* {
    box-sizing: border-box;
}

:root,
:root[data-theme="light"] {
    --page-background: #dfe3e6;
    --main-text: #263238;

    --navbar-background: #20213f;
    --navbar-logo: #71d3d3;
    --navbar-link: #e5f4f4;
    --navbar-link-hover: #71d3d3;

    --section-background: #f7f8f9;
    --section-border: #34789a;
    --section-shadow: rgba(0, 0, 0, 0.1);

    --introduction-background: #34789a;
    --introduction-text: #ffffff;

    --heading-color: #245f78;

    --skill-background: #d8eeee;
    --skill-text: #205f5b;

    --project-background: #e8f3f3;
    --project-border: #71d3d3;

    --education-background: #e3ebef;

    --button-background: #34789a;
    --button-text: #ffffff;
    --button-hover: #359879;

    --input-background: #ffffff;
    --input-border: #71d3d3;
    --input-focus-shadow: rgba(52, 120, 154, 0.25);

    --error-color: #b42318;
    --error-shadow: rgba(180, 35, 24, 0.22);

    --success-color: #26734d;
    --status-color: #245f78;

    --footer-background: #20213f;
    --footer-text: #ffffff;
}

:root[data-theme="dark"] {
    --page-background: #111827;
    --main-text: #e5e7eb;

    --navbar-background: #0f172a;
    --navbar-logo: #71d3d3;
    --navbar-link: #e5f4f4;
    --navbar-link-hover: #71d3d3;

    --section-background: #1f2937;
    --section-border: #71d3d3;
    --section-shadow: rgba(0, 0, 0, 0.35);

    --introduction-background: #245f78;
    --introduction-text: #ffffff;

    --heading-color: #8fdede;

    --skill-background: #304855;
    --skill-text: #d8eeee;

    --project-background: #263746;
    --project-border: #71d3d3;

    --education-background: #263746;

    --button-background: #34789a;
    --button-text: #ffffff;
    --button-hover: #359879;

    --input-background: #111827;
    --input-border: #71d3d3;
    --input-focus-shadow: rgba(113, 211, 211, 0.25);

    --error-color: #ff8a80;
    --error-shadow: rgba(255, 138, 128, 0.22);

    --success-color: #78d9a7;
    --status-color: #8fdede;

    --footer-background: #0f172a;
    --footer-text: #ffffff;
}

body {
    margin: 0;
    background-color: var(--page-background);
    color: var(--main-text);
    font-family: Arial, sans-serif;

    transition:
        background-color 0.3s ease,
        color 0.3s ease;
}

button,
input,
textarea {
    font: inherit;
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 18px 40px;
    background-color: var(--navbar-background);
}

.navbar-logo a {
    color: var(--navbar-logo);
    font-size: 24px;
    font-weight: bold;
    text-decoration: none;
}

.nav-link {
    display: flex;
    gap: 25px;
    margin: 0;
    padding: 0;
    list-style-type: none;
}

.nav-link a {
    color: var(--navbar-link);
    text-decoration: none;

    transition: color 0.2s ease;
}

.nav-link a:hover {
    color: var(--navbar-link-hover);
}

main {
    max-width: 1100px;
    margin: 0 auto;
    padding: 40px 20px;
}

section {
    margin-bottom: 25px;
    padding: 30px;
    background-color: var(--section-background);
    border-left: 5px solid var(--section-border);
    border-radius: 10px;
    box-shadow: 0 4px 10px var(--section-shadow);
}

.hidden {
    display: none;
}

#introduction {
    background-color: var(--introduction-background);
    color: var(--introduction-text);
    border-left: none;
}

h1,
h2,
h3 {
    margin-top: 0;
}

h2 {
    color: var(--heading-color);
}

#introduction h1 {
    color: var(--introduction-text);
}

p {
    line-height: 1.6;
}

.skill-list {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin: 0;
    padding: 0;
    list-style-type: none;
}

.skill-list li {
    padding: 10px 16px;
    background-color: var(--skill-background);
    color: var(--skill-text);
    border-radius: 20px;
}

.projects-box {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
}

.each-project {
    flex: 1;
    min-width: 250px;
    padding: 20px;
    background-color: var(--project-background);
    border: 1px solid var(--project-border);
    border-radius: 10px;
}

.each-project a {
    display: inline-block;
    padding: 10px 16px;
    background-color: var(--button-background);
    color: var(--button-text);
    text-decoration: none;
    border-radius: 5px;

    transition:
        background-color 0.2s ease,
        transform 0.2s ease;
}

.each-project a:hover {
    background-color: var(--button-hover);
    transform: translateY(-2px);
}

.each-project a:active {
    transform: translateY(0);
}

.education-list {
    padding: 20px;
    background-color: var(--education-background);
    border-radius: 8px;
}

.contact {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    margin: 0;
    padding: 0;
    list-style-type: none;
}

.contact a {
    display: inline-block;
    padding: 10px 16px;
    background-color: var(--button-background);
    color: var(--button-text);
    text-decoration: none;
    border-radius: 5px;
}

.contact a:hover {
    background-color: var(--button-hover);
}

footer {
    padding: 20px;
    background-color: var(--footer-background);
    color: var(--footer-text);
    text-align: center;
}

footer p {
    margin: 0;
}

#dark-mode {
    padding: 10px 18px;
    background-color: transparent;
    color: var(--navbar-link);
    font-size: 14px;
    font-weight: 600;
    border: 1px solid var(--navbar-logo);
    border-radius: 999px;
    cursor: pointer;

    transition:
        background-color 0.2s ease,
        color 0.2s ease,
        transform 0.2s ease,
        box-shadow 0.2s ease;
}

#dark-mode:hover {
    background-color: var(--navbar-logo);
    color: var(--navbar-background);
    box-shadow: 0 5px 14px rgba(113, 211, 211, 0.25);
    transform: translateY(-2px);
}

#dark-mode:active {
    transform: translateY(0);
}

#dark-mode:focus-visible {
    outline: 3px solid rgba(113, 211, 211, 0.4);
    outline-offset: 3px;
}


#read-more-button {
    padding: 10px 18px;
    background-color: var(--button-background);
    color: var(--button-text);
    font-size: 14px;
    font-weight: 600;
    border: none;
    border-radius: 999px;
    cursor: pointer;

    transition:
        background-color 0.2s ease,
        transform 0.2s ease,
        box-shadow 0.2s ease;
}

#read-more-button:hover {
    background-color: var(--button-hover);
    box-shadow: 0 5px 14px rgba(52, 120, 154, 0.25);
    transform: translateY(-2px);
}

#read-more-button:active {
    transform: translateY(0);
}

#read-more-button:focus-visible {
    outline: 3px solid rgba(52, 120, 154, 0.35);
    outline-offset: 3px;
}

/* Project filters */

.project-filters {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 20px;
}

.project-filters button {
    padding: 9px 16px;
    background-color: transparent;
    color: var(--heading-color);
    font-weight: 600;
    border: 1px solid var(--project-border);
    border-radius: 999px;
    cursor: pointer;

    transition:
        background-color 0.2s ease,
        color 0.2s ease,
        transform 0.2s ease,
        box-shadow 0.2s ease;
}

.project-filters button:hover {
    background-color: var(--button-background);
    color: var(--button-text);
    transform: translateY(-2px);
}

.project-filters button.active {
    background-color: var(--button-background);
    color: var(--button-text);
    box-shadow: 0 4px 12px rgba(52, 120, 154, 0.25);
}

.project-filters button:active {
    transform: translateY(0);
}

.project-filters button:focus-visible {
    outline: 3px solid rgba(52, 120, 154, 0.35);
    outline-offset: 3px;
}

/* Contact form */

#contact-form {
    display: flex;
    flex-direction: column;
    gap: 18px;
    width: 100%;
    max-width: 650px;
    margin-top: 24px;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 7px;
}

.form-group label {
    color: var(--heading-color);
    font-weight: 600;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 12px 14px;
    background-color: var(--input-background);
    color: var(--main-text);
    font-size: 16px;
    line-height: 1.5;
    border: 1px solid var(--input-border);
    border-radius: 7px;

    transition:
        background-color 0.3s ease,
        color 0.3s ease,
        border-color 0.2s ease,
        box-shadow 0.2s ease;
}

.form-group input:hover,
.form-group textarea:hover {
    border-color: var(--button-background);
}

.form-group input:focus,
.form-group textarea:focus {
    border-color: var(--button-background);
    outline: none;
    box-shadow: 0 0 0 3px var(--input-focus-shadow);
}

.form-group textarea {
    min-height: 150px;
    resize: vertical;
}

.form-group input.input-error,
.form-group textarea.input-error,
.form-group input[aria-invalid="true"],
.form-group textarea[aria-invalid="true"] {
    border-color: var(--error-color);
}

.form-group input.input-error:focus,
.form-group textarea.input-error:focus,
.form-group input[aria-invalid="true"]:focus,
.form-group textarea[aria-invalid="true"]:focus {
    border-color: var(--error-color);
    box-shadow: 0 0 0 3px var(--error-shadow);
}

.form-error {
    min-height: 20px;
    margin: 0;
    color: var(--error-color);
    font-size: 14px;
    line-height: 1.4;
}

#contact-submit {
    align-self: flex-start;
    padding: 11px 20px;
    background-color: var(--button-background);
    color: var(--button-text);
    font-size: 14px;
    font-weight: 600;
    border: none;
    border-radius: 999px;
    cursor: pointer;

    transition:
        background-color 0.2s ease,
        transform 0.2s ease,
        box-shadow 0.2s ease,
        opacity 0.2s ease;
}

#contact-submit:hover:not(:disabled) {
    background-color: var(--button-hover);
    box-shadow: 0 5px 14px rgba(52, 120, 154, 0.25);
    transform: translateY(-2px);
}

#contact-submit:active:not(:disabled) {
    transform: translateY(0);
}

#contact-submit:focus-visible {
    outline: 3px solid rgba(52, 120, 154, 0.35);
    outline-offset: 3px;
}

#contact-submit:disabled {
    opacity: 0.65;
    cursor: wait;
    transform: none;
    box-shadow: none;
}

.form-status,
.form-success {
    min-height: 24px;
    margin: 0;
    font-size: 15px;
    font-weight: 600;
    line-height: 1.5;
}

.form-status {
    color: var(--status-color);
}

.form-success {
    color: var(--success-color);
}


@media (max-width: 700px) {
    .navbar {
        flex-direction: column;
        align-items: flex-start;
        gap: 18px;
        padding: 18px 20px;
    }

    .nav-link {
        flex-direction: column;
        gap: 12px;
        width: 100%;
    }

    main {
        padding: 25px 15px;
    }

    section {
        padding: 22px;
    }

    .projects-box {
        flex-direction: column;
    }

    #contact-form {
        max-width: 100%;
    }

    #contact-submit {
        width: 100%;
        text-align: center;
    }
}