* {
    box-sizing: border-box;
}

/* PF1 lessons retain the shared panels, code blocks, and mobile spacing. */
.pf1-lesson { overflow-wrap: anywhere; }
.pf1-lesson h1 { font-size: clamp(34px, 5vw, 56px); line-height: 1.1; }
.pf1-lesson h2 { font-size: clamp(26px, 3vw, 34px); line-height: 1.2; }
.pf1-lesson > section { max-width: 850px; }

body {
    margin: 0;
    font-family: Arial, sans-serif;
    background: #101010;
    color: #f3f3f3;
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;

    padding: 24px 6%;
    border-bottom: 1px solid #333;
}

.brand {
    display: flex;
    align-items: center;
    flex: 0 1 300px;
    max-width: 100%;
}

.brand img {
    display: block;
    width: 100%;
    height: auto;
}

.nav-links {
    display: flex;
    gap: 28px;
}

.nav-links a {
    color: #ddd;
    text-decoration: none;
}

.nav-links a:hover {
    color: white;
}

.hero {
    min-height: 70vh;

    display: flex;
    flex-direction: column;
    justify-content: center;

    padding: 80px 8%;
    max-width: 1100px;
}

.eyebrow {
    letter-spacing: 3px;
    font-size: 13px;
    color: #aaa;
}

.hero h1 {
    font-size: 72px;
    line-height: 1.05;

    margin: 15px 0;
}

.hero-text {
    max-width: 650px;

    font-size: 20px;
    line-height: 1.6;

    color: #ccc;
}

.hero-buttons {
    margin-top: 30px;
    display: flex;
    gap: 15px;
}

.btn {
    display: inline-block;

    padding: 14px 24px;

    text-decoration: none;
    font-weight: bold;

    border: 1px solid #ddd;
}

.btn-primary {
    background: #f2f2f2;
    color: #111;
}

.btn-secondary {
    color: #f2f2f2;
}

.intro {
    padding: 80px 8%;
    border-top: 1px solid #333;

    max-width: 1100px;
}

.intro h2 {
    font-size: 38px;
}

.intro p {
    max-width: 700px;

    font-size: 18px;
    line-height: 1.6;

    color: #ccc;

}

.page-section {
    padding: 100px 8%;
    max-width: 1100px;
}

.page-section h1 {
    font-size: 56px;
    margin: 0 0 20px;
}

.page-section p {
    font-size: 20px;
    line-height: 1.6;
    color: #ccc;
    max-width: 700px;
}

.navbar,
.nav-links,
.hero-buttons {
    flex-wrap: wrap;
}

.navbar {
    gap: 20px 32px;
}

.nav-links a {
    display: inline-flex;
    align-items: center;
    min-height: 44px;
}

a:focus-visible {
    outline: 2px solid #f2f2f2;
    outline-offset: 5px;
}

.btn {
    text-align: center;
    line-height: 1.4;
}

.btn:hover {
    background: #ddd;
    color: #111;
}

.flagship-course {
    margin-top: 48px;
    padding: 36px;
    background: #181818;
    border: 1px solid #3a3a3a;
    border-top: 3px solid #aaa;
}

.page-section .eyebrow {
    margin: 0 0 16px;
    font-size: 13px;
    color: #aaa;
}

.flagship-course h2 {
    margin: 0 0 20px;
    font-size: clamp(28px, 4vw, 40px);
    line-height: 1.15;
}

.course-details {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 32px;
    margin-top: 32px;
    padding-top: 24px;
    border-top: 1px solid #3a3a3a;
}

.course-details h3 {
    margin: 0 0 16px;
    font-size: 20px;
}

.course-details ul {
    margin: 0;
    padding-left: 20px;
    color: #ccc;
    line-height: 1.6;
}

.course-details li + li {
    margin-top: 10px;
}

.flagship-course .course-process {
    margin: 32px 0 0;
    padding-top: 24px;
    border-top: 1px solid #3a3a3a;
    font-size: 18px;
}

@media (max-width: 760px) {
    .navbar {
        align-items: flex-start;
        flex-direction: column;
        padding: 20px 6%;
        gap: 12px;
    }

    .nav-links {
        gap: 4px 20px;
    }

    .brand {
        flex: none;
        width: 240px;
    }

    .hero,
    .intro,
    .page-section {
        padding: 48px 6%;
    }

    .hero {
        min-height: auto;
    }

    .hero h1 {
        font-size: clamp(36px, 8vw, 56px);
    }

    .page-section h1 {
        font-size: 40px;
    }

    .intro h2 {
        font-size: 30px;
    }

    .hero-text,
    .page-section p {
        font-size: 18px;
    }

    .flagship-course {
        margin-top: 32px;
        padding: 24px;
    }

    .course-details {
        grid-template-columns: 1fr;
        gap: 24px;
    }
}

@media (max-width: 420px) {
    .hero-buttons {
        flex-direction: column;
        align-items: stretch;
    }

    .flagship-course {
        padding: 20px;
    }
}

/* Applied Physics / Computational Modeling */
.modeling-page h1 {
    font-size: clamp(34px, 5vw, 56px);
    line-height: 1.1;
}

.modeling-page h2 {
    margin: 0 0 20px;
    font-size: clamp(26px, 3.5vw, 36px);
    line-height: 1.2;
}

.model-panel,
.model-section {
    margin-top: 48px;
}

.model-panel {
    padding: clamp(20px, 4vw, 36px);
    background: #181818;
    border: 1px solid #3a3a3a;
    border-top: 3px solid #aaa;
}

.model-panel p,
.model-example p {
    font-size: 18px;
}

.model-panel p:last-child,
.model-example p:last-child {
    margin-bottom: 0;
}

.model-steps {
    padding-left: 24px;
    color: #ccc;
    font-size: 18px;
    line-height: 1.6;
}

.model-steps li + li {
    margin-top: 16px;
}

.model-steps strong {
    color: #f3f3f3;
}

.model-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 24px;
}

.model-example {
    padding-top: 24px;
    border-top: 1px solid #3a3a3a;
}

.model-example h3 {
    margin: 0;
    font-size: 22px;
}

.model-code {
    margin: 24px 0;
    padding: 20px;
    background: #101010;
    border: 1px solid #333;
    font-size: 16px;
    line-height: 1.7;
    white-space: pre-wrap;
    overflow-wrap: anywhere;
}

@media (max-width: 760px) {
    .model-grid {
        grid-template-columns: 1fr;
    }

    .model-panel,
    .model-section {
        margin-top: 32px;
    }

    .model-code {
        padding: 12px;
        font-size: 14px;
    }
}

/* About */
.about-page h1 {
    font-size: clamp(34px, 5vw, 56px);
    line-height: 1.1;
}

.about-page h2 {
    margin: 0 0 16px;
    font-size: clamp(26px, 3vw, 34px);
    line-height: 1.2;
}

.about-philosophy,
.about-principles,
.about-background {
    margin-top: 48px;
}

.about-philosophy {
    padding: clamp(20px, 4vw, 36px);
    background: #181818;
    border: 1px solid #3a3a3a;
    border-top: 3px solid #aaa;
}

.about-philosophy p:last-child,
.about-principles p:last-child {
    margin-bottom: 0;
}

.about-principles {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 32px;
}

.about-principles section,
.about-background {
    padding-top: 24px;
    border-top: 1px solid #3a3a3a;
}

.about-principles h2 {
    font-size: 24px;
}

.about-principles p {
    font-size: 18px;
}

@media (max-width: 760px) {
    .about-principles {
        grid-template-columns: 1fr;
        gap: 24px;
    }

    .about-philosophy,
    .about-principles,
    .about-background {
        margin-top: 32px;
    }
}

/* Contact */
.contact-page h1 {
    font-size: clamp(34px, 5vw, 56px);
    line-height: 1.1;
}

.contact-page h2 {
    margin: 0 0 20px;
    font-size: 28px;
    line-height: 1.2;
}

.contact-layout {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.5fr);
    gap: 32px;
    margin-top: 48px;
    align-items: start;
}

.contact-methods {
    padding-top: 24px;
    border-top: 1px solid #3a3a3a;
}

.contact-methods h3 {
    margin: 24px 0 8px;
    font-size: 20px;
}

.contact-methods p,
.contact-panel .contact-notice {
    font-size: 16px;
}

.contact-methods p {
    margin-top: 0;
}

.contact-panel {
    min-width: 0;
    padding: clamp(20px, 3vw, 32px);
    background: #181818;
    border: 1px solid #3a3a3a;
    border-top: 3px solid #aaa;
}

.contact-notice {
    margin: 0 0 28px;
    padding-left: 16px;
    border-left: 2px solid #777;
}

.contact-field {
    margin-bottom: 24px;
}

.contact-field label {
    display: block;
    margin-bottom: 8px;
    font-weight: bold;
}

.contact-field input,
.contact-field textarea {
    display: block;
    width: 100%;
    min-width: 0;
    padding: 12px;
    border: 1px solid #777;
    border-radius: 0;
    background: #101010;
    color: #f3f3f3;
    font: inherit;
    font-size: 16px;
    line-height: 1.5;
}

.contact-field textarea {
    resize: vertical;
    min-height: 144px;
}

.contact-field input:focus-visible,
.contact-field textarea:focus-visible {
    outline: 2px solid #f2f2f2;
    outline-offset: 3px;
}

.contact-submit {
    width: 100%;
    font: inherit;
    font-weight: bold;
}

.contact-submit:disabled,
.contact-submit:disabled:hover {
    background: #333;
    color: #bbb;
    border-color: #666;
    cursor: not-allowed;
}

@media (max-width: 760px) {
    .contact-layout {
        grid-template-columns: 1fr;
        margin-top: 32px;
    }
}

/* Home */
.home-page .hero {
    min-height: auto;
}

.home-audience {
    max-width: 650px;
    margin: 0;
    color: #aaa;
    font-size: 18px;
    line-height: 1.6;
}

.home-page .intro h2 {
    margin: 0 0 24px;
    line-height: 1.2;
}

.home-page .intro .eyebrow {
    margin: 0 0 16px;
    font-size: 13px;
    line-height: 1.5;
    color: #aaa;
}

.home-path-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 24px;
    margin-top: 32px;
}

.home-path {
    display: flex;
    flex-direction: column;
    min-width: 0;
    padding: 28px;
    background: #181818;
    border: 1px solid #3a3a3a;
    border-top: 3px solid #aaa;
}

.home-path h3,
.home-craft h3 {
    margin: 0;
    font-size: 26px;
    line-height: 1.25;
}

.home-path .btn {
    margin-top: auto;
}

.home-path p:not(.eyebrow) {
    margin-bottom: 28px;
}

.home-craft {
    margin-top: 32px;
    padding-top: 24px;
    border-top: 1px solid #333;
}

@media (max-width: 760px) {
    .home-path-grid {
        grid-template-columns: 1fr;
    }

    .home-path {
        padding: 20px;
    }
}

/* Field Notes */
.field-notes-page {
    overflow-wrap: anywhere;
}

.field-notes-page h1 {
    font-size: clamp(34px, 5vw, 56px);
    line-height: 1.1;
}

.field-notes-page a:not(.btn) {
    color: inherit;
    text-underline-offset: 4px;
}

.field-note-list,
.field-note-body {
    max-width: 700px;
    margin: 40px 0;
}

.field-note-card,
.field-note-body {
    padding-top: 24px;
    border-top: 1px solid #333;
}

.field-note-card + .field-note-card {
    margin-top: 32px;
}

.field-note-card h2 {
    margin: 12px 0;
    font-size: clamp(24px, 3vw, 32px);
    line-height: 1.2;
}

.field-notes-page .field-note-meta {
    font-size: 15px;
    color: #aaa;
}

.field-note-pagination {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 20px;
}

.field-note-body h2 {
    margin: 36px 0 16px;
    font-size: clamp(26px, 3vw, 34px);
    line-height: 1.2;
}

.field-note-body h3 {
    margin: 28px 0 12px;
    font-size: 24px;
}

.field-note-body ul,
.field-note-body ol {
    padding-left: 28px;
    color: #ccc;
    font-size: 18px;
    line-height: 1.6;
}

.field-note-body li + li {
    margin-top: 8px;
}

.field-note-body blockquote {
    margin: 24px 0;
    padding: 1px 20px;
    border-left: 3px solid #777;
    background: #181818;
}

.field-note-body code {
    padding: 2px 5px;
    background: #181818;
    font-family: Consolas, monospace;
    font-size: 0.9em;
}

.field-note-body pre {
    max-width: 100%;
    overflow-x: auto;
    padding: 20px;
    background: #181818;
    border: 1px solid #333;
    font-size: 16px;
    line-height: 1.7;
    white-space: pre;
    overflow-wrap: normal;
}

.field-note-body pre code {
    padding: 0;
    font-size: inherit;
}
.site-logo img {
    height: 42px;
    width: auto;
    display: block;
}

.site-logo {
    display: flex;
    align-items: center;
}

/* Shared desktop content width; retain readable paragraph limits. */
@media (min-width: 761px) {
    .hero,
    .intro,
    .page-section {
        max-width: 1440px;
        padding-left: 6%;
        padding-right: 6%;
    }
}