/* ==========================================================================
   StudyBuddy - Modern & Clean 3-File Architecture: style.css
   ========================================================================== */

:root {
  --bg-base: #0b0f19;
  --bg-surface: #111827;
  --bg-card: rgba(19, 26, 42, 0.85);
  --bg-glass: rgba(255, 255, 255, 0.05);
  --bg-glass-hover: rgba(255, 255, 255, 0.09);

  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-highlight: rgba(99, 102, 241, 0.4);

  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  --primary: #6366f1;
  --primary-hover: #4f46e5;
  --primary-gradient: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #ec4899 100%);
  --primary-glow: rgba(99, 102, 241, 0.35);

  --success: #10b981;
  --success-glow: rgba(16, 185, 129, 0.3);
  --danger: #ef4444;
  --danger-glow: rgba(239, 68, 68, 0.3);
  --warning: #f59e0b;

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 26px;
  --radius-full: 9999px;

  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.5);

  --font-main: 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;
  --font-heading: 'Outfit', system-ui, -apple-system, sans-serif;
}

[data-theme="light"] {
  --bg-base: #f8fafc;
  --bg-surface: #ffffff;
  --bg-card: rgba(255, 255, 255, 0.92);
  --bg-glass: rgba(0, 0, 0, 0.03);
  --bg-glass-hover: rgba(0, 0, 0, 0.06);

  --border-subtle: rgba(0, 0, 0, 0.09);
  --border-highlight: rgba(99, 102, 241, 0.4);

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;

  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 8px 25px rgba(99, 102, 241, 0.08);
  --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.1);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-main);
  background-color: var(--bg-base);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.6;
  background-image:
    radial-gradient(at 10% 15%, rgba(99, 102, 241, 0.12) 0px, transparent 50%),
    radial-gradient(at 90% 85%, rgba(236, 72, 153, 0.1) 0px, transparent 50%);
  background-attachment: fixed;
  transition: background-color 0.3s ease, color 0.3s ease;
}

button, input, select, textarea {
  font-family: inherit;
}

button {
  cursor: pointer;
  border: none;
  background: none;
  outline: none;
  transition: all 0.2s ease;
}

.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 1.5rem 1.25rem 3rem 1.25rem;
}

/* Header & Navigation */
.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.5rem;
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
  margin-bottom: 2rem;
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 1rem;
  z-index: 100;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.brand-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background: var(--primary-gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  color: #fff;
  box-shadow: 0 4px 15px var(--primary-glow);
}

.brand-name {
  font-family: var(--font-heading);
  font-size: 1.4rem;
  font-weight: 800;
  background: var(--primary-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.nav-tabs {
  display: flex;
  gap: 0.4rem;
  background: var(--bg-glass);
  padding: 0.3rem;
  border-radius: var(--radius-full);
  border: 1px solid var(--border-subtle);
}

.tab-btn {
  padding: 0.6rem 1.2rem;
  border-radius: var(--radius-full);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
}

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

.tab-btn.active {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 4px 14px var(--primary-glow);
}

.header-utils {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.circle-btn {
  width: 38px;
  height: 38px;
  border-radius: var(--radius-full);
  background: var(--bg-glass);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
}

.circle-btn:hover {
  background: var(--bg-glass-hover);
  color: var(--text-primary);
  border-color: var(--border-highlight);
}

/* Tab Panels */
.tab-panel {
  display: none;
  animation: fadeIn 0.3s ease;
}

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

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ==========================================================================
   FEATURE 1: POMODORO CLOCK
   ========================================================================== */
.pomo-wrap {
  max-width: 620px;
  margin: 0 auto;
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
  padding: 2.5rem 2rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  box-shadow: var(--shadow-lg);
  position: relative;
  overflow: hidden;
}

.pomo-wrap::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: var(--primary-gradient);
}

.pomo-modes {
  display: flex;
  gap: 0.5rem;
  background: var(--bg-glass);
  padding: 0.35rem;
  border-radius: var(--radius-full);
  border: 1px solid var(--border-subtle);
  margin-bottom: 2rem;
}

.mode-pill {
  padding: 0.5rem 1.2rem;
  border-radius: var(--radius-full);
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.mode-pill.active {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 4px 12px var(--primary-glow);
}

.mode-pill[data-mode="short"].active {
  background: var(--success);
  box-shadow: 0 4px 12px var(--success-glow);
}

.mode-pill[data-mode="long"].active {
  background: #06b6d4;
  box-shadow: 0 4px 12px rgba(6, 182, 212, 0.4);
}

/* Circular Timer Graphic */
.dial-box {
  position: relative;
  width: 270px;
  height: 270px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 2rem;
}

.dial-svg {
  width: 100%;
  height: 100%;
  transform: rotate(-90deg);
}

.dial-bg {
  fill: none;
  stroke: var(--bg-glass);
  stroke-width: 10;
}

.dial-progress {
  fill: none;
  stroke: var(--primary);
  stroke-width: 10;
  stroke-linecap: round;
  stroke-dasharray: 785.4;
  stroke-dashoffset: 0;
  transition: stroke-dashoffset 0.8s ease, stroke 0.3s ease;
  filter: drop-shadow(0 0 8px var(--primary-glow));
}

.dial-center {
  position: absolute;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.timer-digits {
  font-family: var(--font-heading);
  font-size: 3.8rem;
  font-weight: 800;
  line-height: 1;
}

.timer-sublabel {
  font-size: 0.88rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-top: 0.4rem;
  font-weight: 600;
}

.pomo-btns {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  margin-bottom: 1.5rem;
}

.start-btn {
  padding: 0.9rem 2.6rem;
  font-size: 1.15rem;
  font-weight: 700;
  background: var(--primary-gradient);
  color: #fff;
  border-radius: var(--radius-full);
  box-shadow: 0 6px 20px var(--primary-glow);
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.start-btn:hover {
  transform: translateY(-2px);
}

.action-btn {
  width: 46px;
  height: 46px;
  border-radius: var(--radius-full);
  background: var(--bg-glass);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  font-size: 1.1rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.action-btn:hover {
  background: var(--bg-glass-hover);
  color: var(--text-primary);
}

.pomo-footer {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 1.25rem;
  border-top: 1px solid var(--border-subtle);
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* ==========================================================================
   FEATURE 2: FLASHCARDS ("FLASK CARD")
   ========================================================================== */
.flashcards-wrap {
  max-width: 760px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.toolbar {
  background: var(--bg-card);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 1rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.select-wrap {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.app-select {
  padding: 0.55rem 1rem;
  background: var(--bg-surface);
  color: var(--text-primary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  outline: none;
  font-weight: 600;
  font-size: 0.9rem;
}

.btn-group {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.btn {
  padding: 0.6rem 1.1rem;
  border-radius: var(--radius-md);
  font-size: 0.88rem;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.btn-primary {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 4px 12px var(--primary-glow);
}

.btn-primary:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
}

.btn-subtle {
  background: var(--bg-glass);
  color: var(--text-primary);
  border: 1px solid var(--border-subtle);
}

.btn-subtle:hover {
  background: var(--bg-glass-hover);
  border-color: var(--border-highlight);
}

.btn-danger {
  background: rgba(239, 68, 68, 0.12);
  color: var(--danger);
  border: 1px solid rgba(239, 68, 68, 0.25);
}

.btn-danger:hover {
  background: var(--danger);
  color: #fff;
}

/* 3D Flip Card */
.scene-3d {
  perspective: 1200px;
  width: 100%;
  height: 360px;
}

.card-box-3d {
  width: 100%;
  height: 100%;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
  border-radius: var(--radius-xl);
}

.card-box-3d.flipped {
  transform: rotateY(180deg);
}

.card-face {
  position: absolute;
  width: 100%;
  height: 100%;
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
  border-radius: var(--radius-xl);
  padding: 2.25rem 2rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  align-items: center;
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-subtle);
  box-shadow: var(--shadow-lg);
  user-select: none;
}

.card-face.back {
  transform: rotateY(180deg);
  background: linear-gradient(145deg, rgba(26, 36, 62, 0.9) 0%, rgba(19, 26, 42, 0.98) 100%);
  border-color: var(--border-highlight);
}

.tag-badge {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 0.25rem 0.75rem;
  border-radius: var(--radius-full);
  background: rgba(99, 102, 241, 0.15);
  color: #818cf8;
  border: 1px solid rgba(99, 102, 241, 0.3);
}

.card-content-area {
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  font-size: 1.45rem;
  font-weight: 600;
  max-width: 600px;
}

.card-face.back .card-content-area {
  font-size: 1.35rem;
  color: #e2e8f0;
}

.card-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.rate-btn {
  padding: 0.65rem 1.25rem;
  border-radius: var(--radius-full);
  font-weight: 700;
  font-size: 0.88rem;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.rate-btn.again {
  background: rgba(239, 68, 68, 0.12);
  color: #f87171;
  border: 1px solid rgba(239, 68, 68, 0.25);
}

.rate-btn.again:hover {
  background: var(--danger);
  color: #fff;
}

.rate-btn.mastered {
  background: rgba(16, 185, 129, 0.12);
  color: #34d399;
  border: 1px solid rgba(16, 185, 129, 0.25);
}

.rate-btn.mastered:hover {
  background: var(--success);
  color: #fff;
}

/* ==========================================================================
   FEATURE 3: QUIZ (WHERE USER CAN SET IT)
   ========================================================================== */
.quiz-wrap {
  max-width: 760px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.quiz-card {
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
  padding: 2.25rem 2rem;
  box-shadow: var(--shadow-lg);
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.quiz-header-status {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.q-badge {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 0.88rem;
  color: var(--primary);
  background: rgba(99, 102, 241, 0.12);
  padding: 0.3rem 0.85rem;
  border-radius: var(--radius-full);
  border: 1px solid rgba(99, 102, 241, 0.3);
}

.q-text {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.45;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.opt-btn {
  background: var(--bg-surface);
  border: 1.5px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 0.95rem 1.25rem;
  text-align: left;
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-primary);
}

.opt-btn:hover:not(:disabled) {
  border-color: var(--border-highlight);
  background: var(--bg-glass-hover);
  transform: translateX(4px);
}

.opt-btn.correct {
  border-color: var(--success);
  background: rgba(16, 185, 129, 0.15);
  box-shadow: 0 0 16px var(--success-glow);
}

.opt-btn.wrong {
  border-color: var(--danger);
  background: rgba(239, 68, 68, 0.15);
  box-shadow: 0 0 16px var(--danger-glow);
}

.explain-box {
  background: var(--bg-glass);
  border-left: 3px solid var(--primary);
  padding: 0.9rem 1.2rem;
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.score-box {
  text-align: center;
  padding: 3rem 2rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.25rem;
}

.score-big {
  font-family: var(--font-heading);
  font-size: 3.5rem;
  font-weight: 800;
  background: var(--primary-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Modals */
.modal-mask {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s ease;
  padding: 1rem;
}

.modal-mask.open {
  opacity: 1;
  pointer-events: auto;
}

.modal-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
  width: 100%;
  max-width: 520px;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: var(--shadow-lg);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.form-group label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.form-ctrl {
  padding: 0.7rem 0.9rem;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  outline: none;
  font-size: 0.95rem;
}

.form-ctrl:focus {
  border-color: var(--primary);
}

.choice-row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* Toast */
.toast-box {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  z-index: 9999;
}

.toast {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-left: 4px solid var(--primary);
  border-radius: var(--radius-md);
  padding: 0.75rem 1.2rem;
  font-size: 0.9rem;
  box-shadow: var(--shadow-md);
}

@media (max-width: 720px) {
  .app-header {
    flex-direction: column;
    gap: 1rem;
    padding: 1rem;
  }
  .nav-tabs {
    width: 100%;
    justify-content: center;
  }
  .dial-box {
    width: 230px;
    height: 230px;
  }
  .timer-digits {
    font-size: 3rem;
  }
}