feat: restructure styles and components for improved design system

- Added typography and design system styles to globals.css.
- Removed deprecated home.css and landing.css files.
- Introduced DiscordSignInButton component for Discord authentication.
- Created Card and CardGrid components for structured content display.
- Implemented ContainerShowcase to demonstrate card usage and layout.
- Added DesignSystemTabs for navigation between design system sections.
- Established typography.css for consistent text styling across components.
- Added tests for typography styles to ensure compliance with design standards.

src/components/design-system/CalendarHeatmap.tsx

@@ -32,7 +32,7 @@ export function CalendarHeatmap({
   historyLabel?: string;
   legend?: ReactNode;
 }) {
-  const [months, setMonths] = useState<MonthView>(6);
+  const [months, setMonths] = useState<MonthView>(12);
   const latestDate =
     allDays.findLast((day) => day.state !== "future")?.date ??
     allDays.at(-1)?.date;

src/components/design-system/Card.tsx

@@ -0,0 +1,44 @@
+import { useId, type HTMLAttributes, type ReactNode } from "react";
+
+/** A flat content group. Actions remain explicit buttons or links inside it. */
+export function Card({
+  eyebrow,
+  heading,
+  children,
+  footer,
+  variant = "soft",
+  span = "standard",
+  className = "",
+  ...props
+}: HTMLAttributes<HTMLElement> & {
+  eyebrow?: string;
+  heading: ReactNode;
+  footer?: ReactNode;
+  variant?: "soft" | "outlined";
+  span?: "standard" | "wide" | "featured";
+}) {
+  const headingId = useId();
+  return (
+    <article
+      aria-labelledby={headingId}
+      className={`ds-card ds-card--${variant} ds-card--${span} ${className}`}
+      {...props}
+    >
+      <header className="ds-card-header">
+        {eyebrow && <p className="ds-eyebrow">{eyebrow}</p>}
+        <h3 id={headingId}>{heading}</h3>
+      </header>
+      {children && <div className="ds-card-body">{children}</div>}
+      {footer && <footer className="ds-card-footer">{footer}</footer>}
+    </article>
+  );
+}
+
+/** Equal cards by default; bento spans keep the same reading order on mobile. */
+export function CardGrid({
+  layout = "equal",
+  className = "",
+  ...props
+}: HTMLAttributes<HTMLDivElement> & { layout?: "equal" | "bento" }) {
+  return <div className={`ds-card-grid ds-card-grid--${layout} ${className}`} {...props} />;
+}

src/components/design-system/ContainerShowcase.tsx

@@ -0,0 +1,64 @@
+import { useState } from "react";
+import { Card, CardGrid } from "./Card";
+import { Button, Checkbox, Counter, SectionHeading } from "./primitives";
+
+export function ContainerShowcase() {
+  const [water, setWater] = useState(3);
+  const [read, setRead] = useState(false);
+
+  return (
+    <section className="ds-section ds-container-showcase" id="containers" aria-labelledby="containers-title">
+      <SectionHeading number="CONTAINERS & LAYOUT" id="containers-title" title={<>A little structure. <em>Room to breathe.</em></>}>
+        Group related content with a quiet surface. Keep open layouts for long lists and calendars.
+      </SectionHeading>
+
+      <div className="ds-spec-heading ds-spec-heading--spaced">
+        <h3>Two quiet surfaces</h3>
+        <span className="ds-code">Card · soft / outlined</span>
+      </div>
+      <CardGrid>
+        <Card eyebrow="SOFT SURFACE" heading="A gentle grouping.">
+          <p>A neutral fill gathers related content without adding another divider. Use it for summaries, guidance, and a small set of actions.</p>
+        </Card>
+        <Card variant="outlined" eyebrow="OUTLINED SURFACE" heading="A clear boundary.">
+          <p>A fine border defines a standalone group on white. Useful when a form or a focused task needs its own space.</p>
+        </Card>
+      </CardGrid>
+
+      <div className="ds-spec-heading ds-spec-heading--spaced">
+        <h3>A day, arranged simply</h3>
+        <span className="ds-code">CardGrid · bento</span>
+      </div>
+      <CardGrid layout="bento" aria-label="Interactive bento layout example">
+        <Card
+          span="featured"
+          eyebrow="TODAY / YOUR OWN PACE"
+          heading={<>Small things, <em>adding up.</em></>}
+          footer={<p className="ds-muted type-small">Interactive example · nothing is saved</p>}
+        >
+          <div className="ds-card-summary" role="status">
+            <p className="type-display">{Number(water === 8) + Number(read)}<span className="type-title ds-muted"> / 2</span></p>
+            <p>habits complete</p>
+          </div>
+          <p>Make room for a glass of water and a few pages. A little progress belongs here, too.</p>
+        </Card>
+        <Card eyebrow="DAILY / 8 GLASSES" heading="Drink water" variant="outlined">
+          <Counter label="bento glasses of water" value={water} target={8} onChange={setWater} />
+          <p className="type-small" role="status">{water === 8 ? "Complete for today" : `${8 - water} glasses to go`}</p>
+        </Card>
+        <Card eyebrow="A FEW PAGES" heading="Read a little" variant="outlined">
+          <Checkbox label="Reading done" checked={read} onChange={(event) => setRead(event.target.checked)} />
+          <p className="type-small">One page is a place to start.</p>
+        </Card>
+        <Card span="wide" eyebrow="A GENTLE REMINDER" heading="There’s no catching up.">
+          <p>Come back to today. Your next small step is enough.</p>
+        </Card>
+      </CardGrid>
+      <div className="ds-container-guidance">
+        <p className="ds-footnote">Equal grids suit peer items. Bento gives one summary more room; smaller cards hold short tasks. Both collapse in reading order on small screens. Use one surface per group, with spacing inside and no shadows.</p>
+        <Button variant="text" onClick={() => { setWater(3); setRead(false); }}>Reset card examples ↺</Button>
+      </div>
+      <pre className="ds-code ds-container-code"><code>{'<CardGrid layout="bento">\n  <Card heading="Today" span="featured">…</Card>\n  <Card heading="Water" variant="outlined">…</Card>\n  <Card heading="Reading" variant="outlined">…</Card>\n  <Card heading="A reminder" span="wide">…</Card>\n</CardGrid>'}</code></pre>
+    </section>
+  );
+}

src/components/design-system/DesignSystemTabs.tsx

@@ -0,0 +1,63 @@
+import { useRef, type ReactNode } from "react";
+import { useLocation, useNavigate } from "react-router";
+
+type SystemTab = { id: string; label: string; content: ReactNode };
+
+export function DesignSystemTabs({ tabs }: { tabs: SystemTab[] }) {
+  const { hash } = useLocation();
+  const navigate = useNavigate();
+  const buttons = useRef<Array<HTMLButtonElement | null>>([]);
+  const selected = tabs.findIndex((tab) => hash === `#${tab.id}`);
+  const active = selected < 0 ? 0 : selected;
+
+  function select(index: number) {
+    navigate({ hash: `#${tabs[index]!.id}` });
+  }
+
+  return (
+    <div className="ds-explorer">
+      <div className="ds-tab-bar" role="tablist" aria-label="Design system sections">
+        {tabs.map((tab, index) => (
+          <button
+            key={tab.id}
+            ref={(element) => { buttons.current[index] = element; }}
+            type="button"
+            role="tab"
+            id={`ds-tab-${tab.id}`}
+            aria-controls={`ds-panel-${tab.id}`}
+            aria-selected={active === index}
+            tabIndex={active === index ? 0 : -1}
+            onClick={() => select(index)}
+            onKeyDown={(event) => {
+              let next = index;
+              if (event.key === "ArrowRight") next = (index + 1) % tabs.length;
+              else if (event.key === "ArrowLeft") next = (index - 1 + tabs.length) % tabs.length;
+              else if (event.key === "Home") next = 0;
+              else if (event.key === "End") next = tabs.length - 1;
+              else return;
+              event.preventDefault();
+              select(next);
+              buttons.current[next]?.focus();
+            }}
+          >
+            {tab.label}
+          </button>
+        ))}
+      </div>
+      {/* Keep panels mounted so editors and examples retain their local state. */}
+      {tabs.map((tab, index) => (
+        <div
+          key={tab.id}
+          id={`ds-panel-${tab.id}`}
+          role="tabpanel"
+          aria-labelledby={`ds-tab-${tab.id}`}
+          tabIndex={0}
+          hidden={active !== index}
+          className="ds-tab-panel"
+        >
+          {tab.content}
+        </div>
+      ))}
+    </div>
+  );
+}

src/components/design-system/EditingWorkbench.tsx

@@ -361,7 +361,7 @@ export function EditingWorkbench({
     >
       <div className="ds-section-top">
         <div>
-          <span className="ds-eyebrow">02 / EDITING & HISTORY</span>
+          <span className="ds-eyebrow">EDITING & HISTORY</span>
           <h2 id="editing-title">
             Room for <em>real life.</em>
           </h2>

src/components/design-system/primitives.tsx

@@ -1,5 +1,6 @@
 import type {
   ButtonHTMLAttributes,
+  AnchorHTMLAttributes,
   InputHTMLAttributes,
   ReactNode,
 } from "react";
@@ -21,19 +22,31 @@ export function Button({
   );
 }
 
+export function ButtonLink({
+  variant = "text",
+  className = "",
+  ...props
+}: AnchorHTMLAttributes<HTMLAnchorElement> & {
+  variant?: "primary" | "secondary" | "text";
+}) {
+  return <a className={`ds-button ds-button--${variant} ${className}`} {...props} />;
+}
+
 export function SectionHeading({
   number,
   title,
   children,
+  id,
 }: {
   number: string;
-  title: string;
+  title: ReactNode;
   children?: ReactNode;
+  id?: string;
 }) {
   return (
     <header className="ds-section-heading">
       <span className="ds-eyebrow">{number}</span>
-      <h2>{title}</h2>
+      <h2 id={id}>{title}</h2>
       {children && <p>{children}</p>}
     </header>
   );