:root, :root[data-theme="light"] {
 color-scheme:light;
 --background:#f9fbfd;--foreground:#172539;--card:#ffffff;--card-foreground:#172539;
 --popover:#ffffff;--popover-foreground:#172539;--primary:#172539;--primary-foreground:#ffffff;
 --secondary:#edf3f8;--secondary-foreground:#172539;--muted:#edf3f8;--muted-foreground:#526478;
 --accent:#e4f3fe;--accent-foreground:#172539;--border:#b7c5d2;--input:#a7b5c4;--ring:#0284c7;
 --ink:#172539;--blue:#60bdf7;--red:#ef7278;--orange:#d48508;
 --soft-blue:#e4f3fe;--correct-bg:#d5edff;--wrong-bg:#ffe2e2;--wrong-strong:#ffb5b5;
 --warning-bg:#fff1dc;--error-bg:#ffeded;--error-border:#c76168;--subtle-border:#dbe4ec;
 --hover-bg:#f0f8ff;--highlight-bg:#eaf6ff;--feature-bg:#60bdf7;--feature-ink:#172539;
 --correct-strong:#60bdf7;--option-border:#7b91a6;--progress:#359dde;--focus:#c97b00;
}
:root[data-theme="dark"] {
 color-scheme:dark;
 --background:#10151f;--foreground:#e7edf7;--card:#192231;--card-foreground:#e7edf7;
 --popover:#202d40;--popover-foreground:#e7edf7;--primary:#7dcbff;--primary-foreground:#101a28;
 --secondary:#263347;--secondary-foreground:#e7edf7;--muted:#243145;--muted-foreground:#acbdd2;
 --accent:#253f59;--accent-foreground:#e7edf7;--border:#42546c;--input:#526980;--ring:#7dcbff;
 --ink:#e7edf7;--blue:#60bdf7;--red:#f59aa0;--orange:#ffc161;
 --soft-blue:#203b52;--correct-bg:#224762;--wrong-bg:#512e38;--wrong-strong:#713440;
 --warning-bg:#453621;--error-bg:#432a34;--error-border:#bd727e;--subtle-border:#354357;
 --hover-bg:#223449;--highlight-bg:#213c52;--feature-bg:#213e59;--feature-ink:#eef7ff;
 --correct-strong:#246392;--option-border:#647e9c;--progress:#60bdf7;--focus:#ffc161;
}
.brand{font-family:Arial,Helvetica,sans-serif;display:inline-flex;align-items:center;gap:12px;color:var(--foreground);text-decoration:none;white-space:nowrap;font-weight:900;font-size:32px;letter-spacing:-1.7px;line-height:1}
.brand-logo{display:block;width:44px;height:44px;flex:none}
.theme-switch{display:inline-flex;gap:3px;padding:4px;background:var(--secondary);border:1px solid var(--border);border-radius:7px;flex:none}
.theme-switch button{display:flex;align-items:center;justify-content:center;gap:6px;font:600 14px Arial,Helvetica,sans-serif;border:0;background:transparent;color:var(--muted-foreground);border-radius:4px;padding:7px 10px;min-height:34px;cursor:pointer}
.theme-switch button svg{width:16px;height:16px;flex:none}
:root[data-theme="light"] .theme-switch [data-set-theme="light"],:root[data-theme="dark"] .theme-switch [data-set-theme="dark"]{background:var(--card);color:var(--foreground);box-shadow:0 1px 3px #0002}
.theme-switch button:hover{color:var(--foreground)}
.theme-switch button:focus-visible{outline:3px solid var(--focus);outline-offset:2px}
@media(max-width:700px){.brand{font-size:26px;gap:9px}.brand-logo{width:36px;height:36px}.theme-switch button{padding:7px 8px}.theme-switch button svg{display:none}}