diff --git a/css/style.css b/css/style.css
new file mode 100644
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+++ b/css/style.css
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+/* style.css — global + responsive styles for the personal blog */
+:root {
+  --text: #1f2933;
+  --muted: #52606d;
+  --accent: #205081;
+  --border: #d9e2ec;
+  --bg: #ffffff;
+}
+
+* {
+  box-sizing: border-box;
+}
+
+body {
+  margin: 0;
+  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
+  line-height: 1.6;
+  color: var(--text);
+  background: var(--bg);
+}
+
+/* --- Site header / navigation (desktop + mobile) --- */
+.site-header {
+  border-bottom: 1px solid var(--border);
+}
+
+.site-nav {
+  max-width: 60rem;
+  margin: 0 auto;
+  padding: 0.75rem 1rem;
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  justify-content: space-between;
+  gap: 0.5rem 1rem;
+}
+
+.brand {
+  font-weight: 700;
+  font-size: 1.1rem;
+  text-decoration: none;
+  color: var(--text);
+}
+
+.nav-links {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 1rem;
+  margin: 0;
+  padding: 0;
+  list-style: none;
+}
+
+.nav-links a {
+  color: var(--muted);
+  text-decoration: none;
+}
+
+.nav-links a:hover,
+.nav-links a:focus {
+  color: var(--accent);
+}
+
+.nav-links a[aria-current="page"] {
+  color: var(--accent);
+  font-weight: 600;
+}
+
+/* --- Main content --- */
+main {
+  max-width: 60rem;
+  margin: 0 auto;
+  padding: 2rem 1rem;
+}
+
+/* --- Contact form --- */
+.contact-form {
+  max-width: 36rem;
+  display: grid;
+  gap: 1rem;
+}
+
+.form-field {
+  display: grid;
+  gap: 0.35rem;
+}
+
+.form-field label {
+  font-weight: 600;
+}
+
+.form-field input,
+.form-field textarea {
+  font: inherit;
+  padding: 0.5rem 0.65rem;
+  border: 1px solid var(--border);
+  border-radius: 6px;
+  width: 100%;
+}
+
+.form-field input:focus,
+.form-field textarea:focus {
+  outline: 2px solid var(--accent);
+  outline-offset: 1px;
+  border-color: var(--accent);
+}
+
+button[type="submit"] {
+  font: inherit;
+  font-weight: 600;
+  padding: 0.55rem 1.25rem;
+  border: none;
+  border-radius: 6px;
+  background: var(--accent);
+  color: #ffffff;
+  cursor: pointer;
+}
+
+button[type="submit"]:hover {
+  filter: brightness(1.1);
+}
+
+/* --- Footer --- */
+.site-footer {
+  border-top: 1px solid var(--border);
+  margin-top: 3rem;
+  padding: 1rem;
+  text-align: center;
+  color: var(--muted);
+  font-size: 0.9rem;
+}
+
+/* --- Mobile: nav links stack under the brand --- */
+@media (max-width: 30rem) {
+  .site-nav {
+    justify-content: flex-start;
+  }
+}