/* ==========================================================================
   Button Component - Unified Button Styles
   모든 버튼에 사용
   ========================================================================== */

/* ---------------------------------------------------------------------------
   Base Button
   --------------------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-2);
  padding: var(--spacing-btn-y) var(--spacing-btn-x);
  font-family: var(--font-family-primary);
  font-size: var(--font-size-md);
  font-weight: var(--font-weight-medium);
  line-height: 1;
  border-radius: var(--radius-full);
  border: none;
  cursor: pointer;
  transition: transform 0.15s ease, background-color 0.15s ease;
  text-decoration: none;
}

.btn:active {
  transform: scale(0.96);
}

.btn:disabled {
  opacity: var(--opacity-disabled);
  cursor: not-allowed;
}

/* ---------------------------------------------------------------------------
   Button Variants
   --------------------------------------------------------------------------- */
.btn--primary {
  background: var(--color-fill-dark);
  color: var(--color-text-inverse);
}

.btn--primary:hover {
  background: var(--color-fill-dark);
  opacity: var(--opacity-pressed);
}

.btn--secondary {
  background: var(--color-bg-primary);
  color: var(--color-text-primary);
  border: 1px solid var(--color-fill-dark);
}

.btn--ghost {
  background: var(--color-bg-primary);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border-soft);
}

.btn--danger {
  background: var(--color-danger);
  color: var(--color-text-inverse);
}

.btn--success {
  background: var(--color-success);
  color: var(--color-text-inverse);
}

.btn--warning {
  background: var(--color-fill-dark);
  color: var(--color-text-inverse);
}

/* ---------------------------------------------------------------------------
   Button Sizes
   --------------------------------------------------------------------------- */
.btn--xs {
  padding: var(--spacing-1) var(--spacing-2);
  font-size: var(--font-size-xs);
  height: var(--avatar-size-sm);
  border-radius: var(--radius-full);
}

.btn--sm {
  padding: var(--spacing-2) var(--spacing-4);
  font-size: var(--font-size-sm);
  height: var(--btn-height-sm);
  border-radius: var(--radius-full);
}

.btn--md {
  height: var(--btn-height-md);
}

.btn--lg {
  padding: var(--spacing-3) var(--spacing-6);
  font-size: var(--font-size-md);
  height: var(--btn-height-lg);
}

.btn--full {
  width: 100%;
}

/* ---------------------------------------------------------------------------
   Icon Button
   --------------------------------------------------------------------------- */
.btn--icon {
  width: var(--btn-icon-size);
  height: var(--btn-icon-size);
  padding: 0;
  border-radius: var(--radius-full);
}

.btn--icon svg {
  width: var(--icon-size-md);
  height: var(--icon-size-md);
}

/* ---------------------------------------------------------------------------
   Header Buttons (Glass Effect) - 40x40 circular
   --------------------------------------------------------------------------- */
.header-btn {
  width: var(--btn-icon-size);
  height: var(--btn-icon-size);
  border-radius: var(--radius-full);
  background: var(--color-bg-glass);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1.5px solid var(--color-glass-border);
  box-shadow: var(--shadow-soft-warm);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: transform 0.15s ease;
  text-decoration: none;
  color: var(--color-text-primary);
}

.header-btn:active {
  transform: scale(0.92);
}

@media (min-width: 768px) {
  .web-layout .header-btn {
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--color-border-soft);
  }
}

.header-btn--danger {
  color: var(--color-danger);
}

.header-btn svg {
  width: var(--icon-size-md);
  height: var(--icon-size-md);
}

/* Header Button Group (96x40 dual icons) */
.header-btn-group {
  display: flex;
  align-items: center;
  justify-content: center;
  width: var(--btn-icon-group-width);
  height: var(--btn-icon-size);
  gap: var(--spacing-6);
  background: var(--color-bg-glass);
  border: 1.5px solid var(--color-glass-border);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-soft-warm);
}

.header-btn-group button,
.header-btn-group a {
  background: none;
  border: none;
  padding: 0;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-primary);
}

.header-btn-group svg {
  width: var(--icon-size-md);
  height: var(--icon-size-md);
}

/* Header Button with Dropdown */
.header-btn-wrapper {
  position: relative;
}

.header-btn-dropdown {
  position: absolute;
  top: calc(100% + var(--spacing-2));
  right: 0;
  min-width: 180px;
  background: var(--color-bg-glass);
  backdrop-filter: blur(10px);
  border: 1.5px solid var(--color-glass-border);
  border-radius: var(--radius-base);
  box-shadow: var(--shadow-dropdown);
  padding: var(--spacing-1);
  z-index: var(--z-dropdown);
}

.header-btn-option {
  display: flex;
  align-items: center;
  gap: var(--spacing-list-sm);
  width: 100%;
  padding: var(--spacing-2) var(--spacing-list-md);
  font-family: var(--font-family-primary);
  font-size: var(--font-size-md);
  font-weight: var(--font-weight-normal);
  color: var(--color-text-primary);
  background: none;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  text-decoration: none;
  text-align: left;
}

.header-btn-option:hover {
  background: var(--color-hover-subtle);
}

.header-btn-option svg {
  width: var(--icon-size-compact);
  height: var(--icon-size-compact);
  flex-shrink: 0;
}

/* ---------------------------------------------------------------------------
   Tab Buttons
   --------------------------------------------------------------------------- */
.tab-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-2);
  font-family: var(--font-family-primary);
  font-size: var(--font-size-md);
  font-weight: var(--font-weight-medium);
  line-height: 1;
  color: var(--color-text-primary);
  background: var(--color-bg-primary);
  border: 1px solid var(--color-border-soft);
  border-radius: var(--radius-base);
  white-space: nowrap;
  cursor: pointer;
  transition: all 0.15s ease;
  text-decoration: none;
  flex-shrink: 0;
}

.tab-btn:active {
  transform: scale(0.96);
}

.tab-btn.active {
  border-color: var(--color-fill-dark);
}

/* ---------------------------------------------------------------------------
   Follow Button States
   --------------------------------------------------------------------------- */
.btn--follow {
  padding: var(--spacing-2) var(--spacing-section);
  font-size: var(--font-size-sm);
  border-radius: calc(var(--spacing-btn-y) * 3.333);
}

.btn--follow.following {
  background: var(--color-gray-100);
  color: var(--color-text-secondary);
}

/* ---------------------------------------------------------------------------
   Join Button (Challenge)
   --------------------------------------------------------------------------- */
.btn--join {
  width: 100%;
  height: var(--btn-icon-size);
  border-radius: var(--radius-full);
}

/* ---------------------------------------------------------------------------
   Action Link (Text Button)
   --------------------------------------------------------------------------- */
.btn--link {
  background: none;
  border: none;
  padding: 0;
  font-family: var(--font-family-primary);
  font-size: var(--font-size-md);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-primary);
  cursor: pointer;
  text-decoration: none;
}

.btn--link:hover {
  text-decoration: underline;
}

.btn--link--danger {
  color: var(--color-danger);
}

.btn--link--muted {
  color: var(--color-text-secondary);
}