/* Science GCSE required practicals: shared navigation and readable controls. */
:root{--bg:#f5f7f9;--text:#1f2933;--muted:#556676;--border:#d9e0e6}
:root[data-subject="biology"]{--accent:#198754;--accent-soft:#eef7f1}
:root[data-subject="chemistry"]{--accent:#b32624;--accent-soft:#fff0f1}
:root[data-subject="physics"]{--accent:#1768ac;--accent-soft:#eef5fc}
body{font-family:Arial,Helvetica,sans-serif;font-size:1rem}header.brand{background:#081a33;border-bottom:4px solid var(--accent)}.brand .bin{max-width:1100px;align-items:center;justify-content:space-between;gap:10px;padding:14px 20px}.brand .logo{font-weight:900;letter-spacing:-.03em;white-space:nowrap;font-size:1.2rem}.logo .gcse{color:#a9dfbd}:root[data-subject="chemistry"] .logo .gcse{color:#ffadb1}:root[data-subject="physics"] .logo .gcse{color:#a2d5ff}.site-links{display:flex;gap:5px;flex-wrap:wrap}.site-links a{font-size:.875rem;color:#fff;text-decoration:none;font-weight:700;padding:7px 9px;border-radius:6px;border:1px solid #ffffff40}.site-links a:hover{background:#ffffff15}.skip-link{position:absolute;left:16px;top:-120px;z-index:100;padding:10px 16px;background:#ffd84d;color:#081a33;font-weight:800}.skip-link:focus{top:8px}.lab-crumb{margin:0 0 14px;color:var(--muted);font-size:.875rem}.lab-crumb a{color:var(--accent);font-weight:700;text-underline-offset:3px}h1{font-size:clamp(1.65rem,4.5vw,2.25rem);line-height:1.2;margin:9px 0 9px}h2{font-size:1.2rem}.sub{font-size:1rem}.tag{font-size:.875rem;font-weight:700;margin:0 5px 4px 0}.tag.course-tag{background:var(--accent-soft);color:var(--accent);border:1px solid var(--border)}.note{font-size:.95rem}.now .lbl,.extra,ol#steps,table,.small,.row2 button,.foot,#big{font-size:.875rem}.now>div:first-child{min-width:0!important;flex-basis:230px!important}button{font-size:1rem;min-height:44px}button.primary{font-weight:700}.q>p{font-weight:700}.q-options{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px}.opt{margin:0;display:flex;min-width:0}.opt button{font-size:1rem;line-height:1.4;margin:0;padding:10px 12px;min-height:50px;overflow-wrap:anywhere}.fb{font-size:.95rem}.q{padding:16px 0}.fb.show{line-height:1.5}#score{font-size:1rem}.foot a{text-underline-offset:3px}a:focus-visible,button:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid #c07700;outline-offset:3px}.retry-row{margin-top:12px}canvas{touch-action:pan-x pan-y}.scroll{max-width:100%}.stripe{display:none}
@media(max-width:640px){.brand .bin{padding:12px 15px}.site-links{width:100%;gap:5px}.site-links a{padding:5px 8px}.brand .logo{font-size:1.12rem}main{padding:17px 15px 30px}.card{padding:12px;border-radius:10px}.now{gap:8px}.now>div:first-child{flex-basis:100%!important}.now #go{width:100%}.row2{gap:7px}.row2 button{flex:1}.tag{font-size:.875rem}.q-options{gap:7px}.opt button{font-size:1rem;padding:8px 9px}#overlay .bar button{font-size:.875rem}#overlay .bar{gap:7px}.foot{line-height:1.6}}
@media(max-width:359px){.q-options{grid-template-columns:1fr}}
@media(prefers-color-scheme:dark){:root:not([data-theme="light"]){--bg:#18212b;--card:#222e3a;--btn:#253544;--text:#eef4fa;--muted:#bdcbd8;--border:#435363}:root[data-subject="biology"]:not([data-theme="light"]){--accent:#9ddebb;--accent-soft:#263f35}:root[data-subject="chemistry"]:not([data-theme="light"]){--accent:#ffc0c4;--accent-soft:#452c32}:root[data-subject="physics"]:not([data-theme="light"]){--accent:#abd5ff;--accent-soft:#253c52}:root:not([data-theme="light"]) button.primary{color:#18212b}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{scroll-behavior:auto!important;transition:none!important;animation:none!important}}