/* ═══════════════════════════════════════════════════════
   projectile_motion_01.css
═══════════════════════════════════════════════════════ */

:root {
  --navy:   #1a2456;
  --blue:   #2c7bb5;
  --orange: #e8943a;
  --green:  #27ae60;
  --red:    #c0394b;
  --teal:   #1a9e72;
  --purple: #7c5cbf;
  --bg:     #f0f2f5;
  --card:   #ffffff;
  --text:   #222222;
  --muted:  #777777;
  --border: #dde0e8;
}

/* ── Reset ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  font-size: 15px;
}

/* ── Screen management ── */
.screen { display: none; min-height: 100vh; }
.screen.active { display: block; }

/* ── Screen badge (top-right, fixed) ── */
#screenBadge {
  position: fixed;
  top: 14px; right: 14px;
  background: var(--orange);
  color: #fff;
  font-size: 12.5px;
  font-weight: 700;
  padding: 5px 14px;
  border-radius: 4px;
  z-index: 999;
  letter-spacing: 0.5px;
  pointer-events: none;
}

/* ════════════════════════════════════════════════════════
   HERO SCREENS (dark navy — screens 1 & 9)
════════════════════════════════════════════════════════ */
.hero-screen {
  background: var(--navy);
  color: #fff;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 50px 24px 60px;
}

.hero-main-title {
  font-size: clamp(38px, 7vw, 76px);
  font-weight: 900;
  letter-spacing: 5px;
  color: #fff;
  margin-bottom: 16px;
}

.hero-part-title {
  font-size: clamp(26px, 5vw, 52px);
  font-weight: 900;
  letter-spacing: 4px;
  color: #fff;
  margin-bottom: 18px;
}

.hero-subtitle {
  font-size: clamp(14px, 2vw, 18px);
  color: #5eb3f0;
  letter-spacing: 1px;
  margin-bottom: 32px;
}

.hero-desc {
  font-size: clamp(13px, 1.5vw, 16px);
  color: #b8cfe0;
  max-width: 600px;
  line-height: 1.8;
  margin-bottom: 44px;
}

.hero-canvas-box {
  border: 2px dashed #3a6090;
  border-radius: 8px;
  width: 100%;
  max-width: 700px;
  height: 230px;
  margin-bottom: 38px;
  overflow: hidden;
  background: rgba(255,255,255,0.04);
}
.hero-canvas-box canvas { display: block; width: 100%; height: 100%; }

.btn-start {
  padding: 17px 84px;
  background: var(--orange);
  color: #fff;
  border: none;
  border-radius: 6px;
  font-size: 16px;
  font-weight: 800;
  letter-spacing: 2.5px;
  cursor: pointer;
  transition: opacity 0.15s, transform 0.1s;
}
.btn-start:hover { opacity: 0.9; transform: translateY(-2px); }

/* ════════════════════════════════════════════════════════
   CONTENT SCREENS (light — screens 2–8, 10–15)
════════════════════════════════════════════════════════ */
.pg-header {
  background: var(--card);
  border-bottom: 2px solid var(--border);
  padding: 22px 36px 16px;
}
.pg-header h1 {
  font-size: clamp(20px, 3vw, 30px);
  font-weight: 800;
  margin-bottom: 2px;
}
.pg-header .pg-sub {
  font-size: 13px;
  color: var(--muted);
  font-style: italic;
}
.pg-body {
  max-width: 1080px;
  margin: 0 auto;
  padding: 28px 24px 80px;
}

/* ── Key concept / insight box ── */
.key-box {
  border-radius: 6px;
  padding: 16px 20px;
  margin-bottom: 24px;
  border-left: 5px solid;
  line-height: 1.75;
  font-size: 14.5px;
}
.key-box .kl {
  font-size: 11px; font-weight: 800;
  text-transform: uppercase; letter-spacing: 1.5px;
  margin-bottom: 5px;
}
.kb-blue   { background: #e7f1fb; border-color: var(--blue);   }
.kb-orange { background: #fef4ea; border-color: var(--orange); }
.kb-purple { background: #f1ecfb; border-color: var(--purple); }
.kb-blue   .kl { color: var(--blue);   }
.kb-orange .kl { color: var(--orange); }
.kb-purple .kl { color: var(--purple); }

/* ── Two / three column grids ── */
.two-col   { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; margin-bottom: 22px; }
.three-col { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 18px; margin-bottom: 22px; }

/* ── Card / panel ── */
.card {
  background: var(--card);
  border-radius: 8px;
  box-shadow: 0 1px 6px rgba(0,0,0,0.07);
  padding: 20px 22px;
}
.card-title {
  font-size: 13.5px; font-weight: 800;
  color: var(--text);
  margin-bottom: 16px;
}

/* Colored card header strip */
.ch {
  margin: -20px -22px 16px;
  padding: 11px 22px;
  border-radius: 8px 8px 0 0;
  font-size: 12.5px; font-weight: 800;
  letter-spacing: 0.8px; text-transform: uppercase;
  color: #fff;
}
.ch-teal   { background: var(--teal);   }
.ch-red    { background: var(--red);    }
.ch-blue   { background: var(--blue);   }
.ch-orange { background: var(--orange); }
.ch-navy   { background: var(--navy);   }

/* ── Equation display helpers ── */
.eq-line   { font-size: 14px; line-height: 2; color: var(--text); }
.eq-note   { font-size: 12.5px; color: var(--muted); font-style: italic; }
.eq-blue   { font-size: 20px; font-weight: 800; color: var(--blue);   display: block; margin: 8px 0; }
.eq-orange { font-size: 18px; font-weight: 700; color: var(--orange); display: block; margin: 8px 0; }
.eq-navy   { font-size: 22px; font-weight: 800; color: var(--navy);   display: block; margin: 8px 0; }
.eq-purple { font-size: 18px; font-weight: 700; color: var(--purple); display: block; margin: 8px 0; }
.eq-green  { font-size: 17px; font-weight: 800; color: var(--green);  display: block; margin: 8px 0; }

/* ── Scenario text panel ── */
.scenario-text h2     { font-size: 16px; font-weight: 800; margin-bottom: 12px; }
.scenario-text p      { font-size: 14.5px; line-height: 1.8; margin-bottom: 10px; }
.bullet-blue          { color: var(--blue);   font-weight: 700; }
.bullet-orange        { color: var(--orange); font-weight: 700; }
.scenario-diagram {
  border: 1.5px dashed var(--border);
  border-radius: 8px;
  background: var(--card);
  box-shadow: 0 1px 6px rgba(0,0,0,0.07);
  padding: 10px;
  overflow: hidden;
}
.scenario-diagram canvas { display: block; width: 100%; height: 320px; }

/* ── Vy bar chart (HTML) ── */
.vy-chart-wrap {
  display: flex;
  align-items: flex-end;
  justify-content: space-around;
  height: 170px;
  padding: 0 20px 8px;
  border-bottom: 2px solid var(--border);
  margin-bottom: 10px;
}
.vy-col { display: flex; flex-direction: column; align-items: center; gap: 5px; }
.vy-t   { font-size: 11.5px; color: var(--muted); white-space: nowrap; }
.vy-bar { width: 28px; background: var(--orange); border-radius: 3px 3px 0 0; min-height: 3px; }
.vy-val { font-size: 13px; font-weight: 700; color: var(--orange); }
.vy-note { text-align: center; font-size: 12.5px; color: var(--muted); font-style: italic; margin-top: 6px; }

/* ── Parabola derivation ── */
.deriv-s1 { font-size: 14px; font-weight: 700; color: var(--blue);   margin: 12px 0 3px; }
.deriv-s2 { font-size: 14px; font-weight: 700; color: var(--orange); margin: 12px 0 3px; }
.deriv-s3 { font-size: 14px; font-weight: 700; color: var(--purple); margin: 12px 0 3px; }
.deriv-eq { font-size: 14px; color: var(--text); line-height: 1.75; }

/* Small graph labels */
.graph-label {
  font-size: 12px; font-weight: 700; letter-spacing: 1px;
  margin-bottom: 6px;
}
.gl-blue   { color: var(--blue);   }
.gl-orange { color: var(--orange); }

/* ── Simulation layout ── */
.sim-wrap {
  display: grid;
  grid-template-columns: 300px 1fr;
  gap: 18px;
  margin-bottom: 18px;
}
.sim-ctrl {
  background: var(--card);
  border-radius: 8px;
  box-shadow: 0 1px 6px rgba(0,0,0,0.07);
  padding: 20px 18px;
}
.ctrl-heading {
  font-size: 11.5px; font-weight: 800;
  letter-spacing: 1.5px; text-transform: uppercase;
  color: var(--text); margin-bottom: 18px;
}
.ctrl-group { margin-bottom: 16px; }
.ctrl-lbl   { display: block; font-size: 13px; font-weight: 600; margin-bottom: 7px; }

.slider-marks { display: flex; justify-content: space-between; font-size: 11px; color: var(--muted); margin-bottom: 3px; }

input[type=range] {
  width: 100%; height: 5px;
  -webkit-appearance: none; appearance: none;
  background: #d0d5e0; border-radius: 3px;
  outline: none; cursor: pointer;
  margin-bottom: 10px;
}
input[type=range]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 17px; height: 17px;
  border-radius: 50%;
  background: var(--blue);
  border: 2px solid #fff;
  box-shadow: 0 1px 4px rgba(0,0,0,0.2);
  cursor: pointer;
}

.vbadge {
  border-radius: 5px;
  padding: 9px 12px;
  text-align: center;
  font-size: 16px; font-weight: 800;
  margin-bottom: 12px;
}
.vb-blue   { background: #e4effa; color: var(--blue);   }
.vb-orange { background: #fef3e8; color: var(--orange); }
.vb-teal   { background: #e0f5ee; color: var(--teal);   }
.vb-purple { background: #f0ebfa; color: var(--purple); }

.live-box {
  background: #f5f7fb;
  border-radius: 5px;
  padding: 11px 13px;
  font-size: 13px;
  line-height: 2;
  margin-bottom: 10px;
}
.ro-blue   { color: var(--blue);   font-weight: 600; }
.ro-orange { color: var(--orange); font-weight: 600; }
.ro-green  { color: var(--green);  font-weight: 600; }

.formula-box {
  background: #f0ebfa;
  border-radius: 5px;
  padding: 9px 12px;
  text-align: center;
  font-size: 13px; font-weight: 600;
  color: var(--purple);
  margin-bottom: 14px;
}

.sim-btns { display: flex; gap: 8px; }
.btn-play  { flex:1; padding:11px; background:var(--green);  color:#fff; border:none; border-radius:5px; font-weight:700; font-size:13.5px; cursor:pointer; transition:opacity 0.15s; }
.btn-reset { flex:1; padding:11px; background:#7a8499;       color:#fff; border:none; border-radius:5px; font-weight:700; font-size:13.5px; cursor:pointer; transition:opacity 0.15s; }
.btn-play:hover, .btn-reset:hover { opacity: 0.88; }

.sim-canvas-panel {
  background: var(--card);
  border-radius: 8px;
  box-shadow: 0 1px 6px rgba(0,0,0,0.07);
  padding: 12px;
  display: flex; flex-direction: column;
}
.canvas-lbl { font-size: 11px; font-weight: 700; letter-spacing: 1px; text-transform: uppercase; color: var(--muted); margin-bottom: 8px; }
.sim-canvas-panel canvas { display: block; width: 100%; border-radius: 4px; background: #f8fafc; }

/* ── Nav buttons ── */
.nav-bar {
  max-width: 1080px;
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.nav-bar.right  { justify-content: flex-end; }
.nav-bar.center { justify-content: center;   }

.btn-back { padding:12px 26px; background:#7a8499; color:#fff; border:none; border-radius:5px; font-size:14px; font-weight:700; letter-spacing:0.8px; cursor:pointer; transition:opacity 0.15s; }
.btn-next { padding:12px 26px; background:#4a7ab5; color:#fff; border:none; border-radius:5px; font-size:14px; font-weight:700; letter-spacing:0.8px; cursor:pointer; transition:opacity 0.15s; }
.btn-back:hover, .btn-next:hover { opacity: 0.88; }

/* ── MCQ ── */
.q-meta { font-size: 11px; font-weight: 800; letter-spacing: 1.5px; text-transform: uppercase; color: var(--muted); margin-bottom: 8px; }
.q-block {
  background: var(--card);
  border-left: 4px solid var(--navy);
  border-radius: 0 8px 8px 0;
  padding: 20px 24px;
  margin-bottom: 26px;
  box-shadow: 0 1px 5px rgba(0,0,0,0.06);
}
.q-text  { font-size: 16px; line-height: 1.75; margin-bottom: 4px; }
.q-given { font-size: 13px; color: var(--muted); font-style: italic; }

.opts { display: flex; flex-direction: column; gap: 10px; margin-bottom: 24px; }
.opt {
  background: var(--card);
  border: 1.5px solid var(--border);
  border-radius: 7px;
  padding: 13px 18px;
  display: flex; align-items: center; gap: 14px;
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s;
  user-select: none;
}
.opt:hover   { border-color: var(--navy); background: #f4f5ff; }
.opt.sel     { border-color: var(--navy); background: #eef0fb; }

.opt-badge {
  width: 30px; height: 30px; flex-shrink: 0;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 13.5px; font-weight: 800; color: #fff;
}
.ob-a { background: #4a7ab5; }
.ob-b { background: var(--teal);   }
.ob-c { background: var(--orange); }
.ob-d { background: var(--red);    }

.opt-txt { font-size: 15px; flex: 1; }

.radio-ring {
  width: 20px; height: 20px; flex-shrink: 0;
  border: 2px solid #b0b5c8;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  transition: border-color 0.15s;
}
.opt.sel .radio-ring { border-color: var(--navy); }
.radio-fill { width: 10px; height: 10px; background: var(--navy); border-radius: 50%; display: none; }
.opt.sel .radio-fill { display: block; }

.submit-area { display: flex; flex-direction: column; align-items: center; gap: 10px; }
.btn-submit {
  padding: 14px 72px;
  background: #4a7ab5;
  color: #fff; border: none; border-radius: 6px;
  font-size: 15px; font-weight: 800; letter-spacing: 1.5px;
  cursor: pointer; transition: opacity 0.15s;
}
.btn-submit:hover { opacity: 0.88; }
.hint-txt  { font-size: 13px; color: var(--muted); font-style: italic; }
.err-msg   { font-size: 13px; color: var(--red); min-height: 18px; text-align: center; }

/* ── Result screen ── */
.result-banner {
  border-radius: 6px;
  border-left: 5px solid;
  padding: 15px 22px;
  margin-bottom: 24px;
  font-size: 18px; font-weight: 800;
  display: flex; align-items: center; gap: 10px;
}
.rb-correct   { background: #e8f8ef; border-color: var(--green); color: var(--green); }
.rb-incorrect { background: #fdecea; border-color: var(--red);   color: var(--red);   }

.sol-card {
  background: var(--card);
  border-radius: 8px;
  box-shadow: 0 1px 6px rgba(0,0,0,0.07);
  padding: 24px 28px;
  margin-bottom: 26px;
}
.sol-card h3   { font-size: 14px; font-weight: 800; letter-spacing: 0.5px; margin-bottom: 14px; }
.sol-given     { font-size: 13.5px; color: var(--muted); margin-bottom: 12px; }
.sol-step      { font-size: 14px; font-weight: 700; color: var(--text); margin: 12px 0 3px; }
.sol-eq        { font-size: 15px; color: var(--orange); font-weight: 600; line-height: 1.75; }
.sol-result    { font-size: 17px; color: var(--blue); font-weight: 700; line-height: 1.5; }
.sol-note      { font-size: 13px; color: var(--green); font-style: italic; margin-top: 8px; }

.res-btns { display: flex; justify-content: flex-end; gap: 12px; }
.btn-try   { padding:12px 24px; background:#7a8499;       color:#fff; border:none; border-radius:5px; font-weight:700; font-size:14px; cursor:pointer; transition:opacity 0.15s; }
.btn-cont  { padding:12px 28px; background:var(--green);  color:#fff; border:none; border-radius:5px; font-weight:700; font-size:14px; cursor:pointer; transition:opacity 0.15s; }
.btn-try:hover, .btn-cont:hover { opacity: 0.88; }

/* ── Path equation summary box ── */
.path-box {
  background: #f0ebfa;
  border-left: 5px solid var(--purple);
  border-radius: 0 8px 8px 0;
  padding: 18px 22px;
  margin-top: 18px;
}
.path-box .pb-lbl  { font-size: 11px; font-weight: 800; color: var(--purple); letter-spacing: 1.5px; text-transform: uppercase; margin-bottom: 8px; }
.path-box .pb-eq   { font-size: 19px; font-weight: 800; color: var(--navy);   margin-bottom: 6px; }
.path-box .pb-note { font-size: 15px; font-weight: 700; color: var(--green);  }

/* ── Angle comparison canvas ── */
.angle-summary {
  background: #f1ecfb;
  border-radius: 8px;
  padding: 16px 22px;
  font-size: 14px;
  line-height: 1.8;
  margin-top: 16px;
}

/* ── Responsive ── */
@media (max-width: 780px) {
  .two-col, .sim-wrap   { grid-template-columns: 1fr; }
  .pg-header            { padding: 18px 18px 12px; }
  .pg-body              { padding: 18px 14px 60px; }
  .nav-bar              { padding: 14px 16px; }
  .res-btns             { flex-direction: column; }
  .sim-ctrl             { order: 2; }
  .sim-canvas-panel     { order: 1; }
}