transition: border-color var(--transition);
}
.form-input:focus, .form-textarea:focus, .form-select:focus {
  border-color: var(--black);
}
.form-input::placeholder, .form-textarea::placeholder { color: var(--gray-400); }
.form-textarea { resize: vertical; min-height: 90px; }

.form-error { font-size: 0.8rem; color: #c00; margin-top: 0.25rem; }
.form-success { font-size: 0.8rem; color: #060; margin-top: 0.25rem; }

/* ── Tag input ────────────────────────────────────────────────── */
.tag-input-wrapper {
  border: 1.5px solid var(--gray-200); border-radius: var(--radius);
  padding: 0.4rem 0.6rem; display: flex; flex-wrap: wrap; gap: 0.4rem;
  cursor: text; transition: border-color var(--transition);
  min-height: 46px; align-items: center;
}
.tag-input-wrapper:focus-within { border-color: var(--black); }
.tag-input-wrapper input {
  border: none; outline: none; flex: 1; min-width: 120px;
  font-size: 0.9rem; background: transparent; color: var(--black);
  padding: 0.2rem 0;
}
.tag-input-wrapper input::placeholder { color: var(--gray-400); }

.tag {
  display: inline-flex; align-items: center; gap: 0.3rem;
  background: var(--black); color: var(--white);
  padding: 0.2rem 0.55rem; border-radius: 999px;
  font-size: 0.78rem; font-weight: 500;
}
.tag-remove {
  background: none; border: none; color: var(--white);
  cursor: pointer; font-size: 1rem; line-height: 1;
  padding: 0; opacity: 0.7; transition: opacity var(--transition);
}
.tag-remove:hover { opacity: 1; }

.tag-display {
  display: inline-flex; align-items: center;
  background: var(--gray-100); color: var(--black);
  border: 1px solid var(--gray-200);
  padding: 0.2rem 0.6rem; border-radius: 999px;
  font-size: 0.78rem; font-weight: 500;
}
.tag-display.want { background: var(--white); border-style: dashed; }

/* ── Cards ────────────────────────────────────────────────────── */
.card {
  background: var(--white); border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg); padding: 1.5rem;
  transition: border-color var(--transition), box-shadow var(--transition);
}
.card:hover { border-color: var(--gray-400); box-shadow: 0 2px 12px rgba(0,0,0,0.06); }

.user-card {
  display: flex; gap: 1rem; align-items: flex-start;
  cursor: pointer;
}
.user-card-avatar {
  width: 52px; height: 52px; border-radius: 50%; flex-shrink: 0;
  background: var(--black); color: var(--white);
  display: flex; align-items: center; justify-content: center;
  font-size: 1.1rem; font-weight: 700;
}
.user-card-body { flex: 1; min-width: 0; }
.user-card-name { font-weight: 700; font-size: 1rem; }
.user-card-bio  { font-size: 0.85rem; color: var(--gray-600); margin-top: 0.2rem;
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.user-card-tags { display: flex; flex-wrap: wrap; gap: 0.3rem; margin-top: 0.6rem; }

/* ── Avatar ───────────────────────────────────────────────────── */
.avatar {
  border-radius: 50%; background: var(--black); color: var(--white);
  display: flex; align-items: center; justify-content: center;
  font-weight: 700; flex-shrink: 0;
}
.avatar-sm  { width: 36px; height: 36px; font-size: 0.85rem; }
.avatar-md  { width: 52px; height: 52px; font-size: 1.1rem; }
.avatar-lg  { width: 80px; height: 80px; font-size: 1.6rem; }
.avatar-xl  { width: 110px; height: 110px; font-size: 2.2rem; }

/* ── Divider ──────────────────────────────────────────────────── */
.divider {
  display: flex; align-items: center; gap: 1rem;
  color: var(--gray-400); font-size: 0.8rem; margin: 1.25rem 0;
}
.divider::before, .divider::after {
  content: ''; flex: 1; height: 1px; background: var(--gray-200);
}

/* ── Alert / Toast ────────────────────────────────────────────── */
.alert {
  padding: 0.75rem 1rem; border-radius: var(--radius);
  font-size: 0.875rem; border: 1px solid;
}
.alert-error   { background: #fff5f5; border-color: #fcc; color: #900; }
.alert-success { background: #f5fff5; border-color: #cfc; color: #060; }
.alert-info    { background: var(--gray-100); border-color: var(--gray-200); color: var(--gray-800); }

#toast-container {
  position: fixed; bottom: 1.5rem; right: 1.5rem; z-index: 9999;
  display: flex; flex-direction: column; gap: 0.5rem;
}
.toast {
  background: var(--black); color: var(--white);
  padding: 0.75rem 1.25rem; border-radius: var(--radius);
  font-size: 0.875rem; font-weight: 500;
  animation: slideIn 0.2s ease; max-width: 320px;
}
.toast.error { background: #900; }
@keyframes slideIn { from { transform: translateX(100%); opacity: 0; } to { transform: translateX(0); opacity: 1; } }

/* ── Spinner ──────────────────────────────────────────────────── */
.spinner {
  width: 20px; height: 20px; border: 2px solid var(--gray-200);
  border-top-color: var(--black); border-radius: 50%;
  animation: spin 0.6s linear infinite; display: inline-block;
}
.spinner-lg { width: 36px; height: 36px; border-width: 3px; }
@keyframes spin { to { transform: rotate(360deg); } }

.loading-state {
  display: flex; flex-direction: column; align-items: center;
  justify-content: center; gap: 1rem; padding: 4rem 0;
  color: var(--gray-600);
}

/* ── Empty state ──────────────────────────────────────────────── */
.empty-state {
  text-align: center; padding: 4rem 1rem; color: var(--gray-600);
}
.empty-state h3 { color: var(--black); margin-bottom: 0.5rem; }

/* ── Modal ────────────────────────────────────────────────────── */
.modal-overlay {
  position: fixed; inset: 0; background: rgba(0,0,0,0.5);
  display: flex; align-items: center; justify-content: center;
  z-index: 200; padding: 1rem;
}
.modal {
  background: var(--white); border-radius: var(--radius-lg);
  padding: 2rem; width: 100%; max-width: 480px;
  max-height: 90vh; overflow-y: auto;
}
.modal-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 1.5rem; }
.modal-close { background: none; border: none; font-size: 1.5rem; cursor: pointer; color: var(--gray-600); }

/* ── Avatar upload widget ─────────────────────────────────────── */
.avatar-upload {
  position: relative; display: inline-block; cursor: pointer;
}
.avatar-upload input[type="file"] { display: none; }
.avatar-upload-overlay {
  position: absolute; inset: 0; border-radius: 50%;
  background: rgba(0,0,0,0.45);
  display: flex; align-items: center; justify-content: center;
  opacity: 0; transition: opacity var(--transition);
  color: var(--white); font-size: 0.7rem; font-weight: 600;
  text-align: center; line-height: 1.3; gap: 0.2rem;
  flex-direction: column;
}
.avatar-upload:hover .avatar-upload-overlay { opacity: 1; }
.avatar-upload-overlay svg { width: 20px; height: 20px; }

.avatar-upload-progress {
  position: absolute; bottom: -1.5rem; left: 50%; transform: translateX(-50%);
  font-size: 0.72rem; color: var(--gray-600); white-space: nowrap;
}

/* ── Footer ───────────────────────────────────────────────────── */
.footer {
  border-top: 1px solid var(--gray-200);
  padding: 1.5rem 0; text-align: center;
  font-size: 0.8rem; color: var(--gray-600);
}

/* ── Responsive ───────────────────────────────────────────────── */
@media (max-width: 640px) {
  .nav-links .nav-link { display: none; }
  .hamburger-btn { display: flex; }
  .hide-mobile { display: none; }
}