/* === Modern Minimal Design System — Dursun Ordu === */

/* --- Custom Properties --- */
:root {
  --color-primary: #0f172a;
  --color-primary-hover: #1e293b;
  --color-primary-light: #334155;
  --color-bg: #f8fafc;
  --color-surface: #ffffff;
  --color-border: #e2e8f0;
  --color-border-focus: #94a3b8;
  --color-text: #1e293b;
  --color-text-secondary: #475569;
  --color-text-muted: #94a3b8;
  --color-accent: #3b82f6;
  --color-success: #059669;
  --color-success-bg: #ecfdf5;
  --color-error: #dc2626;
  --color-error-bg: #fef2f2;
  --color-warning: #d97706;
  --color-warning-bg: #fffbeb;

  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 1px 3px rgba(0, 0, 0, 0.06), 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 4px 12px rgba(0, 0, 0, 0.08);

  --font-sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SF Mono", "Fira Code", "Fira Mono", "Roboto Mono", monospace;

  --transition-fast: 150ms ease;
  --transition-normal: 200ms ease;
}

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

html {
  -webkit-text-size-adjust: 100%;
  -moz-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.5;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* --- Header --- */
.header {
  background: var(--color-primary);
  padding: 1rem 1.5rem;
}

.header-inner {
  max-width: 720px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.header-brand {
  flex-shrink: 0;
}

.header-title {
  color: #ffffff;
  font-size: 1.125rem;
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.01em;
}

.header-subtitle {
  color: var(--color-text-muted);
  font-size: 0.75rem;
  font-weight: 400;
  margin-top: 1px;
}

/* --- Currency Bar --- */
.currency-bar {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.currency-item {
  background: var(--color-primary-hover);
  color: #cbd5e1;
  padding: 0.3rem 0.6rem;
  border-radius: var(--radius-sm);
  font-size: 0.7rem;
  font-weight: 500;
  white-space: nowrap;
  transition: color var(--transition-fast);
}

.currency-item strong {
  color: #e2e8f0;
  font-weight: 600;
}

.currency-loading {
  color: var(--color-text-muted);
  font-size: 0.7rem;
  padding: 0.3rem 0;
}

.currency-error {
  color: #fca5a5;
  font-size: 0.65rem;
}

/* --- Tab Navigation --- */
.tab-bar {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding: 0.5rem 1.5rem;
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(8px);
}

.tab-inner {
  max-width: 720px;
  margin: 0 auto;
  display: flex;
  gap: 0.375rem;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}

.tab-inner::-webkit-scrollbar {
  display: none;
}

.tab-btn {
  flex-shrink: 0;
  padding: 0.5rem 1.125rem;
  border: none;
  border-radius: var(--radius-md);
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  background: transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.tab-btn:hover {
  background: #f1f5f9;
  color: var(--color-text);
}

.tab-btn:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

.tab-btn.active {
  background: var(--color-primary);
  color: #ffffff;
  font-weight: 600;
}

.tab-btn.active:hover {
  background: var(--color-primary-hover);
}

/* --- Main Content --- */
.main {
  max-width: 720px;
  margin: 0 auto;
  padding: 1.5rem;
}

/* --- Calculator Card --- */
.card {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  overflow: hidden;
  border: 1px solid var(--color-border);
}

.card-header {
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--color-border);
}

.card-title {
  font-size: 0.9375rem;
  font-weight: 700;
  color: var(--color-text);
  margin: 0;
}

.card-subtitle {
  font-size: 0.75rem;
  color: var(--color-text-muted);
  margin-top: 0.15rem;
}

.card-body {
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.card-results {
  background: var(--color-bg);
  padding: 1rem 1.5rem;
  display: flex;
  gap: 1rem;
  border-top: 1px solid var(--color-border);
}

/* --- Form Fields --- */
.field {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

.field-label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  letter-spacing: 0.01em;
}

.field-input {
  width: 100%;
  padding: 0.625rem 0.75rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  font-family: var(--font-sans);
  font-size: 0.875rem;
  color: var(--color-text);
  background: var(--color-bg);
  transition: all var(--transition-fast);
  -webkit-appearance: none;
  appearance: none;
}

.field-input::placeholder {
  color: var(--color-text-muted);
}

.field-input:hover {
  border-color: var(--color-border-focus);
}

.field-input:focus {
  outline: none;
  border-color: var(--color-primary);
  background: var(--color-surface);
  box-shadow: 0 0 0 3px rgba(15, 23, 42, 0.08);
}

.field-input:invalid:not(:placeholder-shown) {
  border-color: var(--color-error);
  box-shadow: 0 0 0 3px rgba(220, 38, 38, 0.08);
}

.field-select {
  cursor: pointer;
  appearance: none;
  -webkit-appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath d='M3 5l3 3 3-3' fill='none' stroke='%2394a3b8' stroke-width='1.5' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.75rem center;
  padding-right: 2rem;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.7rem 1.5rem;
  border: none;
  border-radius: var(--radius-md);
  font-family: var(--font-sans);
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  user-select: none;
  -webkit-tap-highlight-color: transparent;
  letter-spacing: 0.01em;
}

.btn:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

.btn-primary {
  background: var(--color-primary);
  color: #ffffff;
  width: 100%;
}

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

.btn-primary:active {
  background: #020617;
  transform: scale(0.985);
}

.btn-reset {
  background: transparent;
  color: var(--color-text-muted);
  font-weight: 500;
  font-size: 0.8125rem;
  padding: 0.5rem 0;
  align-self: center;
}

.btn-reset:hover {
  color: var(--color-text-secondary);
}

/* --- Result Display --- */
.result-item {
  flex: 1;
  min-width: 0;
}

.result-label {
  font-size: 0.65rem;
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 0.2rem;
}

.result-value {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text);
  font-variant-numeric: tabular-nums;
}

.result-value.has-value {
  color: var(--color-success);
}

.result-value.empty {
  color: var(--color-text-muted);
  font-weight: 400;
}

.result-divider {
  width: 1px;
  background: var(--color-border);
  flex-shrink: 0;
}

/* --- Field Row (side by side on desktop) --- */
.field-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

@media (max-width: 480px) {
  .field-row {
    grid-template-columns: 1fr;
  }
}

/* --- Empty State --- */
.empty-results .result-value {
  color: var(--color-text-muted);
  font-weight: 400;
}

/* --- PWA Install Prompt --- */
.pwa-prompt {
  position: fixed;
  bottom: 1.25rem;
  left: 50%;
  transform: translateX(-50%);
  background: var(--color-primary);
  color: #ffffff;
  padding: 1rem 1.25rem;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  z-index: 1000;
  max-width: calc(100% - 2rem);
  width: 360px;
  animation: pwaSlideUp 0.3s ease-out;
  display: none;
}

.pwa-prompt.show {
  display: block;
}

@keyframes pwaSlideUp {
  from {
    bottom: -80px;
    opacity: 0;
  }
  to {
    bottom: 1.25rem;
    opacity: 1;
  }
}

.pwa-prompt-title {
  font-size: 0.875rem;
  font-weight: 700;
  margin-bottom: 0.25rem;
}

.pwa-prompt-text {
  font-size: 0.75rem;
  color: #cbd5e1;
  margin-bottom: 0.75rem;
}

.pwa-prompt-actions {
  display: flex;
  gap: 0.5rem;
}

.pwa-btn-install {
  padding: 0.45rem 1rem;
  border: none;
  border-radius: var(--radius-sm);
  background: #ffffff;
  color: var(--color-primary);
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
  transition: background var(--transition-fast);
  -webkit-tap-highlight-color: transparent;
}

.pwa-btn-install:hover {
  background: #f1f5f9;
}

.pwa-btn-dismiss {
  padding: 0.45rem 1rem;
  border: 1px solid #475569;
  border-radius: var(--radius-sm);
  background: transparent;
  color: #cbd5e1;
  font-family: var(--font-sans);
  font-size: 0.75rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  -webkit-tap-highlight-color: transparent;
}

.pwa-btn-dismiss:hover {
  border-color: #94a3b8;
  color: #ffffff;
}

/* --- Footer --- */
.footer {
  text-align: center;
  padding: 1.5rem;
  color: var(--color-text-muted);
  font-size: 0.7rem;
}

/* --- Animations --- */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

.tab-panel.active {
  animation: fadeIn 0.2s ease-out;
}

/* --- Tab Panel Visibility --- */
.tab-panel {
  display: none;
}

.tab-panel.active {
  display: block;
}

/* --- Responsive --- */
@media (max-width: 480px) {
  .header {
    padding: 0.75rem 1rem;
  }

  .header-inner {
    gap: 0.5rem;
  }

  .header-title {
    font-size: 1rem;
  }

  .currency-item {
    font-size: 0.65rem;
    padding: 0.2rem 0.45rem;
  }

  .tab-bar {
    padding: 0.4rem 0.75rem;
  }

  .tab-btn {
    font-size: 0.75rem;
    padding: 0.4rem 0.875rem;
  }

  .main {
    padding: 1rem;
  }

  .card-header {
    padding: 1rem 1.25rem;
  }

  .card-body {
    padding: 1.25rem;
    gap: 0.875rem;
  }

  .card-results {
    flex-direction: column;
    gap: 0.75rem;
    padding: 0.875rem 1.25rem;
  }

  .result-divider {
    width: 100%;
    height: 1px;
  }

  .result-value {
    font-size: 0.9375rem;
  }

  .btn {
    font-size: 0.8125rem;
    padding: 0.65rem 1.25rem;
  }
}

/* --- Print styles --- */
@media print {
  .header,
  .tab-bar,
  .currency-bar,
  .pwa-prompt,
  .footer {
    display: none;
  }

  .card {
    box-shadow: none;
    border: 1px solid #ddd;
  }
}

/* --- Reduced motion --- */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}