/*
 * theme.css — ThiAZ Math
 * Màu sắc được Admin thay đổi qua trang /admin/cai-dat.html. Không hardcode màu trực tiếp vào HTML.
 */

/* =====================================================
   CSS CUSTOM PROPERTIES (DESIGN TOKENS)
   ===================================================== */
:root {
  /* Brand Colors */
  --color-primary:      #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-navy:         #0f172a;
  --color-emerald:      #059669;
  --color-amber:        #d97706;

  /* Surface & Layout */
  --color-surface: #f8fafc;
  --color-card:    #ffffff;
  --color-border:  #e2e8f0;

  /* Typography */
  --color-text:  #1e293b;
  --color-muted: #64748b;

  /* Font Stack */
  --font-base: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
               "Helvetica Neue", Arial, "Noto Sans", sans-serif;

  /* Spacing / Radius */
  --radius-sm:  0.375rem;   /* 6px  */
  --radius-md:  0.5rem;     /* 8px  */
  --radius-lg:  0.75rem;    /* 12px */
  --radius-xl:  1rem;       /* 16px */

  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);

  /* Transitions */
  --transition-fast:   150ms ease;
  --transition-normal: 250ms ease;
}

/* =====================================================
   TAILWIND CONFIG EXTENSION
   Paste this <script> block into every HTML page that
   loads Tailwind CDN, to align Tailwind utilities with
   the CSS variables above.
   ===================================================== */
/*
<script>
  tailwind.config = {
    theme: {
      extend: {
        colors: {
          primary:      'var(--color-primary)',
          'primary-dark':'var(--color-primary-dark)',
          navy:         'var(--color-navy)',
          emerald:      'var(--color-emerald)',
          amber:        'var(--color-amber)',
          surface:      'var(--color-surface)',
          card:         'var(--color-card)',
          border:       'var(--color-border)',
          muted:        'var(--color-muted)',
        },
        fontFamily: {
          base: 'var(--font-base)',
        },
      },
    },
  };
</script>
*/

/* =====================================================
   BASE STYLES
   ===================================================== */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-base);
  background-color: var(--color-surface);
  color: var(--color-text);
  margin: 0;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Text selection highlight */
::selection {
  background-color: var(--color-primary);
  color: #ffffff;
}

/* =====================================================
   BADGE UTILITIES
   ===================================================== */

/** Badge: Free tier */
.badge-free {
  display: inline-flex;
  align-items: center;
  padding: 0.15rem 0.55rem;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  border-radius: 9999px;
  background-color: var(--color-emerald);
  color: #ffffff;
}

/** Badge: VIP tier */
.badge-vip {
  display: inline-flex;
  align-items: center;
  padding: 0.15rem 0.55rem;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  border-radius: 9999px;
  background-color: var(--color-amber);
  color: #ffffff;
}

/* =====================================================
   BUTTON UTILITIES
   ===================================================== */

.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.55rem 1.25rem;
  font-size: 0.9rem;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-md);
  background-color: var(--color-primary);
  color: #ffffff;
  cursor: pointer;
  text-decoration: none;
  transition: background-color var(--transition-fast), box-shadow var(--transition-fast);
}
.btn-primary:hover {
  background-color: var(--color-primary-dark);
  box-shadow: var(--shadow-md);
}
.btn-primary:active {
  transform: translateY(1px);
}
.btn-primary:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.55rem 1.25rem;
  font-size: 0.9rem;
  font-weight: 600;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  background-color: var(--color-card);
  color: var(--color-text);
  cursor: pointer;
  text-decoration: none;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}
.btn-secondary:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  box-shadow: var(--shadow-sm);
}
.btn-secondary:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

.btn-danger {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.55rem 1.25rem;
  font-size: 0.9rem;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-md);
  background-color: #dc2626;
  color: #ffffff;
  cursor: pointer;
  text-decoration: none;
  transition: background-color var(--transition-fast);
}
.btn-danger:hover {
  background-color: #b91c1c;
}
.btn-danger:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

/* =====================================================
   CARD COMPONENT
   ===================================================== */

.card {
  background-color: var(--color-card);
  border-radius: var(--radius-xl);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition-normal);
  overflow: hidden;
}
.card:hover {
  box-shadow: var(--shadow-md);
}

/* =====================================================
   EXAM CHOICE BUTTONS
   ===================================================== */

.exam-choice-btn {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  width: 100%;
  padding: 0.75rem 1rem;
  margin-bottom: 0.5rem;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-card);
  color: var(--color-text);
  font-size: 0.95rem;
  text-align: left;
  cursor: pointer;
  transition: border-color var(--transition-fast), background-color var(--transition-fast);
}
.exam-choice-btn:hover {
  border-color: var(--color-primary);
  background-color: #eff6ff;
}
.exam-choice-btn.selected {
  border-color: var(--color-primary);
  background-color: #dbeafe;
  font-weight: 600;
}
.exam-choice-btn.correct {
  border-color: var(--color-emerald);
  background-color: #d1fae5;
  color: #065f46;
}
.exam-choice-btn.incorrect {
  border-color: #dc2626;
  background-color: #fee2e2;
  color: #991b1b;
}
.exam-choice-btn:disabled {
  cursor: default;
}

/* True/False item buttons */
.exam-tf-btn {
  padding: 0.35rem 0.85rem;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  background-color: var(--color-card);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: border-color var(--transition-fast), background-color var(--transition-fast);
}
.exam-tf-btn.selected-true {
  border-color: var(--color-emerald);
  background-color: #d1fae5;
}
.exam-tf-btn.selected-false {
  border-color: #dc2626;
  background-color: #fee2e2;
}

/* =====================================================
   VIP LOCKED CONTENT OVERLAY
   ===================================================== */

.content-locked {
  position: relative;
  overflow: hidden;
  max-height: 180px;
  pointer-events: none;
  user-select: none;
}

.content-locked::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    to bottom,
    transparent 0%,
    transparent 40%,
    rgba(248, 250, 252, 0.85) 65%,
    var(--color-surface) 100%
  );
}

.content-locked-banner {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 10;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 1.25rem 1rem;
  text-align: center;
}

/* =====================================================
   TOAST NOTIFICATIONS
   ===================================================== */

#toast-container {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  z-index: 9999;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  pointer-events: none;
}

.toast {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  min-width: 260px;
  max-width: 380px;
  padding: 0.8rem 1.1rem;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  font-size: 0.9rem;
  font-weight: 500;
  color: #ffffff;
  pointer-events: auto;
  animation: toastSlideIn var(--transition-normal) forwards;
}

.toast-success {
  background-color: var(--color-emerald);
}

.toast-error {
  background-color: #dc2626;
}

.toast-info {
  background-color: var(--color-primary);
}

.toast.toast-hiding {
  animation: toastSlideOut var(--transition-normal) forwards;
}

@keyframes toastSlideIn {
  from {
    opacity: 0;
    transform: translateX(100%);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes toastSlideOut {
  from {
    opacity: 1;
    transform: translateX(0);
  }
  to {
    opacity: 0;
    transform: translateX(100%);
  }
}

/* =====================================================
   LOADING OVERLAY
   ===================================================== */

#loading-overlay {
  position: fixed;
  inset: 0;
  z-index: 10000;
  background-color: rgba(15, 23, 42, 0.45);
  display: flex;
  align-items: center;
  justify-content: center;
  backdrop-filter: blur(2px);
}

#loading-overlay.hidden {
  display: none;
}

.spinner {
  width: 48px;
  height: 48px;
  border: 4px solid rgba(255, 255, 255, 0.3);
  border-top-color: #ffffff;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* =====================================================
   RESPONSIVE HELPERS
   ===================================================== */

@media (max-width: 640px) {
  #toast-container {
    left: 1rem;
    right: 1rem;
    bottom: 1rem;
  }
  .toast {
    min-width: unset;
    max-width: 100%;
  }
}