*,*::before,*::after{box-sizing:border-box;margin:0;padding:0;-webkit-tap-highlight-color:transparent}
:root{
  --ink:#0a0a0a;--ink2:#2a2a2a;--paper:#f7f4ef;--paper2:#ede9e1;
  --red:#c0392b;--red-pale:#fdf0ee;--rule:#d4cfc6;
  --mono:'DM Mono',monospace;--serif:'Fraunces',Georgia,serif;
  --r:16px;--rs:10px;
}
html{height:100%;background:var(--ink)}
body{min-height:100vh;font-family:var(--serif);background:var(--paper);color:var(--ink);overflow-x:hidden;-webkit-font-smoothing:antialiased}

/* ── Screen system ── */
.screen{display:none;min-height:100vh;flex-direction:column}
.screen.active{display:flex}

/* ── Top bar ── */
.topbar{background:var(--ink);color:var(--paper);display:flex;align-items:center;justify-content:space-between;padding:0 20px;height:56px;flex-shrink:0;position:sticky;top:0;z-index:100}
.topbar-logo{display:flex;align-items:center;gap:10px}
.topbar-logo-img{width:32px;height:32px;border-radius:6px;object-fit:contain}
.topbar-title{font-family:var(--serif);font-size:15px;font-weight:600;letter-spacing:-.3px}
.topbar-sub{font-family:var(--mono);font-size:10px;opacity:.45;letter-spacing:.05em}
.topbar-right{font-family:var(--mono);font-size:11px;opacity:.55;letter-spacing:.05em;cursor:pointer;text-decoration:underline;text-underline-offset:3px;background:none;border:none;color:inherit}
.prog-bar{height:3px;background:var(--ink2);flex-shrink:0}
.prog-fill{height:100%;background:var(--red);transition:width .4s cubic-bezier(.4,0,.2,1);width:0%}
.scroll{flex:1;overflow-y:auto;-webkit-overflow-scrolling:touch;padding:24px 20px 100px}
.sticky-btn{position:fixed;bottom:0;left:0;right:0;padding:16px 20px calc(16px + env(safe-area-inset-bottom));background:var(--paper);border-top:1px solid var(--rule);z-index:50}

/* ── Intro ── */
.intro-hero{text-align:center;padding:40px 0 32px;border-bottom:1px solid var(--rule);margin-bottom:28px}
.intro-logo{width:80px;height:80px;object-fit:contain;margin:0 auto 20px;border-radius:16px;display:block}
.intro-hero h1{font-size:30px;font-weight:900;letter-spacing:-1px;line-height:1.1;margin-bottom:8px}
.intro-hero p{font-size:15px;font-weight:300;color:#555;line-height:1.7;max-width:320px;margin:0 auto}
.info-grid{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-bottom:28px}
.info-card{background:var(--paper2);border:1px solid var(--rule);border-radius:var(--r);padding:16px 14px}
.info-card .ic-val{font-family:var(--serif);font-size:18px;font-weight:600;margin-bottom:2px}
.info-card .ic-lbl{font-family:var(--mono);font-size:10px;color:#888;letter-spacing:.06em;text-transform:uppercase}

/* ── Form fields ── */
.field{margin-bottom:18px}
.field label{display:block;font-family:var(--mono);font-size:11px;letter-spacing:.08em;text-transform:uppercase;color:#888;margin-bottom:6px}
.field input,.field select,.field textarea{width:100%;padding:13px 14px;border:1px solid var(--rule);border-radius:var(--rs);font-family:var(--serif);font-size:16px;color:var(--ink);background:white;outline:none;transition:border-color .15s;-webkit-appearance:none;appearance:none}
.field textarea{resize:vertical}
.field input:focus,.field select:focus,.field textarea:focus{border-color:var(--ink)}
.field-row{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.form-error{background:var(--red-pale);color:var(--red);padding:10px 14px;border-radius:var(--rs);font-family:var(--mono);font-size:11px}

/* ── Buttons ── */
.btn{width:100%;padding:16px;border:none;border-radius:var(--rs);font-family:var(--serif);font-size:17px;font-weight:600;cursor:pointer;transition:all .15s;letter-spacing:-.3px}
.btn-ink{background:var(--ink);color:var(--paper)}
.btn-ink:active{background:#2a2a2a}
.btn-ink:disabled{opacity:.4;cursor:default}
.btn-outline{background:transparent;border:1px solid var(--rule);color:#888;font-size:14px;padding:12px}
.btn-outline:active{background:var(--paper2)}

/* ── Quiz ── */
.q-num{font-family:var(--mono);font-size:11px;letter-spacing:.1em;text-transform:uppercase;color:#999;margin-bottom:6px}
.q-text{font-size:21px;font-weight:600;line-height:1.4;letter-spacing:-.4px;margin-bottom:28px;min-height:64px}
.options{display:flex;flex-direction:column;gap:10px;margin-bottom:32px}
.opt{display:flex;align-items:center;gap:14px;padding:15px 16px;border:1px solid var(--rule);border-radius:var(--r);background:white;cursor:pointer;transition:border-color .13s,background .13s,transform .1s;text-align:left;font-family:var(--serif);width:100%}
.opt:active{transform:scale(.985)}
.opt.selected{border-color:var(--ink);background:var(--paper)}
.opt-key{width:32px;height:32px;border-radius:8px;border:1px solid var(--rule);display:flex;align-items:center;justify-content:center;font-family:var(--mono);font-size:12px;font-weight:500;flex-shrink:0;color:#999;background:var(--paper2);transition:all .13s}
.opt.selected .opt-key{border-color:var(--ink);color:var(--ink);background:white}
.opt-text{font-size:15px;color:var(--ink);line-height:1.4;font-weight:300}

/* ── Done screen ── */
.done-wrap{display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:calc(100vh - 56px);text-align:center;padding:40px 24px}
.done-icon{width:72px;height:72px;border-radius:50%;background:var(--ink);color:var(--paper);display:flex;align-items:center;justify-content:center;font-size:34px;margin-bottom:20px}
.done-title{font-size:28px;font-weight:900;letter-spacing:-1px;margin-bottom:10px}
.done-sub{font-size:15px;font-weight:300;color:#666;line-height:1.7;max-width:320px;margin:0 auto 20px}
.done-code-box{background:var(--paper2);border:2px solid var(--ink);border-radius:var(--r);padding:24px 20px;margin-top:12px;max-width:320px;width:100%}
.done-code-label{font-family:var(--mono);font-size:10px;color:#888;text-transform:uppercase;letter-spacing:.1em;margin-bottom:8px}
.done-code{font-family:var(--mono);font-size:32px;font-weight:500;letter-spacing:3px;color:var(--ink)}
.done-code-hint{font-family:var(--mono);font-size:10px;color:#aaa;margin-top:8px;line-height:1.5}

/* ── Teacher lookup ── */
.login-wrap{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:center;padding:32px 24px}
.login-wrap h2{font-size:24px;font-weight:900;letter-spacing:-.5px;margin-bottom:6px}
.login-wrap p{font-family:var(--mono);font-size:11px;color:#aaa;margin-bottom:28px;letter-spacing:.06em}
.section-lbl{font-family:var(--mono);font-size:10px;letter-spacing:.1em;text-transform:uppercase;color:#bbb;padding:14px 16px 6px}

/* ── Evaluation screen ── */
.eval-card{background:white;border:1px solid var(--rule);border-radius:var(--r);padding:16px;margin:0 16px 12px}
.eval-card .erow{display:flex;justify-content:space-between;padding:6px 0;border-bottom:1px solid var(--paper2);font-size:14px}
.eval-card .erow:last-child{border-bottom:none}
.eval-card .elbl{font-family:var(--mono);font-size:10px;color:#aaa;text-transform:uppercase;letter-spacing:.06em}
.eval-card .eval{font-weight:600;font-size:15px}
.eval-card .e-level{display:inline-block;padding:4px 12px;border-radius:20px;background:var(--ink);color:var(--paper);font-family:var(--mono);font-size:12px;font-weight:500}
.eval-actions{padding:0 16px;display:flex;flex-direction:column;gap:10px}

/* ── Spinner ── */
.spinner{display:inline-block;width:16px;height:16px;border:2px solid rgba(255,255,255,.3);border-top-color:#fff;border-radius:50%;animation:spin .6s linear infinite;margin-right:8px;vertical-align:middle}
@keyframes spin{to{transform:rotate(360deg)}}

/* ── Error banner ── */
.error-banner{background:var(--red-pale);color:var(--red);padding:12px 16px;margin:12px 16px;border-radius:var(--rs);font-family:var(--mono);font-size:11px}

/* ── Success banner ── */
.success-banner{background:#e8f5e9;color:#2e7d32;padding:12px 16px;margin:12px 16px;border-radius:var(--rs);font-family:var(--mono);font-size:11px}

/* ── Responsive ── */
@media(min-width:640px){
  .scroll,.sticky-btn,.eval-actions{padding-left:calc((100vw - 600px)/2 + 20px);padding-right:calc((100vw - 600px)/2 + 20px)}
  .section-lbl{padding-left:calc((100vw - 600px)/2 + 16px)}
  .eval-card{margin-left:calc((100vw - 600px)/2 + 16px);margin-right:calc((100vw - 600px)/2 + 16px)}
}